Synthesis and Rearrangement of Spiro: A New Approach to Benzophenanthridinones

Article abstract of DOI:10.1021/jo00263a031

An efficient stereoselective synthesis of spiro 4 based on the intramolecular aldol condensation of the dicarbonyl compound 11 is described.The potential of compounds of type 4 as starting materials for the preparation of various ring systems by acid-catalyzed rearrangement was also studied.The results clearly indicate the strong tendency to undergo rearrangement by migration of C-1, affording benzophenanthridinones 5 in very good yield.The course of process proved to be independent of the stereochemistry at C-4 ', as was evidenced by the formation of the same product, 15d, from the C-4' epimers 12 and 13.However, all attempts to force rearrangement of C-4' or the nitrogen atom to C-1 to form indanobenzazepinones (6 or 7) resulted only in substitution and epimerization at C-1.