142039-75-6Relevant academic research and scientific papers
Ammonium Chloride-Promoted Rapid Synthesis of Monosubstituted Ureas under Microwave Irradiation
Lan, Chunling Blue,Auclair, Karine
supporting information, p. 5135 - 5146 (2021/10/19)
Monosubstituted ureas are important scaffolds in organic chemistry. They appear in various biologically active compounds and serve as versatile precursors in synthesis. Monosubstituted ureas were originally prepared using toxic and hazardous phosgene equivalents. Modern methods include transamidation of urea and nucleophilic addition to cyanate salts, both of which suffer from a narrow substrate scope due to the need for a strong acid and prolonged reaction times. We hereby report that ammonium chloride can promote the reaction between amines and potassium cyanate to generate monosubstituted ureas in water. This method proceeds rapidly under microwave irradiation and tolerates a broad range of functional groups. Unlike previous strategies, it is compatible with other nucleophiles, acid-labile moieties, and most of the common protecting groups. The products precipitate out of solution, allowing facile isolation without column chromatography.
Synthesis and Conformational Behavior of Rhodium(I) Metallohosts Derived from Diphenylglycoluril
Coolen, Hein K. A. C.,Leeuwen, Piet W. N. M. van,Nolte, Roeland J. M.
, p. 4739 - 4747 (2007/10/03)
The design and synthesis of molecules containing both a substrate-binding cavity and a nearby catalytically active metal center is a useful approach to the development of synthetic systems that function according to the principles of enzymes.To this end the receptor molecule 2a, derived from diphenylglycoluril, was functionalized with triaryl phosphite ligands to give the recoptor ligand 2d. exchange reactions of 2d with (diketonate)Rh(CO)2, (diketone = acetylacetone, dibenzoylmethane, or dipivaloylmethane) led to the formation of the metallohosts 3a-c, respectively.The properties and conformational behavior of these metal complexes were studied by NMR techniques.Reaction of compounds 3 with H2 in the presence of a small excess of additional triphenyl phosphite yields the rhodium(I) hydride complex 5.The metallohosts are capable of binding dihydroxybenzene guests in their cavities by hydrogen bonding and ?-? stacking interactions.On binding a substrate the conformational behavior of hosts 3a-c was affected considerably.
