Abstract
This dissertation describes the development of new synthetic organic transformation by using gold and zinc salts. Transition metal-catalyzed organic transformations such as Oxidative Cyclization, Di-stereo and Enatioselective [2+2+3] cycloaddition, 1,4-Dioxo Functionalizations, 1,4-Metathesis Reactions of appropriately functionalized organic molecules are described in this dissertation. For sake of convenience and better understanding, the thesis is divided into four chapters. The first chapter deals with the Gold-Catalyzed Oxidative Cyclization of 1,5-Enynes Using External Oxidants (8-Methylquinoline N-Oxide) to deliver indanone frameworks. Such indanone core is one of the most commonly encountering skeletons in nature. The core structure of the resulting products are construct through a formal reactions proceed through prior oxidations of alkyne to form α-carbonyl intermediates, followed by intramolecular carbocyclizations. The second chapter deals with the Gold-catalyzed diastereo- and enantioselective [2+2+3]-cycloaddition reactions of 1,6-enynes with nitrones. The utility of such reactions is manifested by a wide substrate scopes of 1,6-enynes and nitrones. This Gold-catalyzed diastereo- and enantioselective [2+2+3]-cycloaddition reactions of 1,6-enynes with nitrones deliver 1,2-Oxazepane core which has wide aplication in structural and biological importance. The third chapter describes new 1,4-oxo functionalizations of 3-en-1-ynes based on a hydrative oxidation approach. The one-pot dioxo reactions were applicable to various 3-en-1-ynes including unactivated 3-aryl-3-en-1-ynes, giving Z- or E-configured 2-en-1,4-dicarbonyl compounds selectively. In this chapter, mechanistic analysis supported an initial formation of furan intermediates, generated from carbonyl-assisted alkenyl fluorinations of hydration intermediates. This work reports the first success for 1,4-oxo functionations of readily available 3-en-1-ynes to offer highly functionalized alkenes. The fourth chapter presents Catalyst-dependent metathesis reactions between 3-en-1-ynamides and nitrosoarenes are described. Particularly notable are the unprecedented 1,4-metathesis reactions catalyzed by Ag(I) or Zn(II) to give 3-imidoylalkynes and benzaldehyde. With 3-en-1-ynamides bearing a cycloalkenyl group, 1,4-oxoimination products were produced efficiently without molecular fragmentation. We have developed metathesis/alkynation cascades for terminal 3-imidoylalkynes and benzaldehyde species generated in situ, to manifest 1,4-hydroxyimination reactions of 3-en-1-ynes.