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1,2‐Stereoinduction in Radical Reactions: Stereoselective Synthesis of 2‐Alkyl‐3‐hydroxybutanoates
Author(s) -
Bulliard Michel,
Zehnder Margareta,
Giese Bernd
Publication year - 1991
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19910740722
Subject(s) - chemistry , stereoselectivity , steric effects , alkyl , diastereomer , selectivity , radical cyclization , free radical reaction , stereochemistry , medicinal chemistry , organic chemistry , radical , catalysis
Radical addition to 2‐cyclohexyl‐5‐methylidene‐6‐methyl‐1,3‐dioxan‐4‐one ( 2 ) affords stereoselectively 5,6‐ trans ‐products trans ‐ 3 . The size of the radical has no influence on the selectivity. These trans ‐acetals are converted into threo ‐3‐hydroxy‐butanoates 4 . Methyl 2‐methylidene‐3‐[( tert ‐butyl)diphenylsilyloxy]butanoate ( 5 ), treated under the same conditions, leads mainly to the erythro‐isomer of 4 after deprotection. An influence of the steric bulkyness of the radical is observed. The stereochemical course of the reactions is discussed.