Fig. 2.

Structures and synthesis of compounds 1–4 with reagents and conditions: (i) Ethyl chloroacetate, 4 N HCl (aq.), 100 °C, 94%; (ii) (2S)-2-Methylpyrrolidine, Na₂CO₃, CH₃CN, 70%; (iii) H₂, 10% Pd/C, MeOH; (iv) NaH, N-(6-bromohexyl)phthalimide, dimethylformamide, 47.7%; (v) 37% HCl (aq.), 100 °C; (vi) 1-[Bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate, diisopropylethylamine, dichloromethane, 25 °C, 65%; (vii) NH₂NH₂, EtOH, 50 °C, 89%; (viii) 2-(2,6-dioxo-3-piperidinyl)-4-fluoro-1H-isoindole-1,3(2H)-dione, diisopropylethylamine, dimethyl sulfoxide, 90 °C, 44%; (ix) 1-adamantaneacetic acid, condition vi, 64.4%