Synthesis of 3-benzylquinoxalin-2(1H)-ones and 4-formyl-3-benzyl-3,4-dihydroquinoxalin-2(1H)-ones from 3-aryloxirane-2-carboxamides via 5-arylidene-2,2-dimethyl-1,3-oxazolidin-4-ones

3-(2-Nitrobenzyl)quinoxalin-2-ones, and pyrido- and 1,2,5-oxadiazolo-fused 2-(2-nitrobenzyl)pyrazin-3-ones in the synthesis of bi-, bis- and condensed heterocyclic systems

“…The compounds 1-4 were synthetized as previously reported. 10 Melting points were determined on a hot-stage apparatus. Infrared spectra were recorded on a FT-IR spectrometer with reference KBr.…”

“…The characteristics of 4b and 4d matched those when compounds were prepared from 5-(5-chloro-2-nitrobenzylidene)-2,2-dimethyl-1,3-oxazolidin-4-one (3b) according to the method described by us earlier. 10…”

“…[5][6][7] Our research group has recently proposed a mild method for the synthesis of 2-nitrophenylpyruvic acid and its ester from 3-(2-nitrophenyl)oxirane-2,3-carboxamide via 5-(2-nitrobenzyliden)-2,2-dimethyl-1,3oxazolidin-4-one, 8,9 and quite recently by the reaction of 5-(2-nitrobenzyliden)-2,2-dimethyl-1,3-oxazolidin-4one with 1,2-diaminebenzenes were obtained 3-(2-nitrobenzyl)quinoxalin-2(1H)-ones. 10 In this work we use the latest method for synthesizing 3-(2-nitrobenzyl)quinoxalin-2(1H)-ones in order to obtain new representatives of 2-(indole-2-yl)benzimidazoles on their base, and also synthesize 2-(2-nitrobenzyl)pyrido [2,3-b]pyrazin-3(4H)one and 2-(2-nitrobenzylidene)-1,2-dihydro-1,2,5-oxadiazolo [3,4-b]pyrazin-3(4H)-one in a similar way for further study of them under the processes of reduction and in the Mamedov rearrangement. 3,4 The 3-(2-nitrobenzyl)quinoxalin-2(1H)-ones used in the synthesis of 2-(indol-2-yl)benzimidazoles were prepared according to the method described in our previous work 10 (Schema 2).…”

“…10 In this work we use the latest method for synthesizing 3-(2-nitrobenzyl)quinoxalin-2(1H)-ones in order to obtain new representatives of 2-(indole-2-yl)benzimidazoles on their base, and also synthesize 2-(2-nitrobenzyl)pyrido [2,3-b]pyrazin-3(4H)one and 2-(2-nitrobenzylidene)-1,2-dihydro-1,2,5-oxadiazolo [3,4-b]pyrazin-3(4H)-one in a similar way for further study of them under the processes of reduction and in the Mamedov rearrangement. 3,4 The 3-(2-nitrobenzyl)quinoxalin-2(1H)-ones used in the synthesis of 2-(indol-2-yl)benzimidazoles were prepared according to the method described in our previous work 10 (Schema 2). According to this method, 3-(2nitroaryl)oxirane-2,3-carboxamides (1) by the action of hydrobromic acid and acetone were converted into 5-(α-bromo-2-nitrobenzyl)-2,2-dimethyl-1,3-oxazolidin-4-ones (2), which, in turn, under the action of K2CO3 in MeOH were converted into 5-(2-nitroarylidene)-2,2-dimethyl-1,3-oxazolidin-4-ones (3) and the reaction of the latter with 1,2-diaminobenzenes in boiling acetic acid with a small amount of H2SO4 led to the desired products 4.…”