Reaction of aromatic N-oxides with dipolarophiles. II. Reaction of .BETA.-alkypyridine N-oxides with phenyl isocyanate.

Abstract

The reaction of β-alkylpyridine N-oxides (I) with phenyl isocyanate (II) in dimethyl-formamide at 110° gave the cycloadducts (III and IV), although it was noticed that the reaction of pyridine N-oxide with II directly affords α-anilinopyridine. The duration at elevated temperature resulted in an increased yield of the anilino derivatives, while the cycloadducts tended to decrease. The effect by using various sorts of solvents demonstrated that dimethylformamide and dimethylsulfoxide are suitable for the formation of cycloadducts.