O. Mongin et al., METALATION OF PYRIDINE N-OXIDES AND APPLICATION TO SYNTHESIS, Journal of the Chemical Society. Perkin transactions. I, (19), 1995, pp. 2503-2508
Regio- and chemi-selective, directed ortho-lithiation of 2-, 2,5- or 3
,4-substituted pyridine N-oxides has been achieved with diisopropylami
de and butyllithium. Polysubstituted pyridine N-oxides, azaxanthone, a
nd an isomer of orelline have been synthesized by such methods.