申请人:Glaxo Group Limited
公开号:US04399294A1
公开(公告)日:1983-08-16
Ranitidine is prepared by treating an aldehyde of formula (II) ##STR1## with dimethylamine and a reducing agent which is capable of effecting reductive alkylation to introduce the group Me.sub.2 NCH.sub.2 -- but which does not reduce the nitroethene group. The reaction is carried out in a suitable solvent, preferably in the presence of an acid or followed by treatment with an acid. Suitable reducing agents include, diborane, aluminium hydride and alkali or alkaline earth metal borohydrides. The aldehyde (II) may be generated in situ from an acetal of formula (III) ##STR2## where R.sub.1 and R.sub.2 are both alkyl groups or R.sub.1 OCHOR.sub.2 forms a cyclic acetal.
雷尼替丁是通过将化学式(II)的醛与二甲胺和一种还原剂反应制备而成,该还原剂能够进行还原烷基化反应以引入Me.sub.2 NCH.sub.2基团,但不会还原硝基乙烯基团。反应在适当的溶剂中进行,最好在酸的存在下进行或在处理后进行酸处理。适当的还原剂包括二硼烷、铝氢化物和碱金属或碱土金属硼氢化物。醛(II)可以从化学式(III)的缩醛中原位生成,其中R.sub.1和R.sub.2都是烷基或R.sub.1 OCHOR.sub.2形成环状缩醛。