Rapid Access to Kinase Inhibitor Pharmacophores by Regioselective C-H Arylation of Thieno[2,3-d]pyrimidine.

Regioselective C-H arylations of thieno[2,3-d]pyrimidine are accomplished under palladium catalysis. Thieno[2,3-d]pyrimidines react with aryl iodides at the C6-position and with aryl boronic acids at the C5-position, showing excellent regioselectivity. Mechanistic investigations indicate that the regioselectivity is controlled by the nature of the palladium catalyst: the cationic palladium favorably arylates the C5-position. The utility of this direct arylation has been highlighted in the streamlined synthesis of kinase inhibitors and their derivatives.