ChemInform Abstract: Pd(II)‐Catalyzed Reactions of Olefins with Oxygen Nucleophiles

Abstract

The functionalization of alkenes with oxygen nucleophiles is attained by a process being referred to as oxypallation which involves nucleophilic attack toward alkenes co-ordinated to Pd (II). In reactions of this type (the Wacker-type reaction), the redox catalysis of palladium and copper (eqs 1 and 2) has been believed to regenerate Pd (II) from Pd (O) formed in situ. This article describes that the catalysis is not generally operative, but that a hydroperoxopalladium (II) species (XPdOOH) coupled with CuXn is most likely the active catalyst which is formed by the oxygenation of XPdH liberated from oxypalladation adduct. This finding has been deduced from the analysis of Pd (II) -catalyzed asymmetric cyclization of 2- (2-butenyl) phenol, which is the first example of the asymmetric Wacker-type oxidation. Furthermore described is the new aspect of the following Wacker-type reactions ; (i) intramolecular oxidative cyclization of alkenes bearing hydroxy group and (ii) acetalization of terminal alkenes with diols. These reactions have synthetic potential for preparing optically active heterocyclic compounds such as (S) - (+) -tremetone and (S) - (-) -frontaline.