This invention relates to a compound of the formula IMAGE (I) wherein R1, R2, R3, and R4, which may be the same or different, each represent a hydrogen or halogen atom or an alkyl or alkoxy group of from 1 to 6 carbon atoms; R5 and R6, which may be the same or different, each represent a hydrogen atom, an alkyl group of from 1 to 6 carbon atoms, or an alkenyl group of from 3 to 6 carbon atoms, or R5 and R6 together with the nitrogen atom to which they are attached represent a pyrrolidino, piperidino, or morpholino group; and X represents oxygen, sulfur, or a methylene group, or a non-toxic, pharmacologically acceptable acid addition salt thereof, or a racemate, enantiomer, or mixture of enantiomers thereof. The compounds of Formula I are useful in pharmaceutical compositions for treating bronchial asthma and allergic bronchitis.
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