Divergent regioselectivity in the base-promoted reactions of cyclic eight-membered alpha-ketols with activated halides.
[reaction: see text] Deprotonation of 2-hydroxycyclooctanone followed by exposure to an allylic or benzylic halide proceeds very selectively to give the product of C-alkylation. The effect of Delta(5,6)-unsaturation is to promote instead the formation of the O-alkylated derivative. This crossover in kinetic preference is attributed to an inability of the olefinic system to attain a conformation conducive to proton abstraction at C-2.
Paquette
Leo A
LA
Evans Chemical Laboratories, The Ohio State University, Columbus, Ohio 43210, USA. paquette.1@osu.edu
Vilotijevic
Ivan
I
Hilmey
David
D
Yang
Jiong
J