- Synthesis of Weinreb amides using diboronic acid anhydride-catalyzed dehydrative amidation of carboxylic acids
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The first successful example of the direct synthesis of Weinreb amides using catalytic hydroxy-directed dehydrative amidation of carboxylic acids using the diboronic acid anhydride catalyst is described. The methodology is applicable to the concise syntheses of eight α-hydroxyketone natural products, namely, sattabacin, 4-hydroxy sattabacin, kurasoins A and B, soraphinols A and B, and circumcins B and C.
- Shimada, Naoyuki,Takahashi, Naoya,Ohse, Naoki,Koshizuka, Masayoshi,Makino, Kazuishi
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supporting information
p. 13145 - 13148
(2020/11/09)
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- Access to β-Hydroxyl Esters via Copper-Catalyzed Reformatsky Reaction of Ketones and Aldehydes
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An efficient and simple Cu-catalyzed Reformatsky reaction of ketones and aldehydes has been accomplished with ethyl iodoacetate. Excellent yields of β-hydroxyl esters were achieved with a range of ketones and aldehydes, which varied from aromatic to aliphatic, unsaturated to saturated ketones and aldehydes. This practical and convenient transformation was conducted with inexpensive, readily available, and commercial starting materials under mild reaction conditions.
- Ouyang, Lu,Liao, Jian Hua,Xia, Yan Ping,Luo, Ren Shi
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supporting information
p. 1418 - 1422
(2020/10/02)
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- Iron(0)-Mediated Reformatsky Reaction for the Synthesis of β-Hydroxyl Carbonyl Compounds
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An efficient, economical, and practical Reformatsky reaction of α-halo carbonyl compounds with aldehydes/ketones by using cheap and commercial iron(0) powder as reaction mediator is developed. The reactions proceeded effectively in the presence of a catalytic amount of iodine (20 mol %) to afford the synthetically useful β-hydroxyl carbonyl compounds in moderate to good yields.
- Liu, Xuan-Yu,Li, Xiang-Rui,Zhang, Chen,Chu, Xue-Qiang,Rao, Weidong,Loh, Teck-Peng,Shen, Zhi-Liang
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supporting information
p. 5873 - 5878
(2019/08/20)
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- One-pot enol silane formation-Mukaiyama aldol reactions: Crossed aldehyde-aldehyde coupling, thioester substrates, and reactions in ester solvents
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Trimethylsilyl trifluoromethanesulfonate (TMSOTf) and a trialkylamine base promote both in situ enol silane/silyl ketene acetal formation and Mukaiyama aldol addition reactions between a variety of reaction partners in a single reaction flask. Isolation of the required enol silane or silyl ketene acetal is not necessary. For example, crossed aldol reactions between α-disubstituted aldehydes and non-enolizable aldehydes yield β-hydroxy aldehydes in good yield. In a related reaction, the common laboratory solvent ethyl acetate functions as both an enolate precursor and a green reaction solvent. When thioesters are employed as enolate precursors, high yields for additions to non-enolizable aldehydes are routinely observed.
- Downey, C. Wade,Dixon, Grant J.,Ingersoll, Jared A.,Fuller, Claire N.,MacCormac, Kenneth W.,Takashima, Anna,Sediqui, Rohina
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supporting information
(2019/10/14)
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- Vinylogous organocatalytic triple cascade reaction: Forging six stereocenters in complex spiro-oxindolic cyclohexanes
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We report a triple vinylogous cascade reaction, yielding valuable spiro-oxindolic cyclohexane derivatives. The three-component domino process proceeds by way of a catalyzed Michael/1,6-addition/vinylogous aldol sequence affording the products with six stereogenic centers and very high control over the stereochemistry. The chemistry is based on a rare example of asymmetric 1,6-addition to linear 2,4-dienals proceeding with complete δ-site selectivity. Key to the reaction development was a directing group positioned at the β-dienal position, which was essential for achieving highly predictable reaction outcomes. Copyright
- Chatterjee, Indranil,Bastida, David,Melchiorre, Paolo
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supporting information
p. 3124 - 3130
(2013/12/04)
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- A rapid and diverse construction of 6-substituted-5,6-dihydro-4-hydroxy-2- pyrones through double Reformatsky reaction
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A rapid and diverse synthesis of biologically important 6-substituted-5,6-dihydro-4-hydroxy-2-pyrones through a double Reformatsky reaction of aldehydes to δ-hydroxy-β-ketoesters followed by lactonization is described. Due to the high functional group tolerance and reaction site discrimination between aldehyde, nitrile, and ester groups in the substrate, the protocol can provide the dihydropyrones with bromo, nitro, carboxylic acid, and β-ketoester groups, which are suitable for the further derivatizations. Furthermore, the protocol has been successfully applied to the rapid total synthesis of naturally occurring Yangonin.
- Mineno, Masahiro,Sawai, Yasuhiro,Kanno, Kazuaki,Sawada, Naotaka,Mizufune, Hideya
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p. 10921 - 10926
(2014/01/06)
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- N-heterocyclic carbene mediated Reformatsky reaction of aldehydes with a-trimethylsilylcarbonyl compounds
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N-Heterocyclic carbenes have been employed as highly efficient organocatalysts to mediate silyl-Reformatsky type reaction. In the presence of only 0.5 mol % nucleophilic carbene 1, various aldehydes coupled with α-trimethylsilylethylacetate very smoothly in DMF at room temperature to provide the corresponding β-hydroxyesters in moderate to high yields. α-Trimethylsilylketone and α-trimethylsilylamide can also undergo the addition reaction to give β-hydroxyketone and b-hydroxyamide in moderate yields.
- Zou, Xiao-Lei,Du, Guang-Fen,Sun, Wan-Fu,He, Lin,Ma, Xiao-Wei,Gu, Cheng-Zhi,Dai, Bin
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p. 607 - 612
(2013/07/27)
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- Stereoselective synthesis of aryl γ,δ-unsaturated β-hydroxyesters by ketoreductases
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The biocatalytic reduction of aryl γ,δ-unsaturated-β- ketoesters was evaluated utilizing 24 different commercially available ketoreductases. In all cases, both (R) and (S)-enantiomers of γ,δ-unsaturated β-hydroxyesters were synthesized by one or more keto
- Dai, Zhipeng,Guillemette, Kate,Green, Thomas K.
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p. 264 - 269
(2013/10/21)
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- Turnagainolides A and B, cyclic depsipeptides produced in culture by a Bacillus sp.: Isolation, structure elucidation, and synthesis
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Two new cyclic depsipeptides, turnagainolides A (1) and B (2), have been isolated from laboratory cultures of a marine isolate of Bacillus sp. The structures of 1 and 2, which are simply epimers at the site of macrolactonization, were elucidated by analysis of NMR data and chemical degradation. A total synthesis of the turnagainolides confirmed their structures. Turnagainolide B (2) showed activity in a SHIP1 activation assay. (Chemical Equation Presented).
- Li, Dehai,Carr, Gavin,Zhang, Yonghong,Williams, David E.,Amlani, Ashraf,Bottriell, Helen,Mui, Alice L.-F.,Andersen, Raymond J.
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experimental part
p. 1093 - 1099
(2011/08/03)
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- P(i-PrNCH2CH2)3N: Efficient catalyst for synthesizing β-hydroxyesters and α,β-unsaturated esters using α-trimethylsilylethylacetate (TMSEA)
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(Chemical Equation Presented) We present an efficient synthesis of β-hydroxyesters and R,β-unsaturated esters via activation of the silicon-carbon bond of α-trimethylsilylethylacetate using catalytic amounts of the commercially available P(i-PrNCH2CH2) 3N 1a. Selectivity for either of these two products can be achieved simply by altering the catalyst loading and reaction temperature to afford addition or stereoselective condensation. This method is mild and tolerates a wide array of functional groups.
- Wadhwa, Kuldeep,Verkade, John G.
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supporting information; experimental part
p. 4368 - 4371
(2009/09/06)
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- Temporary silicon connection strategies in intramolecular allylation of aldehydes with allylsilanes
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(Chemical Equation Presented) Three γ-(amino)silyl-substituted allylsilanes 14a-c have been prepared in three steps from the corresponding dialkyldichlorosilane. The aminosilyl group has been used to link this allylsilane nucleophile to a series of β-hydroxy aldehydes through a silyl ether temporary connection. The size of the alkyl substituents at the silyl ether tether governs the outcome of the reaction on exposure to acid. Thus, treatment of aldehyde (E)-9aa, which contains a dimethylsilyl ether connection between the aldehyde and allylsilane, with a range of Lewis and Bronsted acid activators provides an (E)-diene product. The mechanism of formation of this undesired product is discussed. Systems containing a sterically more bulky diethylsilyl ether connection react differently: thus in the presence of TMSOTf and a Bronsted acid scavenger, intramolecular allylation proceeds smoothly to provide two out of the possible four diastereoisomeric oxasilacycles, 23 (major) and 21 (minor). A diene product again accounts for the remaining mass balance in the reaction. This side product can be completely suppressed by using a sterically even more bulky diisopropylsilyl ether connection in the cyclization precursor, although this is now at the expense of a slight erosion in the 1,3-stereoinduction in the allylation products. The sense of 1,3-stereoinduction observed in these intramolecular allylations has been rationalized by using an electrostatic argument, which can also explain the stereochemical outcome of a number of related reactions. Levels of 1,4-stereoinduction in the intramolecular allylation are more modest but can be significantly improved in some cases by using a tethered (Z)-allylsilane in place of its (E)-stereoisomer. Oxidation of the major diastereoisomeric allylation product 23 under Tamao-Kumada conditions provides an entry into stereodefined 1,2-anti-2,4-syn triols 28.
- Beignet, Julien,Jervis, Peter J.,Cox, Liam R.
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p. 5462 - 5475
(2008/12/21)
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- Solvent-free synthesis of β-hydroxy esters and β-amino esters by indium-mediated reformatsky reaction
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In a convenient and efficient procedure for the solvent-free synthesis of β-hydroxy esters and β-amino esters, various aldehydes and aldimines undergo a Reformatsky reaction mediated by non-activated indium at room temperature to give the corresponding esters in good to excellent yields. Georg Thieme Verlag Stuttgart.
- Chen, Xi'an,Zhang, Changfu,Wu, Huayue,Yu, Xiaochun,Su, Weike,Cheng, Jiang
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p. 3233 - 3239
(2008/09/16)
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- An efficient cobalt(I)-catalysed reformatsky reaction using α-chloro esters
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An efficient cobalt(I)-catalysed Reformatsky reaction using α-chloro esters has been developed. The catalyst is prepared by reducing the cobalt(II) chloride (5%)/1,2-bis(diphenylphosphino)ethane (dppe)(5%)/zinc iodide (10%) system with zinc metal in acetonitrile in the presence of both the α-chloro ester and the carbonyl compound; good to excellent conversions to β-hydroxy esters are obtained at room temperature in 2.5 h.
- Lombardo, Marco,Gualandi, Alessandra,Pasi, Filippo,Trombini, Claudio
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p. 465 - 468
(2008/02/08)
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- Palladium-catalyzed arylation of α,α-difluoro-allylic-β-hydroxyester
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The aryl-substituted α,α-difluoro-allylic-β-hydroxyesters and aryl-substituted α,α-difluoroketones were obtained via the coupling reaction of aryl iodides with α,α-difluoro-allylic-β-hydroxyester in the presence of Pd(OAc)2 as the catalyst and Et3N as the base.
- Fang, Xiang,Yang, Xueyan,Yang, Xianjin,Zhao, Min,Chen, Guorong,Wu, Fanhong
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p. 8231 - 8234
(2007/10/03)
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- Regioselective palladium-catalyzed allylic alkylations
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Palladium-catalyzed allylic alkylations on asymmetrical allylic carbonates using a variety of chiral ligands gave good to excellent ee's and poor to excellent regioselectivity depending on the nucleophile used.
- Dong, Ying,Teesdale-Spittle, Paul,Hoberg, John O.
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p. 353 - 355
(2007/10/03)
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- New application of bromotrimethylsilane: Elaboration of aldehydes/ketones into homologous α,β-unsaturated esters via β-hydroxy esters
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α,β-Unsaturated esters are formed when β-hydroxy esters react with bromotrimethylsilane which is generated from chlorotrimethylsilane- lithium bromide in acetonitrile. Copyright Taylor & Francis, Inc.
- Suri, Suresh C.,Marcischak, Jacob C.
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p. 379 - 387
(2007/10/03)
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- Metal chloride-promoted aldol reaction of α-dimethylsilylesters with aldehydes, ketones, and α-enones
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In the presence of a catalytic amount of LiCl, α-dimethylsilylesters (α-DMS-esters) 1 smoothly reacted with various aldehydes at 30°C to give aldols in good to high yields. On the other hand, the aldol reaction with ketones was effectively promoted by MgCl2 rather than by LiCl. α-Enones also underwent the metal chloride-promoted addition of 1 at the carbonyl carbon or β-carbon. Georg Thieme Verlag Stuttgart.
- Miura, Katsukiyo,Nakagawa, Takahiro,Hosomi, Akira
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p. 1917 - 1921
(2007/10/03)
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- The β-lactone route to α,β-unsaturated δ-lactones. Total syntheses of (±)-goniothalamin and (-)-massoialactone
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The HF-induced translactonization of 2′-silyloxy-3-trimethylsilyl-2- oxetanones, obtained through Lewis acid-promoted [2+2] cycloaddition between β-silyloxyaldehydes and trimethylsilylsilylketene, into α,β-unsaturated δ-lactones is applied to the syntheses of (±)-goniothalamin and (-)-massoialactone.
- Fournier, Lycia,Kocienski, Philip,Pons, Jean-Marc
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p. 1659 - 1663
(2007/10/03)
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- Studies on the stereoselective selenolactonization, hydroxy and methoxy selenenylation of α- and β-hydroxy acids and esters. Synthesis of δ- and γ-lactones
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The diastereoselective synthesis of hydroxy substituted γ- and δ-lactones was accomplished following two approaches. A 5- or 6-endo cyclization promoted by electrophilic selenium reagents of α- or β-hydroxy acids and a 5- or 6-exo cyclization of hydroxy esters obtained through a diastereoselective hydroxy selenenylation reaction of α- or β-hydroxy esters. Moreover, the diastereoselective methoxy selenenylation of the above compounds was investigated showing a case in which the compound that was unreactive in the hydroxy selenenylation conditions gave, in the methoxy selenenylation conditions, the deprotected diol. The usefulness of the methoxy selenenylation procedure was proven by the preparation of a symmetric compound unsymmetrically functionalized. Yields and selectivities were found to depend on substituents (Ph or alkyl groups at the carbon atom that undergoes the nucleophilic attack), mode of cyclization, kinetic or thermodynamic control conditions. In the latter case, silica gel played an important role.
- Aprile, Carmela,Gruttadauria, Michelangelo,Amato, Maria E.,D'Anna, Francesca,Lo Meo, Paolo,Riela, Serena,Noto, Renato
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p. 2241 - 2251
(2007/10/03)
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- 1-Dodecyloxy-4-perfluoroalkylbenzene as a Novel Efficient Additive in Aldol Reactions and Friedel-Crafts Alkylation in Supercritical Carbon Dioxide
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matrix presented 1-Dodecyloxy-4-perfluoroalkylbenzenes accelerated organic reactions such as aldol-type reactions and Friedel-Crafts alkylation in supercritical carbon dioxide. The perfluoroalkylbenzene worked as a surfactant in the system, and formation of emulsions during the reactions was observed.
- Komoto, Ichiro,Kobayashi, Shu
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p. 1115 - 1117
(2007/10/03)
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- Stereocontrol in a one-pot procedure for anionic oxy-Cope rearrangement followed by intramolecular aldol reaction
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Racemic β-hydroxycyclohexanones with up to three chiral centres have been synthesized in a stereocontrolled way using the novel anionic oxy-Cope (AOC) rearrangement of acyclic enol ethers. The first examples of compounds containing an aldehyde and an enol ether in a 1,5 relationship are reported. Stereocontrol in the cyclisation of these compounds by a 6-(enolendo)-exo-trig intramolecular aldol reaction has been studied: there is high stereoselectivity for an axial hydroxy group in the product β-hydroxycyclohexanones. AM1 calculations show that there is a stabilising electrostatic attraction between the oxygen atom of the axial C-3 hydroxy group and the electron-poor carbon at C-1 in the intermediate oxonium ions. ≥87% of AOC rearrangement occurs via a chair-like transition state giving rise to the 5,6-anti stereochemistry of the β-hydroxycyclohexanones. Trapping the enolate product of AOC rearrangement with oxygen gives fragmentation via a 1,2-dioxetane.
- Rutherford, Alistair P.,Gibb, Cameron S.,Hartley, Richard C.,Goodman, Jonathan M.
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p. 1051 - 1061
(2007/10/03)
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- Lewis acid catalysis in a supercritical carbon dioxide (scCO2)-poly(ethylene glycol) derivatives (PEGs) system: Remarkable effect of PEGS as additives on reactivity of Ln(OTf)3-catalyzed Mannich and aldol reactions in scCO2
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Use of poly(ethylene glycol) derivatives (PEGs) as additives in supercritical carbon dioxide (scCO2) was found to be effective for Mannich and aldol reactions of silyl enolates with aldehydes and imines, and formation of emulsions was observed in these systems.
- Komoto,Kobayashi
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p. 1842 - 1843
(2007/10/03)
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- Substituent effects on the stereochemical course of electrophile- initiated tetrahydropyran-forming reactions: A possible stereoelectronic effect
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A series of 4-penten-1,3-diol derivatives were prepared and treated with phenylselenenyl chloride to provide tetrahydropyrans. The stereochemical course of the reactions is consistent with a chair-like transition state in which the oxygen substituent at the 3-position largely occupies an axial site. A structurally related 3-methyl-4-penten-1-ol derivative gave a major product consistent with a chair transition state in which the methyl group occupies an equatorial site.
- Hart, David J.,Patterson, Suzanne,Zakarian, Alain
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p. 1025 - 1028
(2007/10/03)
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- Uncatalyzed aldol reaction using a dimethylsilyl enolate and α- dimethylsilyl ester in N,N-dimethylformamide
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Dimethylsilyl enolates and α-dimethylsilyl esters reacted with aldehydes in N,N-dimethyl-formamide without an activator to give aldol adducts in moderate to good yields. Under the same conditions, the corresponding trimethylsilyl derivatives exhibited lower reactivities toward the aldol reaction.
- Miura, Katsukiyo,Sato, Hiroshi,Tamaki, Kentaro,Ito, Hajime,Hosomi, Akira
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p. 2585 - 2588
(2007/10/03)
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- Stereoselective synthesis of β-hydroxycyclohexanones
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We have developed a stereoselective route to β-hydroxycyclohexanones using the aldol reaction, the Takai alkylidenation, a novel anionic oxy-Cope rearrangement of acyclic enol ethers and an intramolecular aldol reaction. The stereoselectivity of the acid-induced, 6-(enolendo)-exo-trig, intramolecular, aldol reaction between an aldehyde and an enol ether has been investigated. The strong preference for an axial hydroxyl in the β-hydroxycyclohexanone products is explained in terms of an electrostatic interaction in the oxonium ion intermediate.
- Rutherford, Alistair P.,Gibb, Cameron S.,Hartley, Richard C.
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p. 685 - 688
(2007/10/03)
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- Catalysts for production of β-hydroxy carbonyl compounds
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The invention relates to catalysts for the synthesis of β-hydroxy carbonyl compounds, and in particular to enantioselective catalysts.
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- Rearrangement of Allylic Cyclic Sulfites to Allylic Sultones
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Rearrangement of allylic cyclic sulfites 2 to allylic sultones 8 upon treatment with boron trifluoride etherate is described.
- Duffy, Daniel E.,Condit, Fletcher H.,Teleha, Christopher,Wang, Chia-Lin J.,Calabrese, Joseph C.
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p. 3667 - 3670
(2007/10/02)
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- A Barbier allylation and a Reformatsky reaction of carbonyl compounds mediated by indium(I) iodide
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Indium(I) iodide was found to mediate in the Barbier allylation and in the Reformatsky reaction of aldehydes and ketones to give homoallylic alcohols and β-hydroxy esters, respectively, presumably via allylindium(III) diiodide.
- Araki, Shuki,Ito, Hirokazu,Katsumura, Nobuhito,Butsugan, Yasuo
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p. 291 - 296
(2007/10/02)
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- SYNTHESIS OF β-HYDROXYESTERS BY REFORMATSKY REACTION USUNG INDIUM METAL
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Indium-mediated Reformatsky reaction gave good yields of β-hydroxyesters under very mild reaction conditions.
- Araki, Shuki,Ito, Hirokazu,Butsugan, Yasuo
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p. 453 - 458
(2007/10/02)
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- REFORMATSKY TYPE REACTION WITH NEW ALUMINIUM REAGENTS CONTAINING Al-Sn OR Al-Pb LINKAGE.
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Treatment of alpha -bromo carbonyl compounds with the reagent prepared from n-Bu//3SnLi and Et//2AlCl or from SnCl//2 and Et//2AlCl affords enolates which react with ketone or aldehyde to give beta -hydroxy carbonyl compounds in good to excellent yields. The reactions proceed similarly with the reagents which are generated from R//3PbLi (R equals Ph, n-Bu) and Et//2AlCl. Catalysis by the added Pd(PPh//3)//4 complex promotes the reduction effectively and improves the yields of the desired adducts. The regio- and stereoselectivities are disclosed.
- Matsubara,Tsuboniwa,Morizawa,Oshima,Nozaki
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p. 3242 - 3246
(2007/10/02)
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