α-酰氨基苯丙酮的β-羟基衍生物,用异丙醇铝还原时,立体选择性地得到苏式异构物(threo),再转化成氯霉素或其类似物。但用硼氢化钠、四氢化铝锂一类试剂还原时,则得赤式(erythro)与苏式体的混合物,甚至以赤式为主。可能后一类试剂,因与酰氨基上的活泼氢相作用,而可能沿Cram五员环模型生成赤式异构体。若以邻苯二甲酰基保护氨基上的活泼氢,则有利于经六员环模 The β-hydroxy derivatives of α-amidopropiophenone, when reduced with aluminum isopropoxide, stereoselectively give threo threo and are converted to chloramphenicol or its analogues. However, when sodium borohydride and lithium aluminum hydride are used for the reduction, a mixture of erythro and threo body is obtained, even with erythro-type. It is possible that the latter class of reagents may generate erythro isomers along the Cram five-membered ring model due to interaction with the active hydrogen on the amido group. If the phthaloyl protection of active amino on the hydrogen, is conducive to the six-member ring mold