Cyclocondensation of Acylketene<i>S</i>,<i>N</i>- and<i>N</i>,<i>N</i>-acetals with Maleic Anhydride and Maleimide: A Facile One-Step Synthesis of Pyrano [3,4-<i>c</i>]pyrrole, Pyrrolo [3,4-<i>c</i>]pyridine and Condensed Pyrrole Derivatives
                                
                                    
                                        作者:Akhilesh K. Gupta、H. Ila、H. Junjappa                                    
                                    
                                        DOI:10.1055/s-1988-27544
                                    
                                    
                                        日期:——
                                    
                                    The acylketene S,N-acetals 1a-c react with maleic anhydride (2) in  refluxing acetonitrile to give the corresponding 3-pyrrolin-2-one-3-acetic  acid derivatives 3a-c in good yields. Condensation of S,N-acetals  1a-j and 2 in presence of acetic anhydride directly afforded the  corresponding 2-substituted-3-methylthio-4-aryl (or methyl)-1,6-dioxo-  2,3-dihydropyrano[3,4-c]pyrroles 4 a-j in excellent yields. The reaction  of cyclic S,N- (5a-c) and N,N- (5d-f) acetals with 2 in refluxing  acetonitrile gave the corresponding pyrrolo[2,1-b]thiazole (6a-c) and  pyrrolo[1,2-a]imidazole (6d-f) derivatives, respectively, in good yields.  Similarly, the condensation of S,N-acetals 1a and 1d with maleimide  directly yielded the respective pyrrolo[3,4-c]pyridine derivatives 9a and  9b, while the corresponding pyrrolinone-3-acetamide derivatives 8a  and 8b were obtained under similar conditions, when the reaction time  was reduced.
                                    酰基烯酮S,N-
缩醛1a-c与
马来酸酐(2)在回流
乙腈中反应,以良好的收率得到相应的
3-吡咯啉-2-酮-3-
乙酸衍
生物3a-c。 S,N-
缩醛1a-j和2在
乙酸酐存在下缩合直接得到相应的2-取代-3-甲
硫基-4-芳基(或甲基)-1,6-二氧代-
2,3-二氢吡喃[3 ,4-c]
吡咯 4 a-j 具有优异的产率。环状S,N-(5a-c)和N,N-(5d-f)
缩醛与2在回流
乙腈中反应,得到相应的
吡咯并[2,1-b]
噻唑(6a-c)和
吡咯并[1 ,2-a]
咪唑(6d-f)衍
生物,分别具有良好的收率。  类似地,S,N-
缩醛1a和1d与马来
酰亚胺缩合直接得到各自的
吡咯并[3,4-c]
吡啶衍生物9a和9b,而相应的
吡咯啉酮-3-乙酰胺衍
生物8a和8b在类似条件下得到,当反应时间减少时。