Indium-mediated alkynylation of Baylis–Hillman acetates: a novel route to 1,4-enynes
                                
                                    
                                        作者:Jhillu S. Yadav、Basi V. Subba Reddy、Nagendra Nath Yadav、Ashutosh Pratap Singh、Madavi Choudhary、Ajit C. Kunwar                                    
                                    
                                        DOI:10.1016/j.tetlet.2008.08.019
                                    
                                    
                                        日期:2008.10
                                    
                                    Baylis-Hillman acetates undergo smooth alkynylation with aryl-susbstituted iodoalkynes in the presence of indium metal in refluxing dichloromethane to furnish 1,4-enynes in high yields with (E)-stereoselectivity. In the absence of Lewis acid, the reaction follows both S(N)2 and S(N)2' pathways affording 1:1 mixtures of 1,4-enynes. Upon addition of 10 mol % of InBr(3), the reaction proceeds preferably in the S(N)2' manner. In the case of adducts derived from acrylonitrile, the corresponding products are obtained in fairly good yields and with (Z)-stereoselectivity. (C) 2008 Elsevier Ltd. All rights reserved.