Reaction of Aromatic N-Oxides with Dipolarophiles. XIV. : Inverse-Type Cycloaddition of Pyridine N-Oxides with 1, 4-Epoxy-1, 4-dihydronaphthalene and Its Mechanistic Aspects

Abstract

In connection with the stereoselective exo cycloaddition in the 1, 3-dipolar reaction of 3, 5-lutidine N-oxide and N-arylmaleimides, the inverse-type cycloaddition of some pryidine N-oxides with 1, 4-epoxy-1, 4-dihydronaphthalene was investigated. In these reactions, the armatized furopyridine-type compounds formed from the 1, 5-sigmatropic rearrangement products of the primary cycloadducts were isolated. During the course of the reaction, coloration due to charge-transfer complex formation was observed. The reaction obeyed a second-order rate law and showed little solvent effect. The observed reactivity and stereochemistry are discussed in terms of frontier molecular orbital (FMO) considerations.