To a flame-dried 20-mL microwave vial equipped with a magnetic stir bar was added pyran alcohol SI-8 (61 mg, 0.14 mmol, 1.0 equiv), HO-NH2 and.0 equiv). The reaction vial was evacuated and backfilled with nitrogen for three times. To this flask was added MeOH (2 mL, 0.07 M) at room temperature, and this mixture was transferred to a preheated 80 °C oil bath.