Abstract
This thesis describes nickel-catalyzed tandem reactions of alkenes, alkynes and organoboron reagents. Transition-metal catalyzed tandem reaction is an efficient pathway for constructing functionalized molecular structures which provide considerable options in the application of organic synthesis. In first chapter, we elaborate the highly selective nickel-catalyzed three-component coupling of alkynes with enones and alkenyl boronic acids which affords regio- and stereoselective 1,3-dienes. An intramolecular coupling of enynes with alkenyl boronic acid was also described. In chapter 2, we have developed a nickel-catalyzed tandem cyclization of 1,6-enynes with alkenyl boronic acids which affords a variety of pyrrolidine derivatives. Organoboron reagents proceeded a different chemoselectivity of 1,6-enynes on unusual sp3 carbon results from the protonation on the nucleophilic sp2 carbon of the key nickellacyclopentene intermediate. Chapter 3 describes the nickel-catalyzed borylative cyclization of electron-deficient 1,6-enynes with B2pin2. Pyrrolidones widely exists in the framework of natural products and biological active molecules. This methodology will provide considerable synthetic route for constructing functionalized pyrrolidones. The final chapter focuses on developing two kinds of cycloisomer- ization by means of modified substituents on the alkene-moiety of 1,6-enynes. Variation of substituent has a major impact on the reaction outcome which leads to alder-ene and halo-shift products via different mechanistic pathways. The conditions were acid-free and no additional chloride source which provide a mild route to functionalized pyrrolidines.