58713-33-0

Carbon dioxide is regarded as a reliable C1 building block in organic synthesis because of the nontoxic, abundant, and economical characteristics of carbon dioxide. In this manuscript, a commercially available oxovanadium(v) compound was demonstrated to serve as an efficient catalyst for the catalytic amination of carbon dioxide under ambient pressure in the synthesis of ureas. The catalytic transformation of chiral amines into the corresponding chiral ureas without loss of chirality was also performed. Furthermore, a gram-scale catalytic urea synthesis under ambient pressure was successfully achieved to validate the scalability of this catalytic activation of carbon dioxide. This journal is

Substituted ureas have numerous applications but their synthesis typically requires the use of highly toxic starting materials. Herein we describe the first base-metal catalyst for the selective synthesis of symmetric ureas via the dehydrogenative coupling of methanol with primary amines. Using a pincer supported iron catalyst, a range of ureas was generated with isolated yields of up to 80% (corresponding to a catalytic turnover of up to 160) and with H2 as the sole byproduct. Mechanistic studies indicate a stepwise pathway beginning with methanol dehydrogenation to give formaldehyde, which is trapped by amine to afford a formamide. The formamide is then dehydrogenated to produce a transient isocyanate, which reacts with another equivalent of amine to form a urea. These mechanistic insights enabled the development of an iron-catalyzed method for the synthesis of unsymmetric ureas from amides and amines.

In this article, synthesis of 1,3-disubstituted urea (DSU) from three component reagent systems comprising amine, carbon dioxide, and propylene oxide is described. DSU is synthesized in the presence of a variety of ionic liquids (ILs) with/without promoters. Among used ILs, 1-butyl-3-methylimidazolium tetraiodoindateIII (represented as [Bmim][InI4]) is found to give the highest DSU product. A serious experiment clearly indicates that the tetraiodoindate anion plays an important role for the selective production of the DSU. Based on the in situ infrared spectroscopic studies, a plausible reaction mechanism for producing dicyclohexylurea from cyclohexylamine is proposed. The synthesis and characterization of [Bmim][InI4] are given in details. Moreover, the effect of reaction variables such as time, temperature, pressure, and the molar ratio of substrate to catalyst is also studied.

A novel efficient synthesis of N,N′-disubstituted ureas has been developed. Aromatic and aliphatic primary amines undergo oxidative carbonylation under atmospheric pressure of carbon monoxide using Pd(II) catalyst in combination with its anodic recycling at a graphite electrode.

Aliphatic and araliphatic primary amines react with carbon dioxide at 120-140 deg C in the presence of ruthenium complexes and terminal alkynes, especilly propargyl alcohols, to directly afford N,N'-disubstituted symmetrical ureas.The alkyne ruthenium intermediate acts as a dehydrating reagent.This new and mild method avoids the classical use of carbonyl precursors like phosgene or isocyanates.

A new method is described for the preparation of symmetrically and unsymmetrically disubstituted ureas by aminolysis of bis(4-nitrophenyl) carbonate.The second substitution is slower than the first one, and it is possible to isolate monosubstituted intermediates when equimolar amounts of substrates are used.The reaction of the intermediates with different amines give unsymmetrical derivatives of urea.

In dimethylsulfoxide solution in the presence of excess of powdered sodium hydroxide, N-substituted trichloroacetamides 1 are used as in situ isocyanate generating reagents which can react with carboxamides or sulfonamides 2 to afford acylureas or sulfonylureas 3.