PRACTICAL TITANIUM-CATALYZED SYNTHESIS OF BICYCLIC CYCLOPENTENONES AND ALLYLIC AMINES

A practical titanium-catalyzed synthesis of bicyclic cyclopentenones a nd allylic amines is described. The process converts enyne substrates to iminocyclopentenes using 10 mol% of the air- and moisture-stable pr ecatalyst Cp(2)TiCl(2) in the presence of n-BuLi and triethylsilyl cya nide. The resulting iminocyclopentenes can be hydrolyzed to cyclopente nones in good yields or reduced to allylic silylamines with Red-Al or DIBALH. Treatment of the crude silylamines with acetyl chloride allows isolation of allylic amides in excellent yields.