Thiophene-containing products of the Ugi reaction in an oxidation-triggered IMDA/aromatization cascade: a simple access to 3-oxoisoindolines

A novel approach to skeletally diverse 3-oxoisoindolines has been developed which includes preparation of Ugi adducts containing thiophene and fumaric acid residues. When treated with excess m-CPBA at room temperature, these precursors undergo a simple oxidative cycloaddition/aromatization transformation and the corresponding 3-oxoisoindoline products are isolated in fair chemical yield over two steps. The second step is thought to include S-oxidation/IMDA/S-oxidation/SO2 extrusion/aromatization events.