Suzuki–Miyaura reactions of N-protected tribromopyrazoles. Efficient and site-selective synthesis of 3,4,5-triaryl-pyrazoles, 3,5-diaryl-4-bromopyrazoles and 5-aryl-3,4-dibromopyrazoles
                                
                                    
                                        作者:Rasheed Ahmad Khera、Asad Ali、Hummera Rafique、Munawar Hussain、Jovana Tatar、Aamer Saeed、Alexander Villinger、Peter Langer                                    
                                    
                                        DOI:10.1016/j.tet.2011.05.036
                                    
                                    
                                        日期:2011.7
                                    
                                    Suzuki-Miyaura reactions of N-protected tribromopyrazoles were studied. The reactions proceed with excellent site-selectivity. The first attack occurs at position 5, while the second and third attack occur at positions 3 and 4, respectively. A variety of 3,4,5-triaryl-pyrazoles, 3,5-diaryl-4-bromopyrazoles, and 5-aryl-3,4-dibromopyrazoles were efficiently prepared. The products are not readily available by other methods. (C) 2011 Elsevier Ltd. All rights reserved.