ChemInform Abstract: Intramolecular Addition of Triarylmethanes to Alkynes Promoted by KOtBu/DMF: A Synthetic Approach to Indene Derivatives

A method for the intramolecular addition of triarylmethanes to alkynes has been developed. The reaction was efficiently promoted by KOtBu/DMF without any transition-metal catalyst. A variety of indene derivatives were prepared in moderate to good yields. A cascade cyclization of 2-alkyl-substituted substrates at elevated reaction temperature gave bicyclic indene derivatives. The reaction is proposed to proceed through the generation of a triphenylmethyl radical.