Polyhalogenoaromatic compounds. Part XVIII. Grignard reactions on pentachloropyridine 1-oxide

Abstract

2-Methyl and 2,6-dimethyl derivatives are produced in good yields from methylmagnesium iodide and pentachloropyridine 1-oxide in ether. Use of a large excess of phenyl- or ethyl-magnesium bromide with pentachloro-pyridine 1-oxide in tetrahydrofuran gives the 2,6-diphenyl or 2,6-diethyl derivative in good yield. Attempts to prepare the 2-monosubstituted 1-oxides with an equivalent proportion of these Grignard reagents led to complex mixtures of starting material and mono- and di-substituted 1-oxides, together with tetrachloro-2-hydroxypyridine 1-oxide. Deoxygenation gave in all cases the corresponding pyridine derivatives.