The alkylation of aromatic amines.

Abstract

N-alkylated anilines can be obtained in moderate yields from aniline and methyl formate in the presence of Rh$\sb6$(CO)$\sb $ and KI after 72 hours at 180-200$\sp\circ$C. Ru$\sb3$(CO)$\sb $ gave similar results to the unpromoted rhodium carbonyl system. Formanilide and N-methylformanilide were also formed in the reaction. The (HCr(CO)$\sb5$) -anion in the form of its PPN$\sp+$ and Et$\sb4$N$\sp+$ salts also catalysed this reaction (under hydrogen) but was selective to the formanilide products. The presence of an electron donating group on the aromatic ring favoured the formation of alkylated products in the presence of bis(triphenylphosphine)iminium (PPN$\sp+$) hydridochromiumpenta-carbonyl. Several possible mechanisms were tested and the nature of the polynuclear catalysts investigated.