Scheme 1.
Reagents and conditions: (I) SOCl2, DMF, 50℃, 3–5 h; (II) N2H4·H2O, CH3OH, 75℃, 8 h; (III) Et3N, CH2Cl2, 35℃,8h; MsCl, 8 h. (IV) Pd/C, N2H4·H2O, C2H5OH, 50℃, 2–4 h; (V) C5H5N, DMF, 37℃, 12 h.
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