One-Pot Synthesis of Highly Substituted Cyclopentanols via Titanaheterocycles: Stereoselective Coupling Reactions of α,β-Unsaturated Arylketones

A novel synthesis of highly substituted 1,3,4-triaryl-2-aroylcyclopentanols 1 from unsaturated arylketones 2 and dicarbonyl titanocene 3 via stereoselective twofold C-C-coupling reactions has been developed. The hitherto unknown 2,9-dioxa-titanacyclononadiene complexes 4, well defined products of the initial trans-selective β,β-coupling reaction, can optionally be isolated or hydrolyzed to give 1. The mild and non-hazardous reaction conditions give high yields of 1 as the sole product in most cases. Occasionally only aroyl-cyclopentenes 5 could be found due to a swift follow-up dehydration process.

Metallacycles - Cyclopentanols - Coupling Reactions - α,β-Unsaturated Ketones - Aldol Reaction