AI Article Synopsis
- Oxidative functionalization of a steroidal C18 methyl group is achieved through a new dyotropic rearrangement, transforming a seven-membered fused C-ring lactone into a 6-ring spiro lactone.
- Synthesis of the 23-deoxy South analogue of cephalostatin 1 was completed in 12 steps with a 23% yield, while a strained diene analogue was made in 11 steps with a 28% yield.
- Total syntheses of 23'-deoxy cephalostatin 1 and 16',17'-dehydro-23'-deoxy cephalostatin 1 were achieved with 16 and 15 operations, yielding 9% and 8% overall,
Article Abstract
Oxidative functionalization (or removal) of a steroidal C18 methyl group is possible using a previously unknown dyotropic rearrangement of a seven-membered fused C-ring lactone to a 6-ring spiro lactone. Spiroketal equilibration led to the 23-deoxy South analogue of cephalostatin 1 (1) in only 12 steps (23% overall yield) from hecogenin acetate 4, and to strained diene South 1 analogue 30 in 11 steps (28% overall). Total synthesis of 23'-deoxy cephalostatin 1 (3) was accomplished in 16 operations from 4 (9% overall; average 86% yield per operation), and that of 16',17'-dehydro-23'-deoxy cephalostatin 1 (36) in 15 operations from 4 (8% overall; av 84%/op).
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