Study On The Cyclization Reactions Of Zwitterionic Thiolates And 1,3,5-Triazinanes

This thesis mainly consists of four chapters:（1）the review of the zwitterionic pyridiniums;（2）study on the reaction of pyridinium thiolates withα-functionalized bromoalkanes;（3）study on the reaction of pyridinium thiolates with activated allenes;（4）study on the reaction of para-quinamines with 1,3,5-triazinanes.Chapter 1:the review of the zwitterionic pyridiniumsZwitterionic pyridiniums are widely used in the synthesis of nitrogen-containing heterocyclic compounds due to their stable properties and versatile functions in various reactions.This chapter mainly introduces the research progress of four common zwitterionic pyridiniums.Chapter 2:study on the reaction of pyridinium thiolates withα-functionalized bromoalkanesThe synthesis of pyridothiazines was achieved using pyridinium 1,4-zwitterionic thiolates andα-functionalized bromoalkanes via a formal（5+1）pathway.Owing to the inherent instability of pyridothiazines,these organosulfur compounds could undergo ring-contraction/desulfuration reaction in air,delivering indolizines as the final products.The one-pot transformation was achieved by adding DDQ as an oxidant.Chapter 3:study on the reaction of pyridinium thiolates with activated allenes.Allenes as a class of synthons with high reactivity are widely used in cycloaddition reactions.A 1,5-dipolar cycloaddition reaction of pyridinium 1,4-zwitterionic thiolates and terminal activated allenes has been developed,which allows facile access to pyridothiazepines under thermal conditions.Chapter 4:study on the reaction of para-quinamines with 1,3,5-triazinanes.1,3,5-triazinanes,as stable and readily available surrogate of formaldimine,can participate in various aminomethylation and cycloaddition reactions.Apart from using as aminomethylation or participating in a（2+n）reaction,more atoms of 1,3,5-triazinane can be involved in an elaborated reaction for the synthesis of nitrogen heterocycles.The synthesis of hydrobenzoimidazoles and hydrobenzooxazoles from para-quinamines and 1,3,5-triazinanes was achieved via a formal（3+2）annulation reaction in the presence of In（OTf）₃ as the catalyst.