作者:Reinhard W. Hoffmann、Peter G. Nell、Roland Leo,、Klaus Harms
DOI:10.1002/1521-3765(20000915)6:18<3359::aid-chem3359>3.0.co;2-u
日期:2000.9.15
alpha-Chloro- and alpha-bromoalkyl Grignard reagents 11 and 30 with > 97% ee (enantiomeric excess) were generated by a sulfoxide/magnesium exchange reaction from the enantiomerically and diastereomerically pure sulfoxides 25 and 27. The resulting alpha-haloalkyl Grignard reagents are configurationally stable at -78 degrees C. Racemization sets in at or above -60 degrees C, especially when the solution
通过对映体和非对映体纯亚砜25和27的亚砜/镁交换反应生成了ee> 97%ee(对映体过量)的α-氯代和α-溴代烷基格氏试剂。所得的α-卤代烷基格氏试剂为在-78摄氏度下结构稳定。外消旋化温度在-60摄氏度或以上,尤其是当溶液中含有溴离子时。在不存在卤离子的情况下,当化学分解开始时,构型稳定性可扩展至-20摄氏度。