Preparation of Mono-, Di-, and Trisubstituted Ureas by Carbonylation of Aliphatic Amines with <b><i>S</i></b>,<b><i>S</i></b>-Dimethyl Dithiocarbonate
作者:Rita Fochi、Emma Artuso、Iacopo Degani、Claudio Magistris
DOI:10.1055/s-2007-990813
日期:2007.11
General procedures are reported to prepare N-alkylureas, N,N'-dialkylureas (both symmetrical and unsymmetrical), and N,N,N'-trialkylureas by carbonylation of aliphatic amines, employing S,S-dimethyl dithiocarbonate (DMDTC) as a phosgene substitute. All reactions were carried out in water. Symmetrical disubstituted ureas were prepared directly working at 60 °C with a molar ratio of DMDTC:amine = 1:2
据报道,通过脂肪胺的羰基化制备 N-烷基脲、N,N'-二烷基脲(对称和不对称)和 N,N,N'-三烷基脲的一般程序,采用 S,S-二硫代碳酸二甲酯 (DMDTC) 作为光气替代品。所有反应均在水中进行。在 60°C 下直接制备对称二取代脲,DMDTC: 胺的摩尔比 = 1:2,优选在氮气下。通过在室温下在第一步中选择性形成的 S-甲基 N-烷基-硫代氨基甲酸酯中间体分两步制备不对称脲。这些中间体在第二步中与氨或各种脂肪胺(伯胺和仲胺)在 50 至 70°C 的温度下发生反应。所有目标尿素均以高产率获得(28 个示例,平均收率 94%)和非常高的纯度(通常 >99.2%)。还需要注意的是回收工业利益的副产品甲硫醇,每摩尔 DMDTC 回收量为两摩尔,同时完全利用试剂。