EPC Synthesis of (+)-Heptelidic Acid

An EPC (enantiomerically pure compound) synthesis of the antibiotic natural product (+)-heptelidic acid (1) is presented. Key step of the synthesis is a conjugate addition of the acetal protected vinyl cuprate 4 to the auxiliary shielded enoate 5n which gives the adduct 7n as a single diastereomer. After cleavage of the acetal protecting group and of the chiral auxiliary the enantiomerically pure β-ketoester 12 has been obtained which has been transformed to the title compound 1 (11 steps starting from 5n, 10.6% overall yield).