Cross-coupling versus homocoupling in the reactions of dimethyl(N,N,N',N'-tetramethylethanediamine)palladium with organic halides

Abstract

Reaction of PdMe 2 (tmeda) (tmeda=N,N,N',N'-tetramethylethanediamine) with benzyl and allyl bromide at 20 o C affords the homocoupled product ethane and the organometallic complexes PdBr(η 1 -benzyl)(tmeda) and [Pd(η 3 -allyl)(tmeda)] Br, respectively. Acetyl complexes PdX(COMe)(tmeda) were easily obtained by reaction of PdXMe(tmeda) with carbon monoxide at ambient temperature and pressure. At 0 o C, the reaction of PdMe 2 (tmeda) with benzyl bromide and the reaction of PdMe(benzyl)(tmeda) with methyl bromide both afford the palladium (IV) species a-benzyl-b-bromo-cd-dimethyl-ef-(tmeda) palladium (IV) (4a)