Stereochemistry and mechanisms of cyclopropane ring cleavage. Addition of hydrogen chloride to tetracyclo[3.2.0.02,7.04,6]heptane-1,5-dicarboxylic acid (quadricyclenedicarboxylic acid)

Abstract

Addition of hydrogen chloride to tetracyc10[3.2.0.0^2,7.0^4,6] heptane-l15-dicarboxylic acid (1, quadricyclenedicarboxylic acid) under various conditions results in two products, exo-5-chlorotricyclo[2.2,1.0^2,6] heptane-2,endo-3-dicarboxylic acid (4a) and exo-5-chlorotricyclo[2.2.1.0^2,6] heptane-2,exo-3-dicarboxylic acid (4b). Thus with this cyclopropane ring, cleavage by nucleophile proceeds by inversion and (effective) addition of electrophile proceeds by a combination of retention and inversion. The results are interpreted in terms of a homoconjugate addition process.