Treatment of 6-(N-alkylanilino)uracils with a mixture of phosphorus oxychloride and dimethylformamide (or a mixture of ethyl chloroformate and dimethylformamide) gave the corresponding 5-deazaflavins; reaction of 6-chloro-5-formyl-3-methyluracil with N-alkylanilines also gave the corresponding 5-deazaflavins.