Reinvestigation of Nitrosation of Methylpyridines and Their 1-Oxides and Deoxygenation of 3-Pyridinecarbaldehyde 1-Oxide Oxime

Abstract

Treatment of methylpyridines and their 1-oxides with t-butyl nitrite in the presence of potassium t-butoxide in liquid ammonia afforded the corresponding aldoximes in good yields except for the case of 3-methylpyridine. The reaction of 3-methylpyridine with t-butyl nitrite in the presence of lithium 2,2,6,6-tetramethylpiperidide and N,N,N',N'-tetramethylethylenediamine in tetrahydrofuran at -78°C led to 3-(3-methyl-4-pyridyl)methylpyridine. Deoxygenation of 3-pyridinecarbaldehyde 1-oxide oxime was effected in 78% yield by the action of t-butyldimethylsilyl chloride-imidazole-sodium iodide-zinc followed by desilylation with tetrabutylammonium fluoride to give 3-pyridinecarbaldehyde oxime