Carbozincation Of Acetylenic Sulfones And Its Applications In The Synthesis Of Polysubstituted Olefins

In this thesis, the carbozincation of acetylenic sulfones and its applications in the stereoselective synthesis of polysubstituted olefins were investigated. The thesis consists of the following three parts.Firstly, we studied the carbozincation of acetylenic sulfones with organozinc reagents, which include allyl zinc bromide, benzyl zinc bromide, aryl zinc chloride, alkyl zinc chloride and diethyl zinc. The results showed that these reactions proceeded smoothly and theα-sulfonyl vinyl zinc reagents were obtained. The hydrolysis ofα-sulfonyl vinyl zinc reagents afforded trisubstituted olefins 4. The configuration of compounds 4aa and 4ab were verified by 1H-1H NOESY spectrum, which suggests that the reactions proceeded with high regio- and stereoselectivity. The carbozincation reaction was obviously affected by reaction temperature, reactant concentration, the ratio of reactants and catalyst.Secondly, we investigated the reactions ofα-sulfonyl vinyl zinc reagents with iodine, NBS and NCS. The compounds ofα-Sulfonyl vinyl halides were obtained in high yields. The molecular structure of product 5ba was determined by X-ray diffraction analysis. The result suggests that the halogenation proceeded with the retention of the double bond configuration.Thirdly, we studied the Negishi coupling reaction ofα-sulfonyl vinyl zinc reagents with halohydrocarbons catalyzed by NiCl2(PPh3)2. Tetrasubstituted olefins containing 1, 4-diene structural unit were synthesized regio- and stereoselectively by the three-component tandem reaction of allyl zinc bromide, acetylenic sulfones and halohydrocarbons. The reaction has the advantages of mild reaction conditions, medium to high yields, cheap catalyst and high...