The synthesis of 2-carboxy-6-nitrobenzimidazole 1-oxides by intramolecular oxidation of α-(2,4-dinitrophenylamino)-αβ-unsaturated acyl derivatives
作者:A. E. Luetzow、J. R. Vercellotti
DOI:10.1039/j39670001750
日期:——
β-substituted anologues, α-(2,4-dinitrophenylamino)crotonate and α-(2,4-dinitrophenylamino)cinnamate, in that respective order of reactivity, as well as the propyl amide of α-(2,4-dinitrophenylamino)acrylic acid. These reactions occur in protic and aprotic solvents with a large number of bases, and a tentative concerted mechanism is proposed. Reaction of N-2,4-dinitrophenylglycine methyl ester with base gives
在α-(2,4-二硝基苯基氨基)αβ-不饱和酰基衍生物的碱性溶液中,2-硝基基团分子内氧化不饱和酰基链的β-位。氧化的β-碳的逆醛醇裂解发生在分裂产物的闭环反应中,产生醛和2-羧基-6-硝基苯并咪唑1-氧化物(65-75%)。对于α-(2,4-二硝基苯基氨基)丙烯酸的甲酯及其β-取代的类似物,α-(2,4-二硝基苯基氨基)巴豆酸酯和α-(2,4-二硝基苯基氨基)肉桂酸酯发生该反应。各自的反应顺序,以及α-(2,4-二硝基苯基氨基)丙烯酸的丙基酰胺。这些反应在具有大量碱的质子和非质子溶剂中发生,并提出了一种暂定的协同机制。N的反应与碱混合的-2,4-二硝基苯基甘氨酸甲酯可如上所述产生中等收率(50-60%)的2-羧基-6-硝基苯并咪唑1-氧化物。丝氨酸,苏氨酸和β-苯基丝氨酸的N -2,4-二硝基苯基甲基酯在碱中经历逆醛缩反应,形成相应的醛和N -2,4-二硝基苯基甘氨酸甲酯,后者迅速经历了