A new sapogenin I was synthesized from diosgenin. Treatment of 3-methanesulfonyloxyspirostan-6-one II (R = H, R1 = b-O3SMe), derived from diosgenin, with LiBr in refluxing DMF yielded II (RR1 = bond) in good yield. The latter compound was transformed into II (R = OH, R1 = a-OH) by catalytic osmylation. In the presence of Na2HPO4, the Baeyer-Villiger reaction of II (R = OH, R1 = a-OH) with CF3CO3H gave I in 42% yield. I had plant growth-promoting activity in the rice-lamina test.

Key words: ANALOGUE, ORGANIC SYNTHESIS, UTILIZATION, BRASSINOLIDE