Scheme 3.
Reagents and conditions: a) ClC(O)COOEt, AlCl3, CH2Cl2; b) NaOH 5%, MeOH, rt, 10 min; c) CDI, amine, DMF, 3 h, rt; d) NaOH 5%, MeOH, 16 h, rt; e) 3,4-difluoroaniline, HATU, DIPEA, DMF, 16 h, rt.
Reagents and conditions: a) ClC(O)COOEt, AlCl3, CH2Cl2; b) NaOH 5%, MeOH, rt, 10 min; c) CDI, amine, DMF, 3 h, rt; d) NaOH 5%, MeOH, 16 h, rt; e) 3,4-difluoroaniline, HATU, DIPEA, DMF, 16 h, rt.