The ketene thioacetal group as a cationic cyclization terminator. : A synthesis of the pyrrolizidine ring system.

✍ Scribed by A.Richard Chamberlin; John Y.L. Chung

• Publisher: Elsevier Science
• Year: 1982
• Tongue: French
• Weight: 284 KB
• Volume: 23
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)87412-2

✦ Synopsis

The pyrrolizidines are a group of alkaloids which exhibit an incredible range of biological activity, including antitumor, hypotensive, local anesthetic, anti-spasmotic, anti-inflammatory, carcinogenic, and (especially) hepatotoxic action. 1,2 Syntheses of the deceptively simple aza-[3.3.0]octane ring system common to these alkaloids have focused mainly on the fully saturated derivatives 2, 3 while the unsaturated ones such as 2 have received relatively little attention4 in spite of their more profound physiological activity. 1 We report in this communication a new cyclization-isomerization sequence which efficiently produces the skeleton 2, illustrated by a straightforward synthesis of supinidine ($).