A novel and efficient multicomponent reaction of cyclic 2-diazo-1,3-diketones, carbodiimides, and 1,2-dihaloethanes has been developed, and it leads to unsymmetrical urea derivatives with good yields in a single operation. This transformation involves the cascade formation of C-X (X = Cl, Br, I), C-N and C[double bond, length as m-dash]O bonds through halogenation, nucleophilic addition, ring-opening, and enol-ketone tautomerization processes. This protocol is step- and atom-economical; 1,2-dihaloethane was used as an easily available halogenated reagent, and it is amenable to different functional groups.
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http://dx.doi.org/10.1039/d0ob00683a | DOI Listing |
Molecules
November 2024
Bioorganic & Biophysical Chemistry Laboratory, Linnaeus University Centre for Biomaterials Chemistry, Department of Chemistry & Biomedical Sciences, Linnaeus University, SE-39182 Kalmar, Sweden.
Unsymmetrical urea derivatives are essential structural motifs in a wide array of biologically significant compounds. Despite the well-established methods for synthesizing symmetrical ureas, efficient strategies for the synthesis of unsymmetrical urea derivatives remain limited. In this study, we present a novel approach for the synthesis of unsymmetrical urea derivatives through the coupling of amides and amines.
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December 2024
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata-700009, India.
Ru(III)-PhI(OAc), an unprecedented combination, is a highly efficient reagent system for the in situ generation of a valuable isocyanate intermediate from benzimidate synthons through a rearrangement. It unlocks a powerful platform for forming diverse C-N bonds, enabling the one-pot synthesis of an expansive array of valuable unsymmetrical ureas, carbamates, and their chiral analogues toward complex molecular structures with high selectivity and excellent yields. This new strategy not only exemplifies efficiency but also serves as a versatile tool for the construction of valuable molecular architectures, enhancing the scope and impact of modern synthetic chemistry.
View Article and Find Full Text PDFDalton Trans
November 2024
Department of Chemistry, University of California, Irvine, Irvine, California 92697, USA.
Salen ligands (salen = ,'-ethylenebis(salicylimine)) are well-known for their versatility and widespread utility in chelating metal complexes. However, installation of hydrogen-bonding units on the salen framework, particularly functional groups that require amine-based precursors such as (thio)ureas, is difficult to achieve without the use of protecting group strategies. In this report, we show that the phenylketone analog of salicyladehyde is a stable alternative that enables the facile installation of hydrogen bonding (thio)urea groups on the salen scaffold, thus imparting anion binding abilities to a metal salen complex.
View Article and Find Full Text PDFChem Sci
September 2024
Institute of Organic Chemistry, University of Vienna Währinger Strasse 38 1090 Vienna Austria
Ureas stand out as potent pharmacophores in drug development, rendering them a prime focus for synthesis. Herein, we present an appealing entry point for urea synthesis from protected amines (Nms-amides) and relying on a Lossen-type rearrangement process as an elegant example of deprotective functionalisation. The method developed exhibits an exceptionally broad tolerance towards various protected amines, encompassing numerous drug derivatives, and delivers high reaction yields.
View Article and Find Full Text PDFChemistry
September 2024
School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS, Bristol, UK.
Nucleophilic vinylic substitution (SV) by carbon nucleophiles allows the formation of vinylic C-C bonds without transition metal catalysts. In this paper, we show that tethering two alkenes together through a urea linkage can lead to the formation of a diene by an intramolecular SV reaction. The starting materials are fully substituted N,N'-diallyl ureas; the reaction proceeds in the presence of base, and entails a cascade of deprotonations, reprotonations, and an SV reaction of an allylic carbanion on a rare electrophile: a vinylic urea.
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