有機マグネシウム反応剤を用いた新規合成反応の開拓

抄録

The reaction of β-iodo allylic acetals with EtMgBr in THF afforded tetrahydrofuran derivatives. On the other hand, the reaction in DME provided (3-tetrahydrofuryl) methylmagnesium species that could be trapped by a variety of electrophiles. Treatment of arylmagnesium species with EtMgBr and iodoalkanes in THF afforded 2-aryltetrahydrofurans.ⁿBu₃MgLi induces facile iodine-magnesium exchange at -78°C. ⁱPrⁿBu₂MgLi is more reactive than ⁿBu₃MgLi, and this reagent accomplishes selective bromine-magnesium exchange at -78°C. This procedure was utilized for the preparation of various polyfunctionalized arylmagnesium species. The exchange of alkenyl halides using this method proceeds with retention of configuration at the double bond. The reaction of gem-dibromocyclopropanes with ⁿBu₃MgLi affords butylated cyclopropylmagnesium species that can be trapped with various electrophiles. The reaction of dibromomethylsilanes with ⁿBu₃MgLi in the presence of a catalytic amount of CuCN 2 LiC1 gives α-silylpentylmagnesium compounds that react with electrophiles such as acyl chlorides or α, β-unsaturated ketones to afford α- or γ-silyl ketones respectively. Treatment of dibromodisilylmethanes with Me₃MgLi yields 1-bromo-1, 1-disilylethanes that can be converted into 1, 1-disilylethenes by dehydrobromination.