A practical titanium-catalyzed synthesis of bicyclic cyclopentenones and allylic amines is described. The process converts enyne substrates to iminocyclopentenes using 10 mol % of the air- and moisture-stable precatalyst Cp(2)TiCl(2) in the presence of n-BuLi and triethylsilyl cyanide. The resulting iminocyclopentenes can be hydrolyzed to cyclopentenones 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.
“A Practical Titanium-Catalyzed Synthesis of Bicyclic Cyclopentenones and Allylic Amines”, J. Org. Chem., 1996, 61(8), 2713-2718.