Syntheses of optically active grasshopper ketone and dehydrovomifoliol as a synthetic support for the revised absolute configuration of (+)-abscisic acid

Grasshopper ketone (5) and dehydrovomifoliol (6) were synthesized in their natural and optically active forms. Comments were made on the significance of this work in relation to the (S)-stereochemistry of (+)-abscisic acid (3). Unusual selective hydrogenation of the more hindered CO group of 7 to give 9 is recorded.