Benzoxazole derivatives

Abstract

The invention provides novel 5- and 6-benzoxazolyl alkanoic acids, optionally substituted in the 2-position, and derivatives thereof which possess anti-inflammatory, anti-pyretic and analgesic activity. Also provided is a process for preparing such compounds by cyclizing an appropriately substituted o-aminophenol and, if necessary, converting the resultant benzoxazole to the desired compound.

We claim: 
     
       1. Compound of the formula: ##STR6## wherein the group --CR 1  R 2  R 3  is in the 5- or 6-position of the benzoxazole nucleus, wherein R 4  is cyclohexyl, furyl, thienyl, pyridyl, phenyl or phenyl substituted in any available position by one or two substituents selected from halogen, nitro, amino, .[.hydroxy,.]. C 1-4  alkyl, C 1-4  alkoxy, C 1-3  alkyl-CO, C 1-4  alkyl sulphonyl or substituted in two adjacent positions by methylene- or ethylene-dioxy, R 1  and R 2  are independently hydrogen, methyl or ethyl and R 3  is: ii. the group --COOR 5 , where R 5  is C 1-4  alkyl; or   the group --CO--R 6  where R 6  is --NHOH or --NR 7  R 8  where R 7  and R 8  are hydrogen; or   iii. the group --CH 2  OR 9  where R 9  is hydrogen or C 1-4  alkyl; or   iv. the group --COOH or an alkali or alkaline earth metal, aluminum or ammonium salt thereof.   
     
     
       2. Compound according to claim 1, wherein R 1  is hydrogen, R 2  is methyl, R 3  is --COOR 5 , where R 5  is C 1-4  alkyl; or --COOH or an alkali or alkaline earth metal, aluminum or ammonium salt thereof, and R 4  is phenyl, monohalogenophenyl or dihalogenophenyl. 
     
     
       3. A compound according to claim 1 in which R 1  is H, R 2  is H or CH 3 , R 3  is COOH or CONH 2 , the group CR 1  R 2  R 3  is in the 5 position of the benzoxazole nucleus and R 4  is pyridyl phenyl or phenyl substituted by one or two groups selected from halogen, methyl, methoxy, acetyl, methylsulphonyl, .Iadd.or .Iaddend.nitro .[.or hydroxy.].. 
     
     
       4. Compound according to claim 1, wherein R 1  is hydrogen, R 2  is methyl and R 4  is phenyl optionally substituted by one or two substituents selected from halogen, methyl, methoxy, .Iadd.or .Iaddend.nitro .[.or hydroxy.].. 
     
     
       5. Compound according to claim 2 wherein said compound is 2-(2-p-chlorophenyl-5- or 6-benzoxazolyl)propionic acid. 
     
     
       6. Compound according to claim 2, wherein said compound is 2-(2-p-fluorophenyl-5- or 6-benzoxazolyl)propionic acid. 
     
     
       7. Compound according to claim 2, wherein said compound is 2-[2-(2,4-dichlorophenyl)-5- or 6-benzoxazolyl]propionic acid.