Synthesis of Vicinal Dimethyl Chirons by Asymmetric Hydrogenation of Trisubstituted Alkenes
                                
                                    
                                        作者:Jian Zhao、Kevin Burgess                                    
                                    
                                        DOI:10.1021/ja905458n
                                    
                                    
                                        日期:2009.9.23
                                    
                                    Roche ester derivatives were converted to trisubstituted alkenes with allylic chiral centers. Hydrogenation of these substrates with chiral analogues of Crabtree's catalyst, specifically, an optically active carbene oxazoline derivative, were found to be mostly catalyst controlled. However, the peripheral functionalities and protecting groups had significant effects and could be adjusted to give high stereoselectivities. The upshot of this work is that alpha,omega-functionalized chirons to introduce 1,2-dimethyl functionalities into acyclic chains have been developed.