Base-promoted cascade 5-exo-dig annulation/carboxylation of o-(1-alkynyl)benzenesulfonamides with CO2: divergent synthesis of mono- or gem-dicarboxylic esters

Abstract

A base-promoted cascade 5-exo-dig cyclization/carboxylation of o-alkynylsulfamides with CO₂ has been accomplished, furnishing a variety of benzosultam-containing acrylates in good yields by using CO₂ as the carboxylic source. Notably, in the case of substrates bearing a TMS-alkyne motif, the gem-dicarboxylation products were generated unprecedentedly.