- Ammonium Chloride-Promoted Rapid Synthesis of Monosubstituted Ureas under Microwave Irradiation
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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.
- Lan, Chunling Blue,Auclair, Karine
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supporting information
p. 5135 - 5146
(2021/10/19)
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- Synthesis of carbamates and ureas using Zr(IV)-catalyzed exchange processes
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Equation presented Zirconium(IV)-catalyzed exchange processes have been developed to prepare both carbamates and ureas from dialkyl arbonates and carbamates employing 2-hydroxypyridine (HYP) and 4-methyl-2-hydroxyquinoline (MeHYQ) as catalytic additives, respectively A microwave acceleration effect was observed in Zr(IV)-catalyzed carbamate-urea exchange.
- Han, Chong,Porco Jr., John A.
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p. 1517 - 1520
(2008/02/02)
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- Highly selective aldose reductase inhibitors. 1. 3-(Arylalkyl)-2,4,5- trioxoimidazolidine-1-acetic acids
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A series of 3-(arylalkyl)-2,4,5-trioxoimidazolidine-1-acetic acids (1) was prepared and tested for aldose reductase (AR) and aldehyde reductase (ALR) inhibitory activities. These compounds showed strong inhibitory activity against AR without significant inhibitory activity for ALR. The ratio of IC50(ALR)IC50(AR) was > 1000 in some compounds. On the basis of pharmacological tests such as the recovery of reduced motor nerve conduction velocity and toxicological profile, 3-(3-nitrobenzyl)-2,4,5- trioxoimidazolidine-1-acetic acid (NZ-314) was selected as the candidate for clinical development.
- Ishii,Kotani,Nagaki,Shibayama,Toyomaki,Okukado,Ienaga,Okamoto
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p. 1924 - 1927
(2007/10/03)
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