Chemistry and applications of N-heterocyclic carbene boranes

Chemistry and applications of N-heterocyclic carbene borane complex are demonstrated. Chapter 1 describes and introduces the background of NHC-boranes. Chapter 2 demonstrates the discovery and studies of thiol-catalyzed radical reduction reactions of alkyl and aryl halides with NHC-boranes. The radical reductive cyclization reactions with NHC-boranes were also investigated. These reactions occur by a polarity-reversal process, where thiol is the polarity-reversal catalysis. Chapter 3 describes the development and preparative experiments of first homolytic substitution reactions of NHC-boryl radicals at divalent atoms such as sulfur and selenium. The primary reaction products of heterocycle disulfides undergo a 1,3-boryl shift from S to N to give new class of stable NHC-boranes with B-N heterocycles bonds.;Chapter 4 describes the discovery that disulfides (RSSR), NHC-boryl mono- (NHC-BH2SR) and bis-sulfides (NHC-BH(SR)2) serve as both radical initiators and precatalysts in the radical reductions and reductive cyclizations with NHC-boranes. These reactions are also believed to occur by the polarity reversal catalysis mechanism. Chapter 5 describes the thiolation reactions with new synthesized NHC-boryl sulfides and --amido complexes. Chapter 6 introduces iodine-activated hydroboration and preliminary results of direct hydroboration.