Ap. Rutherford et Rc. Hartley, Unexpected stereoselectivity in the anionic oxy-Cope rearrangement of acyclic enol ethers, TETRAHEDR L, 41(5), 2000, pp. 737-741
The anionic oxy-Cope rearrangement of alkoxides derived from (1E,SZ)-4-meth
yl-5-alkoxy-1-pheny-1,5-heptadien-3-ols proceeds via a chair-like transitio
n state with the oxyanion axial, even when there is a 3,4-relationship betw
een the methyl group and the oxyanion so that both groups are axial in the
transition state of the [3,3]-sigmatropic rearrangement. We believe that th
is is the first example of chelation control in the AOC rearrangement. The
reaction forms the basis of a stereoselective synthesis of beta-hydroxycycl
ohexanones containing four chiral centres. (C) 2000 Elsevier Science Ltd. A
ll rights reserved.