Syntheses of Pyridine Derivatives. IX

Preparation of Pyridinealdehydes. (2). Preparation of Several Derivatives of 2- or 4- Pyridinealdehyde 1-Oxides

Abstract

Oxidation of pyridinemethanol 1-oxides with selenium dioxide generally results in oxidation of the carbinol group and deoxygenation of the N-oxide group, forming pyridinealdehydes, but in the case of 6-methyl-2-pyridinemethanol 1-oxide, a small amount of 6-methyl-2-pyridinealdehyde 1-oxide was obtained besides 6-methyl-2-pyridinealdehyde. Treatment of the diacetyl or acetal compound of pyridinealdehyde with perphthalic acid in ether afforded the corresponding aldehyde N-oxide in 37-45% yield. The deoxygenation of the N-oxide group by selenium dioxide is considered to be an oxidative deoxygenation as by sulfuric and nitric acid mixture.