Quinoxalines. XXII. Aryl Migration of 2-Aroylquinoxalines to 2-Arylquinoxalines

抄録

The reaction of 2-aroylquinoxalines (1) with sodium hydroxide in dimethyl sulfoxide (DMSO) was found to result in aryl migration, fission of the C²-C=O bond, and addition of DMSO to the C=O group, giving 2-arylquinoxalines (2), quinoxaline (4), aroic acids (5), and α-aryl-α-(methylsulfinylmethyl)-2-quinoxalinemethanols (6). Compounds 6 could be separated into two racemates, (αR^*, SR^*)-6 and (αR^*, SS^*)-6. In order to establish the generality of the aryl migration, other aroylated aromatic heterocycles were examined. 3-Aroylpyrido [2, 3-b] pyrazines (7) and 1-benzoyl-4-isoquinolinecarbonitrile (10) both underwent similar aryl migration to give 3-arylpyridopyrazines (14) and 1-phenyl-4-isoquinolinecarbonitrile (18), respectively. On the other hand, the reaction of 1-benzoylisoquinoline (9) and 2-benzoylquinoline (11) resulted not in migration, but in the addition of DMSO to give 1-isoquinolinemethanol (16) and 2-quinolinemethanol derivatives (20), respectively. In the case of 1-benzoylphthalazine (8), migration did not occur, but instead 4-benzoyl-1 (2H)-phthalazinone (15) was formed.