Cyanobenzoylation and hydrocyanation of aldehydes with benzoyl cyanide using no catalyst

In the presence of MS 4Angstrom in DMSO, cyanobenzoylation of various aldehydes with benzoyl cyanide proceeded very smoothly to give the corresponding cyanohydrin benzoates in high to excellent yields without an acid or a base. On the other hand, reaction of aldehydes with BzCN in DMSO-H2O also occurred readily to afford the corresponding free cyanohydrins exclusively.