Copper-catalyzed Direct Decarboxylative Hydrosulfonylation Of Aryl Propiolic Acids With Sulfonylhydrazides

In this thesis, copper-catalyzed direct decarboxylative hydrosulfonylation of aryl propiolic acids with sulfonylhydrazides was developed. The main results obtained are as follows:1. We utilized aryl propiolic acids and sulfonylhydrazides as the substrates, O2 in the air as an oxidant and Cu(I) as a catalyst to synthesize a series of vinyl sulfone derivatives which have wide applications in pharmaceutical intermediates and biologically active compounds. The catalysts and solvents played a crucial role. Comparison with non-polar solvents, polar solvents could promote this transformation. Remarkable features of this reaction include employing inexpensive propiolic acids as new alkene sources, O2 in the air as an oxidant, using minimally toxic and relatively cheap copper salt as catalyst under the mild, operational simplicity, environmental friendliness conditions and without additives and antioxidants. Moreover, this catalytic system was also applied to aliphatic sulfonylhydrazides.2. The reaction of terminal alkynes with sulfonylhydrazides was developed on the base of direct decarboxylative hydrosulfonylation of aryl propiolic acids with sulfonylhydrazides.3. In order to understand the mechanism of the transformations, a number of controlling experiments were carried out to gain more insights into the mechanism. When the decarboxylative hydrosulfonylation of phenylpropiolic acid 2a with 4-methylbenzenesulfonohydrazide 1a was performed under a nitrogen atmosphere instead of under air, only trace amount of desired product 3a could be observed; when the reaction was performed under copper-free conditions, the reaction could not occur at all, which indicates that the copper species and oxygen are essential to the reaction. The addition of radical scavenger TEMPO could dramatically inhibit the formation of 3a, demonstrating that a radical process may be involved in this reaction.