New Tetracyclic Colchicinoids from the Reaction of N-Deacetylthiocolchicine and N-Deacetylcolchicine with Nitrous Acid and tert-Butyl Nitrite

摘要

Reaction of N-deacetylthiocolchicine (3) and N-deacetylcolchicine (4) with nitrous acid (HONO) furnished the new tetracyclic colchicinoids 5 and 6, as wel las the Demyanov-rearrangement products 7 and 8. Star5ting from 3, the pyrazole-containing tetracycle 9 was obtained. The novel compounds were characterized spectroscopically, and an X-ray crystal-structure analysis of 5 allowed us to establish the absolute configuration at the stereogenic centers.