Development of New Synthetic Methods by Use of Heteroatom Elements and their Application to Organic Synthesis

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The aim of this project is to develop the new synthetic reactions based on the characteristics chemical properties of heteroatom elements and to apply these reactions to organic synthesis. The representative results were summarized below. (1) Diorganyl tellurides add to carbon-carbon triple bonds in the presence of a radical initiator to give corresponding vinylic tellurides. By the use of this reaction, a stereoselective synthetic method of divinyl tellurides has been developed. (2) A variety of organolithium compounds have been generated by tellurium-lithium exchange reaction and used for carbon-carbon forming reactions. Kinetic studies of metalloid-lithium exchange, such as I-Li, Se-Li, Te-Li, Sn-Li exchange, have been performed and the relative rates were determined by competitive experiments. (3) Unique cyclic diureas have been synthesized by selenium catalyzed carbonylation of tetraamines with carbon monoxide and their structures were determined by X-ray crystal structure analysis. By the theoretical calculations of selenium catalyzed carbonylation of amines, two possible reaction pathways for the generation of carbonyl selenide, which play an important role as the key intermediate, have been proposed. (3) A new preparative method of selenoesters from organolithiums, selenium, carbon monoxide, and alkyl halides has been developed. The use of isonitriles instead of carbon monoxide affords selenoimidates in good yields under similar conditions. (4) As the synthetic application of radical carbonylation methodology, we developed photoinitiated carbonylation of organoselenium compounds and double carbonylation of halogen substituted alkenes which gives diketones or ketoaldehydes via radical cyclization.