To a solution of 4-(benzyloxy)-2-(2,3-dihydro-1,4-benzothiazepin-4(5H)-yl)quinazoline-6-carbaldehyde (3.0 g, 7.0 mmol) in methanol (20 mL) and tetrahydrofuran (20 mL) was added sodium borohydride (270 mg, 7.13 mmol) at 0° C. After being stirred at 0° C. for 15 minutes, the resulting mixture was warmed to room temperature, diluted with water (10 mL) and extracted with ethyl acetate (20 mL×3). The combined organic layers were washed with a saturated aqueous solution of ammonium chloride (40 mL) and brine (40 mL), dried over anhydrous sodium sulfate, and concentrated in vacuo to afford 2.85 g of the desired product as a yellow solid (yield was 95%), MS obsd. (ESI+) [(M+H)+] 430.
