A practical synthesis of the title compounds (3a-c, e) from commercially available 3-hydroxy- 2-pyridine carboxylic acid (4) is reported. The key step in the synthetic sequence involves a Pd-catalyzed cross coupling reaction of the triflate 6 with the appropriate alkyl or aryl derivatives to generate the substituted picolinic acid esters 7a-b, 8 and 11. Catalytic reduction of these picolinic acid esters provided the title compounds in good yields.
