Synthetic Plant Growth Regulators. III. The Preparation of Further Tricyclic Helminthosporic Acid Analogues with Gibberellin-like Properties

Abstract

7-Methyl-7,8-dihydro-4a,7-methano-4aH-benzocycloheptene-2,6(9H,5H-dione (6) was prepared and reduced to a 3 : 7 mixture of the trans- and cis-decalin derived ketones (8) and (15). Each compound was further elaborated to the plant-growth-promoting acids (13), (14), (16) and (17). Dienone (5) was also reduced (NaBH₄, hydrogenation) to a 7 : 3 mixture of the cis- and trans-decalin derivatives (11) and (9). The stereochemistry of (11), and by inference (12), was determined by correlation with the known ketone (7).