Enyne Metathesis (Part I) and Development of New Methods for Functionalized Arenes (Part II)

This thesis has two main parts. Part I is composed of two chapters which describe the structure and reactivity of alkyne-chelated ruthenium alkylidene complexes and newly discovered non-metathetic activity of Grubbs catalysts. Part II consists of four chapters describing transition metal-catalyzed new synthetic methods for functionalized arenes via metal-complexed aryne intermediates generated in situ from multiynes. Specifically, in chapter one, recent advances of olefin metathesis are briefly reviewed and the first well-defined alkyne-chelated ruthenium alkylidene is delineated. In chapter two, a brief summary of previously reported notable non-metathetic reactions using Grubbs-type ruthenium alkylidenes is presented and a new 1,4-hydrovinylative cyclization of various multiynes with ethylene using Grubbs type ruthenium alkylidene is discussed. In chapter three, a brief survey for the progress of aryne chemistry and recent computational studies on regioselectivity of nucleophile addition to aryne intermediates is provided. In chapter four, a new paradigm of a catalytic hydrohalogenation to form structurally elaborated aryl halides using ruthenium alkylidene complex is described. In chapter five, a new C-H bond insertion reaction mediated by silver-stabilized arynes generated directly from alkyne building blocks is discussed. Preliminary mechanistic studies to elucidate the reaction mechanism are also presented. Finally, in chapter six a conceptually distinctive method capable of generating Ar-F, Ar-CF3 and Ar-SCF3 from non-aromatic precursors is described. Mechanistic novelty, broad substrate scope and excellent regioselectivity of this method allow an expeditious access to pharmaceutically important functionalized indoline and isoindoline derivatives.