Chloro-, bromo-, and iodo-benzenes photoreact with cyclopentene to give, principally, products derived from insertion into the C–halogen bond, a type of reaction hitherto unknown in this series, but fluorobenzene mainly forms meta- and para-cycloadducts with only a minor proportion of the cis-insertion product.
氯苯,
溴苯和
碘苯与
环戊烯发生光反应,主要产生的产物是插入到C卤素键后生成的,这是该系列反应中迄今未知的一种反应,但
氟苯主要形成间位和对位加环基。仅少量的顺式插入产物。