The reductive coupling of carbonyl compounds constitutes an important method for the formation of carbon-carbon bonds. In present paper, we have found for the first time that the products of the carbonyl coupling reaction not only depend on reactants and reagent systems, but also operation sequence. It is believed that the coupling reaction occurs on the surface of the active titanium particle.

Key words: COUPLING REACTION, ZINC POWDER, TITANIUM COMPOUNDS, PINACOL REARRANGEMENT, SURFACE REACTION, ARYL GROUP, ACETONE P, REDUCTION REACTION