、 5-(2-hydroxypropoxy)-4-oxo-4H-1-benzopyran-2-carboxylic acid, ethyl ester 、 氨 以to give 23.3 parts of 5-(2-hydroxy propoxy)-4-oxo-4H-1-benzopyran-2-carboxamide, which的产率得到
There are described compounds of formula I, ##STR1## in which R.sub.5, R.sub.6, R.sub.7 and R.sub.8, which may be the same or different, are hydrogen, alkyl C2 to 6, alkoxy C2 to 8, hydroxy-alkoxy C3 to 8, and R.sub.5 may be hydroxy, provided that one or two of R.sub.5, R.sub.6, R.sub.7 and R.sub.8 are other than hydrogen, and pharmaceutically acceptable derivatives thereof. The compounds of formula I are indicated for use in the treatment of asthma, and pharmaceutical compositions containing them and processes for their preparation are also described.