Reactions of Pyridine N-Oxide with Some Hydroxypyrimidines in the Presence of Platinated Palladium-Carbon Catalyst

The reactions of pyridine N-oxide (1) with hydroxypyrimidine derivatives (2-7) in the presence of platinated palladium-carbon (Pd-Pt/C) catalyst were studied. 5-Hydroxypyrimidine (2), 4-hydroxypyrimidines(3 and 4) and 1-methyl-2-pyrimidinone (6) gave the corresponding dimers and 2-pyridyl derivatives by this condensation with high regioselectivity at the dehydrogenative position, while 2-hydroxypyrimidine (5) gave only the 2-pyridyl derivative. 2, 4-Dihydroxypyrimidine (7) did not react under similar reaction conditions. All products obtained these reactions are new compounds.These dimerization reactions may be useful for the synthesis of the dimers of N-heteroaromatic compounds.