Comparing the Stereoselective Biooxidation of Cyclobutanones by Recombinant Strains Expressing Bacterial Baeyer–Villiger Monooxygenases
作者:Florian Rudroff、Joanna Rydz、Freek H. Ogink、Michael Fink、Marko D. Mihovilovic
DOI:10.1002/adsc.200700072
日期:2007.6.4
cyclobutanone structural motif was investigated using a collection of eight monooxygenases of different bacterial origin. This platform of enzymes is able to perform stereoselective biotransformations on an array of structurally diverse substrates. With several ketone precursors, biooxidations yielded enantiocomplementary butyrolactones as key intermediates for the synthesis of natural products and bioactive compounds
Catalytic Enantioselective Conjugate Reduction of Lactones and Lactams
作者:Gregory Hughes、Masanari Kimura、Stephen L. Buchwald
DOI:10.1021/ja0351692
日期:2003.9.1
A dramatic acceleration of the enantioselective copper-catalyzed conjugatereduction of alpha,beta-unsaturated lactones, lactams, and esters is reported upon addition of alcohol additives. Good to excellent yields and enantioselectivities were realized using a catalyst generated in situ from CuCl(2).H(2)O, t-BuONa, p-tol-BINAP, and PMHS, and this methodology was applied to the synthesis of (-)-Paroxetine
β-alkyl substituted γ-lactones and whiskey lactone analogues were synthesized, and the odor properties were evaluated. During the preparation of the chiral intermediates, we found good reaction conditions for the highly enantioselective esterification of 3-arylmethyl-2-methyl-1-propanols to kinetically resolve them. The results of the olfactoryevaluations of the synthesized lactones revealed that the alkyl
A micellar environment enables catalytic, diastereoselective and enantioselective BaeyerâVilliger oxidation of cyclobutanones (ee up to 90%) with H2O2 as oxidant using Co(Salen) catalyst 1, while the same catalytic system is inactive in organic solvents.
Azabis(oxazolines) prove to be superior ligands for the enantioselective, cobalt(II)-catalyzed conjugatereduction of α,β-unsaturated carbonylcompounds with sodium borohydride. β-Trisubstituted α,β-unsaturated esters and amides as well as γ-butenolides are readily converted to their corresponding saturated counterparts with enantioselectivities up to 97% ee.