5-exo cyclisation regiospecifically. A competitive 1,5-hydrogen shift leading to imidoyl radicals was noticed. An analogous behaviour is also exhibited by vinyl radicals when allowed to add to carbon-nitrogen double bonds.
自由基6a,b的环化对5-exo过程具有高度区域选择性;6-内环闭环是次要路线,它们的比例取决于取代基。没有观察到五元自由基
中间体7a,b的环膨胀。自由基27a,27b特异性地引起5-exo环化。注意到竞争性的1,5-
氢转移导致亚
氨基自由基。当被允许加成
碳氮双键时,
乙烯基基团也表现出类似的行为。