| abstract |
Provided are methods for the synthesis of heterocyclic compounds such as benzimidazole carboxylic acid core structures having Formula Ia-2 and their synthetic intermediates: wherein X 1 , X 2 , X 5 , R 1 , R 2 and R 4 are as defined herein. Compounds of Formula Ia-2 and their synthetic intermediates can be used to prepare heterocyclic derivatives such as benzimidazole derivatives. |