Dimethylformamide dimethyl acetal → N'-(2-cyano-4-methoxy-5-benzyloxyphenyl)-N,N-dimethylimidoformamide

2-amino-4-(benzyloxy)-5-methoxybenzonitrile (100 g, 394 mmol) in toluene (1400 ml) was treated with dimethylformamide dimethylacetal (100 ml, 940 mmol) at reflux with slow distillation of solvent to maintain the internal temperature at 105° C. After 3 hours the solution was cooled and filtered to remove a small amount of solid. The filtrate was evaporated in vacuo, the residue triturated with diethyl ether, the solid collected by suction filtration and dried in vacuo to yield N′-(5-(benzyloxy)-2-cyano-4-methoxyphenyl)-N,N-dimethylimidoformamide (110 g, 90% yield) as a brown solid: