Thermolysis of N-arylnicotinamide oximes III ☆

Abstract Thermolysis of N-arylnicotinamide oximes 1a–c (R =  H, CH 3 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.