Scheme 1. Synthesis of compounds PBP-NH₂, PBP-tam, PBP-C2 to PBP-C12, and PBP-NC6 to PBP-NC16. Reagents and conditions: (a) MsOH, rt, 3 days, 59%; (b) R-I (R = ethyl, n-hexyl, n-octyl, n-decyl, n-dodecyl), K₂CO₃, MeCN, 60–100 °C, 16–47%; (c) 1,2-dichloroethane, K₂CO₃, MeCN, 48 h, 19%; (d) R-NH₂ (R = n-hexyl, n-octyl, n-decyl, n-dodecyl, n-hexadecyl), MeCN, microwave, 120 °C, 4 h, 20–42%; (e) benzyl (2-bromoethyl)carbamate or 2-chloro-N,N-dimethylethylamine Cs₂CO₃, NaI, DMF, 100 °C, 21 h, 6%; (f) Pd(OH)₂, H₂, MeOH, rt, 26 h, 25%.