Stereoelectronic effects in hydrogen-atom transfer reactions of substituted cyclohexyl radicals
作者:Athelstan L. J. Beckwith、Christopher J. Easton
DOI:10.1039/p29830000661
日期:——
cycloalkenes and cycloalkanes by hydrogen-atom transfer reactions of the initially formed conformationally biased 4-t-butyl-, 4-t-butyl-cis,cis-2,6-dimethyl-, 4-t-butyl-cis,trans-2,6-dimethyl-, 4-t-butyl-cis-2-methyl-, 4-t-butyl-trans-2-methyl-, and 5-t-butyl-cis-2-methylcyclohexyl radicals (12)–(17). The composition of the product mixtures indicates that transfer of axial β-hydrogen atoms occurs more
过氧草酸酯(1)-(7)和二酰基过氧化物(8)-(11)在环己烷中于100°C进行热解,通过最初形成的构象偏向的4-叔丁基-氢原子转移反应生成环烯烃和环烷烃,4-叔丁基-顺式,顺式-2,6-二甲基-,4-叔丁基-顺式,反式-2,6-二甲基-,4-叔丁基-顺式-2-甲基-,4-叔丁基-反-2-甲基和5-叔丁基-顺-2-甲基环己基自由基(12)-(17)。产物混合物的组成表明,轴向β-氢原子的转移比赤道β-氢原子的转移发生得更快。这些结果支持这样的假设:当C–H键靠近相邻的半占领轨道的平面时,倾向于进行C–H键的同质裂变。