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Upstream product

• 3240-34-4 [bis(acetoxy)iodo]benzene 
• 108-91-8 cyclohexylamine 
• 3173-56-6 benzyl isothiocyanate 
• 166985-86-0 N²-Benzylcyclohexanecarboximidamide 
• 7107-58-6 benzyl N-cyclohexylcarbamate 
• 100-46-9 benzylamine 
• 5817-68-5 cyclohexyl-carbamic acid methyl ester 
• 3712-40-1 tert-butyl cyclohexylcarbamate 
• 56379-88-5 cyclohexylcarbamic acid phenyl ester 
• 124068-97-9 4‐nitrophenyl N‐benzylcarbamate 
• 4663-83-6 β-hydroxyethyl benzylcarbamate 
• 96-49-1 [1,3]-dioxolan-2-one 
• 3173-53-3 Cyclohexyl isocyanate 
• 5330-97-2 N-hydroxy-2-phenylacetamide 

Downstream Products

• 64075-39-4 N-((benzylimino)methylene)cyclohexanamine 
• 698-90-8 N'-cyclohexylurea 

Relevant academic research and scientific papers

Di-urea compounds as gelators for organic solvents

Simple diurea compounds form thermoreversible gels with several organic solvents. These gels are stable up to temperatures of 100°C, and can be stored for months. Electron microscopy reveals that in these solvents the gelation agents assemble into very thin rectangular sheets which are several tens of micrometers long.

P(III)-Assisted Electrochemical Access to Ureas via in situ Generation of Isocyanates from Hydroxamic Acids

An external oxidant-free protocol for the generation of isocyanates from hydroxamic acids assisted by trivalent phosphine under mild electrochemical conditions was reported. The process started with the anodic oxidation of hydroxamic acids, followed by reacting with phosphine to form corresponding alkoxyphosphoniums and subsequent rearrangement with the release of tri-substituted phosphine oxide as the driving force to give isocyanates, which were trapped by N-based nucleophiles to produce various ureas. This method provides a broadly applicable procedure to access isocyanate intermediates under mild electrochemical conditions.

Palladium-Catalyzed Aerobic Oxidative Carbonylation of Amines Enables the Synthesis of Unsymmetrical N,N′-Disubstituted Ureas

A ligand-free palladium-catalyzed aerobic oxidative carbonylation of amines for the synthesis of ureas, particular unsymmetrically N,N′-disubstituted ureas, which cannot be accessed by any other palladium-catalyzed oxidative carbonylation of amines to date, is presented. An array of symmetrical and unsymmetrical ureas were straightforwardly synthesized by using inexpensive, readily available, stable, and safe amines with good to excellent yields under a pressure of 1 atm. This novel method employs oxygen as the sole oxidant and offers an attractive alternative to transition-metal-based oxidant systems.

Lanthanum(III) Trifluoromethanesulfonate Catalyzed Direct Synthesis of Ureas from N-Benzyloxycarbonyl-, N -Allyloxycarbonyl-, and N -2,2,2-Trichloroethoxycarbonyl-Protected Amines

A novel lanthanum triflate mediated conversion of N -benzyloxycarbonyl-, N -allyloxycarbonyl-, and N -trichloroethoxycarbonyl-protected amines into nonsymmetric ureas was discovered. In this study, lanthanum triflate was found to be an effective catalyst for preparing various nonsymmetric ureas from protected amines. A variety of protected aromatic and aliphatic carbamates reacted readily with various amines in the presence of lanthanum triflate to generate the desired ureas in high yields. This result demonstrated that this novel lanthanum triflate catalyzed preparation of ureas from Cbz, Alloc, and Troc carbamates can be employed for the formation of various urea structures.

Formamides as Isocyanate Surrogates: A Mechanistically Driven Approach to the Development of Atom-Efficient, Selective Catalytic Syntheses of Ureas, Carbamates, and Heterocycles

Despite the hazardous nature of isocyanates, they remain key building blocks in bulk and fine chemical synthesis. By surrogating them with less potent and readily available formamide precursors, we herein demonstrate an alternative, mechanistic approach to selectively access a broad range of ureas, carbamates, and heterocycles via ruthenium-based pincer complex catalyzed acceptorless dehydrogenative coupling reactions. The design of these highly atom-efficient procedures was driven by the identification and characterization of the relevant organometallic complexes, uniquely exhibiting the trapping of an isocyanate intermediate. Density functional theory (DFT) calculations further contributed to shed light on the remarkably orchestrated chain of catalytic events, involving metal-ligand cooperation.

Chemoselective isocyanide insertion into the N-H bond using iodine-DMSO: Metal-free access to substituted ureas

Insertion of isocyanides into the N-H bond gives access to many medicinally important and structurally diverse complex nitrogen-containing heterocycles. Although the transition metal catalyzed isocyanide insertion into the N-H bond is very common, polymerization of isocyanides in the presence of a transition metal and their strong coordination with metals are the common drawbacks. On the other hand, the inertness of most of the isocyanides towards amines in the absence of a metal catalyst has stymied the growth of the metal-free approach for isocyanide insertion into amines. As a result, only a handful of metal catalysed methods with limited substrate scopes have been reported for the synthesis of ureas via isocyanide insertion into amines and no metal-free version has been reported yet. Interestingly, chemoselective isocyanide insertion into amines has not been reported in the literature. We employed the I2-DMSO reagent system for the chemoselective synthesis of ureas, where isocyanides react with aliphatic amines only, while aromatic amines need a nucleophilic activator (DABCO) to facilitate the formation of ureas. This method gave direct and chemoselective access to ureas by evading the commonly used yet toxic isocyanates.

Facile direct synthesis of unsymmetrical ureas from N-Alloc-, N-Cbz-, and N-Boc-protected amines using DABAL-Me3

A practical synthetic method for the direct synthesis of unsymmetrically substituted ureas from N-Alloc-, N-Cbz-, and N-Boc-protected amines is described. In this study, efficient direct conversion of the Alloc-, Cbz-, and Boc-carbamate compounds to ureas was achieved in the presence of DABAL-Me3, an air stable and easily handled reagent. Using this reaction method, both protected aromatic and aliphatic amines were successfully transformed into various trisubstituted and tetrasubstituted ureas with high yields without side product. Our findings offer promising guidelines for direct preparation of useful ureas from N-Alloc-, N-Cbz-, and N-Boc-carbamates.

Method for synthesizing asymmetric disubstituted urea through catalytic oxidation and carbonylation

The invention discloses a novel method for directly synthesizing asymmetric disubstituted urea compounds. The method comprises the step of adding a palladium catalyst into a solvent polyethylene glycol or a polyethylene glycol water solution under the action of alkali, an iodine compound and an oxidant so as to catalyze direct cross coupling reaction of primary amine and carbon monoxide, so as to prepare the asymmetric disubstituted urea compounds. The method for preparing the asymmetric disubstituted urea compounds through the coupling reaction has the advantages that the catalyst is wide in source and environment-friendly; a substrate is wide in source, cheap and easy to process; a carbonyl is stable in source and cheap and does not generate waste; a ligand is not required in the reaction, and the reaction activity is good; reaction conditions are mild, and the reaction selectivity is high; the substrate has good functional group consistency and is wide in application range; and a reaction medium is environment-friendly and can be circularly recycled. The separation yield of a target product can reach up to about 97% under optimized reaction conditions.

A facile method for the preparation of unsymmetrical ureas utilizing zirconium (IV) chloride

A facile synthetic method for the preparation of unsymmetrical ureas from amines is described. Carbamoyl imidazole compounds were prepared by the reaction of 1, 1-carbonyldiimidazole with primary or secondary amines, and further activation by treatment with zirconium(IV) chloride to generate the desired urea. This reaction protocol was applied to the synthesis of tri and tetrasubstituted ureas with high yields. This study provides an alternative guideline for the practical preparation of various unsymmetrical ureas.

Ruthenium-Catalyzed Urea Synthesis Using Methanol as the C1 Source

An unprecedented protocol for urea synthesis directly from methanol and amine was accomplished. The reaction is highly atom-economical, producing hydrogen as the sole byproduct. Commercially available ruthenium pincer complexes were used as catalysts. In addition, no additive, such as a base, oxidant, or hydrogen acceptor, was required. Furthermore, unsymmetrical urea derivatives were successfully obtained via a one-pot, two-step reaction.