A theoretical study for the regioselective Diels–Alder reaction of 5,6-fulleroid with strained anti-Bredt olefins

International Journal of Quantum Chemistry

3 years ago

A theoretical study for the regioselective Diels–Alder reaction of 5,6-fulleroid with strained anti-Bredt olefins

Naohiko Ikuma

Regioselectivity of Diels–Alder reaction of the anti-Bredt olefin of fulleroid, the 5,6-methylene-bridged fullerene derivative, is theoretically clarified by DFT calculations. In transition state calculations, the addition of a noncyclic diene 2,3-dimethyl-1,3-butadiene (DMBD) at the anti-Bredt olefin has considerably lower activation energy than those at the other sixteen olefins, while the reaction of a rigid cyclic diene cyclohexadiene (CHD) has similar activation energy at both anti-Bredt and another nontwisted olefin. The changes in strain and interaction of the reactants are estimated along its reaction coordinate by activation strain model. Noncyclic diene shows asynchronous CC bond formation with a significant gain of interaction energy, while the rigid cyclic diene shows a large growth of strain energy canceling out the interaction energy between diene and fulleroid. DFT calculations and activation strain model clarify the higher regioselectivity of anti-Bredt olefin of fulleroid, the 5,6-methylene bridged fullerene derivative. The addition of noncyclic diene at the anti-Bredt olefin shows lower activation energy due to the larger increase of interaction energy than the destabilization of strain energy, while cyclic diene has similar activation energies in both anti-Bredt and another olefin additions.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/qua.25438