| 摘要 |
<p>Benzopyrans of formula (I): (where Ra is H and Rb is 4-carboxyphenyl or Ra and Rb together with the adjacent C atoms form a benzene ring substd. by COOH, R1, R2, R3 and R4 are H, OH, alkenyl, alkanoyl or alkyl and X is 2-10C hydrocarbyl opt. substd. by OH). together with their salts esters or amides, are antagonists of the anaphylaxis- slow reaction substance (SRS-A) and are also used as bronchodilators and bronchospasmolytics. (I) are prepd. by (1) the corresp. cpd where the substit. in Rb is a gp. hydrolysable to the carboxyl gp. or (2) forming the -OXO- linkage by reacting corresp. benzopyran and phenol derivs.</p> |
