A highly efficient and environmentally benign synthesis of N-fused heterocyclic compounds including pyrido[1,2-a]pyrimidine-6-one moiety is successfully achieved via a sequential four-component reaction. The process involves the formation of diversely substituted 9-nitro-1,2,3,4,7,8-hexahydro-6H-pyrido[1,2-a]pyrimidin-6-ones from the reaction of Meldrum’s acid, benzaldehydes, 1,1-bis(methylthio)-2-nitroethylene and various diamines in the presence of p-toluene sulfonic acid (PTSA) as an acidic catalyst in water as a green solvent. The salient features of the present methodology are easily available starting materials, the use of water as environmentally benign solvent, simple execution, applicable to a wide range of starting materials and good to excellent yields.

通过连续的四组分反应成功地实现了包括吡啶并[1,2 - a ]嘧啶-6-部分在内的N稠合杂环化合物的高效，环境友好的合成。该过程涉及由麦德鲁姆酸，苯甲醛的反应形成不同取代的9-硝基-1,2,3,4,7,8-六氢-6 H-吡啶并[1,2- a ]嘧啶-6- ，p，1,1-双（甲硫基）-2-硝基乙烯和各种二胺的存在-甲苯磺酸（PTSA）在水中作为酸性催化剂作为绿色溶剂。本方法的显着特征是容易获得的起始原料，使用水作为对环境无害的溶剂，易于实施，适用于多种起始原料以及良好至优异的产率。