Substituent effect on the asymmetric induction with (1R,2S,5R)-and (1S,2R,5S)-menthol auxiliaries

Abstract

Substituted benzaldehydes reacts in cis-diastcrcoselective manner with mentliyl haloacetates in the presence of phase transfer catalyst and a base in THF at room temperature to give the corresponding 3-arvloxirane-2-carboxvlates (2/3a-h) in moderate to high yields The magnitude of asymmetric induction in the latter reaction was quantified by a Hammett type equation log(2/3)x = ??r - log(2/3)X-H The stereochemistry of compounds 2 and 3 was elucidated b\ correlation with (4S. 5R)-2.4-diphenyll-4,5- dihydrooxazole-5-carboxylic acid (+)-8 as well as its enantiomer (-)-8.