epoxidation of α,β-enones 1a–d with hydroperoxides 2 and mediated by cinchonine- and cinchonidine-derived phase-transfer catalysts (PTCs) 3 affords the optically active epoxides 4 with moderate to very good e.e.s and in near quantitative yields. For the conformationally flexible enone 1b, the enantioselectivity decreases with more sterically demanding tertiary hydroperoxides, while an opposite trend is observed
α,β-烯酮1a – d与氢过氧化物2的不对称Weitz–Scheffer环氧化反应,并由
辛可宁和
辛可尼定衍生的相转移催化剂(
PTC)3介导,提供了具有中等至非常好的ee且接近于ee的旋光性环氧
树脂4。定量产量。对于构象柔性烯酮1b,对映体选择性随空间要求更高的叔氢过氧化物而降低,而对于刚性s-顺式-烯酮1则观察到相反的趋势。使用笨重的氢过氧化枯基异丙基苯2c和
PTC 3c,烯酮1迄今为止,使用氢过氧化物作为氧源,将
PTC转化为具有最高对映选择性(95%ee)的
环氧化物4c。