The syn/anti-dichotomy in the palladium-catalyzed addition of nucleophiles to alkenes

Chemistry. 2015 Jan 2;21(1):36-56. doi: 10.1002/chem.201404070. Epub 2014 Nov 5.

Abstract

In this review the stereochemistry of palladium-catalyzed addition of nucleophiles to alkenes is discussed, and examples of these reactions in organic synthesis are given. Most of the reactions discussed involve oxygen and nitrogen nucleophiles; the Wacker oxidation of ethylene has been reviewed in detail. An anti-hydroxypalladation in the Wacker oxidation has strong support from both experimental and computational studies. From the reviewed material it is clear that anti-addition of oxygen and nitrogen nucleophiles is strongly favored in intermolecular addition to olefin-palladium complexes even if the nucleophile is coordinated to the metal. On the other hand, syn-addition is common in the case of intramolecular oxy- and amidopalladation as a result of the initial coordination of the internal nucleophile to the metal.

Keywords: alkenes; catalysis; nucleophilic addition; palladium; stereochemistry.