Dibenzotropone- and Dibenzosuberonecarboxylic Acids with Bronchodilator Activity

The syntheses of 44 5H-dibenzo[a,d]cyclohepten-5-one derivatives bearing a carboxyl gropu at the 1, 2, 3, or 10 position and various substituents at the 7, 8, or 9 position are described. Some of the compounds showed significant bronchodilator activity in guinea pigs and protected the animals against a histamine challenge administered either by aerosol or intravenously. The most active compounds were 10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-one-2-carboxylic acids bearing a methyl or halogen substituent at the 9 position. These compounds were approximately as active as aminophylline by intraperitoneal administration.