Mechanistic details of the domino reaction of nitronaphthalenes with the electron-rich dienes. A DFT study

The reaction of 1-nitronaphthalene (1) with the Danishefsky diene (2) to give the dihydrophenanthrene derivative 11 has been theoretically studied using DFT methods. This reaction is a domino process that is initialized by a polar Diels-Alder reaction between 1 and 2 to give the formally [2 + 4] cycloadduct 3. The subsequent concerted elimination of nitrous acid (4) from 3 yields 11. Analysis of the global reactivity indices as well as the thermodynamic data for this domino process indicate that while the large electrophilic character of 1 together with the large nucleophilic character of 2 are responsible for the participation of these reagents in a polar Diels-Alder reaction, the irreversible extrusion of 4 is the factor responsible for the feasibility of the overall process.