Hydroxy complexes of palladium(II) and platinum(II) as catalysts for the acetalization of aldehydes and ketones

The acetalization of aldehydes or ketones is a reaction of synthetic interest in organic chemistry that is commonly catalyzed by Bronsted or Lewis acids. We have found that a class of Pd(II) and Pt(II) complexes of the type [(P-P)M(mu-OH)](2)(2+) (P-P = a series of diphosphines; M = Pd, Pt) are effective catalysts for the acetalization of a variety of aldehydes and ketones in the presence of alcohols or glycols. The use of epoxides instead of alcohols resulted in lower rates and yields. The rate and yield of the reaction is not affected by the size of the diphosphine in the series dppe, dppp, dppb. Attempts to perform the reaction in a stereoselective fashion showed no difference depending on whether regular achiral catalysts or catalysts modified with chiral diphosphines were used. (C) 1999 Elsevier Science B.V. All rights reserved.