GSK-376501

Two short, high-yielding routes to the selective PPARγ agonist GSK376501A were developed and carried out on large scale.The key bond -forming reaction in each synthesis was the substitution of a 3,5-difluoro or 3,5-dibromo aryl intermediate with 2-methoxyethanol.A nucleophilic aromatic (S_NAr) substitution reaction under basic conditions was developed for the aryl fluoride substrate.The 3,5-dibromo aryl halide intermediate required copper-catalyzed conditions to achieve substitution of the second bromide.In addition, a 2-methoxyethanol decomposition pathway to generate methanol and ethylene oxide under basic reaction conditions and its effect on impurity formation, was elucidated.Both the difluoro and dibromo intermediates were considered as the basis for the final route of manufactureThe difluoro substrates were chosen due to straightforward chem., controllable impurity profile, and ease of fluoride removal.