MASS-SPECTRAL DETERMINATION OF THE CONFIGURATION OF ETA-TETRAHYDROPYRANYLOXY-19-NORANDROSTAN-3-BETA-OL

The stereochemistry of 17 beta-tetrahydropyranyloxy-19-norandrostan-3 beta-ol was determined by mass spectral measurements of the extent of water elimination from the molecular ion under electron impact conditi ons. The [M - H2O](+)/[M](+) ratio of the 3 beta-OH isomer was found t o be three to four times higher than that of the 3 alpha-OH isomer. Th e 3 alpha-OH isomer produced a crystalline 3 alpha-benzyloxy derivativ e; its configuration and stereochemistry of the steroidal rings were d etermined by X-ray crystallography. The 3 alpha-OH isomer was obtained by reduction of the corresponding carbonyl group with NaBH4. The 3 be ta-OH isomer was synthesized by Walden inversion of the 3 alpha-OH iso mer. The 3 beta configuration of 17 beta-tetrahydropyranyloxy-19-noran drostan-3 beta-ol was also supported by its ability to bind digitonin. Published by Elsevier Science B.V.