The 1,2-addition of formaldehyde N,N-dialkylhydrazones to simple aldehydes takes place in the presence of ZnCl2 or Et2AlCl to afford the corresponding α-hydroxyhydrazones. More reactive aldehydes undergo addition of these reagents in the absence of promoters. Use of (S)-1-methyleneamino-2-(diphenylmethoxymethyl) pyrrolidine as the reagent afforded separable mixtures of diastereoisomers, thereby allowing for the isolation of optically pure adducts in a single step.
在 ZnCl2 或 Et2AlCl 的存在下,
甲醛 N,N-二烷基
肼与简单的醛发生 1,2-加成反应,生成相应的 δ-羟基
肼。在没有
促进剂的情况下,活性更强的醛会与这些试剂发生反应。使用(S)-1-亚甲基
氨基-2-(二
苯基甲氧基甲基)
吡咯烷作为试剂,可得到非对映异构体的可分离混合物,因此只需一步就能分离出光学纯加合物。