Synthesis of compounds 20,16,17,18 and 19
Reagents and conditions: a) Mel, K2CO3; b) 1-(4-nitrophenyl)piperazine, Cul, L-Proline, K2CO3, 80 °C, 2h; c) i. KOH, H2O/THF/MeOH, reflux; ii. H2, Pd/C; iii. 4-fluoro-3-nitrobenzene-1-sulfonyl chloride, pyridine; iv. (R)-N1,N1-dimethyl-4-(phenyltriio)butane-1,3-diamine, DIPEA, DMF; d) 3-(4-methylpiperazin-1-yl)propan-1-amine, EDCI, HOBt, DIEA, DCM; e) methyl amine, EDCI, HOBt, DIEA, DCM, f) TFA, CH2CI2; g) EtOH, N,N'-Diisopropylcarbodiimide, 4-(dimethylamino)pyridine, THF.