Under an argon atmosphere, to a suspension of zinc powder (7.5 g) in THF (50 mL) were added dibromoethane (200 μL) and trimethylsilylchloride (200 μL), and then a solution of iodomethyl benzoate (15 g) in THF (50 mL) was added thereto, followed by stirring at room temperature for 1 hour. Then, a solution of 7-chloro-2-(4,4-dimethylcyclohexyl)-5-methyl[1,3]thiazolo[5,4-d]pyrimidine (10.9 g) in THF (50 mL) and Pd(PPh3)4 (4.25 g) were added thereto, followed by stirring at room temperature for 15 hours. The reaction mixture was filtered through Celite and then concentrated under reduced pressure. To the residue was added a 1 M aqueous NH4Cl solution, followed by extraction with EtOAc. To the organic layer were added MgSO4 and basic silica gel, followed by stirring, filtrating, and then concentrating under reduced pressure. The residue was purified by silica gel column (hexane/EtOAc) to obtain [2-(4,4-dimethylcyclohexyl)-5-methyl[1,3]thiazolo[5,4-d]pyrimidin-7-yl]methyl benzoate (13.8 g).
