Catalytic regioselective synthesis of structurally diverse indene derivatives from N-benzylic sulfonamides and disubstituted alkynes
An unprecedented protocol has been developed for the regioselective synthesis of structurally diverse indene derivatives from readily accessible N-benzylic sulfonamides and disubstituted alkynes through FeCl 3-catalyzed cleavage of sp3 carbon-nitrogen bonds to generate benzyl cation intermediates. In the presence of 10 mol % of FeCl 3, a broad range of N-benzylic sulfonamides smoothly react with internal alkynes, alkynylcarbonyl compounds, alkynyl chalcogenides, or alkynyl halides to afford various functionalized indene derivatives with extremely high regioselectivity.