Kinetic Study of the 7-<i>endo</i> Selective Radical Cyclization of <i>N</i>-<i>tert</i>-Butyl-<i>o</i>-bromobenzylmethacryl Amides: Kinetic Investigation of the Cyclization and 1,7-Hydrogen Transfer of Aromatic Radicals
作者:Akio Kamimura、Tomoko Kotake、Yuriko Ishihara、Masahiro So、Takahiro Hayashi
DOI:10.1021/jo400326b
日期:2013.4.19
concentration. These results revealed that regioselectivity is controlled in a kinetic manner and that there is no possibility of a neophyl rearrangement. The use of Bu3SnD revealed that 1,7-hydrogen transfer, in which an aryl radical abstracts a hydrogen atom from the methallylic methyl group, occurs during the reaction. Hydrogen abstraction from toluene, the reaction solvent, was also observed. The
的自由基环化反应的动力学调查ñ -叔丁基- ö -bromobenzylmethacryl酰胺,得到经由7- 2-苯并吖庚因内选择性环化物进行。通过用Bu 3 SnH处理由酰胺前体产生的芳基基团给出了三种化合物,它们是7-内环化的加合物,6-外环化的加合物和还原产物。通过GC分析追踪在各种Bu 3 SnH浓度下的环化反应。不论Bu 3的变化如何,7-内基/ 6- exo的选择性都是恒定的SnH浓度。这些结果表明,以动力学方式控制区域选择性,并且没有新叶重排的可能性。使用Bu 3 SnD揭示了在反应过程中发生了1,7氢转移,其中芳基从甲基烯丙基甲基中夺取了氢原子。还观察到从反应溶剂甲苯中提取氢。1,7-转移速率取决于Bu 3 SnX(X = H或D),并检查了反应动力学。从Bu 3中夺取芳基的氢的k H / k D值。SnX(X = H或D)使用4-溴茴香醚估算。这些值的利用揭示了Bu 3