Reaction of Aromatic N-Oxides with Dipolarophiles. V. 1,3-Cycloaddition of 2-Substituted Pyridine N-Oxides with Phenyl Isocyanates
The reaction of 2,3-lutidine N-oxide (I) with phenyl isocyanate (IIa) in dimethylformamide at 110 deg C gave a 1:2 adduct (IIIa).Under reflux in ethanolic potassium hydroxide, IIIa readily lost a component of IIa and was converted to 5-methyl-6-N-phenylca