title: Asymmetric dihydroxylations of 1-substituted (E)- and (Z)-3-methylpent-2-en-4-ynes: full compliance with the Sharpless mnemonic re-established and embellished.
abstract: 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.
authors.affiliation: Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Freiburg im Breisgau, Germany.
authors.forename: Heike
authors.initials: H
authors.lastname: Burghart-Stoll
authors.forename: Oliver
authors.initials: O
authors.lastname: Böhnke
authors.forename: Reinhard
authors.initials: R
authors.lastname: Brückner