A mechanism of addition of a new aromatic electrophile,nitrobenzofuroxan, to cyclopentadiene

The reaction mechanisms of cycloaddition of nitrobenzofuroxan to cyclopentadiene are studied using DFT calculations at the B3LYP/6-31G* level in the gas phase and with account of the solvation effects. The reaction follows a three-step mechanism and includes the formation of a prereaction donor-acceptor complex, endo 4+2] cycloaddition with inverse electron demands (IED), and 3,3]-sigmatropic rearrangement to the final endo 2+4] adduct. No formation of stable bipolar σ-complexes on the minimum-energy reaction pathways occurs.