A FACILE SYNTHESIS OF SUBSTITUTED 5,11-DIHYDRO[1]BENZOXEPINO[3,4-B]PYRIDINES

5-Amino-5,11-dihydro[1]benzoxepino[3,4-b]pyridines (1) show antiulcer and antiarrhythmic activity. An efficient method for the preparation o f a key intermediate, furo[3,4-b]pyridin-5(7 H)-one (4), and the facil e synthesis of 1 were described. The reduction of quinolinic anhydride (5) with sodium borohydride in the presence of acetic acid regioselec tively gave the lactone 4. Lactone 4 was then reacted with substituted phenols under basic conditions and the resultant products, 2-(phenoxy methyl)-3-pyridinecarboxylic acids (3), underwent Friedel-Crafts cycli zations 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 succes sively reduced with zinc in acetic acid to the desired compounds 1.