Development of two synthetic routes to CE-178,253, a CB1 antagonist for the treatment of obesity
                                
                                    
                                        作者:Thomas A. Brandt、Stéphane Caron、David B. Damon、Joseph DiBrino、Arun Ghosh、David A. Griffith、Sandeep Kedia、John A. Ragan、Peter R. Rose、Brian C. Vanderplas、Lulin Wei                                    
                                    
                                        DOI:10.1016/j.tet.2008.10.067
                                    
                                    
                                        日期:2009.4
                                    
                                    CE-178,253 benzenesulfonate (1) is a CB1 antagonist discovered by Pfizer medicinal chemists. Two syntheses Of this compound are described. The first, based on the discovery synthesis, involves assembly of an aryl-substituted pyrazolotriazine core onto which the second aryl moiety is installed by a Suzuki Coupling: this route has been scaled to provide up to 6 kg of API. A second. more convergent route is also described, which installs the pyrazolotriazine containing both aryl substituents by condensation of a bromoketone with a substituted thiosemicarbazide. This route has been demonstrated on laboratory scale and is viewed as the preferred bond-forming sequence. (C) 2008 Elsevier Ltd. All rights reserved.