3-(1<i>H</i>-1,5-Benzodiazepin-2(3<i>H</i>)-ylidenemethyl)quinoxalin-2(1<i>H</i>)-ones in reactions with nucleophiles. Synthesis and structure of 3-(hetarylmethyl)quinoxalin-2-ones

Abstract

3-(1Н-1,5-Benzodiazepin-2(3Н)-ylidenemethyl)quinoxalin-2(1H)-ones react with hydrazines and hydroxylamine in acidic medium, leading to conversion of seven-membered ring to five-membered ring and formation of the respective dihetarylmethanes in 40–79% yields. The starting materials containing an electron-donating substituent (R = Ph, 4-ClC₆H₄, 2-naphthyl, 2-thienyl, Me) at position 4 of the benzodiazepine ring reacted predominantly at the С-4 atom, while another starting material containing an electron-withdrawing substituent (R = CF₃) at the same position reacted at the С-2 atom. The synthesized 3-(hetarylmethyl)quinoxalin-2-ones existed in DMSO-d₆ solution as tautomeric imine and enamine forms, the ratio of which depended on the possibility of a strong intramolecular hydrogen bond and indicated regioselective formation of pyrazole or isoxazole rings. Acidic hydrolysis of the benzodiazepinоquinoxaline system resulted in loss of the diazepine ring and formation of diketoquinoxalines in 41–82% yields, having a different reactivity than their synthetically equivalent benzodiazepine analogs.

How to Cite
Obydennov, D. L.; Sosnovskikh, V. Ya. Chem. Heterocycl. Compd. 2015, 51, 503. [Khim. Geterotsikl. Soedin. 2015, 51, 503.]

For this article in the English edition see DOI 10.1007/s10593-015-1729-y