NEW MATERIAL:Carboxylic derivatives of formula I (A is O, S; R1 is H, methyl; R2 is H, lower alkyl).

EXAMPLE: 2-[Dibenz(b,f)apin-2-yl]propioic acid.

USE: They have anti-inflammatory activity and are used as anti-inflammotory. They are both orally and nonorally administered.

PREPARATION: A compound of formula II is heated in the presence of a dehydration agent as phosphoric acid, sulfuric acid, phosphorus pentoxide, or zinc chloride to produce the compound of formula I. The compound of formula II is obtained by reduction of compound of formula III. In another method, a compound of formula IV (R3 is alkyl) is hydrolyzed using an alkali to give the compound of formula I.