AbstractWe 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 third product being formed, presumably by a [3+2] cycloaddition reaction followed by rearrangement. Electrochemical studies revealed cathodic shifts of the first reduction potential of the buta‐1,3‐dienes obtained from the CA–RE reaction as cyano groups are substituted for ester moieties. Post‐CA–RE functionalization of the ester‐substituted buta‐1,3‐dienes by transesterification, diazonium chemistry, and cross‐coupling is described. The formation of a pharmacologically interesting pyrazolopyran illustrates the synthetic utility of ester‐substituted CA–RE products.