Asymmetric Dihydroxylations of 1-Substituted (<i>E</i>)- and (<i>Z</i>)-3-Methylpent-2-en-4-ynes: Full Compliance with the Sharpless Mnemonic Re-established and Embellished
                                
                                    
                                        作者:Heike Burghart-Stoll、Oliver Böhnke、Reinhard Brückner                                    
                                    
                                        DOI:10.1021/ol103063t
                                    
                                    
                                        日期:2011.3.4
                                    
                                    Asymmetric dihydroxylations ("ADs") of the pentenynyl chlorides (E)- and (Z)-1 or the pentenyne-based ester (Z)-3 in the presence of (DHQ)(2)-containing ligands delivered diol stereoisomers (2R,3S)-2, (2R,3R)-2, and (3S,4R)-4, respectively. The ADs of pentenynyl ethers (E)-10 and (Z)-12, respectively, have the same stereochemical preference under analogous conditions; these reattributions correct previous reports of the contrary. The Sharpless mnemonic rationalizes all these results implying that each substrate prefers a Sharpless/Norrby instead of a Chapleur orientation in the transition state.