Novel spirocyclic scaffold accessed via tandem Claisen rearrangement – intramolecular Michael addition

A straightforward access to novel spiro[benzofuran-2,3'-pyrrolidine]-2',5'-diones based on Rh2(esp)2-catalyzed insertion of carbenes derived from diazo arylidene succinimides (DAS) into O-H bond of phenols is described. The initial adducts underwent a thermally promoted Claisen rearrangement followed by DABCO-catalyzed intramolecular 5-exo-dig Michael addition.