作者:Fraser F. Fleming、Zhiyu Zhang、Guoqing Wei、Omar W. Steward
DOI:10.1021/jo052102j
日期:2006.2.1
C-magnesiated nitriles with alkyl halides, sulfonates, and unstrained ketones occurs with the retention of the CMg configuration, whereas aldehyde and acyl cyanide acylations proceed with inversion of the stereochemistry. Mechanistic probes indicate that the stereoselectivity is controlled by stereoelectronic effects for most electrophiles, except allylic, benzylic, and cyclopropyl halides where single-electron-transfer
将格氏试剂依次羰基加成-共轭加成到3-氧代环己-1-烯-1-腈中,生成C-镁化的腈,其烷基化立体选择性直接取决于亲电试剂的性质。这些C-镁化的腈与烷基卤化物,磺酸盐和未应变的酮的烷基化在保留C Mg构型的情况下发生,而醛和酰基氰化物的酰化则随着立体化学的进行而进行。机理探针表明,对于大多数亲电试剂,其立体选择性是受立体电子效应控制的,除了单电子转移过程介入的烯丙基,苄基和环丙基卤化物外。筛选C的许多烷基化具有多种亲电试剂的氨基苯甲酸酯化的镁揭示了反应范围,并描绘了引起高度不寻常的亲电试剂依赖性烷基化的基本立体电子效应。