SYNTHESIS OF ARYZINC COMPOUNDS AND THEIR APPLICATIONS TO ORGANIC SYNTHESIS

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Organozinc compounds continue to attract synthetic organic chemists to a great extent because if their high chemoselectivity and specific reactivity observed in their further transformations. In this research, we investigated for the first time the direct synthesis of arylzinc compounds from aryl halides and zinc powder promoted by the irradiation of ultrasound. In this method, arylzinc compounds containing electron-withdrawing groups at ortho-positions were obtained readily. The zinc compounds were converted into multi-functional biaryls, which are othewise very difficult to prepare, in high yields by their reaction with aryl halides in the presence of Pd (0)-catalysts.This activation method was also applied to the reaction of o-diiodobenzene with zinc powder, which resulted in the first formation of o-phenylenedizinc compound. After the treatment with chlorotrimethyltin, the zinc compound was identified as the known tin-compound of the corresponding structure. Then, the zinc compound was converted into symmetrical o-terphenyls or 1,2-diacylbenzenes in high yields by the reaction with aryl halides or acyl halides in the presence of Pd (0)-catalyst. Selective monoacylation was also accomplished by the same reaction with acyl halides, except for the use of tris-(2,4,6-trimethoxyphenyl) phosphine in place of other phosphorus ligands in Pd (0) complex.In these studies, we also found the novel displacement of metal ions from organozinc compounds with such nucleophilic reagents as halide ion, thiocyanate ion, or N,N-dialkyldi-thiocarbamate ions by the assistance of NCS.Whereby various organic N,N-dialkyldithio-carbamates or organic thiocyanates were obtained in high yields.