Study On The Annulation Reactions Of Zwitterionic Thiolates And α-Enolic Dithioesters

This thesis mainly consists of four chapters:(1)the development of versatile sulfur-containing synthons;(2)study on the reaction of zwitterionic thiolates with alkyl propiolates;(3)study on the reaction of α-enolic dithioesters with 1,3,5-triazinanes;(4)study on the reaction of α-enolic dithioesters with active 1,3-dipoles.Chapter 1: the development of versatile sulfur-containing synthonsOrganosulfur compounds are ubiquitous in natural products,pharmaceutical molecules and functional materials.Thus,the synthesis of sulfur-containing compounds occupies a significant position in organic chemistry.Now,many versatile sulfurcontaining synthons accompanied with efficient methods have been disclosed to introduce sulfur atoms into target molecules.Sulfur powder,inorganic metal sulfides and sulfur-containing small organic molecules have been developed as sulfuration agents.However,the use of these synthons to incorporate sulfur into organic molecules does have some drawbacks,such as high temperature and transition-metal catalysts.This chapter focuses on the development and application of thiolates and α-enol dithioesters using as sulfur-containing synthons.Chapter 2: study on the reaction of pyridinium thiolates with alkyl propiolatesA novel cyclization reaction of pyridinium 1,4-zwitterionic thiolates and propiolic acid derivatives mediated by triethylamine is described,which allows facile synthesis of indolizine under mild reaction conditions.The net transformation involves an acetylide-driven formal(5 + 1)annulation reaction followed by a spontaneous ringcontraction/sulfur extrusion process from transient pyridothiazine intermediates.Chapter 3: study on the reaction of α-enolic dithioesters with 1,3,5-triazinanesThe synthesis of 1,3-thiazines from α-enolic dithioesters and 1,3,5-triazinanes has been achieved via a formal(3 + 3)annulation reaction under thermal conditions,where1,3,5-triazinanes were utilized as three atom synthons.This transformation is catalystfree and additive-free.Chapter 4: study on the reaction of α-enolic dithioesters with active 1,3-dipolesThe synthesis of two kinds of five-membered organosulfur heterocycles(i.e.,1,4,2-oxathiazoles and 1,3,4-thiadiazoles)from α-enolic dithioesters with active 1,3-dipoles(nitrile oxides and nitrilimines)generated in situ was achieved under mild reaction conditions.This transformation further expands the synthetic application of α-enolic dithioesters using as the sulfur-containing building blocks.