Abstract
The l-azaspiro[4.4]nonane portion 11 of cephalotaxine was prepared via an intramolecular S N 2′ substitution reaction followed by ozonolysis; condensation of ll with the aromatic portion 13 gave compound 15; a Friedel-Crafts cyclization of 15 in polyphosphoric acid smoothly afforded the cephalotaxine skeleton 16. A single-crystal X-ray analysis of the HCl salt of 16 confirmed the structure of 16. © 1991, American Chemical Society. All rights reserved.