Preparation Of Polysubstituted Pyrrole By [3+2] Cyclization Reaction Of Ketene Dithioacetals With Imine

Pyrrole is an important heterocyclic compound,which exists widely in natural products and plays an important role in the life movement.In addition,many drug molecules also contain pyrrole ring skeleton.How to efficiently construct polysubstituted pyrrole derivatives has been a hot topic in the field of synthetic chemistry and medicinal chemistry.At present,many simple synthetic methods of pyrrole derivatives have been successfully applied to practical production.Ketene dithioacetals as a kind of multi functional organic molecule,its conversion type is varied,its structural changes are abundant,and it is easy to prepare.Therefore,it is widely used in organic synthesis.Based on Ketene dithioacetals many reaction modes were developed,include: the conversion of its alpha functional groups,as 1,3-or 1,5-amphiphilic electrons are involved in the construction of various cyclization products,and the transformation based on the transition metal catalyzes the activation of carbon and sulfur bonds,and so on.Our research group has long been committed to the research of ketene dithioacetals chemistry,and has also made a deep exploration for the synthesis of heterocyclic compounds.Based on this,a simple,efficient and mild method for the construction of multi substituted pyrrole derivatives was developed from ketene dithioacetals and N-benzyl-1-phenyl methimide,and the electrical effect of the substituent on the selectivity of the reaction region was also studied.It provides a new idea for the further research of the ketene dithioacetals and the exploration of the synthesis method of pyrrole derivatives.The main contents of this paper are as follows:1.The importance of pyrrole derivatives and their application in the study and production were reviewed.The methods of preparing the pyrrole heterocyclic ring by the preparation of the precursors containing the [CNC] three element synthon and the [3+2] cyclization reaction were summarized.The structural characteristics of the organic intermediates of ketene dithioacetals,as well as the cytoskeleton with the polar alkenes of ketene dithioacetals,and the involvement of the beta-alkyl sulphide in the ring-forming reaction are described.2.Through the systematically condition screening,the [3+2] cyclization of ketene dithioacetals and N-benzyl-1-phenyl imide was successfully realized,and a series of pyrrole derivatives were prepared,which provided a new way for the application of ketene dithioacetals in the cyclization reaction and the synthesis method of pyrrole ring skelton.