For the conversion of 10 into 2, hydroxylamine hydrochloride in dry acetic acid was found to be the best reagent15: up to 40% yield of 2 was reached by heating 10 under these conditions for 6 h (Scheme 11). The main byproduct (23%) of this reaction was unsubstituted 2-(2'-pyridyl) pyridine, which was isolated and identified by comparison of its MS and NMR spectra with those of an authentic sample. This compound is formed presumably by ...
