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 beta-ketoester 12 has been obtained which has been transformed to the title compound 1 (11 steps starting from 5n, 10.6% overall yield).
A key step towards EPC synthesis of (+)-heptelidic acid
作者:Gerhard Riehs、Ernst Urban、Horst Völlenkle
DOI:10.1016/0040-4020(96)00428-0
日期:1996.6
blocks for the EPCsynthesis of the antibiotic (+)-heptelidicacid, was determined by X-ray structure analysis. Conjugate addition of an acetal protected vinylcuprate to the 5′R configurated enoate 3n gave adduct 9n as a single diastereomer in 79% yield. Further, cleavage of the auxiliary and of the acetal protecting group from 9n were studied. Finally, we obtained the silyl protected β-ketoester 13
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 beta-ketoester 12 has been obtained which has been transformed to the title compound 1 (11 steps starting from 5n, 10.6% overall yield).