Regiocontrolled SNAr Reaction on 2,3-Dihalopyridines with NaSMe To Obtain Bromo(methylthio)pyridines as Key Precursors of 3-Halo-2-(hetero)arylthieno[2,3-b]pyridines and Thieno[3,2-b]pyridines
                                
                                    
                                        作者:Maria-João Queiroz、Agathe Begouin、Daniela Peixoto                                    
                                    
                                        DOI:10.1055/s-0033-1338442
                                    
                                    
                                        日期:——
                                    
                                    The synthesis of 3-halo-2-(hetero) arylthieno[2,3-b]pyridines and 3-halo-2-(hetero) arylthieno[3,2-b]pyridines has been performed through a three-step methodology from 3-bromo-2-chloropyridine or 2-bromo-3-fluoropyridine, respectively. The key step of this methodology is the formation of the required bromo(methylthio)pyridines by a regiocontrolled nucleophilic aromatic substitution (SNAr) with sodium methanethiolate (NaSMe). Then, the Sonogashira coupling with (hetero)arylalkynes followed by a halocyclization with bromine or iodine, afforded the expected 3-halo-2-(hetero)arylthienopyridines.