5020-93-9Relevant academic research and scientific papers
Copper(I)-catalyzed cycloaddition of 4-bromosydnones and alkynes for the regioselective synthesis of 1,4,5-trisubstituted pyrazoles
Decuypere, Elodie,Specklin, Simon,Gabillet, Sandra,Audisio, Davide,Liu, Hui,Plougastel, Lucie,Kolodych, Sergii,Taran, Frédéric
, p. 362 - 365 (2015)
Copper-catalyzed cycloaddition of alkynes with 4-bromosydnones provides a convenient, mild, and regioselective method for the synthesis of a wide range of bromopyrazoles. The broad functional group tolerance of the cycloaddition reaction and further palla
Facile access to 3,5-dihalogenated pyrazoles by sydnone cycloaddition and their versatile functionalization by Pd-catalyzed cross-coupling processes
Delaunay, Thierry,Es-Sayed, Mazen,Vors, Jean-Pierre,Monteiro, Nuno,Balme, Genevieve
scheme or table, p. 3837 - 3848 (2011/09/12)
The 1,3-dipolar cycloaddition of diversely N-substituted 4-iodosydnones with 3-halopropiolates produces easily separable mixtures of dihalogenated pyrazolylcarboxylic esters at a preparative scale level, with the 3,5-dihalogenopyrazole regioisomers always predominating. Further decarboxylation of the major isomers provided the corresponding 3,5-dihalogenopyrazoles with a free C-4 position. These were found to be valuable scaffolds for the elaboration of unsymmetrically 1,3,5-trisubstituted pyrazole derivatives by site-selective Pd-catalyzed cross-coupling reactions. Notably, the flexible and site-selective introduction of different (hetero)aryl, vinyl, or alkyl substituents at the C-5 and C-3 positions of the pyrazole core could be achieved through sequential Suzuki-type reactions with various boron compounds. Copyright
Catalytic activity of 1,3-dibromo-5,5-dimethylhydantoin (DBH) in the one-pot transformation of N-arylglycines to N-arylsydnones in the presence of NaNO2/Ac2O under neutral conditions: Subsequent bromination of these sydnones to their
Azarifar, Davood,Ghasemnejad-Bosra, Hassan
, p. 1123 - 1126 (2007/10/03)
1,3-Dibromo-5,5-dimethylhydantoin (DBH) has been found to efficiently catalyze the one-pot conversion of various N-arylglycines through N-nitrosation and cyclization to sydnones in combination with NaNO2 and Ac 2O in high yields (80-
