TOTAL SYNTHESIS OF GIBBERELLIC-ACID - NEW AND EFFECTIVE ROUTE TO A KEY TRICYCLIC INTERMEDIATE

A stereospecific total synthesis of gibbereilic acid (GA3,1),the first to be realized, has recently been reported.1 A crucialpart of this effort was the construction of the tricyclic diene 2, a substance whose synthesis is considerably more challengingthan might be expected for a molecule of its size. The problemof developing effective approaches to the tricyclic bridgedstructure 2 is of interest not only in connection with the synthesis of GA3, but because it exposes some major gaps in cur-rent synthetic methodology. This communication outlinesanother approach to the synthesis of 2 which has emerged fromour program.© 1979, American Chemical Society. All rights reserved.