isocyanates via base-induced β-elimination of haloform N-monosubstituted trihaloacetamides is described. The rate of reaction exhibits a strong dependence on the nature of the trihalomethyl group. Thus, while the reaction of tribromoacetamides proceeds at room temperature and the reaction of trichloroacetamides requires heating in polar solvents, no reaction could be observed for any of the corresponding
Iron(iii) catalysed synthesis of unsymmetrical di and trisubstituted ureas – a variation of classical Ritter reaction
作者:Hosamani Basavaprabhu、Vommina V. Sureshbabu
DOI:10.1039/c2ob06916d
日期:——
An application of the classical Ritter reaction for the synthesis of unsymmetrical di and trisubstituted ureas catalyzed by FeCl3 is described. The protocol is of significant interest in view of the easy availability of precursors, mild reaction conditions employed and interestingly its applicability for the alkylation of alcohols capable of forming stable carbocationic intermediates even to the sterically hindered moieties.
A fast and efficient protocol for the synthesis of N,N'-disubstituted urea derivatives from alkyl halides and primary or secondary amines has been developed. The synthetic pathway combines nucleophilic substitutions and a Staudinger-aza-Wittig reaction in the presence of polymer-bound diphenylphosphine under 14 bar of CO2 pressure and has been performed in a one-pot two-step process. The protocol has
已开发出一种快速有效的方案,用于从烷基卤化物和伯胺或仲胺合成 N,N'-二取代脲衍生物。合成途径结合了亲核取代和 Staudinger-aza-Wittig 反应,在聚合物结合的二苯基膦存在下,在 14 bar 的 CO2 压力下,并在一个一锅两步法中进行。该协议在微波辐射下进行了优化,放大实验是在帕尔反应器的常规条件下进行的。最终化合物在简单过滤后以几乎定量的总产率分离,这使得该过程容易且快速执行。
Copper catalyzed oxidative coupling of amines with formamides: a new approach for the synthesis of unsymmetrical urea derivatives
Direct access to unsymmetrical urea derivatives via copper catalysed C–H/N–H coupling of formamides with amines has been developed at room temperature. This protocol is also applied to the synthesis of chiral urea derivatives.