| 摘要 |
PURPOSE:To prepare the title compound useful as a medicine having antiallergic effect, carcinostatic effect, antirheumatic effect, etc., easily, in high yield, by the ring-closing reaction of a pyridine derivative. CONSTITUTION:A compound of formula II (Y is O or S), e.g. 7-(1H-tetrazol-5- yl)-oxo-5H[1]benzopyrano[2,3-b]pyridine, is prepared by the ring-closing reaction of a compound of formula I (Py is pyridine ring; R<1>,<2> are H, halogen, lower alkyl, lower alkoxy, (substituted) phenyl, etc.; one of Y<1> and Y<2> is halogen, OH, mercapto, etc., and the other is OH, mercapto, lower alkyl, etc.; Z is acyl, carbamoyl, carboxyl, etc.), pref. in the presence of an acid such as HCl, a Friedel-Crafts catalyst such as AlCl3, and/or an alkali condensing agent such as NaH, at 20- 250 deg.C. |
