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Application of Sharpless asymmetric epoxidation on the preparation of the optically active flavours 3‐methylthiohexanal and 5(6)‐butyl‐1,4‐dioxan‐2‐one
Author(s) -
Tian Hongyu,
Sun Baoguo,
Tang Liwei,
Ye Honglin
Publication year - 2011
Publication title -
flavour and fragrance journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.393
H-Index - 70
eISSN - 1099-1026
pISSN - 0882-5734
DOI - 10.1002/ffj.2017
Subject(s) - chemistry , racemization , enantiomeric excess , enantiomer , chloride , optically active , organic chemistry , swern oxidation , medicinal chemistry , stereochemistry , enantioselective synthesis , catalysis , dimethyl sulfoxide
Optically active 2,3‐epoxyhexanol obtained from Sharpless asymmetric epoxidation (AE) was regioselectively reduced to 1,3‐hexandiol or 1,2‐hexandiol. 1,3‐Hexandiol was converted to 3‐mesyloxyhexyl acetate. The following reaction with CH 3 SK gave 3‐methylthiohexanol, which was oxidized through Swern oxidation to produce 3‐methylthiohexanal. 5‐ and 6‐Butyl‐1,4‐dioxan‐2‐one were formed concurrently by the reaction of 1,2‐hexandiol with 2‐bromoacetic chloride and the ratio of 5‐butyl isomer to 6‐butyl isomer was about 1:4. The enantiomeric excess values of both enantiomers of 3‐methylthiohexanal and 5(6)‐butyl‐1,4‐dioxan‐2‐one were about 90%, which were very close to those of 2,3‐epoxyhexanol (about 94% ee). No obvious racemization occurred during the transformation from the Sharpless AE products to the final products.