Synthesis of unusual compounds from abundant betulin

Modifications that included cleavage and oxidation of the 19-side chain of betulin 3β,28-diacetate; and the contraction of ring A of readily available betulin 1, followed by cleavage and oxidation, yielded three unusual compounds with moderate microbial activity against a number of micro-organisms. Of the three compounds investigated, the most active was 18β,28-epoxy-6-hydroxy-5-oxo-3,5-seco-A[4], 23,24-trinor-18α-olean-6-en-3oic acid 2, with minimum inhibitory concentration of 11µg/ml against C. albicans. Further modification of this compound by methylation and acetylation did not increase the activity of the compound.