Intramolecular substitution reaction of geminal dibromo alkenes proceeds to afford indenes, dihydronaphthalenes, dihydrofurans, and dihydropyran via in situ generated lithium alkylidene carbenoids, which have a carbon or oxygen nucleophilic moiety. This reaction provides a regioselective method for the preparation of polysubstituted indenes.
intramolecular substitutionreaction with alkoxide moiety occurs at the lithium alkylidene carbenoid center to give dihydrofurans. The reaction mechanism of this intramolecular substitutionreaction is studied by B3LYP density functional calculations with the 6-31+G(d) basis set, and the substitution is found to proceed in a concerted manner. This substitutionreaction is applied to the regioselective preparation