Amino carboxylic acids and derivatives thereof

Compounds of the formula (IX): <CHEM> or an ester, or amide thereof, wherein X is nitrogen; the group R<1>CO2H is attached to the 6-position of the pyridine ring; R<1> is (CH2)n wherein n is an integer 1 to 7, or (CH2)aCH=CH(CH2)b wherein a and b are independently 0 to 5 and the sum of a and b does not exceed 5; and R<4> is hydrogen, halogen, C1-4 alkyl, C1-4 alkoxy or trifluoromethyl. The compounds are useful intermidiates for the preparation of certain aromatic compounds having antihistaminic activity.