## 3 Experimental Section
### Synthesis and Characterization
#### 3.2.3 Synthesis of Unsymmetrical 1,3,4-Oxadaizoles (**4a-e**)
173-175 \({}^{\circ}\)C. 1H-NMR (400 MHz, DMSO): 8 4.76 (s, 2H), 7.53 (t, \(J\) = 8 Hz, 1H), 7.47 (d, \(J\) = 8 Hz, 3H), 7.60 (d,\(J\) = 8 Hz, 1H), 7.95 (m, 5H); 13C-NMR (100 MHz, DMSO): $ 33.1, 126.2, 127.1, 128.8, 128.9, 129.1, 129.4, 129.5, 144.3, 165.6. HRMS (ESI): \(m/z\) calcd for C\({}_{15}\)H\({}_{11}\)BrN\({}_{2}\)O + H\({}^{+}\): 315.0133, 317.0114; found 315.0133, 317.0112.  
2-(Bromomethyl)-5-phenyl-1,3,4-oxadiazole (**4b**)  
The product was obtained as slightly yellow liquid (1.15 g, 60%). 1H-NMR (400 MHz, DMSO): $ 5.14 (s, 2H), 7.51 (t, \(J\) = 8 Hz, 1H), 7.65 (m, 3H), 8.04 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, DMSO): $ 16.2, 123.0, 126.8, 128.6, 129.6, 163.0, 165.1. HRMS (ESI): \(m/z\) calcd for C\({}_{9}\)H\({}_{7}\)BrN\({}_{2}\)O + H\({}^{+}\): 238.9820, 240.9800; found 238.9832, 240.9812.  
2-(2-Bromoethyl)-5-phenyl-1,3,4-oxadiazole (**4c**)  
The product was obtained as slightly yellow liquid (0.69 g, 34%). 1H-NMR (400 MHz, DMSO): $ 3.57 (t, \(J\) = 8 Hz, 2H), 3.90 (t, \(J\) = 8 Hz, 2H), 7.61 (m, 3H), 8.01 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, DMSO): $ 28.5, 28.6, 117.5, 126.4, 129.4, 131.9, 164.1, 164.5. HRMS (ESI): \(m/z\) calcd for C\({}_{10}\)H\({}_{9}\)BrN\({}_{2}\)O + H\({}^{+}\): 252.9977, 254.9957; found 252.9973, 254.9960.  
2-(3-Bromopropyl)-5-phenyl-1,3,4-oxadiazole (**4d**)  
The product was obtained as slightly yellow liquid (1.55 g, 73%). 1H-NMR (400 MHz, DMSO): $ 2.33 (d, \(J\) = 8 Hz, 2H), 3.09 (t, \(J\) = 8 Hz, 2H), 3.68 (t, \(J\) = 8 Hz, 2H), 7.60 (m, 3H), 8.00 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, DMSO): $ 23.5, 29.0, 33.6, 123.6, 126.5, 129.4, 131.9, 164.0, 165.8. HRMS (ESI): \(m/z\) calcd for C\({}_{11}\)H\({}_{11}\)BrN\({}_{2}\)O + H\({}^{+}\): 267.0133, 269.0113; found 267.0120, 269.0111.  
2-(4-Bromobutyl)-5-phenyl-1,3,4-oxadiazole (**4e**)  
The product was obtained as slightly yellow liquid (1.39 g, 62%). 1H-NMR (400 MHz, DMSO): $ 1.22 (m, 2H), 1.93 (m, 2H), 2.99 (t, \(J\) = 8 Hz, 2H), 3.60 (t, \(J\) = 8 Hz, 2H), 7.62 (m, 3H), 7.99 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, DMSO): $ 23.8, 24.4, 31.4, 34.5, 123.6, 126.4, 129.4, 131.8, 163.9, 166.5. HRMS (ESI): \(m/z\) calcd for C\({}_{12}\)H\({}_{13}\)BrN\({}_{2}\)O + H\({}^{+}\): 281.0290, 283.0270; found 281.0284, 283.0265.  
3.2.4. Synthesis of Diisopropyl Iminodiacetate (**6**)  
Iminodiacetic acid (**5**) (15.0 g, 0.11 mol) was introduced into isopropanol (120 mL), and concentrated sulfuric acid (7.5 mL) was added there. The mixture was heated to reflux for 12 h. Excess isopropanol was then rotary-evaporated, and the residue was neutralized with aqueous sodium bicarbonate solution. Then, the resulting mixture was extracted twice with ethyl acetate (2 \(\times\) 20 mL), and dried over anhydrous magnesium sulfate. The filtrate was evaporated to dryness, producing slightly yellow liquid.  
Diisopropyl Iminodiacetate (**6**)  
The product was obtained as slightly yellow liquid (12.41 g, 52%) [38]. 1H-NMR (400 MHz, CDCl\({}_{3}\)): $ 1.29 (d, \(J\) = 8 Hz, 12H), 3.85 (s, 4H), 5.11 (m, 2H); 13C-NMR (100 MHz, CDCl\({}_{3}\)): $ 21.7, 48.6, 70.0, 167.6. HRMS (ESI): \(m/z\) calcd for C\({}_{10}\)H\({}_{19}\)NO\({}_{4}\) + H\({}^{+}\): 218.1392; found 218.1403.  
3.2.5. Synthesis of Unsymmetrical Ester Derivatives of 2-Alkyl-5-phenyl-1,3,4-oxadiazole (**7a-e**)  
5-Phenyl-1,3,4-oxadiazole (**4a-e**, 0.004 mol), iminodiacetic acid ester (**6**, 0.004 mol), and sodium carbonate (4.24 g, 0.04 mol) were introduced into acetonitrile (40 mL). The mixture was heated at 60-80 \({}^{\circ}\)C for 12 h. Then, water (20 mL) was added there and extracted twice with ethyl acetate (2 \(\times\) 25 mL). The organic extract was separated, dried over anhydrous magnesium sulfate, and rotary-evaporated. The crude products were purified by means of column chromatography with the use of ethyl acetate.  
Diisopropyl1,2,2'-((4-(5-phenyl-1,3,4-oxadiazol-2-yl)benzyl)azanediyl)diacetate (**7a**) The product was obtained as slightly yellow liquid (1.69 g, 94%). 1H-NMR (400 MHz, CDCl\({}_{3}\)): 8 1.27 (d, \(J\) = 8 Hz, 12H), 3.53 (s, 4H), 4.01 (s, 2H), 5.07 (m, 2H), 7.54 (m, 3H), 7.60 (d, \(J\) = 8 Hz, 2H), 8.11 (d, \(J\) = 8 Hz, 2H), 8.16 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, CDCl\({}_{3}\)): 8 21.9, 54.7, 57.4, 69.0, 123.0, 124.0, 126.9, 127.0, 129.0, 129.5, 131.6, 142.8, 164.4, 164.5, 170.6. HRMS (ESI): \(m/z\) calcd for C\({}_{25}\)H\({}_{29}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 452.2185; found 452.2169.  
Diisopropyl1,2,2'-(((5-phenyl-1,3,4-oxadiazol-2-yl)methyl)azanediyl)diacetate (**7b**) The product was obtained as slightly yellow liquid (1.15 g, 76%). 1H-NMR (400 MHz, CDCl\({}_{3}\)): 8 1.25 (d, \(J\) = 8 Hz, 12H), 3.69 (s, 4H), 4.31 (s, 2H), 5.06 (m, 2H), 7.52 (m, 3H), 8.06 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, CDCl\({}_{3}\)): 8 21.8, 48.1, 55.0, 68.4, 123.8, 127.0, 128.9, 131.7, 163.5, 165.4, 170.0. HRMS (ESI): \(m/z\) calcd for C\({}_{19}\)H\({}_{25}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 376.1873; found 376.1850.  
Diisopropyl1,2,2'-((2-(5-phenyl-1,3,4-oxadiazol-2-yl)methyl)azanediyl)diacetate (**7c**) The product was obtained as slightly yellow liquid (1.07 g, 69%). 1H-NMR (400 MHz, CDCl\({}_{3}\)): 8 1.26 (d, \(J\) = 8 Hz, 12H), 3.43 (s, 4H), 3.53 (t, \(J\) = 8 Hz, 2H), 3.77 (t, \(J\) = 8 Hz, 2H), 5.07 (m, 2H), 7.53 (m, 3H), 8.05 (m, 2H); 13C-NMR (100 MHz, CDCl\({}_{3}\)): 8 21.8, 26.1, 50.3, 60.3, 68.4, 126.8, 128.2, 129.0, 131.7, 163.9, 165.1, 171.1. HRMS (ESI): \(m/z\) calcd for C\({}_{20}\)H\({}_{27}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 390.2029; found 390.2021.  
Diisopropyl1,2,2'-((3-(5-phenyl-1,3,4-oxadiazol-2-yl)propyl)azanediyl)diacetate (**7d**) The product was obtained as slightly yellow liquid (1.10 g, 68%). 1H-NMR (400 MHz, CDCl\({}_{3}\)): 8 1.23 (d, \(J\) = 4 Hz, 12H), 2.36 (m, 2H), 2.89 (t, \(J\) = 8 Hz, 2H), 3.04 (t, \(J\) = 8 Hz, 2H), 3.52 (s, 2H), 5.00 (m, 2H), 7.51 (m, 3H), 8.04 (d, \(J\) = 4 Hz, 2H); 13C-NMR (100 MHz, CDCl\({}_{3}\)): 8 21.8, 22.9, 24.8, 43.6, 55.3, 68.0, 124.0, 126.7, 128.9, 131.4, 164.6, 166.8, 170.8. HRMS (ESI): \(m/z\) calcd for C\({}_{21}\)H\({}_{29}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 404.2185; found 404.2095.  
Diisopropyl1,2,2'-((4-(5-phenyl-1,3,4-oxadiazol-2-yl)butyl)azanediyl)diacetate (**7e**) The product was obtained as slightly yellow liquid (1.66 g, 80%). 1H-NMR (400 MHz, CDCl\({}_{3}\)): 8 1.28 (d, \(J\) = 8 Hz, 12H), 1.94 (m, 2H), 2.05 (m, 2H), 2.99 (t, \(J\) = 8 Hz, 2H), 3.52 (s, 4H), 3.61 (t, \(J\) = 8 Hz, 2H), 5.08 (m, 2H), 7.52 (m, 3H), 8.05 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, CDCl\({}_{3}\)): 8 21.7, 24.1, 25.2, 27.1, 53.5, 55.3, 68.1, 123.9, 126.8, 129.0, 131.6, 164.8, 166.7, 170.6. HRMS (ESI): \(m/z\) calcd for C\({}_{22}\)H\({}_{31}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 418.2342; found 418.2339.  
2.6 Synthesis of Unsymmetrical 2-Alkyl-5-phenyl-1,3,4-oxadiazol Derivatives Containing Bis(carboxymethyl)amino Group (**8a-e**)  
The unsymmetrical ester derivatives of 2-alkyl-5-phenyl-1,3,4-oxadiazol (**7a-e**, 0.26 mmol) were introduced into the mixture of methanol (24 mL), water (6 mL), and NaOH (0.1 g, 2.6 mmol). The whole was heated at 50 \({}^{\circ}\)C for 30 min. Then, the mixture was neutralized with 1 M HCl and evaporated to dryness. The crude solid products were recrystallized from methanol.  
2,2'-((4-(5-Phenyl-1,3,4-oxadiazol-2-yl)benzyl)azanediyl)diacetic Acid (**8a**) The product was obtained as white powder (0.05 g, 51%). 1H-NMR (400 MHz, DMSO): 8 3.90 (s, 4H), 4.34 (s, 2H), 7.67 (t, \(J\) = 8 Hz, 3H), 7.77 (d, \(J\) = 8 Hz, 2H), 8.17 (m, 4H); 13C-NMR (100 MHz, DMSO): 8 53.7, 57.6, 123.3, 123.4, 126.7, 126.8, 129.4, 131.4, 132.1, 144.7, 163.8, 164.1, 167.7. HRMS (ESI): \(m/z\) calcd for C\({}_{19}\)H\({}_{17}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 368.1246; found 368.1241.  
2,2'-((5-Phenyl-1,3,4-oxadiazol-2-yl)methyl)azanediyl)diacetic Acid (**8b**) The product was obtained as white powder (0.036 g, 47%). 1H-NMR (400 MHz, DMSO): 8 3.61 (s, 4H), 4.23 (s, 2H), 7.60 (t, \(J\) = 4 Hz, 3H), 7.96 (d, \(J\) = 4 Hz, 2H); 13C-NMR (100 MHz, DMSO): 8 47.5, 54.2, 123.5, 126.6, 129.5, 132.0, 163.8, 164.4, 171.9. HRMS (ESI): \(m/z\) calcd for C\({}_{13}\)H\({}_{31}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 292.0934; found 292.0930.  
2,2'-((2-(5-Phenyl-1,3,4-oxadiazol-2-yl)ethyl)azanediolyl)diacetic Acid (**8c**)  
The product was obtained as slightly yellow powder (0.033 g, 42%). 1H-NMR (400 MHz, DMSO): $ 3.53 (s, 4H), 3.60 (t, \(J\) = 8 Hz, 2H), 3.78 (t, \(J\) = 8 Hz, 2H), 7.61 (m, 3H), 7.91 (d, \(J\) = 8 Hz, 2H); 13C-NMR (100 MHz, DMSO): $ 25.8, 46.6, 58.0, 126.5, 127.9, 128.8, 132.0, 164.1, 165.2, 169.7. HRMS (ESI): _m/z_ calcd for C\({}_{14}\)H\({}_{15}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 306.1090; found 306.1089.  
2,2'-((3-(5-Phenyl-1,3,4-oxadiazol-2-yl)propyl)azanediolyl)diacetic Acid (**8d**)  
The product was obtained as slightly yellow powder (0.035 g, 44%). 1H-NMR (400 MHz, DMSO): $ 2.11 (m, 2H), 2.25 (m, 2H), 2.98 (m, 2H), 4.09 (s, 4H), 7.43 (m, 3H), 7.83 (d, \(J\) = 4 Hz, 2H); 13C-NMR (100 MHz, DMSO): $ 20.8, 22.1, 54.3, 54.7, 123.6, 129.6, 129.6, 132.0, 164.1, 166.0, 168.2. HRMS (ESI): _m/z_ calcd for C\({}_{15}\)H\({}_{17}\)N\({}_{3}\)O\({}_{5}\) + H\({}^{+}\): 320.1246; found 320.1233.  
2,2'-((4-(5-Phenyl-1,3,4-oxadiazol-2-yl)butyl)azanediolyl)diacetic Acid (**8e**)  
The product was obtained as slightly yellow powder (0.036 g, 41%). 1H-NMR (400 MHz, DMSO): $ 1.93 (m, 4H), 2.99 (t, \(J\) = 4 Hz, 2H), 3.48 (s, 4H), 3.71 (t, \(J\) = 4 Hz, 2H), 7.50 (m, 3H), 7.92 (m, 2H); 13C-NMR (100 MHz, DMSO): $ 23.2, 23.9, 31.2, 50.4, 54.7, 123.5, 126.4, 129.4, 131.8, 163.9, 165.5, 171.3.