Low-valent titanium reagents have exceedingly high ability to promote reductive coupling of carbonyl compounds and are attracting increasing interest in organic synthesis. 1, 1a, 1b, 1c, 1d, 1e and 1f Recently, we have reported the cyclodimerization of α,β-unsaturated ketones and α,β-unsaturated nitriles promoted by this reagent yielding functional cyclopentanes 2 and cyclopentenes, 3 respectively. ... Over the past decade, the synthesis of heterocycles has ...
