Tricyclic dibenzo condensed derivatives and process for their preparation

Abstract From the Canadian patent

Tricyclic dibenzo condensed derivatives The invention relates to compounds having the general formula (I), (I), wherein, R1 is carboxy, esterified carboxy or an amide of formula or , in which R9 is hydrogen or, C1-C6 alkyl A is C2-C6 alkylene and Ra and Rb are, hydrogen or C1-C6 alkyl or Ra and Rb taken together with the nitrogen atom to which they are linked form a saturated, optionally substituted, heteromonocyclic ring; R2 is hydrogen or C1-C6 alkyl;, each of R3 to R8 is independently hydrogen halogen, C1-C6-, alkyl, C3-C4 alkenyloxy or C1-C6 alkoxy; and the pharmaceutically acceptable salts thereof, which are useful as immunomodulating and anti-viral agents