Catalytic Asymmetric Synthesis of Alkyl Substituted Lactones by Enantioselective and Chemoselective Alkylation of Formylesters with Dialkylzincs UsingN,N-Dibutylnorephedrine
Enzymatic Kinetic Resolution and Chemoenzymatic Dynamic Kinetic Resolution of δ-Hydroxy Esters. An Efficient Route to Chiral δ-Lactones
作者:Oscar Pàmies、Jan-E. Bäckvall
DOI:10.1021/jo016096c
日期:2002.2.1
A successful kinetic resolution of a racemic mixture of delta-hydroxy esters 1 was obtained via lipase-catalyzed transesterification (E value up to 360). The combination of the enzymatic kinetic resolution with a ruthenium-catalyzed alcohol racemization led to an efficient dynamic kinetic resolution (ee up to 99% and conversion up to 92%). The synthetic utility of this procedure was illustrated by
Aldol reaction of 4-trimethylsiloxy-6-methylene-1,3-dioxines with chiral aldehydes: Enantioselective synthesis of 1,3-dioxin-4-ones having a 2,3-dihydroxylated alkyl group at the 6-position
A novel enantioselectivesynthesis of 1,3-dioxin-4-ones having a 2,3-dihydroxylated alkyl group at the 6-position has been accomplished by titaniumtetrachloride-mediatedaldolcondensation of silyl enol ethers derived from the 6-alkylated dioxinones with chiral 2-benzyloxypropanal. The keto group of the corresponding β-keto esters obtained after cleavage of the acetal function affords, by 1,3-syn