Efficient Control of the Stereoselectivity in Reactions of 2-Oxy-Substituted Benzylic Radicals
作者:Nadira Moufid、Philippe Renaud、Carla Hassler、Bernd Giese
DOI:10.1002/hlca.19950780422
日期:1995.6.28
The stereoselectivity in reactions of 2-oxy-substituted radicals of type B was investigated. As expected, minimization of allylic 1,3-strain was the major controlling factor. Under standard conditions, only a modest level of stereoselectivity was observed. E.g., deuteration of the benzylated radical (R1 = benzyl) gave diastereoisomer ratios ≤ 2:1. Use of a bulky protective group on the O-atom (R1 =
研究了B型2-氧取代基在反应中的立体选择性。如预期的那样,最小化烯丙基1,3-菌株是主要的控制因素。在标准条件下,仅观察到适度的立体选择性。例如,苄基化的基团的氘代(R 1=苄基)给出的非对映异构体比率≤2∶1。在O原子上使用庞大的保护基(R 1 =(t -Bu)Ph 2Si)略微提高了选择性(比率4.1:1)。但是,当用庞大的甲基铝双(酚盐)衍生物(甲基铝双[2,6-二(叔丁基-丁基] -4-甲基苯氧基](MAD)和甲基铝双(2,6-二苯基苯氧基)(MAPH))。