Low-Valent Titanium-Mediated Reductive Coupling of Carbonyl Compounds

This account describes recent organic synthesis applications and developments in mechanistic understanding of low-valent titanium-mediated reductive coupling of carbonyl compounds. Pinacol and McMurry coupling reactions are among the most powerful methods for constructing carbon-carbon bonds, and have served as the key step in the synthesis of various natural and synthetic products. The range and selectivity of low-valent titanium reagents that mediate pinacol and McMurry reactions are discussed. The nature of their active species is discussed in conjunction with relevant chemistry of well-characterized low-valent titanium complexes, all of which serve to inform current understanding of the reaction mechanisms.