Reaction conditions: (a) CH2Cl2-H2O, pH 8~9, 50 °C, TBAB, N2, 5~6 hr, 92%(→4) or 86%(→5), respectively; (b) EtOH, AcOH (20 μL), benzoic hydrazide, nicotinic hydrazide or isoniazide (1.1 equiv.), 80°C, N2, 4~5 hr, 100%(→6), 90%(→7), 95%(→8), 95%(→9), 100%(→10) and 93%(→11) respectively; (c) 0.5M NH3-MeOH, 0°C→r.t., 24 hr, quantitative yields.