with tri-n-butyltin hydride in the presence of azobisisobutyronitrile gave chiefly (E)-2-ethoxymethylenecyclopentane-1,1-d2 by way of a radical cyclization. This fact demonstrates clearly that the radical addition took place to give an intermediate vinylic radical in a bent form, in which the half-filled sp2 hybrid orbital is disposed in the trans position with respect to the carbon group which has
1-ethoxy-6-iodo-1-hexyne-3,3-d2 与三正丁基
氢化
锡在
偶氮二异丁腈存在下的反应主要得到 (E)-2-ethoxymethylenecyclopentane-1,1-d2自由基环化。这一事实清楚地表明,发生自由基加成以产生弯曲形式的中间
乙烯基自由基,其中半填充的 sp2 杂化轨道相对于刚刚添加的
碳基团位于反式位置。