| abstract |
The invention provides compounds of formula (I) and pharmaceutically acceptable salts thereof, wherein R 1 is H, chlorine, or bromine; R 2 is electron attractive groups selected from the group consisting of CF 3 , CN, fluorine, CH 3 SO 3 , CF 3 SO 3 , and NO 2 ; R 3 is linear or branched alkyl having 1 to 10 carbon atoms, linear or branched alkoxyalkyl having 2 to 10 carbon atoms, aliphatic alcohol having 1 to 10 carbon atoms, or cycloalkyl having 3 to 6 carbon atoms. The invention also relates to methods for preparing the said compounds and the composition comprising the same. The compounds of the present invention have the effect of β 2 -receptor agonist and can be used for the treatment of asthma and bronchitis |