The title diol (6a) has been shown to be a metabolite of Rhizoctonia leguminicola, the fungus that produces two toxic indolizidine alkaloids, swainsonine (1) and slaframine (2). The structure of 6a was established spectroscopically and confirmed by synthesis of both C-8a epimers 6a and 7a. The absolute configuration was inferred from the efficient reutilization of the isolated 6a to form 1. Diol 7a could not be detected among the products of fermentation. It is noteworthy that 6a is probably an intermediate in the biosynthesis of swainsonine although it differs from the alkaloid in being epimeric at the 8a position.