Chiral bicyclic Lactams as homoenolate equivalents: An asymmetric route to 5-substituted cyclohexenones

✍ Scribed by Jacob B. Schwarz; Paul N. Devine; A.I. Meyers

• Book ID: 104208393
• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 891 KB
• Volume: 53
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(97)90391-4

✦ Synopsis

Bicyclic Lactam 2 was transformed into a-cyanoenamine 8 in a four-step, high-yielding process. TMetalation of 8 was achieved using LiTMP in THFIHMPA, and the resultant homoenolate equivalent underwent stereoselective alkylation and subsequent hydrolysis to provide lactams of type 10 as a single diastereomer. Partial reduction and hydrolysis of lactams 10 furnished enantiopure 5-substituted cyclohexenones 13 in good overall yield. 0 1997 Elsevier .kience Ltd.

Bicyclic lactams 2, derived from the commercially available aminodiol 1, have previously been shown to alkylate, via their enolate, to the a,a-dialkyl derivatives 3. The latter, which were formed or purified to a single diastereomer gave, upon reduction or alkyllithium addition and subsequent hydrolysis, either the 4,4-disubstituted or the 6,6-disubstituted cyclohexenones 4 or 5 in high enantiomeric purity.1 This novel approach to chiral cyclohexenones has also led to (W-1