Ionic liquids and microwave irradiation as synergistic combination for polar Diels–Alder reactions using properly substituted heterocycles as dienophiles. A DFT study related

For the DA reactions between nitropyrrole derivatives and isoprene, the combination of microwave irradiation and protic ionic liquids, has a notable synergistic effect. DFT calculations suggest that a supplementary energy ranking in the IR region of 1.700–1400 cm−1 can favour the structural changes in the reactants to reach the TS.