A stirred solution of thiazole (0.14 mL, 2 mmol) in dry THF (10 mL) at −78° C., under argon was treated n-BuLi (1.6-M in hexanes, 1.25 mL, 2 mmol), stirred for 15 min, treated with ZnCl2 solution (1-M in Et2O, 2 mL, 2 mmol) then allowed to warm gradually to room temperature. The mixture was treated with 4-chloro-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-d]pyrimidine-6-amine (278 mg, 1 mmol) and Pd(PPh3)4 (100 mg, 10 mol %) refluxed for 2 h, diluted with saturated NH4Cl solution, extracted with EtOAc, dried (MgSO4) and concentrated in vacuo. The resulting brown oil was purified by chromatography [SiO2; heptane:EtOAc (4:1) then (3:1)] to give the title compound (101 mg, 31%) as a cream solid.
