The first synthesis of dihydro-3H-pyrido[2,3-b][1,4]diazepinols and a new alternative approach for diazepinone analogues

The first synthesis of a series of 2-aryl(heteroaryl)-4-trifluoromethyl-4,5-dihydro-3H-pyrido[2,3-b][1,4]diazepin-4-ols, where aryl = C6H5, 4-FC6H4, 4-ClC6H4, 4-BrC6H4, 4-CH3C6H4, 4-OCH3C6H4, 4,4′-biphenyl, 1-naphthyl and heteroaryl = 2-thienyl, 2-furyl obtained from the direct cyclocondensation reaction of 4-methoxy-1,1,1-trifluoroalk-3-en-2-ones with 2,3-diaminopyridine in 54–71% yield, is reported. Another alternative and efficient route for the synthesis of a series of 2-aryl(heteroaryl)-3H-pyrido[2,3-b][1,4]diazepin-4(5H)-ones from the reaction 4-methoxy-1,1,1-trichloroalk-3-en-2-ones with 2,3-diaminopyridine, in 54–70% yield, is also reported.

Graphical abstractThe new application of 4-methoxy-1,1,1-trifluoro(chloro)alk-3-en-2-ones for the synthesis of novel pyrido[2,3-b][1,4]diazepines, is reported.Figure optionsDownload full-size imageDownload as PowerPoint slide