detected as main product, suggesting that a competitive reaction would probably take place. The results clearly confirmed the dienophilic nature of nitronaphthalenic doublebonds and provided an alternative procedure for phenanthrene derivatives and N-naphthylpyrroles' synthesis. The relative reactivity of the reactants and the viability of the reactions were discussed from a theoretical point of view.
electron-demand Diels–Alder reaction between 1,4-disubstituted naphthalenes, nitro being one of these two groups, and 1-methoxy-3-trimethylsililoxy-1,3-butadiene gives hydroxyphenanthrene derivatives, the yields being enhanced by placement of more electron-withdrawing groups on the dienophilic system. The nitro group as substituent directs the cycloaddition, and its cis-extrusion as nitrous acid along with the