AbstractThe cycloadditions of 3‐hydroxy‐1‐methylpyridinium betaines with electron‐deficient olefins have been extended to a variety of 1‐substituents in place of methyl. Application of resonance theory and later of quantum chemical methods led to rationalization of preceding results and prediction of new reactions. Thermal additions of 2π‐ and 6π‐electron addends at the 2,6‐positions and of 4π‐electron addends at the 2,4‐positions are described. The cycloadducts are highly interesting potential syn