Dipyridine cobalt chloride as an efficient and chemoselective catalyst for the synthesis of 1,1-diacetates under solvent-free conditions

1,1-Diacetates(acylals) were prepared by direct condensation of various aldehydes with acetic anhydride using dipyridine cobalt chloride (CoPy2Cl2) as an efficient and green catalyst under solvent-free conditions at room temperature. The important features of this catalyst method are that the catalyst is solid, stable at high temperatures, soluble in water, stable in air, immiscible in common organic solvents, and low toxic and, above all, it is reusable. CoPy2Cl2 can be recycled after a simple work-up and reused at least five runs without appreciable loss of its catalytic activity. High chemo-selectivity toward aldehyde in the presence of ketones is another advantage of the present method which provides selective protection of aldehydes in their mixtures with ketones.