Annulation of 2-formyl-2-cyclohexenones by reaction with enamines

✍ Scribed by Walter L. Meyer; Michael J. Brannon; Andrew Merritt; Dieter Seebach

• Book ID: 104218365
• Publisher: Elsevier Science
• Year: 1986
• Tongue: French
• Weight: 247 KB
• Volume: 27
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)84282-3

✦ Synopsis

3-Methyl-2-pyrrolidino-libutene reacts with a series of 2-formyl-2-cyclohexenones to give mixtures of 7,7-dimethyl-A -octalin-1,6-diones and 7,7-dimethyl-8-hydroxy-transdecalin-1,6-diones which are dehydrated by TFA to afford the octalindiones in overall yields of 80% or better; annulation is >95% diastereoselective with 4-monosubstituted formyl enones. We recently described details of a new method for annulation of cyclohexanones, through conversion of the ketone to its 2-formyl-2,3-dehydro derivative& Michael addition of the enolate of a 6-keto ester, and cyclodehydration !L+ 2+ 7,.2 A distinctive feature of this sequence is that it attaches the new ring to the a and 8 carbons of the cyclohexanone rather than the a and carbonyl carbons as in most other annulation procedures. It also offers considerable structural versatility; substituents may be included on the y-carbon of the keto 1971, 54, 1767.