Syntheses of 5-deazaflavines

Abstract

Treatment of 6-(N-alkylanilino)uracils with Vilsmeier-type reagents (dimethylformamide–phosphoryl chloride or dimethylformamide–ethyl chloroformate) gave 5-deazaflavines {10-alkylpyrimido[4,5-b]quinoline-2,4(3H,10H)-diones}; this cyclization was also achieved with triethyl orthoformate. Treatment of 3-methylbarbituric and barbituric acids with dimethylformamide–phosphoryl chloride gave 6-chloro-5-formyl-3-methyluracil and 2,4,6-trichloro-5-formylpyrimidine, respectively. Reactions of these 6-chloro-5-formylpyrimidines with N-substituted anilines gave directly the corresponding 5-deazaflavines.