Bicyclo[2.2.1]heptanes as intermediates in the synthesis of steroids. Total synthesis of estrone

✍ Scribed by Grieco, Paul A.; Takigawa, Tetsuo; Schillinger, William J.

• Book ID: 121423607
• Publisher: American Chemical Society
• Year: 1980
• Tongue: English
• Weight: 626 KB
• Volume: 45
• Category: Article
• ISSN: 0022-3263
• DOI: 10.1021/jo01299a042

✦ Synopsis

A synthesis of dl-estrone has been accomplished by employing the key bicyclo[2.2.l]heptene intermediate 2 prepared from ketal ester 16 via a series of reactions featuring the remarkable stereospecific alkylation of 16 with 2-(4-methoxybenzocyclobutenyl)ethyl iodide. Intermediate 2 provided direct access to benzocyclobutene derivative 3 ?which upon thermolysis underwent intramolecular cycloaddition via the corresponding o-quinodimethane.