The stereoselective allylation of methyl ketones is described to give tertiary homoallylic
ethers, which can easily be transformed into homoallylic alcohols by a Birch reduction.
Reaction of methyl ketones 4 with allylsilane 5 in the presence of the chiral TMS ether 3a and a catalytic amount of trifluoromethanesulfonic acid led to homoallylic ethers
6 in high yield with a selectivity of 9:1 to >20:1. The TMS ether 3a was prepared from inexpensive mandelic acid, which is commercially available in both
enantiomeric forms, in four steps.
allylations - allylsilannes - amino alcohols - asymmetric synthesis - Birch reduction
- homoallylic alcohols