QUANTUM CHEMICAL AND NMR STUDY OF NITROFUROXANOQUINOLINE CYCLOADDITION

Abstract

Using DFT/B3LYP and ab initio RHF quantum chemical calculations in the triple-zeta basis set 6-31++G** the endo- and exo-cycloaddition mechanisms for the interaction of ethylvinyl ether, trimethylsilyloxybutadiene and cyclopentadiene with 5-nitro-7,8-furoxanoquinolines were studied in details. Considering that both in solutions and crystals nitroarene exists as an inseparable mixture of two N-oxide tautomers, all cycloaddition processes were studied for both of them. The studied mechanisms practically do not depend on the location of the exocyclic oxygen atom in nitrofuroxanoquinoline. At the first stage of all reactions the conjugated C=C-N=O nitroarenes fragments react with nucleophilic reagents following the mechanism of [4+2] endo-cycloaddition with inverse electronic demands. Further (in the cases of trimethylsilyloxybutadiene and cyclopentadiene) [4+2] endo-cycloadducts recycle spontaneously according to the mechanism of [3,3] sigmatropic rearrangement into more thermodynamically stable, experimentally detected [2+4] endo-cycloadducts. Both [4+2] and [2+4] endo-cycloadducts obtained from the cyclopentadiene and   nitrofuroxanoquinoline have been experimentally isolated and characterized. For this case kinetic and activation parameters of [4+2] → [2+4] transformation have been studied by 1H NMR method, which have shown an excellent agreement with quantum chemical results. In all cases the exo-processes are one-step reactions, less favorable kinetically than their endo-competitors.

How to Cite
Steglenko, D. V.; Shevelev, S. A.; Kletskii, M. E.; Burov, O. N.; Lisovin, A. V.; Starosotnikov, A. M.; Morozov, P. G.; Kurbatov, S. V.; Minkin, V. I.; Bastrakov, M. A. Chem. Heterocycl. Compd. 2015, 51, 845. [Khim. Geterotsikl. Soedin. 2015, 51, 845.]

For this article in the English edition see DOI 10.1007/s10593-015-1785-3