Synthesis of targeted compounds (12c−e) and (13a,c−e), Reagents and conditions: a SOCl2, DCM, reflux, 7 h, 50–60% b TEA, DCM, rt, 24–48 h, 20–60% c LiOH.H2O, EtOH, reflux, 24 h, 60–70% d 1−benzhydrylpiperazine, TBTU, DMAP, DMF, under N2, rt, 24–48 h, 20–40%