Diastereoselectivity in the addition of allylzinc reagents to delta-alkoxy-gamma,delta-disubstituted alkenyllithium compounds.
The carbometalation reaction of allyl- and crotylzinc bromide with metalated disubstituted homoallylic ethers gives tri- or tetrasubstituted 5-hexenyl ethers with excellent control of the diastereoselectivity. The stereochemistry of this reaction is discussed and has been attributed to an early transition state with chelation to the oxygen atom in the energetically favored conformer as the stereodetermining step.
Laboratoire de Chimie des OrganoEléments, Tour 44-45 2ème étage - Bte 183, Université Pierre et Marie Curie, 4 place Jussieu, 75252 Paris Cedex 05, France.
Nicolas
N
Bernard
Fabrice
F
Chemla
Franck
F
Ferreira
Naouel
N
Mostefai
Jean-F
JF
Normant