| abstract |
(57) [Summary] (Modified) [Objective] To provide a compound having a smooth muscle relaxing action and useful as a therapeutic or prophylactic drug for heart / circulatory system diseases, respiratory system diseases, brain diseases and the like. [Structure] General formula [I] The 1,3-benzoxazine derivative represented by or a salt thereof. [In the formula, Is an optionally substituted benzene ring, R 1 is, for example, Represents a homologous or heterocyclic group bonded to the 4-position of the benzoxazine ring with a carbon atom, and R 2 and R 3 are each a hydrogen atom or an optionally substituted C 1-6 alkyl, Alternatively, they represent a C 3-6 alkylene group which may be bonded to each other and substituted. ] |