Synthesis, Crystal Structures and their Utilities in Tishchenko Reaction of N,O-Bidentate Aluminum Compounds

Deprotonolysis of the N,O-bidentate pyridyl functionalized alkoxy ligands, 1,1-dimethyl-2-(pyridin-2-yl)ethanol (L (1) H), 1-phenyl-2-(pyridin-2-yl)ethanol (L (2) H) and 1,1-diphenyl-2-(pyridin-2-yl)ethanol (L (3) H), with 1 equiv of AlMe3 gave the corresponding dimeric metal-monoalkyl compounds [L (1) AlMe2](2) (1), [L (2) AlMe2](2) (2), and [L (3) AlMe2](2) (3), respectively. Compounds 1-3 were characterized by H-1 and C-13 NMR spectroscopy analysis, and the molecular structures of 1 and 2 were further confirmed by X-ray diffraction analysis. In the presence of (i) PrOH, aluminum compounds 1-2 exhibited excellent catalytic activity for the solvent-free Tishchenko reaction under mild conditions. In addition, the catalyst 3 can be easily isolated and recycled three times without a significant decrease in activity.