Thermolysis of N-arylnicotinamide oximes III

Thermolysis of N-arylnicotinamide oximes 1a–c (R = H, CH3 and Cl) under nitrogen gives rise to benzimidazoles 3a–c as the major products (60–62%), in addition to nicotinonitrile 4, arylamines 5a–c, nicotinic acid 6, phenols 7a–c and 8a–c, nicotinanilides 9a–c, 2-(pyridin-3-yl) benzoxazoles 10a and carbazoles 11a–c. In the presence of naphthalene, thermolysis of 1a gave α- and β-naphthols 12 and 13 beside the previous products. Also pyrolysis of 1a in boiling tetralin lead to the formation of 1-hydroxytetralin 14, α-tetralone 15 and 1,1′-bitetralyl 16 as the major products. The isolated products have been interpreted in the terms of a free radical mechanism involving the homolysis of N–O and/or C–N bonds.