[reaction: see text] We describe a catalyticasymmetricsynthesis of bothsyn- and anti-3,5-dihydroxy esters. The method relies upon catalyticasymmetric epoxidation of alpha,beta-unsaturated imidazolides and amides, using lanthanide-BINOL complexes, and diastereoselective reduction of ketones. The method was applied to the enantioselective syntheses of 1,3-polyol/alpha-pyrone natural products 9a,
Asymmetric synthesis of (S)-vigabatrin® and (S)-dihydrokavain via cobalt catalyzed hydrolytic kinetic resolution of epoxides
作者:I. Victor Paul Raj、A. Sudalai
DOI:10.1016/j.tetlet.2008.02.064
日期:2008.4
A concise route to the asymmetricsynthesis of (S)-vigabatrin® and (S)-dihydrokavain has been described using Co-catalyzed hydrolytic kinetic resolution of racemic epoxides and regiospecific opening of terminal epoxides with dimethylsulfonium methylide as the key steps.
Organocatalytic Asymmetric Peroxidation of γ,δ-Unsaturated β-Keto Esters—A Novel Route to Chiral Cycloperoxides
作者:Mary C. Hennessy、Hirenkumar Gandhi、Timothy P. O’Sullivan
DOI:10.3390/molecules28114317
日期:——
A methodology for the asymmetric peroxidation of γ,δ-unsaturated β-ketoesters is presented. Using a cinchona-derived organocatalyst, the target δ-peroxy-β-keto esters were obtained in high enantiomeric ratios of up to 95:5. Additionally, these δ-peroxy esters can be readily reduced to chiral δ-hydroxy-β-keto esters without impacting the β-ketoester functionality. Importantly, this chemistry opens
Versatile Asymmetric Synthesis of the Kavalactones: First Synthesis of (+)-Kavain
作者:Thomas E. Smith、Mabel Djang、Alan J. Velander、C. Wade Downey、Kathleen A. Carroll、Sophie van Alphen
DOI:10.1021/ol0493960
日期:2004.7.1
Three asymmetric pathways to the kavalactones have been developed. The first method is chiral auxiliary-based and utilizes aldol reactions of N-acetyl thiazolidinethiones followed by a malonate displacement/decarboxylation reaction. The second approach uses the asymmetric catalytic Mukaiyama additions of dienolate nucleophile equivalents developed by Carreira and Sato. Finally, tin-substituted intermediates, prepared by either of these routes, can serve as advanced general precursors of kavalactone derivatives via Pd(0)-catalyzed Stille couplings with aryl halides.
Application of the Cosford cross-coupling protocol for the stereoselective synthesis of (R)-(+)-goniothalamin, (R)-(+)-kavain and (S)-(+)-7,8-dihydrokavain
作者:Gowravaram Sabitha、K. Sudhakar、J.S. Yadav
DOI:10.1016/j.tetlet.2006.09.122
日期:2006.11
An efficient and versatile synthetic method has been developed and utilized for the stereoselective synthesis of (R)-(+)goniothalamin 1, (R)-(+)-kavain 2 and (S)-(+)-7,8-dihydrokavain 3. Application of the Cosford protocol and direct conversion of aldehydes to P-keto-esters are the key steps in our approach. (c) 2006 Elsevier Ltd. All rights reserved.