( R)- or ( S)-4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoic acid as a new chiral auxiliary for solid phase asymmetric Diels–Alder reactions

Abstract

The synthesis of enantiopure ( R)- and ( S)-4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoic acid is described and the corresponding supported chiral acrylate derivative has been used as a dienophile in solid phase asymmetric Diels–Alder reactions with different dienes. In all cases, the reaction gave the expected compound in good yield and with high regio or endo selectivity. Moreover, a high facial diastereoselectivity (86–99% de) was obtained using 2,3-dimethylbutadiene, cyclopentadiene or 1,3-cyclohexadiene. In contrast, low to moderate facial diastereoselectivity (40–76% de) was observed with isoprene depending on the polymer used.