Orthoamides. LIII. A new synthesis for aromatic aldehydes of wide scope

Diformamide (1) reacts with activated aromatic compounds like toluene, anis ole, m-xylene, 1,2-dimethoxybenzene in the presence of AlCl3 to give N-(dia rylmethyl)formamides 2a-d, the corresponding aromatic aldehydes 3-6 are for med as by-products in low yields. From N,N-dimethylaniline and 1/AlCl3 the triphenylmethane derivative 7 can be obtained. The reaction of anisole with N-methyl-diformamide (9) affords the formamide 10. The mixture of formamid e, P4O10 and AlCl3 reveals to be a reagent which is capable to formylate to luene and anisole, resp. Triformamide (14)/AlCl3 is an effective formylating system which allows the preparation of aromatic aldehydes (e.g. 3,4,17-32) from the corresponding aromatic hydrocarbons. Aluminiumchloride can be replaced by borontrichlorid e. The yields of the formylation reactions depend strongly from the reactio n conditions (molar ratio: aromatic hydrocarbon/AlCl3/14; solvent, reaction temperature). The scope of the reaction covers nearly complete those of th e Gattermann-Koch-, Gattermann- and Vilsmeier-Haack-reaction.