Chlorination reactions of ephedrines revisited. Stereochemistry and functional groups effect on the reaction mechanisms
作者:Angelina Flores-Parra、Patricia Suárez-Moreno、Sonia A Sánchez-Ruı́z、Margarita Tlahuextl、Javier Jaen-Gaspar、Hugo Tlahuext、Raúl Salas-Coronado、Alejandro Cruz、Heinrich Nöth、Rosalinda Contreras
DOI:10.1016/s0957-4166(98)00155-4
日期:1998.5
The stereochemistry of the chlorination reactions with SOCl2 of free ephedrine and pseudoephedrine and their hydrochlorides, oxamides and sulfonamides was analyzed. Chlorination of free and hydrochloride erythro isomers occurs with 100% inversion of configuration at C-1 (SN2 mechanism). Chlorination of oxamides and sulfonamides of erythro isomers occurs with retention of the configuration at C-1, (SNi
分析了游离麻黄碱和伪麻黄碱与SOCl 2氯化反应的立体化学及其盐酸盐,草酰胺和磺酰胺。的自由和盐酸赤式异构体的氯化与C-1(S构型的100%反转发生Ñ 2机构)。赤型异构体的草酰胺和磺酰胺发生氯化反应,保留C-1构型(S N i机理)。所有苏式异构体及其衍生物的盐酸盐,草酰胺或磺酰胺中的氯化反应均得到相同比例的赤型(40%)和苏型(60%)(S N1机制)。用HCl处理DMSO中的盐酸氯脱氧麻黄碱和氯脱氧伪麻黄碱的异构体混合物会改变异构体比例,增加赤型异构体含量(65%)。如果该化合物事先被甲苯磺酸化或转化为酰胺,或者如果该化合物直接被SOCl 2氯化,则使用赤型乙醇胺可以有选择地到达赤型氯胺。