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New bisfuran derivative from sarsasapogenin. An X-ray and NMR analysis.

López Y, Santillan R, Farfán N

Departamento de Química, CINVESTAV-IPN, Apdo. Postal 14-740, 07000 México, D.F., Mexico.

The new bisfuran derivative, (22S,23S)-22,23-dihydroxy-23,26-epoxyfurostane, was obtained from the known oxidation of sarsasapogenin acetate with NaNO2/BF3 in 5% aqueous acetic acid. The structure of was established using one and two-dimensional 1H, 13C experiments (DEPT, COSY, HETCOR and HMBC) and the configurations at the newly formed stereogenic centers were established as 22S,23S by an X-ray diffraction analysis. Addition of TiCl4 to bisfuran 5 confirmed that this compound is an intermediate in the rearrangement to 22-oxo-23-spiroketals since it was transformed quantitatively into the latter product. The 23-nitroimino intermediate 2 was isolated from the same reaction and its structure established also by an X-ray diffraction analysis; this compound was further transformed into the 23-nitramine 7 which could find application in functionalization of position 24.

Published 5 December 2005 in Steroids, 71(1): 12-7.
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