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DOI: 10.1055/s-1997-1503
A Facile Synthesis of Substituted 5-11-Dihydro[1]benzoxepinol[3,4-b]pyridines
Publication History
Publication Date:
31 December 2000 (online)
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5-Amino-5,11-dihydro[1]benzoxepino[3,4-b]pyridines (1) show antiulcer and antiarrhythmic activity. An efficient method for the preparation of a key intermediate, furo[3,4-b]pyridin-5(7 H)-one (4), and the facile synthesis of 1 were described. The reduction of quinolinic anhydride (5) with sodium borohydride in the presence of acetic acid regioselectively gave the lactone 4. Lactone 4 was then reacted with substituted phenols under basic conditions and the resultant products, 2-(phenoxymethyl)-3-pyridinecarboxylic acids (3), underwent Friedel-Crafts cyclizations to produce the 5,11-dihydro[1]benzoxepino[3,4-b]pyridin-5-ones (2). Compounds 2 were then converted to imines with amines and successively reduced with zinc in acetic acid to the desired compounds 1.
quinolinic anhydride - regioselective reduction - azaphthalide Friedel-Crafts cyclization - 5,11-dihydro[1]benzoxepino-[3,4-b]pyridine