Studies on the Syntheses of Diterpenoids and Macrolides

Abstract

<p>Firstly, synthetic routes to diterpenoids based on the labdane skeleton from naturally occurring podocarpic acid were studied. The diterpenoids lambertianic acid and methyl 12-hydroxylabd-8(17)-en-19-oate as well as the lactones 8α-hydroxy-(13→17)-pentanor-9β-labdan-12,19-dioic acid 19-methyl ester 8α→12 lactone and 8α-hydroxy-(13→17)-pentanor-9α-labdan-12, 19-dioic acid 19-methyl ester 8α→12 lactone have been synthesized. The conformational analyses of these and two other lactones in the series were performed by application of the nuclear Overhauser effect. Alternative routes to the synthetically useful intermediate dimethyl (13→16)-tetranorlabd-8(17)-en-12, 19-dioate and the application of another intermediate methyl 12-oxo-(13→16)-tetranorlabd-8(17)-en-19-oate to the synthesis of other diterpenoid systems were investigated.</p> <p>Secondly, a unique approach to the synthesis of erythromycin A, involving the stereoselective synthesis of the precursor, (±)2(R), 4-dimethyl-3(R)-methoxymethoxy-4(E)-heptenoic acid, of the 9→13 carbon fragment, was studied.</p>