SYNTHESIS OF 2, 6-DISUBSTITUTED PYRIDINES BY LITHIATION OF PYRAZOLO[1, 5-a]PYRIDINES

Abstract

Lithiation of 3-(4, 4-dimethyl-2-oxazolin-2-yl)pyrazolo[1, 5-a]pyridine (1a) with 2 molar equivalents of n-BuLi followed by reaction with benzaldehyde yielded α-(4, 4-dimethyl-2-oxazolidinylidene)-6-(α-hydroxybenzyl)-2-pyridineacetonitrile (2a). Upon similar treatment of other electrophiles, the corresponding 2, 6-disubstituted pyridines 2 were produced. The formation of the pyridines proceeded through lithiation, reaction with an electrophile, and ring-cleavage of the pyrazole ring.