Pii: S0968-0896(99)00042-5

نویسندگان

  • Andrea C. Bruttomesso
  • Eduardo G. Gros
چکیده

ÐUtilization of 17-keto-androstanes as starting materials for the synthesis of aor b-oriented steroidal 20!16-g-carbolactones has been explored following two di€erent strategies. A highly ecient, stereospeci®c protocol has been developed for the boriented cis-g-lactone. A di€erent approach, involving prior attachment of a 3-carbon side chain on C-17 of a 17-oxo-16b-acetoxyandrostane led to the epimeric, a-oriented lactone. The mechanism of the rearrangement of epimeric 16bor 16a-hydroxy-17-ketoandrostanes to 17b-hydroxy-16-keto-androstanes was studied by C NMR spectroscopy. The former occurs through a 1,2-sigmatropic H-shift, while the latter is likely to take place by simple enolization±reprotonation.# 1999 Elsevier Science Ltd. All rights reserved.

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تاریخ انتشار 1999