hetero- and carbocycles by intramolecular nucleophilicsubstitution at the sp2 carbon centers. The density functional theory calculations suggest that the cyclization proceeds through SN2-type substitution (the in-plane vinylic nucleophilicsubstitution, SNVσ), when vinyl halides are substituted with oxygen, nitrogen, and carbon nucleophiles. The substitution with sulfur nucleophiles, in contrast, proceeds