Relative stereochemistry of altersolanol A

Abstract

Altersolanol A (1) forms a monoisopropylidene derivative which in turn yields a triacetate and a dimethylether monoacetate. Both of the latter compounds can be aromatized but the products indicate that either an acyl or a methyl migration has taken place. The former possibility is considered to be much more likely. This and other considerations lead to structure 2 for altersolanol A acetonide. Analysis of the nuclear magnetic resonance spectra of 1 and 2 and their derivatives allows assignments of their relative configurations and conformations as 7 and 8 respectively.