1,4-addition reaction of 5H-oxazol-4-ones to vinyl ketones catalyzed by chiral guanidines
                                
                                    
                                        作者:Akane Morita、Tomonori Misaki、Takashi Sugimura                                    
                                    
                                        DOI:10.1016/j.tetlet.2014.11.079
                                    
                                    
                                        日期:2015.1
                                    
                                    In this Letter, a chiral guanidine-catalyzed 1,4-addition reaction of 5H-oxazol-4-ones to vinyl ketones is described. The 1,4-addition reaction proceeded with a high enantioselectivity using 5H-oxazol-4-ones, substituted with a 3-chloro-5-methylphenyl group, as pronucleophiles and a newly developed chiral guanidine as a catalyst. The optimized reaction conditions were also effective in achieving excellent enantioselectivity in the 1,6-addition to dienones. Subsequent solvolysis of the 1,4-addition adduct yielded the corresponding alpha-hydroxy-5-oxocarboxylates. (C) 2014 Elsevier Ltd. All rights reserved.