title: Diastereoselectivity in scalemic tartrate/titanium epoxidations.
abstract: Nonlinearity in the diastereoselectivity of epoxidation of allylic alcohols with mixtures of titanium isopropoxide, tertbutyl hydroperoxide, and diethyl tartrate was observed. Racemic and enantiomerically pure alcohols E-2-methyl-4-hexen-3-ol and E-1-methoxy-5-(O-tertbutyldimethylsilyloxy)-2-penten-4-ol were prepared. Epoxidation reactions were carried out with Ti(OPri)4 and ButOOH accompanied by diethyl tartrate of varying enantiomeric purity. The simplest explanation of these results is that a dimeric epoxidation reagent is involved, with significantly different reactivity for the homochiral and racemic forms.
authors.affiliation: Dyson Perrins Laboratory, Oxford, UK. bjm@ermine.ox.ac.uk
authors.forename: J M
authors.initials: JM
authors.lastname: Brown
authors.forename: S J
authors.initials: SJ
authors.lastname: Leppard
authors.forename: J
authors.initials: J
authors.lastname: Oakes
authors.forename: D
authors.initials: D
authors.lastname: Thornthwaite