Abstract
Two chiral quaternary carbon-containing fragments suitable for elaboration to the briaran diterpenes were obtained by regioselective methylation of functionalized 3,3-disubstituted 2,3-epoxy-1-ols. The factors which favor methylation at the more hindered position of a trisubstituted 2,3-epoxy alcohol were determined.
Regioselective methylation of 3,3-disubstituted 2,3-epoxy-1-ols established the C(1) and C(8) quaternary centers of the briaran ten-membered ring.