A new chiral, oxidatively removable auxiliary for the Staudinger reaction is presented. When diazo ketones 1-3 prepared from suitably protected amino acids reacted with p-methoxyphenethyl (PMPE)-substituted imines, the corresponding trans-substituted β-lactams 7 and 8a-h were formed. With the (S)-configured imine 5, an improvement of the selectivities is observed in comparison with achiral p-methoxybenzyl (PMB)-substituted imines by double stereoselection; consequently, the ratio of isomers decreased with the (R)-imine 4. The auxiliary could be removed with cerium ammonium nitrate (CAN).
本文介绍了一种用于斯陶丁格反应的新型手性、可氧化去除的助剂。当由适当保护的
氨基酸制备的重
氮酮 1-3 与对
甲氧基苯乙基(
PMPE)取代的
亚胺反应时,生成了相应的反式取代的δ-内酰胺 7 和 8a-h。与非手性对甲氧基苄基(PMB)取代的
亚胺相比,(S)-
亚胺 5 通过双立体选择提高了选择性;因此,(R)-
亚胺 4 的异构体比例降低。
硝酸铈铵 (CAN) 可以去除辅助剂。