Regiochemical control in intramolecular cyclization of methylene-interrupted epoxydiols.
[reaction: see text] Methylene-interrupted epoxydiols have multiple regiochemical routes for cyclization. The 5-exo process is the most prevalent under acidic conditions. However, the regioselectivity can be controlled by the appropriate choice of acid promoter and pendant groups adjacent to the epoxide. The 5-exo product is obtained exclusively without the presence of a carbocation-stabilizing pendant group. Alkenyl and thiophenyl groups adjacent to the epoxide alter the regioselectivity and enable access to the 5-endo tetrahydrofuran and 6-endo tetrahydropyran products.
Narayan
R S
RS
Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
Sivakumar
M
M
Bouhlel
E
E
Borhan
B
B