New Syntheses of Highly Reactive and Functional Organometallic Compounds and its Application to Organic Syntheses

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The following results are obtained in this research project.Acid-Catalyzed Cyclization ofVinylsilanes Bearing an Amino Group. Stereoselective Synthesis ofPyrrolidinesIn the presence of an acid catalyst, vinylsilanes bearing an amino group protected by an electron-withdrawing group were smoothly bychzed to 2-(silylmethyl) pyrrolidines. This cyclization was utilized for the Stereoselective synthesis of 2 ndisubstituted pyrrqlidines (n = 3-5).Radical Cyclization of 1-6-Enynes Using Allylstannanes and New Radical Reactions Using Stannyl Enolates as Radical Transfer AgentsIn the presence of AEBN, allyltributylstannanes bearing a radical-stabilizing group at the β-position smoothly reacted with 1,6-enynes to give cyclized products incorporated with the stannyl and allyl groups in moderate to good yields This cyclization is valuable for the synthesis of highly functionalized 5-membered carbocycles and heterocycles The reactions with β-cyanoallylstannane formed a certain amount of bicyclo[4.3. … More 0]non-l-enes along with monocyclized products. The radicaHmtiated reactions of α-halo-esters, -nitriles, and -ketones with stannyl enolates gave the corresponding γ-keto denvatives in moderate to high yields. This homolytic process was applied to the three-component coupling reaction among stannyl enolates, haloalkanes, and electron-deficient alkenes.Silicon-directed Cyclization of Vinylysilanes : Stereoselective Synthesis of Tetrahydrofurans and TetrahydropyransSilicon-directed Stereoselective syn addition of hydroxy group to olefmic double bond occurs intramolecularly in an acid-catalyzed cyclization of vinylsilanes bearing hydroxy group. The cyclization proceeds by stereospecific syn addition of the hydroxy group Vinylsilanes, (Z)-5-silyl-4-penten-l-ols bearing a substituent on the methylene tether, smoothly undergo the acid-catalyzed cyclization to give trans-2,5-, cis-2,4-, and trans-2,3-disubstituted tetrahydrofurans respectively, with moderate to high stereoselectivitv.Manganese Ate Species: Generation,and Reactions with ElectrophilesTrialkylmanganese (II) ate reagents, "RMnLi" reacted with iodomethylsulfides to produce thiomethylmanganese reagents, where the manganate serves as a reductant not an alkylation agent. The reductive behavior of trialkylmanganese (II) ate reagents provides a protocol for the direct generation of a new class of reagents thiomethylmanganese reagents with structural variety, and the generated thiomethylmanganese reagents reacted with allyl bromides, enones and aldehydes.New Method for Introduction of a Silyl Group into α,β-Enones Using a Disilane Catalyzed by a Copper(I) salt.The reaction of a disilane with a Cu(I) salt efficiently induces cleavage of the Si-Si bond to generate a silyl nucleophile in aprotic polar solvent and its 1,4-addition to α,β-unsaturated enones smoothly proceeds with a catalytic amount of a Cu(I) salt were found. This reaction is successfully applied to hexamethyldisilane to generate a trimethylsilyl nucleophile hitherto not easily accessible.Unprecedented Manganese-Mediated Reactions : Generation of Non-Stabilized Carbonyl Ylids.Activated manganese generates nonstabilized carbonyl ylides from bis (chloromethyl) ethers as a precursor, and using this system with manganese as a reductant, the reactions of the ylides with electron-deficient dipolarophiles can be attained without the direct reduction of dipolarophiles by the reductant. Less