SYNTHESIS, CHARACTERIZATION, AND CARBONYLATION REACTIONS OF METHYLPALLADIUM AMIDE, CARBAMATE, AND ALKYL CARBONATE COMPLEXES

A series of trans- and cis-methylpalladium carbamate complexes PdMe(OCONRR')L2 (L = tertiary phosphine; R, R' = H, alkyl, and phenyl) was prepared by the reaction of dimethylpalladium complexes with primary or secondary amine and carbon dioxide. When diphenylamine was used, methylpalladium amide complexes trans-PdMe(NPh2)L2 (L = PMe3 and PEt2Ph) were isolated instead of carbamates. The carbamate and amide complexes thus prepared were characterized by IR and NMR spectroscopy and elemental analysis. The carbamate complex trans-PdMe(OCONEt2)(PMe3)2 released one of the PMe3 ligands on recrystallization to form a dimeric compound Pd2Me2(mu-OCONEt2)2(PMe3)2, whose structure was determined by X-ray diffraction study. The carbamate complexes reacted with carbon monoxide under pressure to give corresponding alpha-keto amide (MeCOCONRR') and amide (MeCONRR'). Reactions of dimethylpalladium complexes with alcohols and carbon dioxide gave methylpalladium alkyl carbonate complexes trans-PdMe(OCOOR)L2 (R = Me, (s)Bu; L = PMe3, PPh 3). Treatment of alkyl carbonate complexes with carbon monoxide afforded the corresponding alkyl acetate as the sole carbonylation product.