A new strategy for the enantioselective synthesis of aspidosperma alkaloids: II - Achievement of the pentacyclic system.

✍ Scribed by Didier Desmaele; Jean d'Angelo

• Publisher: Elsevier Science
• Year: 1990
• Tongue: French
• Weight: 271 KB
• Volume: 31
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)94654-9

✦ Synopsis

Carbazolone 5 has been converted in eleven steps into alkaloid analog Z (R = Me) (13 46 overall yield).

In the preceding paper l, we proposed a new approach to pentacyclic Aspidosperma alkaloids [(e.g. (-)-aspidospermldine, 1, R = Et], based on the disconnection [l -+ 2 -+ 31, in which carbazolones 3 constitute the key [ABC]-type tricyclic subunits.

In this respect, the optically active (R)-keto-ester 5 was efftciently prepared fmm cyclohexanone 4. COOMe ""-"" ) &-36 % overall yield