title: Synthesis of enantiopure homoallylic ethers by reagent controlled facial selective allylation of chiral ketones.
abstract: The stereoselective allylation of chiral methyl ketones to give tertiary homoallylic ethers, which can easily be transformed into homoallylic alcohols, is described. Reaction of the enantiopure ketones 8a-d and the racemic ketones 26a-d with the norpseudoephedrine derivative 2 or ent-2 and allylsilane in the presence of a catalytic amount of trifluoromethanesulfonic acid, led to a series of homoallylic ethers with good to excellent diastereoselectivity (85:15 to > 97:3). The allylation is reagent controlled and nearly independent from the stereogenic centers in the substrates. A partial kinetic resolution was observed using the racemic ketones 26a-d. In the reaction of the chiral ketones 8a-d with the achiral reagents ethoxytrimethylsilane and allylsilane only a low diastereoselectivity was observed.
authors.affiliation: Institut für Organische Chemie, Georg-August-Universität Göttingen, Germany. ltietze@gwdg.de
authors.forename: L F
authors.initials: LF
authors.lastname: Tietze
authors.forename: B
authors.initials: B
authors.lastname: Weigand
authors.forename: L
authors.initials: L
authors.lastname: Völkel
authors.forename: C
authors.initials: C
authors.lastname: Wulff
authors.forename: C
authors.initials: C
authors.lastname: Bittner