Efficient and Selective Palladium‐Catalysed C‐3 Urea Couplings to 3,5‐Dichloro‐2(1H)‐pyrazinones

Abstract

GISING, J.; SVENSSON, F.; AAKERBLOM, E.; SKOELD, C.; SANDSTROEM, A.; Eur. J. Org. Chem. 2015, 5, 978-986, http://dx

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

“…Additionally, the use of L7 gave superior results compared to when other bidentate ligands (e.g., dppe and L11 ) were employed for the Pd-catalyzed cross-coupling of monosubstituted ureas and chloropyrazinone 417 , a structural unit for the development of complex protease inhibitors. 351 Belfrage and co-workers applied this transformation to couple urea 416 in the synthesis of a new hepatitis C virus (HCV) NS3 protease inhibitor candidate ( Scheme 98 b). The corresponding intermediate was obtained in excellent yield (84%) as a mixture of methyl and benzyl esters.…”

Selective Carboxylate Recognition Using Urea-Functionalized Unclosed Cryptands: Mild Synthesis and Complexation Studies

“…The lowest energy conformation of the complex of receptor 4c with PhCO 2 − was found after conducting a conformational search analysis, and selected conformers with lowest energies were optimized without any constrains at the DFT/M06-2X/6-31G(d)/C-PCM:DMSO level of theory using program Spartan'18 Parallel Suite (see Supporting Information for details). 22−24 tert-Butyl N-{4,11,17,24-Tetraoxo-2,26-dioxa-5,10,18,23,32pentaazatricyclo[25.3.1.1 12,16 ]dotriaconta-1(31),12,14,16-(32),27,29-hexaen-31-yl}carbamate 3. The product 3 was obtained as previously described.…”

“…Urea derivatives, due to their specific geometry, are capable of selectively binding the Y-shaped carboxylates. 10 Urea functions can be introduced easily into the structure of most molecular receptors, 11 and its importance is demonstrated by the key role they play in catalysis; 6 they are also often found in pharmaceuticals 12 and natural compounds. 13 In an earlier paper, we presented a procedure for synthesizing macrocyclic tetralactams using sodium methoxide.…”

One-Pot Synthesis of N-Monosubstituted Ureas from Nitriles via Tiemann Rearrangement

“…16 Other methods include addition of ammonia or ammonia equivalents to organic isocyanates and hydrolysis of N-substituted cyanamides (Scheme 1,D and E). 5,6,17,18 The methods depicted in Scheme 1 (B-E) are mutually complementary since they are all originated from the corresponding primary amines with multistep manipulations. SYNLETT0 9 3 6 -5 2 1 4 1 4 3 7 -2 0 9 6 © Georg Thieme Verlag Stuttgart · New York 2015, 26, 1823-1826 letter C.-H. Wang et al…”

“…Urea is among the most stable nitrogen-containing functionalities which widely exists in natural substances, 1 biological metabolites, 2 synthetic reagents or catalysts, 3,4 pharmaceutical or agricultural ingredients, [5][6][7] and functional macromolecules. 8 Owing to its broad application prospect, various synthetic approaches for multisubstituted ureas have been developed and utilized for laboratorial and industrial preparation.…”