Iron-Catalyzed Cyclization of Alkynols with Diorganyl Diselenides: Synthesis of 2,5-Dihydrofuran, 3,6-Dihydro-2<i>H</i>-pyran, and 2,5-Dihydro-1<i>H</i>-pyrrole Organoselanyl Derivatives
                                
                                    
                                        作者:Kamila K. Casola、Davi F. Back、Gilson Zeni                                    
                                    
                                        DOI:10.1021/acs.joc.5b01448
                                    
                                    
                                        日期:2015.8.7
                                    
                                    An iron-catalyzed system, using diorganyl diselenides as an organoselenium source, was used for the cyclization of 1,4-butyne-diols in the preparation of 3,4-bis(organoselany1)-2,5-dihydrofurans. The optimized reaction conditions are compatible with many functional groups in 1,4-butyne-diols and diorganyl diselenides. In addition, this catalyst system was also efficient with diorganyl disulfides, but it did not work for diorganyl ditellurides. The same reaction conditions were also extended to pentyne-1,5diol for the preparation of 4,5-bis(organoselany1)-3,6-dihydro-2H-pyrans and to 4-amino-butynol for the preparation of 2,5-dihydro1H-pyrrole derivatives. The synthetic utility of these heterocycles was studied using 5-bis(organoselany1)-3,6-dihydro-2H-pyrans as substrate in a Kumada-type cross-coupling reaction.