Synthesis of quaternary carbon centered chromans from the reactions of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with allenic ester or allenic sulfone catalyzed by tertiary phosphine and SPTS
                                
                                    
                                        作者:Fangle Hu、Xiaoyang Guan、Min Shi                                    
                                    
                                        DOI:10.1016/j.tet.2012.04.036
                                    
                                    
                                        日期:2012.6
                                    
                                    Cyclization reactions of ethyl 2-(2-hydroxyaryl)-2-oxoacetates with ethyl 2,3-butadienoate and allenylsulfone proceeded smoothly in the presence of tertiary phosphine and sodium p-toluenesulfinate (SFTS) to give the corresponding quaternary carbon centered chromans in moderate to good yields under mild conditions, which provides an alternative efficient approach for the synthesis of biologically active chroman products. (C) 2012 Elsevier Ltd. All rights reserved.