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.