Studies on Structure and Reactivity of Novel Organometallic Reagents

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Investigators of this group extended the research on generation of new functionalized organometallic reagents and innovation on new synthetic methodologies using the reagents. Research was focused on the generation of multifunctional organometallic reagents, mainly dimetallic reagents, and the development of new highly selective reactions using multi-metal complex system. Main research results obtained within the term of the research project are follows.1.Studies on gem-Dimetallic Reagents : Generation and Synthetic Applications.A possibility of direct preparation of gem-dizinc reagents from gem-dihalides was suggested by the use of Pb-catalyzed reaction with Zn. Then, gem-dizinc reagents have been obtained in good yields. Dimetallic reagents thus obtained, RCH (ZnX)_2 where R=H,Me, Me_3Si etc, are useful in organic synthesis ; olefination of carbonyl compounds including ester, and stepwise reaction of electrophiles.2.New Reactions using Organolanthanoid Reagents.Generation of chiral a … More lpha-haloalkyl building block from achiral dihalides has been discovered : SmI_2-mediated reaction of 1,1-diiodoethane with chiral aldehydes gave chiral halohydrin in high diastereoselective manner. Chiral 1-iodoethyl reactive block was generated. Ethyl 2-bromoacetate gives ethyl 4-diiodosamario-3-oxo-butanoate selectively in low temperature, whose reaction with ketones and mixed anhydrides afforded hydroxy keto esters and diketo esters, respectively.3.Organic Synthesis Using Functional Organosilicon Reagents.Several synthetic reactions using silacyclobutane, dibromomethylsilanes, and acylsilanes have been disclosed. Various new carbon-carbon forming reactions have been studied, including threecomponent coupling of haloacylsilanes, acylsilane, and carbonyl compounds.4.Use of Manganese in Organic Synthesis.Some organic reactions using organomanganese and manganese ate-complexes have been studied ; organic synthesis using these manganese species in stereoselective addition to unsaturated bonds and reduction of organic halides were reported. Less