Molecular Design for Creation of Synthetic Equivalents and Reseach Development for the Application to Organic Synthesis

点击翻译按钮获取中文摘要

1.Synthesis of new di-exo-methylene compounds and fused isoxazolesWe have prepared and used methyl (trimethylsilylmethyl) acetylenecarboxylate as a dipolarophile and a common key compound leading to precursors for di-exo-methylene compounds which subsequently react with olefins in [4+2] cycloaddition mode to afford fused heterocyclic compounds. We found a new and general route toward the synthesis of the precursor for di-exo-methyleneisoxazolines and their Diels-Alder reactions leading to fused isoxazoles.2.New access to di-exo-methylenecyclobutanes via [2+2] cycloaddition of 3-methylthio-4-trimethylsilyl-1,2-butadiene with alkenes mediated by a Lewis acidIn the course of studies in organic synthesis using allylsilanes and propargylsilanes, we found a new and general route toward the synthesis of di-exo methylenecyclobutanes via the [2+2] cycloaddition of 3-methylthio-4-trimethylsilyl-1,2-butadiene with alkenes promoted by a Lewis acid followed by sequential reactions to sulfones by oxidation and 1,2-elimination. Di-exo-methylenecyclobutanes were also successfully applied to construct a bicyclo [5.2.0] nonane ring system by the [4+3] cycloaddition with an 2-oxyallyl cation. The title compound can be viewed formally as a synthetic equivalent of 1,2,3-butatriene or 1,3-butadien-2,3-diyl.3.Creation and Reactions of Carbonyl Ylides and Related 1,3-Dipolar Reagents1,3-Dipolar reagents are important and interesting chemical species from both synthetic and theoretical points of view. We found that the novel findings that simple carbonyl ylides, otherwise inaccessible, were indeed expediently generated by the silicon-based 1,3-elimination from alpha-aryl-substituted chloromethyl trimethylsilylmethyl ether under mild and neutral conditions which provided the powerful one-step synthesis of dihydrofurans and tetrahydrofurans and related heterocylesvia[3+2]cycloadditions to a vareity of multiple pi-bonds including C=C,C*C,C=O,C=S,C=N,N=N.