SELECTIVE MONO-BENZYLATION OF METHYLENE ACTIVE COMPOUNDS WITH DIBENZYL CARBONATE - BENZYLATION OF PHENOL

Dibenzyl carbonate (DBzlC) has been used to benzylate phenylacetonitri le, benzyl phenylacetate and phenol. In refluxing N,N-dimethylformamid e (DMF) as solvent, and in the presence of K2CO3 phenol yielded benzyl phenyl ether and phenylacetonitrile the mono b enzylated comp ound 2, 3 -diphenylpropionitrile. Likewise, in refluxing N,N-diethylformamide (DEF), benzyl phenyl acetate gave the benzyl 2,3-diphenylpropionate. S electivity in mono-C-benzyl derivatives was 98-99% at a conversion up to 90%. Such unusually high selectivity is explained in terms of a mec hanism involving, initially, carboxybenzylation followed by benzylatio n, rather than direct benzylation.