Intramolecular Diels-Alder Reaction with Furan-Diene. 1. A Novel Entry to the BCD-Ring System of 11-Ketosteroids

✍ Scribed by Luc A. van Royen; Roelant Mijngheer; Pierre J. De Clercq

• Publisher: Wiley (John Wiley & Sons)
• Year: 2010
• Weight: 1012 KB
• Volume: 93
• Category: Article
• ISSN: 0037-9646
• DOI: 10.1002/bscb.19840931113

✦ Synopsis

A novel Approach f o r t h e s y n t h e s i s of t h e BCD-ring system i n s t e r o i d s i s d e s c r i b e d . The sequence centers about t h e i n t r a m o l e c u l a r Diels-Alder r e a c t i o n of f u r a n 1 5 , which, depending on t h e r e a c t i o n c o n d i t i o n s , l e a d s predominantly t o a d d u c t 7 6 ( k i n e t i c c o n t r o l ) or 27 (thermodynamic c o n t r o l ) . The p r e c u r s o r is o b t a i n e b f r o m e n o l e t h e r 2, prepared v i a d i s s o l v e d metal r e d u c t i o n o f 5.

Only i n reduced adduct 34 is t h e oxygen b r i d g e Opened without concomitant e p im r i e a t i o n a t c-14. T h r s y n t h e s i s of o t h e r d i e n o p h i l e e (17, 19, 2 And 25) and t h e i r Diels-Alder r e a c t i v i t y is d i s c u s s e d .