Unexpected formation of acylformamidines by reaction of primary carboxamides with MeONa in DMF in the presence of CHCl3

Article abstract of DOI:10.1016/S0040-4020(97)10041-2

Dichlorocarbene, which is generated by reaction of CHCl₃ with MeONa, is likely to chlorinate DMF to produce tile Vilsmeier-Haack-Arnold salt that in the presence of excess MeONa, gives DMF dimethylacetal (2). This latter reacts with primary amides to yield the corresponding N,N-dimethyl-N'-acylformamidines. Solid state structure of N-[(dimethylamino)methylene]phenoxyacetamide (4) obtained by X-ray crystallography is also reported.