o-Quinodimethane Generation from α,α'-Dihalo-o-xylenes by Use of Sodium Benzenetellurolate

Article abstract of DOI:10.1246/bcsj.59.3013

Treatment of α,α'-dihalo-o-xylenes with sodium benzenetellurolate gave o-quinodimethane which readily reacted with dienophiles leading to Diels-Alder adducts.The best yields were obtained when the reaction was carried out in refluxing ethanol using two molar equivalents of the benzenetellurolate to α,α'-dihalo-o-xylenes.This reaction competes with substitution of the halogen atoms with the benzenetellurolate anion to afford α,α'-bis(phenyltelluro)-o-xylene, which did not give o-quinodimethane under identical conditions.It is likely that the reaction proceeds through nucleophilic attack of benzenetellurolate anion at the tellurium atom of α-halo-α'-phenyltelluro-o-xylene which is formed in situ by the substitution of one of the halogen atoms of the starting α,α'-dihalo-o-xylene with the benzenetellurolate anion.When sodium benzeneselenolate was employed, no evidence of o-quinodimethane formation was observed under similar conditions.