Fragmentation of dialkyl peroxides and ozonides is strongly influenced by the choice of Lewis acid. TiCl4 promotes C–O ionization (SN1 reaction) of tertiary peroxides while SnCl4 and BF3·OEt2 promote O–O heterolysis (Hock reaction). The cationic intermediates are trapped with allyltrimethylsilane to afford allylated alkanes and homoallyl ethers. In the absence of a nucleophile, ozonides (1,2,4-trioxolanes) invariably undergo O–O heterolysis. However, the combination of allyltrimethylsilane and SnCl4 results in formation of 1,2-dioxolanes via trapping of intermediates derived from SN1 ionization.
二烷基过氧化物和
臭氧化物的断裂强烈受到
路易斯酸选择的影响。TiCl4促进叔过氧化物的C-O离子化(SN1反应),而SnCl4和
BF3·OEt2促进O-O异裂(Hock反应)。阳离子中间体被烯丙基三甲基
硅烷捕获,得到烯丙基化的
烷烃和同
烯丙基醚。在缺少亲核试剂的情况下,
臭氧化物(1,2,4-三氧杂
环戊烷)不可避免地发生O-O异裂。然而,烯丙基三甲基
硅烷和SnCl4的组合导致通过捕获SN1离子化产生的中等体形成1,2-二氧杂
环戊烷。