77943-78-3Relevant academic research and scientific papers
Convenient Preparation of Optically Pure Propargylic Alcohols Using 2-(Trimethylsilyl)vinyl Sulfoxide As A Novel Chiral Synthon
Kusuda, Shinya,Kawamura, Kiyoshi,Ueno, Yoshio,Toru, Takeshi
, p. 6587 - 6590 (2007/10/02)
Both enentiomers of optically pure propargylic alcohols are conveniently prepared by the reaction of α-vinyl anion of 2-(trimethylsilyl)vinyl p-tolyl sulfoxide with aldehydes and subsequent either desilylsulfination or thermal elimination of the sulfinyl group.
Selective Reductions. 37. Asymmetric Reduction of Prochiral Ketones with B-(3-Pinanyl)-9-borabicyclononane
Brown, Herbert C.,Pai, G. Ganesh
, p. 1384 - 1394 (2007/10/02)
The chiral trialkylborane B-(3-pinanyl)-9-borabicyclononane, either with the neat reagents or concentrated solutions, 2 M, reduces a wide range of prochiral carbonyl compounds with good to excellent asymmetric induction.Reduction of simple dialkyl ketones, 2-butanone, 2-octanone, 3-methyl-2-butanone, and 3,3-dimethyl-2-butanone, yields the corresponding alcohols with 43percent, 48percent, 62percent, and 0.7percent asymmetric induction.Acetophenone is reduced to 1-phenylethanol in 85percent ee.The α,β-unsaturated ketones 3-buten-2-one, 1-acetyl-1-cyclohexene, 3-methyl-2-cyclohexenone, and trans-4-phenyl-3-buten-2-one are reduced to the corresponding allylic alcohols with 57percent, 64percent, 11percent, and 97percent asymmetric induction, respecticvely.The α,β-conjugated acetylenic ketones 3-butyn-2-one, 4-methyl-1-pentyn-3-one, and 4-phenyl-3-butyn-2-one underwent a rapid reduction to afford the corresponding propargylic alcohols with 79percent, 99percent, and 91percent enantiomeric purities.The α-haloalkyl aromatic ketones α-chloroacetophenone, α-bromoacetophenone, α-iodoacetophenone, α,p-dibromoacetophenone, α-bromo-p-cyanoacetophenone,α-bromo-2'-acetonaphthone,and α,α,α-trifluoroacetophenone afforded the corresponding halohydrins with 96percent,93percent,93percent,96percent,96percent,90percent,and35percent enantiomeric purities, respectively.The corresponding aliphatic analogue 1-bromo-3-methyl-butanone gave the halohydrin in 66percent ee.The other isomer of this ketone, 3-bromo-3-methyl-2-butanone, failed to undergo reduction.Both the aliphatic and aromatic α-keto esters underwent rapid reduction to give the corresponding α-hydroxy esters with excellentenantiomeric excesses.Thus, methyl, ethyl, isopropyl, and tert-butyl pyruvates afforded the corresponding lactates with 86percent,83percent,78percent, and 92percent ee at 25 deg C,respectively.Lowering the reaction temperature to 0 deg C gave the tert-butyl lactate in 100percent ee.Other aliphatic α-keto esters such as metyl and ethyl 2-oxopentanoates, methyl 3-methyl-2-oxobutanoate, and ethyl 4-methyl-2-oxopentanoate were reduced to the corresponding α-hydroxy esters with 96percent, 96percent, 11percent, and 82percent ee.The methyl, isopropyl, and tert-butyl benzoylformates were reduced to the corresponding mendelic esters with 90percent, 96percent and 100percent ee, respectively.The reduction of the β-keto esters, however, proceeded slowly and ethyl acetoacetate gave the corresponding alcohol with 55percent ee.
Asymmetric Reduction of Ketones with B-(cis-10-Pinanyl)-9-borabicyclononane. Observation of a Change in Enantioselection between Similar Organoborane and Organoaluminium Reagents
Midland, Mark M.,McLoughlin, Jim I.
, p. 4101 - 4102 (2007/10/02)
The title reagent reduces prochiral ketones of moderate steric bulk in modest to good enantiomeric excesses of the S alcohols.The absolute configuration is the opposite of that obtained with a similar organoaluminium reagent.
Improved Procedure for the Asymmetric Reduction of Prochiral Ketones by B-(3-Pinanyl)-9-borabicyclononane
Brown, Herbert C.,Pai, Ganesh G.
, p. 1606 - 1608 (2007/10/02)
An improved experimental procedure gives good optical induction in the reduction of nonacetylenic prochiral ketones, using the chiral trialkylborane B-(3-pinanyl)-9-borabicyclononane (Midland's reagent).
