- Rhodium-Catalyzed Spiro Indenyl Benzoxazine Synthesis via C-H Activation/Annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines and Alkynes
-
The rhodium (III)-catalyzed annulation of 3-Aryl-2H-Benzo[b][1,4]oxazines with alkynes via C–H activation has been developed. This reaction afforded a series of spiro indenyl benzoxazine in high yields under mild reaction condition with good functional group tolerance.
- Tan, Heng,Laishram, Ronibala Devi,Zhang, Xuexin,Shi, Guangrui,Li, Kangkui,Chen, Jingchao
-
-
Read Online
- Rhodium(III)-catalyzed [4+1] annulation of aromatic and vinylic carboxylic acids with allenes: An efficient method towards vinyl-substituted phthalides and 2-furanones
-
A highly regio- and stereoselective synthesis of 3,3-disubstituted phthalides from aryl carboxylic acids and allenes using a rhodium(III) catalyst has been demonstrated. The reaction features broad functional group tolerance and provides a simple and straightforward route to the synthesis of various 3-vinyl-substituted phthalides. Furthermore, the catalytic reaction can also be applied to the synthesis of biologically active 5-vinyl-substituted 2-furanones from α,β-unsaturated carboxylic acids and allenes. The reactions proceed through a carboxylate-assisted ortho-C-H activation and [4+1] annulation. The preliminary mechanistic studies suggest that a C-H cleavage is the rate-determining step. An efficient synthesis of highly substituted phthalides and 2-furanones from aryl and vinyl carboxylic acids with allenes by using a RhIII catalyst is demonstrated (see scheme). The reactions proceed through a carboxylate-assisted ortho-C-H activation and [4+1] annulation.
- Gandeepan, Parthasarathy,Rajamalli, Pachaiyappan,Cheng, Chien-Hong
-
-
Read Online
- Palladium-Catalyzed Electrochemical C-H Bromination Using NH4Br as the Brominating Reagent
-
The palladium-catalyzed electrochemical C-H bromination of benzamide derivatives under divided cells is developed, in which NH4Br serves as a brominating reagent and electrolyte. The protocol avoids the use of chemical oxidants and provides an alternative method for the synthesis of aryl bromides.
- Yang, Qi-Liang,Wang, Xiang-Yang,Wang, Tong-Lin,Yang, Xiang,Liu, Dong,Tong, Xiaofeng,Wu, Xin-Yan,Mei, Tian-Sheng
-
-
Read Online
- Diastereoselective [3+2] Annulation of Aromatic/Vinylic Amides with Bicyclic Alkenes through Cobalt-Catalyzed C-H Activation and Intramolecular Nucleophilic Addition
-
A highly diastereoselective method for the synthesis of dihydroepoxybenzofluorenone derivatives from aromatic/vinylic amides and bicyclic alkenes is described. This new transformation proceeds through cobalt-catalyzed C-H activation and intramolecular nucleophilic addition to the amide functional group. Transition-metal-catalyzed C-H activation reactions of secondary amides with alkenes usually lead to [4+2] or [4+1] annulation; to the best of our knowledge, this is the first time that a [3+2] cycloaddition is described in this context. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. Mechanistic studies imply that the C-H bond cleavage may be the rate-limiting step. [3+2] instead of [4+2] or [4+1]: The diastereoselective [3+2] annulation of secondary amides with alkenes proceeds by cobalt-catalyzed C-H activation and intramolecular nucleophilic addition to the amide functional group under mild conditions. Mechanistic studies suggest that the C-H bond cleavage is the rate-limiting step.
- Gandeepan, Parthasarathy,Rajamalli, Pachaiyappan,Cheng, Chien-Hong
-
-
Read Online
- Cobalt-catalyzed electrochemical C–H/N–H functionalization of N-(quinolin-8-yl)benzamide with isocyanides
-
An efficient synthesis of functionalized iminoisoindolinone derivatives has been achieved via a mild electrochemical oxidative C–H/N–H functionalization/intramolecular annulations with isocyanides in undivided cell equipped with a nickel cathode. In the presence of earth abundant cobalt catalyst, versatile iminoisoindolinone derivatives obtained in good yields and in a sustainable manner by using electricity as an oxidant in place of stoichiometric amount of silver and copper salts.
- Chen, Jinkang,Jin, Licheng,Zhou, Jian,Jiang, Xinpeng,Yu, Chuanming
-
-
Read Online
- Mechanistic study of the rhodium-catalyzed carboxylation of simple aromatic compounds with carbon dioxide
-
A detailed mechanism of the Rh(i)-catalyzed carboxylation of simple aromatic compounds via C-H bond activation was investigated. Kinetic studies with model compounds of the postulated key intermediates revealed that 14-electron complexes, RhMe(dcype) and RhPh(dcype), participated in the C-H bond activation step and the carboxylation step, respectively. Interestingly, the undesired carboxylation of RhMe(dcype) to give acetic acid was found to be much faster than the desired C-H bond activation reaction under stoichiometric conditions, however, the C-H bond activation reaction could occur under catalytic conditions. Careful controlled experiments revealed that C-H bond activation using RhMe(dcype) became competitive with its direct carboxylation under the condition that the concentration of CO2 in the liquid phase was rather low. This factor could be controlled to some extent by mechanical factors such as the stirring rate and the shape of the reaction vessel. The resting state of the rhodium species under catalytic conditions was found to be [RhCl(dcype)]2, and the proposed intermediates such as RhMe(dcype) and Rh(OBz)(dcype) were readily converted to the most stable state, [RhCl(dcype)]2, via transmetallation with [Al]-Cl species, thus preventing the decomposition of the active catalytic species.
- Suga, Takuya,Saitou, Takanobu,Takaya, Jun,Iwasawa, Nobuharu
-
-
Read Online
- Copper-Promoted Thiolation of C(sp2)–H Bonds Using a 2-Amino Alkylbenzimidazole Directing Group
-
A copper-promoted thiolation of C(sp2)–H bonds with disulfides was achieved by using 2-amino alkylbenzimidazole (MBIP amine) as a new and removable N,N-bidentate directing group. This strategy gives a variety of functionalized thioethers in moderate to excellent yields in a simple and efficient way. Importantly, the substrate scope is not limited to aromatic amides; diverse alkenyl amides are also compatible. Furthermore, this synthetic approach provides a potentially feasible way to achieve structural modification of related benzimidazole-containing compounds through direct C–H activation.
- Liu, Shuang-Liang,Li, Xue-Hong,Shi, Tan-Hao,Yang, Guang-Chao,Wang, Hai-Li,Gong, Jun-Fang,Song, Mao-Ping
-
-
Read Online
- Copper/Palladium Bimetallic System for the Synthesis of Isobenzofuranones through [4 + 1] Annulation between Propiophenones and Benzoic Acids
-
A copper/palladium-catalyzed annulation from benzoic acids and propiophenones for the synthesis of isobenzofuranones was reported. The Cu-(2,2,6,6-tetramethylpiperidin-1-yl)oxyl system showed a great ability to activate the C-H bond on the α- and β-carbons of a carbonyl group, and the in situ-generated enone intermediate in this reaction could be further transformed to construct isobenzofuranones with the catalysis of Pd(dba)2 (dba = dibenzylideneacetone). Various isobenzofuranones could be obtained in moderate to good yields, and a great atom economy was highlighted by utilizing this method.
- Liang, Xiao,Xiong, Mingteng,Zhu, Heping,Shi, Keqiang,Zhou, Yifeng,Pan, Yuanjiang
-
-
Read Online
- Two methods for direct ortho-arylation of benzoic acids
-
Two new palladium-catalyzed methods for the direct ortho-arylation of free benzoic acids have been developed. The first method employs stoichiometric silver acetate for iodide removal, aryl iodide as the coupling partner, and acetic acid solvent. This method is applicable to the arylation of electron-rich to moderately electron-poor benzoic acids and tolerates chloride and bromide substituents on both coupling partners. The second method involves the use of aryl chloride, cesium carbonate base, n-butyl-di-1-adamantylphosphine ligand, and DMF solvent and is suitable for both electron-rich and electron-poor benzoic acids. Mechanistic studies of the second method point to the heterolytic C-H bond cleavage as the rate-determining step.
- Chiong, Hendrich A.,Pham, Quynh-Nhu,Daugulis, Olafs
-
-
Read Online
- Photoinduced FeCl3-Catalyzed Alkyl Aromatics Oxidation toward Degradation of Polystyrene at Room Temperature?
-
While polystyrene is widely used in daily life as a synthetic plastic, the subsequently selective degradation is still very challenging and highly required. Herein, we disclose a highly practical and selective reaction for the catalytically efficient oxidation of alkyl aromatics (including 1°, 2°, and 3° alkyl aromatics) to carboxylic acids. While dioxygen was used as the sole terminal oxidant, this protocol was catalyzed by the inexpensive and readily available ferric compound (FeCl3) with irradiation of visible light (blue LEDs) under only 1 atmosphere of O2 at room temperature. This system could further facilitate the selective degradation of polystyrene to benzoic acid, providing an important and practical tool to generate high-value chemical from abundant polystyrene wastes.
- Zhang, Guoxiang,Zhang, Zongnan,Zeng, Rong
-
supporting information
p. 3225 - 3230
(2021/09/28)
-
- Highly regioselective and stereoselective synthesis of C-Aryl glycosidesvianickel-catalyzedortho-C-H glycosylation of 8-aminoquinoline benzamides
-
C-Aryl glycosides are of high value as drug candidates. Here a novel and cost-effective nickel catalyzedortho-CAr-H glycosylation reaction with high regioselectivity and excellent α-selectivity is described. This method shows great functional group compatibility with various glycosides, showing its synthetic potential. Mechanistic studies indicate that C-H activation could be the rate-determining step.
- Chen, Xi,Ding, Ya-Nan,Gou, Xue-Ya,Liang, Yong-Min,Luan, Yu-Yong,Niu, Zhi-Jie,Shi, Wei-Yu,Zhang, Zhe,Zheng, Nian
-
supporting information
p. 8945 - 8948
(2021/09/10)
-
- Diastereoselective synthesis of chiral 3-substituted isoindolinonesviarhodium(iii)-catalyzed oxidative C-H olefination/annulation
-
A new method for the direct and stereoselective synthesis of 3-substituted isoindolinonesviaRh(iii)-catalyzed chiralN-sulfinyl amide directed asymmetric [4 + 1] annulation of benzamides with acrylic esters has been developed. The reaction proceeded through an oxidative C-H olefination and a subsequent cyclization by intramolecular aza-Michael addition, producing a series of diastereoisomeric chiral isoindolinones (20 examples) in generally good yields with a dr value up to 5.5?:?1. The absolute configurations of the newly formed C-stereocenters in the major and minor diastereomers of the catalysis product have been determined by X-ray crystal diffraction analysis to beSandR, respectively. The separation of the major diastereoisomers from the catalysis products and subsequent removal of theN-sulfinyl chiral auxiliary afforded enantiomerically pure (S)-isoindolinones. The application of the obtained (S)-isoindolinones in the synthesis of several biologically active isoindolinones such as (S)-PD172938, (S)-pazinaclone and (S)-pagoclone is presented.
- Gong, Jun-Fang,Li, Xue-Hong,Song, Mao-Ping
-
supporting information
p. 5876 - 5887
(2021/07/12)
-
- Efficient continuous-flow HD exchange reaction of aromatic nuclei in D2O/2-PrOH mixed solvent in a catalyst cartridge packed with platinum on carbon beads
-
Herein, a continuous-flow deuteration methodology for various aromatic compounds is developed based on heterogeneous platinum-catalyzed hydrogen-deuterium exchange. The reaction entails the transfer of a substrate dissolved in a mixed solvent of 2-propanol and deuterium oxide into a catalyst cartridge packed with platinum on carbon beads (Pt/CB). Pt/ CB could be continuously used without significant deterioration of catalyst activity for at least 24 h. Deuteration proceeded within 60 s of the substrate solutions being passed through the Pt/CB layer in the Pt/CB-packed cartridge.
- Park, Kwihwan,Ito, Naoya,Yamada, Tsuyoshi,Sajiki, Hironao
-
supporting information
p. 600 - 605
(2021/03/29)
-
- New Pd-phosphorus ylide complexes based on FC60 as heterogeneous nano-catalyst for H/D exchange reaction
-
In this account, new Pd(0) complexes of phosphorus ylides based on fullerene C60 (FC60) were synthesized and utilized as the first fullerene-based heterogeneous nano-catalysts for H/D exchange reaction. Four new palladacyclopropa-[60]fullerene complexes 1–4, [(η2-C60)Pd(Y1–4)2] (Y1 = PPh3CHC(O)C6H4-p-NO2, Y2 = PPh3CHC(O)C6H4-p-CH3, Y3 = (p-tolyl)3P-CHC(O)C6H4-p-NO2, and Y4 = (p-tolyl)3P-CHC(O)C6H4-p-CH3), were prepared through dissolving the related α-keto stabilized phosphorus ylide in toluene solution in the presence of FC60 and Pd (dba)2 (dba = dibenzylideneacetone). All of the complexes were characterized using Nuclear magnetic resonance (NMR) (1H, 13C, and 31P), Infrared spectroscopy (IR), Ultraviolet-visible spectroscopy (UV-visible), fluorescence, Electrospray Ionisation Mass Spectrometry (ESI-MS), and Energy-dispersive X-ray spectroscopy (EDX) spectroscopies, and scanning electron microscopy (SEM) and TEM techniques. The data proved that FC60 and two ylides were coordinated to Pd(0) center through two hexagons and two ylidic carbon atoms, respectively. An evaluation was also performed to compare the catalytic activity of synthesized Pd complex 1 and a conventional heterogeneous catalyst, 10% Pd on carbon, in H/D exchange reaction. The results indicate that the process of H/D exchange reaction in aromatic rings of benzoic acid derivatives progressed more efficiently by Pd complex 1.
- Yousefi, Abed,Sabounchei, Seyyed Javad,Hashemi, Ali
-
-
- Biosynthesis of Benzylic Derivatives in the Fermentation Broth of the Edible Mushroom, Ischnoderma resinosum
-
Employing isotope incubation studies, the biosynthetic pathway leading to a series of benzylic derivatives was elucidated in the fermentation broth of the edible mushroom Ischnoderma resinosum (P. Karst). Twenty-six hydroxy- and methoxy- benzylic derivatives were screened by gas chromatography-mass spectrometry (GC-MS) of which 13 were detected in the culture media. Results from the isotope incubation studies showed the transformation of both benzyl alcohol and benzoic acid into benzaldehyde. Benzaldehyde was then converted into 4-methoxybenzaldehyde via hydroxylation and subsequent methylation of the 4-C position. The resulting 4-methoxybenzaldehyde was then hydroxylated in the 3-C position followed by methylation into 3,4-dimethoxybenzaldehyde. Based on these findings, a novel metabolic scheme for the biosynthesis of benzylic derivatives in I. resinosum was proposed. The knowledge of the biosynthetic pathway was utilized to produce 4-hydroxy-3-methoxybenzaldehyde (vanillin) from 4-hydroxy-3-methoxybenzoic acid (vanillic acid). This is the first report to elucidate the biosynthetic pathway of benzyl derivatives and production of vanillin from I. resinosum.
- Wickramasinghe, Purni C. K.,Munafo, John P.
-
p. 2485 - 2492
(2020/02/27)
-
- Expeditious synthesis of phenanthridines through a Pd/MnO2-mediated C-H arylation/oxidative annulation cascade from aldehydes, aryl iodides and amino acids
-
The expeditious construction of phenanthridine scaffolds via a Pd/MnO2-mediated C-H arylation/oxidative annulation cascade involving aldehydes, aryl iodides and amino acids is disclosed. This reaction proceeds smoothly involving the formation of multiple chemical bonds with the tolerance of a wide range of functional groups. The control experiments suggest a radical mechanism for C-N bond formation via MnO2-promoted oxidative annulation of imine compounds. The synthetic utility of this transformation has been demonstrated via the straightforward access to bioactive natural alkaloid trisphaeridine and its analogue.
- Fan, Jian,Li, Li,Xie, Meihua,Zhang, Jitan
-
supporting information
p. 2775 - 2778
(2020/03/13)
-
- Harnessing hypervalent iodonium ylides as carbene precursors: C-H activation of: N -methoxybenzamides with a Rh(iii)-catalyst
-
Hypervalent iodonium ylides expeditiously generate carbenes which undergo domino intermolecular C-H activation followed by intramolecular condensation in the presence of N-methoxybenzamide as a starting material and a Rh(iii)-catalyst to afford dihydrophenanthridines. KIE studies and DFT calculations were performed to substantiate the mechanistic pathway. To extend the synthetic utilisation, fluorescent pyranoisocoumarins were achieved by using Rh(iii)-catalyzed peri-C-H/O-H activation/annulation reactions.
- Mayakrishnan, Sivakalai,Tamizmani, Masilamani,Maheswari, Naryanan Uma
-
supporting information
p. 15462 - 15465
(2020/12/25)
-
- Iridium-catalyzed, ligand-controlled directed alkynylation and alkenylation of arenes with terminal alkynes
-
We report iridium-catalyzed C-C formation between benzamides and terminal alkynes. With the choice of a suitable ligand, a C-H alkynylation or alkenylation product could be obtained selectively. The directed C-H alkynylation proceeded without the need for an external oxidant, while the directed C-H alkenylation likely involves an unusual vinylidene mechanism. This divergent reactivity provides access to both alkynylation and alkenylation products from the same set of starting materials.
- Sun, Xin,Zhao, Wei,Li, Bi-Jie
-
supporting information
p. 1298 - 1301
(2020/02/04)
-
- H-D Exchange Deuteration of Arenes at Room Temperature
-
Arene nuclei efficiently underwent the hydrogen (H)-deuterium (D) exchange reaction catalyzed by platinum group metals on carbon in a mixed solvent of 2-propanol and D2O at room temperature to produce deuterium-labeled arenes. Platinum on carbon (Pt/C) and iridium on carbon (Ir/C) were applicable catalysts, and the various arenes bearing a carbonyl group, fluorine, phenolic hydroxy group, amino group, or phosphonic acid on the aromatic nucleus were effectively deuterated. Nonheating conditions are valuable for the scalable industrial preparation.
- Sawama, Yoshinari,Nakano, Akihiro,Matsuda, Takumi,Kawajiri, Takahiro,Yamada, Tsuyoshi,Sajiki, Hironao
-
p. 648 - 653
(2019/02/14)
-
- Co(III)-Catalyzed [4+1] Annulation of Amides with Allenes via C?H Activation
-
A Co(III)-catalyzed [4+1] annulation of amides with allenes to synthesize isoindolone and 1,5-dihydro-pyrrol-2-one derivatives is reported. A wide range of aromatic and vinylic amides react with allenes to give the corresponding annulation products in good to excellent yields. The mechanistic studies strongly support that the catalytic reaction proceeds through an amide-directed C?H activation, followed by carbocobaltation of allene, β-hydride elimination, and an intramolecular 1,2-hydroamination. (Figure presented.).
- Boobalan, Ramadoss,Santhoshkumar, Rajagopal,Cheng, Chien-Hong
-
supporting information
p. 1140 - 1145
(2019/01/30)
-
- Two-in-One Strategy for the Pd(II)-Catalyzed Tandem C-H Arylation/Decarboxylative Annulation Involved with Cyclic Diaryliodonium Salts
-
We report here a two-in-one strategy for the Pd(II)-catalyzed tandem C-H arylation/decarboxylative annulation between readily available cyclic diaryliodonium salts and benzoic acids. The carboxylic acid functionality can be used as both a directing group for the ortho-C-H arylation and the reactive group for the tandem decarboxylative annulation. By a step-economical double cross-coupling annulation procedure, the privileged triphenylene frameworks were efficiently constructed, which have potential applications in material chemistry.
- Hu, Tao,Xu, Kai,Ye, Zenghui,Zhu, Kai,Wu, Yanqi,Zhang, Fengzhi
-
supporting information
p. 7233 - 7237
(2019/10/02)
-
- Cp?CoIII-catalyzed formal [4+2] cycloaddition of benzamides to afford quinazolinone derivatives
-
A Cp?CoIII-catalyzed arene C-H bond amidation/annulation of benzamides was developed to afford quinazolinone derivatives in one-pot with high yields and broad substrate scope. This method could be applied to the synthesis of quinazolinone drugs and late-stage modification of natural products.
- Yang, Jingshu,Hu, Xiao,Liu, Zijie,Li, Xueyuan,Dong, Yi,Liu, Gang
-
supporting information
p. 13840 - 13843
(2019/11/21)
-
- Synthetic method of pentadeuterium-substituted malachite green salt
-
The invention relates to a synthetic method of pentadeuterium-substituted malachite green salt. According to the method disclosed by the invention, a traditional synthesis method in the prior art is completely abandoned; instead, a new synthetic route is employed, wherein the method comprises the following steps: firstly, preparing a Grignard reagent and pentadeuterium substituted tert-butyl benzoate; then the pentadeuterium-substituted leucomalachite green is synthesized in a nucleophilic addition mode; it is unexpectedly found that few by-products are synthesized through the method, the yield of the products is high, and pentadeuterium-substituted malachite green salt prepared from the synthesized pentadeuterium-substituted leucomalachite green is few in impurity and can serve as a high-quality candidate of malachite green standard substances. More importantly, in a traditional synthesis method, hydrogen-deuterium exchange is extremely easy to occur in the reaction process, and high-abundance deuterium-substituted malachite green salt is difficult to synthesize; however, unnecessary hydrogen-deuterium exchange can be avoided in the method, so that the high-abundance deuterium-substituted malachite green salt can be obtained under mild reaction conditions.
- -
-
Paragraph 0054-0057; 0061
(2019/12/02)
-
- Steric control and the mechanism of benzaldehyde oxidation by polypyridyl oxoiron(IV) complexes: Aromatic: versus benzylic hydroxylation of aromatic aldehydes
-
The present study describes the first example of the hydroxylation of benzaldehydes by synthetic nonheme oxoiron(iv) complexes, where the reactivity, chemoselectivity, and mechanism were strongly influenced by the ligand environment of the iron center.
- Turcas, Ramona,Lakk-Bogáth, Dóra,Speier, Gábor,Kaizer, József
-
supporting information
p. 3248 - 3252
(2018/03/21)
-
- Multicomponent Synthesis of Isoindolinone Frameworks via RhIII-Catalysed in situ Directing Group-Assisted Tandem Oxidative Olefination/Michael Addition
-
A RhIII-catalysed three-component synthesis of isoindolinone frameworks via direct assembly of benzoyl chlorides, o-aminophenols and activated alkenes has been developed. The process involves in situ generation of o-aminophenol (OAP)-based bidentate directing group (DG), RhIII-catalysed tandem ortho C?H olefination and subsequent cyclization via aza-Michael addition. This protocol exhibits good chemoselectivity and functional group tolerance. Computational studies showed that the presence of hydroxyl group on the N-aryl ring could enhance the chemoselectivity of the reaction.
- Wang, Liang,Liu, Xi,Liu, Jian-Biao,Shen, Jun,Chen, Qun,He, Ming-Yang
-
supporting information
p. 765 - 769
(2018/03/07)
-
- Cp?CoIII-Catalyzed syn-Selective C-H Hydroarylation of Alkynes Using Benzamides: An Approach Toward Highly Conjugated Organic Frameworks
-
Hydroarylation of internal alkynes by cost-effective CoIII-catalysis, directed by N-tert-butyl amides, is achieved to avail mono- or dihydroarylated amide products selectively in an atom and step economic way. Several important functional groups were tolerated under the reaction conditions, and syn-hydroarylation products were exclusively isolated. Notably, a 4-fold C-H hydroarylation provided a highly conjugated organic framework in one step. Kinetic study with extensive deuterium labeling experiments were performed to support the proposed mechanism.
- Bera, Sourav Sekhar,Debbarma, Suvankar,Ghosh, Avick Kumar,Chand, Santanu,Maji, Modhu Sudan
-
p. 420 - 430
(2017/04/26)
-
- Aqueous Oxidations Started by TiO2 Photoinduced Holes Can Be a Rate-Determining Step
-
In aqueous TiO2 photocatalytic hydroxylation of weakly polar aromatics, a series of inverse H/D KIEs of 0.7–0.8 were observed, which is different than the normal H/D kinetic isotope effects (KIEs) usually observed for polar aromatics. This result indicated that the oxidation started by photo-induced hvb + can be the rate-determining step.
- Gong, Yuanzheng,Yang, Chun,Ji, Hongwei,Chen, Chuncheng,Ma, Wanhong,Zhao, Jincai
-
supporting information
p. 2048 - 2051
(2017/08/23)
-
- Synthesis of isoquinolones: Via Rh-catalyzed C-H activation of substituted benzamides using air as the sole oxidant in water
-
Most of the metal-catalyzed C-H activation/annulation reactions were carried out in organic solvents using expensive oxidants such as Cu(ii) and Ag(i) salts. Here, we reported a new approach for a highly regioselective synthesis of isoquinolones from N-alkyl benzamides and alkynes using an Rh(iii) catalyst and inexpensive oxygen as the sole oxidant in an aqueous medium. In the reaction, water gave the highest product yield among the solvents used. In addition, at the end of the reaction, the isoquinolone product directly precipitated out from the aqueous solution. The methodology can be applied to a gram scale synthesis. This Rh(iii)-catalyzed reaction shows interesting meta selectivity with the meta substituted benzamide and shows various regioselectivities with different substituted alkynes. Moreover, the methodology can be applied to the preparation of biologically active compounds having the isoquinolone core.
- Upadhyay, Nitinkumar Satyadev,Thorat, Vijaykumar H.,Sato, Ryota,Annamalai, Pratheepkumar,Chuang, Shih-Ching,Cheng, Chien-Hong
-
supporting information
p. 3219 - 3224
(2017/07/28)
-
- Cobalt-Catalyzed Carbonylation of C(sp2)-H Bonds with Azodicarboxylate as the Carbonyl Source
-
A novel and efficient approach for the C(sp2)-H bond carbonylation of benzamides has been developed using stable and inexpensive Co(OAc)2·4H2O as the catalyst and the commercially available and easily handling azodicarboxylates as the nontoxic carbonyl source. A broad range of substrates bearing diverse functional groups were tolerated. This is the first example where cobalt-catalyzed C(sp2)-H bond carbonylation occurs with azodicarboxylate as the carbonyl source.
- Ni, Jiabin,Li, Jie,Fan, Zhoulong,Zhang, Ao
-
supporting information
p. 5960 - 5963
(2016/11/29)
-
- Ruthenium-Catalyzed C-H Alkynylation of Aromatic Amides with Hypervalent Iodine-Alkyne Reagents
-
An efficient C-H activation method for the ortho alkynylation of aromatic N-methoxyamides with hypervalent iodine-alkyne reagent using a ruthenium catalyst is described. The reaction proceeds under mild reaction conditions with broad substrate scope. A possible catalytic cycle involving a ruthenium carboxylate assisted C-H bond cleavage is proposed from the preliminary mechanistic evidence.
- Boobalan, Ramadoss,Gandeepan, Parthasarathy,Cheng, Chien-Hong
-
supporting information
p. 3314 - 3317
(2016/07/23)
-
- Product Control using Substrate Design: Ruthenium-Catalysed Oxidative C?H Olefinations of Cyclic Weinreb Amides
-
A new class of Weinreb amides has been developed as directing groups for the ruthenium-catalysed regioselective oxidative C?H olefination. The new Weinreb amides successfully inhibit the N?O bond reductive cleavage usually associated with the cationic ruthenium system, thereby keeping intact the synthetic utility of Weinreb amides. Mechanistic studies reveal interesting aspects of the directing group capabilities of Weinreb amides when compared to simple amides of similar structures.
- Das, Riki,Kapur, Manmohan
-
supporting information
p. 16986 - 16990
(2016/11/17)
-
- Solvent-Controlled, Tunable β-OAc and β-H Elimination in Rh(III)-Catalyzed Allyl Acetate and Aryl Amide Coupling via C-H Activation
-
The Heck reaction between arenes and allyl acetate has led to cinnamyl derivatives and allyl products depending on the regioselectivity of β-elimination. The regioselectivity can be controlled by the solvent in the Rh(III)-catalyzed arene-allyl acetate coupling via C-H activation: (1) in THF, cinnamyl derivatives via β-H elimination were generated; (2) in MeOH, allyl products via β-OAc elimination were produced. Both routes have advantages such as excellent γ-selectivity toward allyl acetate, good to excellent yields, and broad substrate scope.
- Dai, Huimin,Yu, Chao,Wang, Zihao,Yan, Hong,Lu, Changsheng
-
supporting information
p. 3410 - 3413
(2016/07/26)
-
- Synthesis of dibenzo[c,e]oxepin-5(7H)-ones from benzyl thioethers and carboxylic acids: Rhodium-catalyzed double C-H activation controlled by different directing groups
-
A rhodium(III)-catalyzed cross-coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (C-H, C-S, O-H) and the formation of two bonds (C-C, C-O). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double C-H activation, the first of such examples in cross-oxidative coupling.
- Zhang, Xi-Sha,Zhang, Yun-Fei,Li, Zhao-Wei,Luo, Fei-Xian,Shi, Zhang-Jie
-
supporting information
p. 5478 - 5482
(2015/04/27)
-
- Rh-catalyzed oxidizing group-directed ortho C-H vinylation of arenes by vinylstannanes
-
An efficient method for the synthesis of functionalized vinyl arenes from the reaction of N-methoxybenzamides or N-phenoxyacetamides with vinylstannanes via rhodium(III)-catalyzed C-H activation is described. The application of the methodology for the synthesis of a natural product thalactamine and a 7-membered ring oxepine are also demonstrated.
- Prakash, Sekar,Muralirajan, Krishnamoorthy,Cheng, Chien-Hong
-
supporting information
p. 13362 - 13364
(2015/08/24)
-
- Copper-mediated hydroxylation of arenes and heteroarenes directed by a removable bidentate auxiliary
-
A copper-mediated C-H hydroxylation of arenes and heteroarenes using our newly developed PIP directing group has been developed. This procedure is scalable and compatible with a wide range of functional groups and heteroarenes, providing an operationally simple protocol for the synthesis of o-hydroxybenzamides. The hydroxylation of nicotinamides gave 4-oxo-1,4-dihydropyridine-3-carboxamides selectively. Preliminary mechanistic studies implicate that a basic ligand-enabled, irreversible, rate-determining CMD step is most likely involved in this process.
- Li, Xin,Liu, Yan-Hua,Gu, Wen-Jia,Li, Bo,Chen, Fa-Jie,Shi, Bing-Feng
-
supporting information
p. 3904 - 3907
(2014/08/18)
-
- Platinum on carbon-catalyzed H-D exchange reaction of aromatic nuclei due to isopropyl alcohol-mediated self- activation of platinum metal in deuterium oxide
-
An efficient and simple deuteration method of arenes using the platinum on carbon-isopropyl alcohol-cyclohexane-deuterium oxide combination under hydrogen gas-free conditions was accomplished. Since the hydrogen-deuterium exchange reaction cannot be promoted without isopropyl alcohol, zerovalent platinum metal (on carbon) is self-activated by the in situ-generated very low amount of hydrogen or hydrogen-deuterium gas derived from isopropyl alcohol or isopropyl alcohol-d1. Deuterium-labeled compounds with high deuterium contents can be easily isolated by the filtration of platinum on carbon and simple extraction. The present hydrogen gas-free method is safe from the viewpoint of process chemistry and various arenes possessing a variety of reducible functionalities within the molecule could be effectively and directly deuterium-labeled without undesired reduction. Copyright
- Sawama, Yoshinari,Yamada, Tsuyoshi,Yabe, Yuki,Morita, Kosuke,Shibata, Kyoshiro,Shigetsura, Masahiro,Monguchi, Yasunari,Sajiki, Hironao
-
supporting information
p. 1529 - 1534
(2013/06/27)
-
- Synthesis of phenanthridinones from N-methoxybenzamides and aryltriethoxysilanes through RhIII-catalyzed C-H and N-H bond activation
-
An efficient method for the one-pot synthesis of substituted phenanthridinone derivatives from N-methoxybenzamides and aryltriethoxysilanes through rhodium-catalyzed dual C-H bond activation and annulation reactions is described. A double-cycle mechanism is proposed to account for this catalytic reaction. In addition, isotope-labeling studies were performed to understand the intimate mechanism of the reaction. Keeping active: The rhodium-catalyzed C-H bond activation and annulation reactions of N-methoxybenzamides with aryltriethoxysilanes to give substituted phenanthridinone derivatives in good-to-excellent yields is described. Copyright
- Senthilkumar, Natarajan,Parthasarathy, Kanniyappan,Gandeepan, Parthasarathy,Cheng, Chien-Hong
-
supporting information
p. 2175 - 2181
(2013/09/23)
-
- Synthesis of N-alkyl and N-aryl isoquinolones and derivatives via Pd-catalysed C-H activation and cyclization reactions
-
Relatively less expensive Pd-catalysed oxidative coupling reactions for the preparation of N-alkyl and N-aryl substituted isoquinolones and their derivatives have been developed. A broad reaction scope has been demonstrated. In addition, studies of the reaction additives and mechanistic insights, as well as KIE studies for a better understanding of the reaction pathway, have been discussed.
- Zhang, Nana,Li, Binyao,Zhong, Hongban,Huang, Jianhui
-
p. 9429 - 9439
(2013/01/15)
-
- Rhodium(III)-catalyzed oxidative ciH coupling of N-methoxybenzamides with aryl boronic acids: One-pot synthesis of phenanthridinones
-
General solution: An efficient rhodium-catalyzed dual CiH bond activation and cyclization of N-methoxybenzamides 1 with aryl boronic acids 2 (see scheme; Cp=Me5C5) provides a straightforward and general approach to the phenanthridinone structure, which occurs widely in natural products and drugs. Highly regioselective CiC and CiN bond formation under mild conditions afforded a wide range of substituted phenanthridinones 3. Copyright
- Karthikeyan, Jaganathan,Haridharan, Radhakrishnan,Cheng, Chien-Hong
-
supporting information
p. 12343 - 12347
(2013/02/23)
-
- Ruthenium-catalyzed oxidative annulation by cleavage of C-H/N-H bonds
-
Bond activation in action: Unprecedented ruthenium-catalyzed oxidative annulations of alkynes through cleavage of C-H bonds set the stage for an efficient 1(2H)-isoquinolone synthesis with ample scope (see scheme; tAm=tert-amyl). Mechanistic studies provided strong evidence for a rate-limiting C-H bond metalation through carboxylate assistance. Copyright
- Ackermann, Lutz,Lygin, Alexander V.,Hofmann, Nora
-
supporting information; experimental part
p. 6379 - 6382
(2011/09/12)
-
- Efficient and selective Pt/C-catalyzed H-D exchange reaction of aromatic rings
-
An effective and applicable deuteration method for aromatic rings using Pt/C-D2O-H2 system was established. Especially, phenol was fully deuterated even at room temperature, and other electron-rich aromatic nuclei were efficiently deuterated under mild conditions. The scope and limitations of the presence method and its application to the synthesis of deuterium-labeled biologically active compounds and deuterium-labeled building blocks for practical multi-gram scale syntheses are reported. 2008 The Chemical Society of Japan.
- Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Imamiya, Eikoh,Maegawa, Tomohiro,Sajiki, Hironao
-
experimental part
p. 278 - 286
(2009/03/12)
-
- Aromatic ring favorable and efficient H-D exchange reaction catalyzed by Pt/C
-
An effective and applicable Pt/C-catalyzed deuteration method of aromatic rings using D2O as a deuterium source under hydrogen atmosphere was developed. Five percent Pt/C would lead to quite effective H-D exchange results on the aromatic ring systems. The reaction is general for a variety of aromatic compounds including biologically active compounds.
- Sajiki, Hironao,Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Maegawa, Tomohiro,Hirota, Kosaku
-
p. 6995 - 6998
(2007/10/03)
-
- Reaction of magnesium pinacolone enolate with benzaldehyde: Polar or ET mechanism?
-
The carbonyl-carbon kinetic isotope effect (KIE) and the substituent effect were measured for the reaction of magnesium pinacolone enolate (CH2=C(OMgBr)C(CH3)3, 1) with benzaldehyde. The results were compared with those for lithium enolate (CH2=C(OLi)C(CH3)3, 2). A normal carbonyl-carbon KIE, a medium-sized Hammett ρ value and the results of chemical probe experiments indicated that the reaction of 1 proceeds via the polar mechanism as in the reaction of 2.
- Yamataka, Hiroshi,Shimizu, Makoto,Mishima, Masaaki
-
p. 127 - 129
(2007/10/03)
-
- Homolytic dissociation of 1-substituted cyclohexa-2,5-diene-1-carboxylic acids: An EPR spectroscopic study of chain propagation
-
Hydrogen abstraction from 1-substituted cyclohexa-2,5-diene-1-carboxylic acids containing linear, branched and cyclic alkyl substituents, as well as allyl, propargyl (prop-2-ynyl), cyanomethyl and benzyl substituents, has been studied by EPR spectroscopy. For each carboxylic acid, EPR spectra of the corresponding cyclohexadienyl radicals were observed at lower temperatures, followed by spectra due to ejected carbon-centred radicals at higher temperatures. Rate constants, for release of the carbon-centred radicals from the cyclohexadienyl radicals, were determined from radical concentration measurements for the above range of substituents. The rate of cyclohexadienyl radical dissociation increased with branching in the 1-alkyl substituent and with electron delocalisation in the ejected carbon-centred radical; 3,5-and 2,6-dimethyl-substitution of the cyclohexadienyl ring led to reductions in the dissociation rate constants. Rate data for abstraction of bisallylic hydrogens from the cyclohexadienyl acids were also obtained for ethyl, n-propyl and isopropyl radicals. These results indicated a sharp drop in the rate of hydrogen abstraction as the degree of branching in the attacking radical increased. Small decreases in the hydrogen abstraction rate constants were observed for cyclohexadienes containing CO2R substituents.
- Jackson, Leon V.,Walton, John C.
-
p. 1758 - 1764
(2007/10/03)
-
- On the mechanism of addition of lithium pinacolone enolate to benzaldehyde: Polar or electron transfer?
-
The carbonyl-carbon kinetic isotope effect (KIE) and the substituent effect were measured for the reaction of lithium pinacolone enolate (CH2=C(OLi)C(CH3)3) with benzaldehyde, and the results were compared with those for other lithium reagents such as MeLi, PhLi, and CH2=CHCH2Li. Ab initio MO calculations (HF/6-31+G*) were carried out to estimate the equilibrium IE on the addition to benzaldehyde. A carbonyl addition reaction, in general, proceeds by way of either a polar direct nucleophilic attack (PL) in a one-step or a two-step process going through a radical ion intermediate (eq 1). The carbonyl-carbon KIE is of primary nature for the PL or the RC rate-determining ET mechanism, while it is considered to be secondary for the ET rate-determining mechanism. The reaction of lithium pinacolone enolate with benzaldehyde gave a small positive KIE (12k/13k = 1.019), which is larger than the theoretical equilibrium IE (12K/13K = 1.006) determined by the MO calculations. Thus, there is a reaction-coordinate contribution to the observed KIE. This is in sharp contrast to the absence of KIE (12k/14k = 1.000) measured previously for the MeLi addition. Dehalogenation and enone-isomerization probe experiments showed no evidence of a single electron transfer to occur during the course of the reaction. The primary carbonyl-carbon KIE together with the substituent effect and chemical probe experiments led to the conclusion that the reaction of lithium pinacolone enolate with benzaldehyde proceeds via the polar mechanism.
- Yamataka, Hiroshi,Sasaki, Daizo,Kuwatani, Yoshiyuki,Mishima, Masaaki,Tsuno, Yuho
-
p. 9975 - 9979
(2007/10/03)
-
- Semi-empirical and vibrational studies of flavone and some deuterated analogues
-
The infrared solid state, Raman solid state and tetrachloride solution spectra of flavone have been obtained.Assignments of most of the vibrational data have been performed by comparison between the spectra of flavone and three isotopic species, deuterated on the A, B and C rings, respectively.The vibrational frequencies for all the investigated compounds have been calculated from the conformational analysis of flavone using the semi-empirical AM1 method and compared with experimental values.The correlation is more or less satisfactory; however, for some vibrational modes, the calculated isotopic shifts agree better with experiment than do the frequencies themselves.Specific vibrational modes which retain a benzene ring mono-substituted and ortho-distributed character have been recognized in the spectra, according to literature data, isotopic frequency shifts and graphic representation of the atomic displacements.
- Vrielynck, L.,Cornard, J. P.,Merlin, J. C.,Lautie, M. F.
-
p. 2177 - 2188
(2007/10/02)
-
- Single-crystal proton ENDOR studies of the [Fe4S4]3+ cluster: Determination of the spin population distribution and proposal of a model to interpret the1H NMR paramagnetic shifts in high-potential ferredoxins
-
Proton ENDOR spectroscopy has been used in single crystals of the synthetic compound [N(C2D5)2[Fe4S4-(SCH 2C6D5)4], which is a good biomimetic model of the active sites of many four-iron-four-sulfur proteins. The eight protons of the four thiolate CH2 groups have been used in order to probe in detail the distribution of the unpaired electron spin population in a paramagnetic [Fe4S4]3+ center created by gamma irradiation in the crystals. The thus obtained hyperfine tensors of the eight protons constitute an original, abundant, and precise source of information on this oxidation state. They have been analyzed in two separate parts. From their anisotropic parts, it is possible to deduce the distribution of the unpaired spin population on the different iron and sulfur atoms with the help of a point-dipole model. Within the limitations of the simple and symmetric vectorial spin coupling model which involves two equivalent mixed-valence iron atoms and two equivalent ferric iron atoms, we find that this paramagnetic center is close to the |7/2,3,1/2) state, the first number representing the spin state of the mixed-valence pair, the second one the spin state of the ferric pair, and the last one the resulting spin of the cluster. This attribution is in contrast with recent proposals considering that the [Fe4S4]3+ spin state is |9/2,4,1/2). Finally, the analysis of the isotropic parts of the tensors leads us to propose a new quantitative model establishing the law existing between these isotropic couplings and two different parameters: a magnetic parameter which is the spin population on the adjacent iron and an angular parameter defining the orientation of each CH bond. This model seems indeed able to provide the basis of a quantitative interpretation of 1H paramagnetic shifts in the NMR spectra of high-potential proteins in their oxidized state. Through the variety of results obtained, the interest of the present study is also that it gives the capacity to unify the interpretations of results concerning the [Fe4S4]3+ state in the proteins and in model compounds which have been derived from the EPR, ENDOR, M?ssbauer, and NMR spectroscopies.
- Mouesca,Rius,Lamotte
-
p. 4714 - 4731
(2007/10/02)
-
- SELECTIVE MONO- OR DIMETALATION OF ARENES BY MEANS OF SUPERBASIC REAGENTS
-
If employed in tetrahydrofuran, stoichiometric amounts of butyllithium and potassium tert-butoxide react with benzene under clean monometalation.In hexane suspension, however, considerable amounts of meta- and para-disubstituted by-products are obtained (approx. 10percent).They become preponderant if a three-fold excess of the metalating agent is used.Naphthalene leads under the same conditions to a mixture of two mono- and ten di-substituted derivatives. - Alkyl groups, as present in tert-butylbenzene, retard the metalation at both m- and p-positions, while trialkylsilyl groups deactivate only m-position.In either case exclusive monosubstitution occurs. - Perdeuterobenzene undergoes metalation and subsequent electrophilic mono- or disubstitution to afford isotope labeled compounds with moderate, though synthetically attractive yields.The kinetic isotope effects and product ratios can be taken as evidence for aggregate formation at the level of both the superbasic metalating reagent and the organometallic intermediates.
- Schlosser, Manfred,Choi, Jung Hoon,Takagishi, Sadahito
-
p. 5633 - 5648
(2007/10/02)
-
- "DEUTERATED" RANEY NICKEL: DEUTERATION (REDUCTION) OF ALKENES, CARBONYL COMPOUNDS AND AROMATIC RINGS. PROTON-DEUTERIUM EXCHANGE OF "ACTIVATED" ALIPHATIC AND AROMATIC RING HYDROGENS.
-
In the absence of deuterium gas, the reaction of deuterated Raney nickel with benzene derivatives, carbonyl compounds, alkenes and activated methylene grops gave either fully deuterated (reduced) products or led to hydrogen-deuterium exchange.
- Pojer, Peter M.
-
p. 2507 - 2508
(2007/10/02)
-
- Preparation of All the Possible Ring-deuteriated Benzoic Acids by Reductive Dehalogenation of the Corresponding Halogenobenzoic Acids with Raney Alloys in an Alkaline Deuterium Oxide Solution
-
All the possible undeuteriated benzoic acids were prepared mainly by treatment of the corresponding bromobenzoic acid with Raney Cu-Al alloy in 10percent NaOD-D2O solution. 5>Benzoic acid was obtained from pentafluorobenzoic acid by a similar reaction.However, only 4>benzoic acid was prepared by decarboxylation of 4>phthalic acid.
- Tashiro, Masashi,Nakayama, Kouji,Fukata, Gouki
-
p. 2315 - 2318
(2007/10/02)
-