Ester‐Substituted Electron‐Poor Alkenes for Cycloaddition–Retroelectrocyclization (CA–RE) and Related Reactions

We report the reactions of electron‐deficient alkenes, tetrasubstituted by carboxylic ester and cyano groups, with electron‐rich (dimethylamino)phenyl‐substituted alkynes. Mono‐ or diester‐substituted alkenes exclusively undergo the [2+2] cycloaddition–retroelectrocyclization (CA–RE) reaction, well established for multicyanated ethenes, whereas tri‐ and tetraester‐substituted alkenes also undergo a [4+2] hetero‐Diels–Alder (HDA) reaction with a...