Asymmetric dihydroxylation of vinyl sulfones: routes to enantioenriched α-hydroxyaldehydes and the enantioselective syntheses of furan-2(5H)-ones
作者:Paul Evans、Mélanie Leffray
DOI:10.1016/j.tet.2003.08.003
日期:2003.9
dihydroxylation of α,β-unsaturated sulfones under Sharpless conditions affords enantioenriched α-hydroxyaldehydes in a complex mixture of dimeric species. These mixtures undergo olefination generating the corresponding α,β-unsaturated esters or furan-2(5H)-ones with high levels of enantiomeric excess. The application of this method for the rapid stereoselective synthesis of the furanone natural products; quercus
Chemoenzymatic synthesis of optically active γ-alkyl-γ-butenolides
作者:Mikio Fujii、Motonori Fukumura、Yumiko Hori、Yasuaki Hirai、Hiroyuki Akita、Kaoru Nakamura、Kazuo Toriizuka、Yoshiteru Ida
DOI:10.1016/j.tetasy.2006.08.001
日期:2006.9
rac-Hept-1-en-3-ol 4 was subjected to an enantioselective esterification in the presence of Novozyme 435 and vinyl crotonate as the acyl donor to give (3S)-oct-1-en-3-yl crotonate 7 in >99% ee and (3R)-alcohol 4 in 99% ee. The E-value of this enzymatic reaction was found to be >1000. The (S)-crotonic ester 7 was converted by ring-closing metathesis (RCM) using Grubbs’ catalyst to give (S)-oct-2-en-4-olide
An asymmetric isomerization of β,γ-unsaturated butenolides with a newly developed betaine catalyst at a 0.2–2 mol% loading, an improvement upon available methods that use 0.5–2.0 mol% catalyst.
First example of hydrolytic kinetic resolution of acrylate of secondary alcohols by lipase Amano AK
作者:Pranjal P. Bora、Ghanashyam Bez、Jasha Momo H. Anal
DOI:10.1016/j.molcatb.2011.06.015
日期:2011.11
Lipase Amano AK is found to be extremely efficient catalyst for hydrolytic kinetic resolution of acrylates of secondary alcohols in aqueous phosphate buffer at pH 7.0. Both aliphatic and benzylic secondary alcohols show good to excellent E values. (C) 2011 Elsevier B.V. All rights reserved.