- Green synthesis of metal oxide nanoparticles and their catalytic activity for the reduction of aldehydes
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In the present work, a green synthesis of Metal Oxide nanoparticles was demonstrated using the freshly prepared aqueous extract of the immature fruit of Cocos nucifera and the MO nanoparticles were characterized by the analytical techniques such as UV–vis, FT-IR, XRD, SEM, TEM and EDAX. Characterization techniques confirmed that the biomolecules involved in the formation of nanoparticles and also they stabilized the nanoparticles. The synthesized MO nanoparticles were used as catalysts for the reduction of aromatic aldehydes. The reduction was done at mild reaction conditions using ammonium formate as a green hydrogen donor and the corresponding alcohols were obtained in 2–24 h with excellent yields. The reduction reaction was optimized using various solvents, loading of catalyst and at different temperatures.
- Muthuvinothini,Stella
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Read Online
- Hydrogenation of Esters by Manganese Catalysts
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The hydrogenation of esters catalyzed by a manganese complex of phosphine-aminopyridine ligand was developed. Using this protocol, a variety of (hetero)aromatic and aliphatic carboxylates including biomass-derived esters and lactones were hydrogenated to primary alcohols with 63–98% yields. The manganese catalyst was found to be active for the hydrogenation of methyl benzoate, providing benzyl alcohol with turnover numbers (TON) as high as 45,000. Investigation of catalyst intermediates indicated that the amido manganese complex was the active catalyst species for the reaction. (Figure presented.).
- Li, Fu,Li, Xiao-Gen,Xiao, Li-Jun,Xie, Jian-Hua,Xu, Yue,Zhou, Qi-Lin
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- Unifying Scheme for the Biosynthesis of Acyl-Branched Sugars: Extended Substrate Scope of Thiamine-Dependent Enzymes
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Thiamine diphosphate (ThDP) dependent enzymes are useful catalysts for asymmetric C?C bond formation through benzoin-type condensation reactions that result in α-hydroxy ketones. A wide range of aldehydes and ketones can be used as acceptor substrates; however, the donor substrate range is mostly limited to achiral α-keto acids and simple aldehydes. By using a unifying retro-biosynthetic approach towards acyl-branched sugars, we identified a subclass of (myco)bacterial ThDP-dependent enzymes with a greatly extended donor substrate range, namely functionalized chiral α-keto acids with a chain length from C4 to C8. Highly enantioenriched acyloin products were obtained in good to high yields and several reactions were performed on a preparative scale. The newly introduced functionalized α-keto acids, accessible by known aldolase-catalyzed transformations, substantially broaden the donor substrate range of ThDP-dependent enzymes, thus enabling a more general use of these already valuable catalysts.
- Clapés, Pere,Hernández, Karel,Krug, Leonhard,Müller, Michael,R?hr, Caroline,Steitz, Jan-Patrick,Walter, Lydia
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supporting information
(2022/02/05)
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- Sodium Aminodiboranate, a New Reagent for Chemoselective Reduction of Aldehydes and Ketones to Alcohols
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Sodium aminodiboranate (NaNH 2(BH 3) 2, NaADBH) is a new member of the old borane family, which exhibits superior performance in chemoselective reduction. Experimental results show that NaADBH can rapidly reduce aldehydes and ketones to the corresponding alcohols in high efficiency and selectivity under mild conditions. There are little steric and electronic effects on this reduction.
- Wang, Jin,Guo, Yu,Li, Shouhu,Chen, Xuenian
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supporting information
p. 1104 - 1108
(2021/05/25)
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- Uranyl(VI) Triflate as Catalyst for the Meerwein-Ponndorf-Verley Reaction
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Catalytic transformation of oxygenated compounds is challenging in f-element chemistry due to the high oxophilicity of the f-block metals. We report here the first Meerwein-Ponndorf-Verley (MPV) reduction of carbonyl substrates with uranium-based catalysts, in particular from a series of uranyl(VI) compounds where [UO2(OTf)2] (1) displays the greatest efficiency (OTf = trifluoromethanesulfonate). [UO2(OTf)2] reduces a series of aromatic and aliphatic aldehydes and ketones into their corresponding alcohols with moderate to excellent yields, using iPrOH as a solvent and a reductant. The reaction proceeds under mild conditions (80 °C) with an optimized catalytic charge of 2.3 mol % and KOiPr as a cocatalyst. The reduction of aldehydes (1-10 h) is faster than that of ketones (>15 h). NMR investigations clearly evidence the formation of hemiacetal intermediates with aldehydes, while they are not formed with ketones.
- Kobylarski, Marie,Monsigny, Louis,Thuéry, Pierre,Berthet, Jean-Claude,Cantat, Thibault
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supporting information
p. 16140 - 16148
(2021/11/01)
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- Hydrosilylation of Aldehydes and Ketones Catalyzed by a 2-Iminopyrrolyl Alkyl-Manganese(II) Complex
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A well-defined and very active single-component manganese(II) catalyst system for the hydrosilylation of aldehydes and ketones is presented. First, the reaction of 5-(2,4,6-iPr3C6H2)-2-[N-(2,6-iPr2C6H3)formimino]pyrrolyl potassium (KL) and [MnCl2(Py)2] afforded the binuclear 2-iminopyrrolyl manganese(II) pyridine chloride complex [Mn2{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}2(Py)2(μ-Cl)2] 1. Subsequently, the alkylation reaction of complex 1 with LiCH2SiMe3 afforded the respective (trimethylsilyl)methyl-Mn(II) complex [Mn{κ2N,N′-5-(2,4,6-iPr3C6H2)-NC4H2-2-C(H)═N(2,6-iPr2C6H3)}(Py)CH2SiMe3] 2 in a good yield. Complexes 1 and 2 were characterized by elemental analysis, 1H NMR spectroscopy, Evans' method, FTIR spectroscopy, and single-crystal X-ray diffraction. While the crystal structure of complex 1 has been identified as a binuclear entity, in which the Mn(II) centers present pentacoordinate coordination spheres, that of complex 2 corresponds to a monomer with a distorted tetrahedral coordination geometry. Complex 2 proved to be a very active precatalyst for the atom-economic hydrosilylation of several aldehydes and ketones under very mild conditions, with a maximum turnover frequency of 95 min-1, via a silyl-Mn(II) mechanistic route, as asserted by a combination of experimental and theoretical efforts, the respective silanes were cleanly converted to the respective alcoholic products in high yields.
- Cruz, Tiago F. C.,Gomes, Pedro T.,Veiros, Luís F.
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- CeO2-nanocubes as efficient and selective catalysts for the hydroboration of carbonyl groups
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The CeO2-nanoparticle catalysed hydroboration of carbonyl compounds with HBpin (pin = OCMe2CMe2O) is reported to afford the corresponding borate esters in excellent yield. A series of aromatic and aliphatic aldehydes and ketones having synthetically important functional groups were well-Tolerated under mild reaction conditions. Further, chemoselective hydroboration of aldehydes over other reducible functional groups such as ketone, nitrile, hydroxide, alkene, alkyne, amide, ester, nitro, and halides was achieved. Importantly the catalyst can be recycled up to ten runs with slight loss in activity. This journal is
- Bhawar, Ramesh,Bose, Shubhankar Kumar,Patil, Kiran S.
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supporting information
p. 15028 - 15034
(2021/09/04)
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- Experimental and density functional theory studies on hydroxymethylation of phenylboronic acids with paraformaldehyde over a Rh-PPh3 catalyst
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The synthesis of benzyl alcohols (BAs) is highly vital for their wide applications in organic synthesis and pharmaceuticals. Herein, BAs was efficiently synthesized via hydroxymethylation of phenylboronic acids (PBAs) and paraformaldehyde over a simple Rh-PPh3 catalyst combined with an inorganic base (NaOH). A variety of BAs with the groups of CH3?, CH3O?, Cl?, Br?, and so on were obtained with moderate to good yields, indicating that the protocol had a good universality. Density functional theory (DFT) calculations proposed the Hayashi-type arylation mechanism involved the arylation step of PBA and Rh(OH)(PPh3)2 catalyst to form Rh(I)-bound aryl intermediates and the hydrolysis step of Rh(I)-bound aryl intermediates and HCHO to generate BA product (the rate-determining step). The present route provides a valuable and direct method for the synthesis of BAs and expands the application range of paraformaldehyde.
- Wang, Kuan,Lan, Jie,He, Zhen-Hong,Cao, Zhe,Wang, Weitao,Yang, Yang,Liu, Zhao-Tie
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- BiCl3-Facilitated removal of methoxymethyl-ether/ester derivatives and DFT study of -O-C-O- bond cleavage
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A simple method for the cleavage of methoxymethyl (MOM)-ether and ester derivatives using bismuth trichloride (BiCl3) is described. The alkyl, alkenyl, alkynyl, benzyl and anthracene MOM ether derivatives, as well as MOM esters of both aliphatic and aromatic carboxylic acids, were deprotected in good yields. To better understand the molecular roles of BiCl3and water for MOM cleavage, two possible binding pathways were investigated using the density functional theory (DFT) method. The theoretical results indicate the differential initial binding site preferences of phenolic and alcoholic MOM substrates to the Bi atom and suggest that water plays a key role in facilitating the cleavage of the MOM group.
- Pacherille, Angela,Tuga, Beza,Hallooman, Dhanashree,Dos Reis, Isaac,Vermette, Mélodie,Issack, Bilkiss B.,Rhyman, Lydia,Ramasami, Ponnadurai,Sunasee, Rajesh
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supporting information
p. 7109 - 7116
(2021/05/03)
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- Disproportionation of aliphatic and aromatic aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions
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Disproportionation of aldehydes through Cannizzaro, Tishchenko, and Meerwein–Ponndorf–Verley reactions often requires the application of high temperatures, equimolar or excess quantities of strong bases, and is mostly limited to the aldehydes with no CH2 or CH3 adjacent to the carbonyl group. Herein, we developed an efficient, mild, and multifunctional catalytic system consisting AlCl3/Et3N in CH2Cl2, that can selectively convert a wide range of not only aliphatic, but also aromatic aldehydes to the corresponding alcohols, acids, and dimerized esters at room temperature, and in high yields, without formation of the side products that are generally observed. We have also shown that higher AlCl3 content favors the reaction towards Cannizzaro reaction, yet lower content favors Tishchenko reaction. Moreover, the presence of hydride donor alcohols in the reaction mixture completely directs the reaction towards the Meerwein–Ponndorf–Verley reaction. Graphic abstract: [Figure not available: see fulltext.].
- Sharifi, Sina,Sharifi, Hannah,Koza, Darrell,Aminkhani, Ali
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p. 803 - 808
(2021/07/20)
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- Application of bis(phosphinite) pincer nickel complexes to the catalytic hydrosilylation of aldehydes
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A series of bis(phosphinite) (POCOP) pincer ligated nickel complexes, [2,6-(tBu2PO)2C6H3]NiX (X = SH, 1; SCH2Ph, 2; SPh, 3; NCS, 4; N3, 5), were used to catalyse the hydrosilylation of aldehydes. It was found that both complexes 1 and 2 are active in catalysing the hydrosilylation of aldehydes with phenylsilane and complex 1 is comparatively more active. The expected alcohols were isolated in good to excellent yields after basic hydrolysis of the resultant hydrosilylation products. However, no reaction was observed when complex 3 or 4 or 5 was used as the catalyst. The results are consistent with complexes 1 and 2 serving as catalyst precursors, which generate the corresponding nickel hydride complex [2,6-(tBu2PO)2C6H3]NiH in situ, and the nickel hydride complex is the active species that catalyses this hydrosilylation process. The in situ generation of the nickel hydride species was supported by both experimental results and DFT calculation.
- Chang, Jiarui,Fang, Fei,Tu, Chenhao,Zhang, Jie,Ma, Nana,Chen, Xuenian
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- Method for synthesizing primary alcohol in water phase
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The invention discloses a method for synthesizing primary alcohol in a water phase. The method comprises the following steps: taking aldehyde as a raw material, selecting water as a solvent, and carrying out catalytic hydrogenation reaction on the aldehyde in the presence of a water-soluble catalyst to obtain the primary alcohol, wherein the catalyst is a metal iridium complex [Cp*Ir(2,2'-bpyO)(OH)][Na]. Water is used as the solvent, so that the use of an organic solvent is avoided, and the method is more environment-friendly; the reaction is carried out at relatively low temperature and normal pressure, and the reaction conditions are mild; alkali is not needed in the reaction, so that generation of byproducts is avoided; and the conversion rate of the raw materials is high, and the yield of the obtained product is high. The method not only has academic research value, but also has a certain industrialization prospect.
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Paragraph 0033-0034
(2021/07/14)
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- Ambient-pressure highly active hydrogenation of ketones and aldehydes catalyzed by a metal-ligand bifunctional iridium catalyst under base-free conditions in water
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A green, efficient, and high active catalytic system for the hydrogenation of ketones and aldehydes to produce corresponding alcohols under atmospheric-pressure H2 gas and ambient temperature conditions was developed by a water-soluble metal–ligand bifunctional catalyst [Cp*Ir(2,2′-bpyO)(OH)][Na] in water without addition of a base. The catalyst exhibited high activity for the hydrogenation of ketones and aldehydes. Furthermore, it was worth noting that many readily reducible or labile functional groups in the same molecule, such as cyan, nitro, and ester groups, remained unchanged. Interestingly, the unsaturated aldehydes can be also selectively hydrogenated to give corresponding unsaturated alcohols with remaining C=C bond in good yields. In addition, this reaction could be extended to gram levels and has a large potential of wide application in future industrial.
- Wang, Rongzhou,Yue, Yuancheng,Qi, Jipeng,Liu, Shiyuan,Song, Ao,Zhuo, Shuping,Xing, Ling-Bao
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- KB3H8: An environment-friendly reagent for the selective reduction of aldehydes and ketones to alcohols
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Selective reduction of aldehydes and ketones to their corresponding alcohols with KB3H8, an air- and moisture-stable, nontoxic, and easy-to-handle reagent, in water and THF has been explored under an air atmosphere for the first time. Control experiments illustrated the good selectivity of KB3H8 over NaBH4 for the reduction of 4-acetylbenzaldehyde and aromatic keto esters. This journal is
- Li, Xinying,Mi, Tongge,Guo, Wenjing,Ruan, Zhongrui,Guo, Yu,Ma, Yan-Na,Chen, Xuenian
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supporting information
p. 12776 - 12779
(2021/12/10)
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- Hydroboration Reaction and Mechanism of Carboxylic Acids using NaNH2(BH3)2, a Hydroboration Reagent with Reducing Capability between NaBH4and LiAlH4
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Hydroboration reactions of carboxylic acids using sodium aminodiboranate (NaNH2[BH3]2, NaADBH) to form primary alcohols were systematically investigated, and the reduction mechanism was elucidated experimentally and computationally. The transfer of hydride ions from B atoms to C atoms, the key step in the mechanism, was theoretically illustrated and supported by experimental results. The intermediates of NH2B2H5, PhCH= CHCOOBH2NH2BH3-, PhCH= CHCH2OBO, and the byproducts of BH4-, NH2BH2, and NH2BH3- were identified and characterized by 11B and 1H NMR. The reducing capacity of NaADBH was found between that of NaBH4 and LiAlH4. We have thus found that NaADBH is a promising reducing agent for hydroboration because of its stability and easy handling. These reactions exhibit excellent yields and good selectivity, therefore providing alternative synthetic approaches for the conversion of carboxylic acids to primary alcohols with a wide range of functional group tolerance.
- Wang, Jin,Ju, Ming-Yue,Wang, Xinghua,Ma, Yan-Na,Wei, Donghui,Chen, Xuenian
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p. 5305 - 5316
(2021/04/12)
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- Homoleptic cobalt(II) phenoxyimine complexes for hydrosilylation of aldehydes and ketones without base activation of cobalt(II)
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Air-stable, easy to prepare, homoleptic cobalt(II) complexes bearing pendant-modified phenoxyimine ligands were synthesized and determined. The complexes exhibited high catalytic performance for reducing aldehydes and ketones via catalytic hydrosilylation, where a hydrosilane and a catalytic amount of the cobalt(II) complex were added under base-free conditions. The reaction proceeded even in the presence of excess water, and excellent functional-group tolerance was observed. Subsequent hydrolysis gave the alcohol in high yields. Moreover, H2O had a critical role in activation of the Co(II) catalyst with hydrosilane. Several additional results also indicated that the cobalt(II) center acts as an active catalyst in the hydrosilylation of aldehydes and ketones.
- Hori, Momoko,Ishikawa, Ryuta,Koga, Yuji,Matsubara, Kouki,Mitsuyama, Tomoaki,Shin, Sayaka
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p. 1379 - 1387
(2021/05/29)
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- Efficient Solvent-Free Hydrosilylation of Aldehydes and Ketones Catalyzed by Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH
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An efficient solvent-free catalyst system for hydrosilylation of aldehydes and ketones was developed based on iron pre-catalyst Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH. The reactions were tolerant of many functional groups and the corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the reaction products. The reaction is likely catalyzed by an in situ generated pincer ligated iron hydride complex. Graphic Abstract: [Figure not available: see fulltext.]
- Fang, Fei,Chang, Jiarui,Zhang, Jie,Chen, Xuenian
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p. 3509 - 3515
(2021/03/16)
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- Ruthenium-catalyzed ester reductions applied to pharmaceutical intermediates
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Ruthenium pincer complexes were synthesized and used for catalytic ester reductions under mild conditions (~5 bar of hydrogen). An experimental design approach was used to optimize the conditions for yield, purity, and robustness. Evidence for the catalytically active ruthenium dihydride species is presented. Observed intermediates and side products, as well as time-course data, were used to build mechanistic insight. The optimized procedure was further demonstrated through scaled-up reductions of two pharmaceutically relevant esters, both in batch and continuous flow.
- Shaalan, Youssef,Boulton, Lee,Jamieson, Craig
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supporting information
p. 2745 - 2751
(2020/11/30)
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- Synthesis and structure activity relationships of cyanopyridone based anti-tuberculosis agents
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Mycobacterium tuberculosis, the causative agent of tuberculosis, relies on thymidylate kinase (MtbTMPK) for the synthesis of thymidine triphosphates and thus also DNA synthesis. Therefore, this enzyme constitutes a potential Achilles heel of the pathogen. Based on a previously reported MtbTMPK 6-aryl-substituted pyridone inhibitor and guided by two co-crystal structures of MtbTMPK with pyridone- and thymine-based inhibitors, we report the synthesis of a series of aryl-shifted cyanopyridone analogues. These compounds generally lacked significant MtbTMPK inhibitory potency, but some analogues did exhibit promising antitubercular activity. Analogue 11i demonstrated a 10-fold increased antitubercular activity (MIC H37Rv, 1.2 μM) compared to literature compound 5. Many analogues with whole-cell antimycobacterial activity were devoid of significant cytotoxicity.
- Boshoff, Helena I. M.,Caljon, Guy,Forbes, He Eun,Hulpia, Fabian,Jian, Yanlin,Munier-Lehmann, Héle?ne,Risseeuw, Martijn D. P.,Van Calenbergh, Serge
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- Cerium(IV) Carboxylate Photocatalyst for Catalytic Radical Formation from Carboxylic Acids: Decarboxylative Oxygenation of Aliphatic Carboxylic Acids and Lactonization of Aromatic Carboxylic Acids
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We found that in situ generated cerium(IV) carboxylate generated by mixing the precursor Ce(OtBu)4 with the corresponding carboxylic acids served as efficient photocatalysts for the direct formation of carboxyl radicals from carboxylic acids under blue light-emitting diodes (blue LEDs) irradiation and air, resulting in catalytic decarboxylative oxygenation of aliphatic carboxylic acids to give C-O bond-forming products such as aldehydes and ketones. Control experiments revealed that hexanuclear Ce(IV) carboxylate clusters initially formed in the reaction mixture and the ligand-to-metal charge transfer nature of the Ce(IV) carboxylate clusters was responsible for the high catalytic performance to transform the carboxylate ligands to the carboxyl radical. In addition, the Ce(IV) carboxylate cluster catalyzed direct lactonization of 2-isopropylbenzoic acid to produce the corresponding peroxy lactone and ?3-lactone via intramolecular 1,5-hydrogen atom transfer (1,5-HAT).
- Hirosawa, Keishi,Mashima, Kazushi,Satoh, Tetsuya,Shinohara, Koichi,Shirase, Satoru,Tamaki, Sota,Tsurugi, Hayato
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supporting information
(2020/03/25)
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- Selective hydrogenation of primary amides and cyclic di-peptides under Ru-catalysis
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A ruthenium(II)-catalyzed selective hydrogenation of challenging primary amides and cyclic di-peptides to their corresponding primary alcohols and amino alcohols, respectively, is reported. The hydrogenation reaction operates under mild and eco-benign conditions and can be scaled-up.
- Subaramanian, Murugan,Sivakumar, Ganesan,Babu, Jessin K.,Balaraman, Ekambaram
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supporting information
p. 12411 - 12414
(2020/10/30)
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- Potassium Fluoride-Catalyzed Hydroboration of Aldehydes and Ketones: Facile Reduction to Primary and Secondary Alcohols
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A catalytic hydroboration of various ketones and aldehydes can be achieved in the presence of inexpensive and commercially available inorganic salts containing fluoride anion. As a result, the reduction of carbonyl moieties to the corresponding primary and secondary alcohols can be achieved at room temperature under mild conditions.
- Kuciński, Krzysztof,Hreczycho, Grzegorz
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supporting information
p. 552 - 555
(2020/02/04)
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- Palladium-Catalyzed Selective Reduction of Carbonyl Compounds
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Two new examples of structurally characterized β-diketiminate analogues i.e., conjugated bis-guanidinate (CBG) supported palladium(II) complexes, [LPdX]2; [L= {(ArHN)(ArN)–C=N–C=(NAr)(NHAr)}; Ar = 2,6-Et2-C6H3], X = Cl (1), Br (2) have been reported. The synthesis of complexes 1–2 was achieved by two methods. Method A involves deprotonation of LH by nBuLi followed by the treatment of LLi (insitu formed) with PdCl2 in THF, which afforded compound 1 in good yield (75 %). In Method B, the reaction between free LH and PdX2 (X = Cl or Br) in THF allowed the formation of complexes 1 (Yield 73 %) and 2 (Yield 52 %), respectively. Moreover, these complexes were characterized thoroughly by several spectroscopic techniques (1H, 13C NMR, UV/Vis, FT-IR, and HRMS), including single-crystal X-ray structural and elemental analyses. In addition, we tested the catalytic activity of these complexes 1–2 for the hydroboration of carbonyl compounds with pinacolborane (HBpin). We observed that compound 1 exhibits superior catalytic activity when compared to 2. Compound 1 efficiently catalyzes various aldehydes and ketones under solvent-free conditions. Furthermore, both inter- and intramolecular chemoselectivity hydroboration of aldehydes over other functionalities have been established.
- Sarkar, Nabin,Mahato, Mamata,Nembenna, Sharanappa
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p. 2295 - 2301
(2020/05/18)
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- Lithium Bromide/HBpin: A Mild and Effective Catalytic System for the Selective Hydroboration of Aldehydes and Ketones
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The catalytic hydroboration of aldehydes and ketones with HBpin was examined using simple and commercially available metal salts (Li, Na, and K). Among the tested salts, LiBr (0.5–1.0 mol%) was found to be an efficient catalyst for the hydroboration of various aldehydes and ketones at room temperature. Further, the chemoselective hydroboration of aldehydes over ketones was also demonstrated.
- An, Duk Keun,Choi, Hyeon Seong,Hwang, Hyonseok,Kim, Hanbi,Lee, Ji Hye,Shin, Hye Lim,Yi, Jaeeun
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p. 1009 - 1018
(2020/10/12)
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- Application of deprotonated phenyl bridged beta-ketimine lithium compound in preparation of alcohol from ester
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The invention discloses application of a deprotonated phenyl bridged beta-ketimine lithium compound in the preparation of alcohol from ester. Ester and borane are used as raw materials, a hydroboration reaction is carried out; and after the hydroboration reaction is finished, silica gel and methanol are added, and a hydrolysis reaction is carried out to obtain alcohol. According to the applicationof the invention, the deprotonated phenyl bridged beta-ketimine lithium compound disclosed for the first time is used for catalyzing the hydroboration reaction of the ester and pinacol borane, so that a kind of efficient catalytic borohydride method is developed; the compound is simple in structure, easy to synthesize and capable of catalyzing the hydroboration reaction of the ester and borane with high activity. Compared with an existing catalytic system, the compound is easy to store, and particularly, exerts far smaller harm in use than an existing organic lithium reagent.
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Paragraph 0019-0020
(2020/10/21)
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- Combined KOH/BEt3Catalyst for Selective Deaminative Hydroboration of Aromatic Carboxamides for Construction of Luminophores
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The selective catalytic C-N bond cleavage of amides into value-added amine products is a desirable but challenging transformation. Molecules containing iminodibenzyl motifs are prevalent in pharmaceutical molecules and functional materials. Here we established a combined KOH/BEt3 catalyst for deaminative hydroboration of acyl-iminodibenzyl derivatives, including nonheterocyclic carboxamides, to the corresponding amines. This novel transition-metal-free methodology was also applied to the construction of Clomipramine and luminophores.
- Li, Jinshan,Wang, Jiali,Yang, Jianguo,Yao, Wubing,Zhong, Aiguo
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supporting information
p. 8086 - 8090
(2020/11/03)
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- Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
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The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
- Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
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p. 6291 - 6300
(2020/11/30)
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- Bimetallic Bis-NHC-Ir(III) Complex Bearing 2-Arylbenzo[d]oxazolyl Ligand: Synthesis, Catalysis, and Bimetallic Effects
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Herein, an unprecedented bimetallic bis-NHC Cp*Ir complex 1 bearing 2-arylbenzo[d]oxazolyl and NHC ligands is reported. A significant increase in activity was observed for N-methylation of amines and reduction of aldehydes with MeOH catalyzed by 1 compared to the monometallic analogues (2-11). Under the optimal conditions, it showed to be highly effective in N-methylation of nitroarenes with MeOH as both C1 and H2 source. Substrates, including aromatic amines, ketones, and nitro compounds with various functional groups, can be well-tolerated. Mechanistic studies and DFT calculation highlight the significance of bimetallic centers cooperativity.
- Huang, Shuang,Hong, Xi,Cui, He-Zhen,Zhan, Bing,Li, Zhi-Ming,Hou, Xiu-Feng
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p. 3514 - 3523
(2020/10/09)
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- BETA-LACTAM COMPOUNDS AND METHODS OF USE THEREOF
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Beta-lactam compounds to detect carbapenemases or microbial carbapenem resistance are disclosed. The compounds contain a chemical probe. Upon hydrolysis by carbapenemases, the compounds undergo intramolecular rearrangement and release the chemical probe. Detection of the released chemical probe indicates the presence of carbapenemases and the presence of microbial carbapenem resistance.
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Page/Page column 91
(2020/04/25)
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- Microwave-heated γ-Alumina Applied to the Reduction of Aldehydes to Alcohols
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The development of cheap and robust heterogeneous catalysts for the Meerwein-Ponndorf-Verley (MPV) reduction is desirable due to the difficulties in product isolation and catalyst recovery associated with the traditional use of homogeneous catalysts for MPV. Herein, we show that microwave heated γ-Al2O3 can be used for the reduction of aldehydes to alcohols. The reaction is efficient and has a broad substrates scope (19 entries). The products can be isolated by simple filtration, and the catalyst can be regenerated. With the use of microwave heating, we can direct the heating to the catalyst rather than to the whole reaction medium. Furthermore, DFT was used to study the reaction mechanism, and we can conclude that a dual-site mechanism is operative where the aldehyde and 2-propoxide are situated on two adjacent Al sites during the reduction. Additionally, volcano plots were used to rationalize the reactivity of Al2O3 in comparison to other metal oxides.
- Dhokale, Bhausaheb,Susarrey-Arce, Arturo,Pekkari, Anna,Runemark, August,Moth-Poulsen, Kasper,Langhammer, Christoph,H?relind, Hanna,Busch, Michael,Vandichel, Matthias,Sundén, Henrik
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p. 6344 - 6355
(2020/10/28)
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- NOVEL APOPTOSIS SIGNAL-REGULATING KINASE 1 INHIBITORS
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The present invention relates to inhibitors of apoptosis signal-regulating kinase 1 ("ASK1"), a process for synthesis of the compounds of the present invention, composition comprising the compounds and use of the compounds for inhibition of ASK1.
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Page/Page column 64
(2021/01/23)
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- Reduction of Aldehydes with Formic acid in Ethanol using Immobilized Iridium Nanoparticles on a Triazine-phosphanimine Polymeric Organic Support
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A novel triazine-phosphanimine polymeric organic support (TPA) was synthesized successfully by a controllable one-pot method using melamine (1,3,5-triazine-2,4,6-triamine) and trichlorophosphane (PCl3). The TPA substrate is a material incorporating P and N atoms which can coordinate with metals as a pincer ligand to stabilize them, providing an efficient heterogeneous support to prepare recyclable transition metal catalyst systems. In this study, TPA was used as support to immobilize iridium nanoparticles in the range of ~8 nm on its surface, resulting in the generation of a novel iridium nanocatalyst system (INP-TPA-POP). This catalyst system was characterized using different microscopic and spectroscopic techniques such as FT-IR, TEM, XPS, XRD, SEM, EDX, elemental analysis, ICP and BET analysis. The INP-TPA-POP nanocatalyst exhibited remarkable activity in reduction of aldehydes to alcohols using formic acids as reducing agent in ethanol as solvent.
- Panahi, Farhad,Haghighi, Fatemeh,Khalafi-Nezhad, Ali
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- Pyridine: N-oxide promoted hydrosilylation of carbonyl compounds catalyzed by [PSiP]-pincer iron hydrides
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Five [PSiP]-pincer iron hydrides 1-5, [(2-Ph2PC6H4)2HSiFe(H)(PMe3)2 (1), (2-Ph2PC6H4)2MeSiFe(H)(PMe3)2 (2), (2-Ph2PC6H4)2PhSiFe(H)(PMe3)2 (3), (2-(iPr)2PC6H4)2HSiFe(H)(PMe3) (4), and (2-(iPr)2PC6H4)2MeSiFe(H)(PMe3)2 (5)], were used as catalysts to study the effects of pyridine N-oxide and the electronic properties of [PSiP]-ligands on the catalytic hydrosilylation of carbonyl compounds. It was proved for the first time that this catalytic process could be promoted with pyridine N-oxide as the initiator at 30 °C because the addition of pyridine N-oxide is beneficial for the formation of an unsaturated hydrido iron complex, which is the key intermediate in the catalytic mechanism. Complex 4 as the best catalyst shows excellent catalytic performance. Among the five complexes, complex 3 was new and the molecular structure of complex 3 was determined by single crystal X-ray diffraction. A proposed mechanism was discussed.
- Chang, Guoliang,Fenske, Dieter,Fuhr, Olaf,Li, Xiaoyan,Sun, Hongjian,Xie, Shangqing,Yang, Wenjing,Zhang, Peng
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p. 9349 - 9354
(2020/09/09)
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- Copper-Catalyzed Decarboxylative Hydrophosphinylation of α-Acyl-α-Diazoacetates
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A simple copper-catalyzed decarboxylation–denitrogenation C–P coupling reaction of α-acyl-α-diazoacetates with hydrophosphoryl compounds is reported. The reaction may proceed via a process involving the generation of (diazomethyl)ketones after hydrolysis in the presence of water and the hydrophosphinylation of the copper carbene intermediates. This finding may suggest the potential use of the relatively more readily available α-acyl-α-diazoacetates as replacement of (diazomethyl)ketones in some cases.
- Zhang, Can,Dong, Chao,Wang, Xin,Shen, Ruwei
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supporting information
p. 7440 - 7444
(2020/12/01)
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- Linear β-amino alcohol catalyst anchored on functionalized magnetite nanoparticles for enantioselective addition of dialkylzinc to aromatic aldehydes
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A linear β-amino alcohol ligand, previously found to be a very efficient catalyst for enantioselective addition of dialkylzinc to aromatic aldehydes, has been anchored on differently functionalized superparamagnetic core-shell magnetite-silica nanoparticles (1a and 1b). Its catalytic activity in the addition of dialkylzinc to aldehydes has been evaluated, leading to promising results, especially in the case of 1b for which the recovery by simple magnetic decantation and reuse was successfully verified. This journal is
- Ciprioti, Stefano Vecchio,De Angelis, Martina,Di Pietro, Federica,Iannoni, Marika,Pilloni, Luciano,Primitivo, Ludovica,Ricelli, Alessandra,Righi, Francesco,Righi, Giuliana,Sappino, Carla,Suber, Lorenza
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p. 29688 - 29695
(2020/10/26)
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- Hydrosilylation of Aldehydes and Ketones Catalysed by Bis(phosphinite) Pincer Platinum Hydride Complexes
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Bis(phosphinite) pincer platinum hydride complexes, [2,6-(R2PO)2C6H3]PtH (R=tBu, iPr), were synthesized, characterized and applied to the hydrosilylation of aldehydes and ketones. NMR study and single crystal X-ray diffraction analysis indicated that the hydrides in these two platinum complexes are comparatively less hydridic: down-field 1H NMR resonances (0.71 and 0.98 ppm) and weak Pt?H interactions were observed. Both the platinum complexes were found to be good catalysts for the hydrosilylation of aldehydes and ketones with phenylsilane. The corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the resultant hydrosilylation products and turnover frequencies (TOFs) up to 3200 h?1 were achieved at 60 °C in toluene, which are much higher than those of the hydrosilylation catalysed by the corresponding nickel pincer hydride complexes. A possible mechanism for the present hydrosilylation process was discussed. (Figure presented.).
- Chang, Jiarui,Fang, Fei,Zhang, Jie,Chen, Xuenian
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p. 2709 - 2715
(2020/06/02)
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- Structural Elucidation of Silver(I) Amides and Their Application as Catalysts in the Hydrosilylation and Hydroboration of Carbonyls
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This study details the isolation and characterisation of three novel silver(I) amides in solution and solid-state, [Ag(Cy3P)(HMDS)] 2, [Ag(Cy3P){N(TMS)(Dipp)}] 3 and [Ag(Cy3P)2(NPh2)] 4. Their catalytic abilities have proved successful in hydroboration and hydrosilylation reactions with a full investigation performed with complex 2. Both protocols proceed under mild conditions, displaying exceptional functional-group tolerance and chemoselectivity, in excellent conversions at competitive reaction times. This work reveals the first catalytic hydroboration of aldehydes and ketones performed by a silver(I) catalyst.
- Blair, Victoria L.,Boutland, Aaron J.,Kelly, John A.,Orr, Samantha A.
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supporting information
p. 4947 - 4951
(2020/04/22)
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- Revealing the A-Site Effect of Lead-Free A3Sb2Br9 Perovskite in Photocatalytic C(sp3)?H Bond Activation
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The lead-free halide perovskite A3Sb2Br9 is utilized as a photocatalyst for the first time for C(sp3)?H bond activation. A3Sb2Br9 nanoparticles (A3Sb2Br9 NPs) with different ratios of Cs and CH3NH3 (MA) show different photocatalytic activities for toluene oxidation and the photocatalytic performance is enhanced when increasing the amount of Cs. The octahedron distortion caused by A-site cations can change the electronic properties of X-site ions and further affect the electron transfer from toluene molecules to Br sites. After the regulation of A-site cations, the photocatalytic activity is higher with A3Sb2Br9 NPs than that with classic photocatalysts (TiO2, WO3, and CdS). The main active species involved in photocatalytic oxidation of toluene are photogenerated holes (h+) and superoxide anions (.O2?). The octahedron distortion by A-site cations affecting photocatalytic activity remains unique and is also a step forward for understanding more about halide-perovskite-based photocatalysis. The relationship between octahedron distortion and photocatalysis can also guide the design of new photocatalytic systems involving other halide perovskites.
- Chen, Langxing,Li, Qi,Wang, Yingying,Xu, Dongsheng,Yang, Lanlan,Yang, Yuying,Zhang, Zhenzhen
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supporting information
p. 18136 - 18139
(2020/08/19)
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- Olefin-tethered organoruthenium carbene complexes: Synthesis, X-ray structure and catalytic insights on hydrogenation of esters
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A series of Ru(II) complexes encompassing imidazolylidene olefin arm have been designed. The newly synthesized ligands and complexes were fully characterized by 1H, 13C NMR, and elemental analyses. Structural geometry for one of the envoy Ru(II) carbene complexes 3a was confirmed by single-crystal X-ray diffraction studies. The complexes acquired a distorted octahedral geometry. The highly active [Ru(II)-NHC] complex 3b, showed excellent catalytic performance for the hydrogenation of esters in 1,4-dioxane medium. The effects of solvent, base, wingtip substituents, time and catalyst loading were also investigated. The reported catalyst performed exceptionally well for a range of esters and furnishes very good yield of hydrogenated products.
- Nirmala, Muthukumaran,Murugan, Kaliyappan,Vijayapritha, Subbarayan,Viswanathamurthi, Periasamy,Bertani, Roberta,Malecki, Jan Grzegorz
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- Base-Free Iron Catalyzed Transfer Hydrogenation of Esters Using EtOH as Hydrogen Source
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Herein, we report on the use of the iron pincer complex Iron-MACHO-BH, in the base-free transfer hydrogenation of esters with EtOH as a hydrogen source. More than 20 substrates including aromatic and aliphatic esters and lactones were reduced affording the desired primary alcohols and diols with moderate to excellent isolated yields. It is also possible to reduce polyesters to the diols with this method, enabling a novel way of plastic recycling. Reduction of the renewable substrate methyl levulinate proceeds to form 1,4-pentanediol directly. The yields are largely governed by the equilibrium between the alcohol and the ethyl ester.
- Farrar-Tobar, Ronald A.,Wozniak, Bartosz,Savini, Arianna,Hinze, Sandra,Tin, Sergey,de Vries, Johannes G.
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supporting information
p. 1129 - 1133
(2019/01/04)
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- TETRADENTATE LIGAND, AND PRODUCTION METHOD THEREFOR, SYNTHETIC INTERMEDIATE THEREOF, AND TRANSITION METAL COMPLEX THEREOF
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The present invention relates to: a compound as a ligand in a variety of catalytic organic synthetic reactions; a method for producing the compound; a synthetic intermediate of the compound; and a transition metal complex which has the compound as a ligand. The compound includes a compound represented by the following general formula (1A):
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Paragraph 0265-0267
(2019/05/15)
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- Dehydrogenative Coupling of Aldehydes with Alcohols Catalyzed by a Nickel Hydride Complex
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A nickel hydride complex, {2,6-(iPr2PO)2C6H3}NiH, has been shown to catalyze the coupling of RCHO and R′OH to yield RCO2R′ and RCH2OH, where the aldehyde also acts as a hydrogen acceptor and the alcohol also serves as the solvent. Functional groups tolerated by this catalytic system include CF3, NO2, Cl, Br, NHCOMe, and NMe2, whereas phenol-containing compounds are not viable substrates or solvents. The dehydrogenative coupling reaction can alternatively be catalyzed by an air-stable nickel chloride complex, {2,6-(iPr2PO)2C6H3}NiCl, in conjunction with NaOMe. Acids in unpurified aldehydes react with the hydride to form nickel carboxylate complexes, which are catalytically inactive. Water, if present in a significant quantity, decreases the catalytic efficiency by forming {2,6-(iPr2PO)2C6H3}NiOH, which causes catalyst degradation. On the other hand, in the presence of a drying agent, {2,6-(iPr2PO)2C6H3}NiOH generated in situ from {2,6-(iPr2PO)2C6H3}NiCl and NaOH can be converted to an alkoxide species, becoming catalytically competent. The proposed catalytic mechanism features aldehyde insertion into the nickel hydride as well as into a nickel alkoxide intermediate, both of which have been experimentally observed. Several mechanistically relevant nickel species including {2,6-(iPr2PO)2C6H3}NiOC(O)Ph, {2,6-(iPr2PO)2C6H3}NiOPh, and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh have been independently synthesized, crystallographically characterized, and tested for the catalytic reaction. While phenol-containing molecules cannot be used as substrates or solvents, both {2,6-(iPr2PO)2C6H3}NiOPh and {2,6-(iPr2PO)2C6H3}NiOPh·HOPh are efficient in catalyzing the dehydrogenative coupling of PhCHO with EtOH.
- Eberhardt, Nathan A.,Wellala, Nadeesha P. N.,Li, Yingze,Krause, Jeanette A.,Guan, Hairong
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p. 1468 - 1478
(2019/04/17)
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- Selective Hydroboration of Carboxylic Acids with a Homogeneous Manganese Catalyst
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Catalytic reduction of carboxylic acid to the corresponding alcohol is a challenging task of great importance for the production of a variety of value-added chemicals. Herein, a manganese-catalyzed chemoselective hydroboration of carboxylic acids has been developed with a high turnover number (>99?000) and turnover frequency (>2000 h-1) at 25 °C. This method displayed tolerance of electronically and sterically differentiated substrates with high chemoselectivity. Importantly, aliphatic long-chain fatty acids, including biomass-derived compounds, can efficiently be reduced. Mechanistic studies revealed that the reaction occurs through the formation of active manganese-hydride species via an insertion and bond metathesis type mechanism.
- Barman, Milan K.,Das, Kuhali,Maji, Biplab
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p. 1570 - 1579
(2019/01/30)
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- Facile reduction of carboxylic acids to primary alcohols under catalyst-free and solvent-free conditions
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We report the development of a facile protocol for the deoxygenative hydroboration of aliphatic and aryl carboxylic acids to afford corresponding primary alcohols under solvent-free and catalyst-free conditions. The reaction proceeds under ambient temperature exhibits good tolerance towards various functional groups and generates quantitative yields. The plausible mechanism involves the formation of Lewis acid-base adducts as well as the liberation of hydrogen gas.
- Harinath, Adimulam,Bhattacharjee, Jayeeta,Panda, Tarun K.
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supporting information
p. 1386 - 1389
(2019/02/05)
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- n-Butyllithium (1 mol %)-catalyzed Hydroboration of Aldehydes and Ketones with Pinacolborane
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A practical and efficient protocol for the hydroboration of aldehydes and ketones using a pinacolborane and alkyl lithium system is demonstrated. A systematic evaluation showed that 1 mol % n-butyllithium afforded catalyzed hydroboration of aldehydes and ketones in a short reaction time under ambient conditions. Excellent yield, functional group tolerance, short reaction time, low catalyst loading, and gram-scale synthesis are the salient features of the proposed protocol.
- Yang, Su Jin,Jaladi, Ashok Kumar,Kim, Jea Ho,Gundeti, Shankaraiah,An, Duk Keun
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- Method for preparing alcoholic compound from anilino lithium compound as catalyst
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The invention relates to an application of an anilino lithium compound, in particular to a method for preparing an alcoholic compound from the anilino lithium compound as a catalyst. The catalyst, borane and carboxylic acid are stirred and mixed uniformly, subjected to a reaction and exposed to air to terminate the reaction, a reacted liquid is subjected to reduced-pressure treatment for solvent removal, silica gel and methanol are added, and the alcoholic compound is obtained by hydrolysis. The anilino lithium compound can perform high-activity catalysis on the reaction between carboxylic acid and borane at room temperature, dose of the catalyst is only 0.8mol% of the mole ratio of carboxylic acid, compared with the conventional catalysis system, the commercial reagent anilino lithium compound is used, reaction conditions are mild, and yield of borate with different substituents under limit conditions can reach 90% or higher.
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Paragraph 0022
(2019/03/06)
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- Based on n-butyl aromatic carboxylic acid preparation of alcohol compound
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The present invention relates to n-butyl application, in particular to based on n-butyl aromatic carboxylic acid preparation of alcohol compound, the catalyst sequentially, borane and carboxylic acid uniformly stirred and mixed, exposed to the air after the reaction terminated in the reaction, the reaction solution under reduced pressure to remove the solvent, then adding silica gel methanol hydrolyzed to obtain the alcohol compound. The invention discloses a butyl lithium can be high activity under the room temperature condition of catalytic carboxylic acid and borane borohydride reaction, the catalyst levels are only the molar amount of carboxylic acid 0.5 μM %, compared with the prior catalytic system, using the commercial reagent is BuLi, mild reaction conditions, in under a limited condition of different substituents of the yield of the ester can reach 90% or more.
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Paragraph 0022
(2019/03/29)
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- Lithium tert-Butoxide-catalyzed Hydroboration of Carbonyl Compounds
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We report the successful hydroboration of aldehydes and ketones with pinacolborane using 1 mol % lithium tert-butoxide under ambient conditions. The present protocol was applicable to various aldehydes and ketones, and the corresponding boronate esters and subsequent alcohols were obtained in good to excellent yields. In addition, this high-yielding practical method could be extended to the reduction of ester groups. Under optimized conditions, LiOtBu facilitate the hydroboration of ester groups quantitatively.
- Kim, Jea Ho,Jaladi, Ashok Kumar,Kim, Hyun Tae,An, Duk Keun
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p. 971 - 975
(2019/08/30)
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- New Zinc Catalyst for Hydrosilylation of Carbonyl Compounds
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A new zinc complex was synthesized and applied in the catalytic hydrosilylation of carbonyl compounds. Optimization of the reaction conditions showed that the presence a substoichiometric amount of methanol accelerates the process significantly. The reaction can proceed at very low catalyst load (down to 0.1 molpercent) under mild reaction conditions. The reaction tolerates the presence of C=C bonds, and thus can be useful for the synthesis of allylic alcohols from α,β-unsaturated aldehydes and ketones.
- Alshakova, Iryna D.,Nikonov, Georgii I.
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p. 3305 - 3312
(2019/08/28)
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- Nanoporous Na+-montmorillonite perchloric acid as an efficient and recyclable catalyst for the chemoselective protection of hydroxyl groups
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Nanoporous Na+-montmorillonite perchloric acid as a novel heterogeneous reusable solid acid catalyst was easily prepared by treatment of Na+-montmorillonite as a cheap and commercially available support with perchloric acid. The catalyst was characterized using a variety of techniques including X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX), pH analysis and determination of the Hammett acidity function. The prepared reagent showed excellent catalytic activity for the chemoselective conversion of alcohols and phenols to their corresponding trimethylsilyl ethers with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) at room temperature. Deprotection of the resulting trimethylsilyl ethers can also be carried out using the same catalyst in ethanol. All reactions were performed under mild and completely heterogeneous reaction conditions in good to excellent yields. The notable advantages of this protocol are: short reaction times, high yields, availability and low cost of the reagent, easy work-up procedure and the reusability of the catalyst during a simple filtration.
- Mashhadinezhad, Maryam,Shirini, Farhad,Mamaghani, Manouchehr
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p. 2099 - 2107
(2019/01/03)
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