Facial (syn–anti) stereoselectivity in the Diels–Alder reactions of spiro(bicyclo[2.2.2]octane-2,1′-[2,4]cyclopentadiene)

Abstract

Spiro(bicyclo[2.2.2]octane-2,1′-[2,4]cyclopentadiene) (3) has been synthesized in ten steps, and its Diels–Alder cycloadditions, both thermal and catalysed, have been studied with a variety of Z-ethylenic dienophiles. No significant differences in facial stereoselectivity were observed. This suggests that, in the exo region, the distance between the addends at the transition state is approximately the same in all the cases studied.