Selectivity of Intramolecular Radical Addition Reactions Cyclization of ω‐Alkenyl Radicals

Small ω‐alkenyl radicals are known to cyclize exclusively via the unexpected Anti‐Markownikow pathway which leads to cycloalkyl‐methyl radicals as the observed reaction products. The strong kinetic preference diminishes, as the linking methylene chain becomes larger. Semiempirical calculations using MINDO/3‐UHF allow to classify the observed reaction pathways as individual probes between allowed (n = 1, route A) and electronically favourable (n = ∞, route M) routes of reactions.