A New Annelation Reaction: [3+3] Cyclocondensation of Cyclic Azomethines with beta-Ketoesters

摘要

Progress in the chemistry of nitrogen-containing heterocycles is in many respects determined by the development of new methods for determined by he development of new methods for designing their molecular skeletons [1-3]. Despite lengthy development of this field of organic chemistry (Hantzsch, 1882; Friedlander, 1882; Doebner, 1887; Meyer-Mohr, 1895; Einhorn, 1905; Ullmann-Fetvandjian, 1903; Tiedtke, 1090; and others [4]), its potentialities are far from being exhausted, which has been demonstrated by recent achievements [5-9]. One of the most promising directions of the development of heterocyclic synthesis is study of the reactions of azomethines with carbonyl, beta-di-, and beta,beta'-tricarbonyl compounds or with their enol and functional derivatives [5, 6, 9-11]. On the one hand, this is due to the fact that azomethines are multicenter compounds, which is caused by the tautomerism and polarity of the C=N and C=N bonds. On the other hand, this is due to the fact that the carbonyl (beta-di, beta,beta'-tricarbonyl) compounds are multicenter, which is cause, as in the case of azomethines, by the tautomerism and posarity of the C=O and C=C bonds. The results of recent research in this area of heterocyclic synthesis have led to detectionof annelation reactions (cyclocondensation, heterocyclization of cyclic azomethines (Schiff bases) by beta-ketoesters [5], beta-di- or beta,beta'-tricarbonyl compounds [6, 10, 11],hydroxy(aminomethylene(di)carbonyl compounds [9], and other reagents [7, 8, 12], which can serve a convincing confirmation of this statement.