Organocatalytic Michael addition-lactonisation of car boxylic acids using α,β-unsaturated trichloromethyl ketones as α,β-unsaturated ester equivalents

摘要

Isothiourea HBTM-2.1 catalyses the Michael addition-lactonisation of 2-aryl and 2-alkenylacetic acids and α,β-unsaturated trichloromethyl ketones. Ring-opening of the resulting dihydropyranones and subsequent alcoholysis of the CCl_3 ketone with an excess of methanol gives a range of diesters in high dia-stereo- and enantioselectivity (up to 95:5 dr and ＞99% ee). Sequential addition of two different nucleophiles to a dihydropyranone gives the corresponding differentially substituted diacid derivative.