Sodium hydride → 1-(5,6-Diphenylpyrazin-2-yloxy)-4-(2-tetrahydropyranyloxy)butane

1.57 g of 4-(2-tetrahydropyranyloxy)-1-butanol was dissolved in 20 ml of tetrahydrofuran and 360 mg of 60% sodium hydride was added under ice cooling, followed by stirring at room temperature for 1.5 hours. The mixture was refluxed for 30 minutes and ice-cooled again and 2.00 g of 5-chloro-2,3-diphenylpyrazine was added. After stirring for 40 minutes, the mixture was heated to 80° C., stirred at the same temperature for 4.5 hours and then stirred at room temperature for 88 hours. The reaction solution was combined with ice water, extracted with ethyl acetate and then washed with saturated brine. The extract was dried over anhydrous magnesium sulfate and the solvent was evaporated under reduced pressure to obtain 2.39 g of the desired compound as an oily substance.