“…-benzhydryl-4-((5-(4-methylphenyl)-1,3, 4-oxadiazol-2-yl)methyl)piperazine (4e) Yield: 51.06%; mp: 143 to 145°C; Anal Calcd for C27 H 28 N 4 O: C,76.39, H, 6.65, N, 13.20; found C, 76.40, H, 6.64, N, 13.21; IR (ν max cm −1 ): 3301 (NH stretch), 3289, 3123 (Ar-H), 2900, 2885 (piperazine ring), 1618, 1458 (C=N, C=C), 1242, 1117 (C-O-C), 1263 (C-N); 1 H-NMR (DMSO-d 6 ) δ (ppm): 7.38 to 7.37 (d, 4H, Ar-H, J = 6.6 Hz), 7.33 to 7.31 (t, 4H, Ar-H, J = 6.7 Hz), 7.24 to 7.19 (m, 5H, phenyl), 7.13 to 7.12 (d, 2H, Ar-H, J = 6.6 Hz), 4.81 (s, 2H, -CH 2 ), 4.47 (s, 1H, -CH), 3.23 (br, s, 4H, -CH 2 -N-CH 2 , piperazine ring), 2.46 (br, s, 4H, -CH 2 -N-CH 2 , piperazine ring) 13 C-NMR (DMSO-d 6 ) δ (ppm) 172.25, 164.53, 151.52, 143.52, 134.45, 132.11, 129.36, 127.48, 126.73, 122.28, 117.12, 114.21, 112.45, 67.94, 64.32, 45.85, 41.31; ESI-MS m/z: [M + H] + 425.54.N-benzhydryl-4-((5-(4-tertbutylphenyl)-1,3, 4-oxadiazol-2-yl)methyl)piperazine (4f) Yield: 47.34%; mp: 161 to 163°C; Anal Calcd for C 30 H 34 N 4 O: C,77.22, H, 7.34, N, 12.01; found C, 77.21, H, 7.33, N, 12.02; IR (ν max cm −1 ): 3388 (NH stretch), 3206, 3101 (Ar-H), 2900, 2865 (piperazine ring), 1623, 1515 (C=N, C=C), 1276, 1106 (C-O-C), 1253 (C-N); 1 H-NMR (CDCl 3 ) δ (ppm): 7.32 to 7.31 (d, 4H, Ar-H, J = 6.6 Hz), 7.28 to 7.26 (t, 4H, Ar-H, J = 6.7 Hz), 7.20 to 7.15 (m, 5H, phenyl), 7.10 to 7.09 (d, 2H, Ar-H, J = 6.6 Hz), 4.76 (s, 2H, -CH 2 ), 4.47 (s, 1H, -CH), 3.19 (br, s, 4H, -CH 2 -N-CH 2 , piperazine ring), 2.44 (br, s, 4H, -CH 2 -N-CH 2 , piperazine ring) 13 C-NMR (DMSO-d 6 ) δ (ppm) 170.56, 165.30, 153.67, 141.82, 135.75, 132.11, 130.96, 128.98, 127.03, 123.18, 116.82, 113.82, 111.56, 65.74, 63.72, 44.09, 40.90; ESI-MS m/z: [M + H] + 467.62. N-benzhydryl-4-((5-(2-nitrophenyl)-1,3, 4-oxadiazol-2-yl)methyl)piperazine (4g) Yield: 38.12%; mp: 173 to 175°C; Anal Calcd for C 26 H 25 N 5 O 3 : C,68.56, H, 5.53, N, 15.37; found C, 68.55, H, 5.54, N, 15.38; IR (ν max cm −1 ): 3309 (NH stretch), 3275, 3112 (Ar-H), 2900, 2812 (piperazine ring), 1626, 1523 (C=N, C=C), 1246, 1123 (C-O-C), 1234 (C-N) 1 H-NMR (CDCl 3 ) δ (ppm): 7.36 to 7.35 (d, 4H, Ar-H, J = 6.6 Hz), 7.26 to 7.24 (t, 4H, Ar-H, J = 6.7 Hz), 7.15 to 7.10 (m, 5H, phenyl), 7.12 to 7.11 (d, 2H, Ar-H, J = 6.6 Hz), 4.86 (s, 2H, -CH 2 ), 4.56 (s, 1H, -CH), 3.46 (br, s, 4H, -CH 2 -N-CH 2 , piperazine ring), 2.83 (br, s, 4H, -CH 2 -N-CH 2 , piperazine ring) 13 C-NMR (CDCl 3 ) δ (ppm) 172.40, 163.32, 152.87, 140.45, 134.23, 132.46, 129.32, 128.12, 123.31, 121.32, 115.21, 114.23, 112.98, 64.10, 62.39, 42.13, 41.45; ESI-MS m/z: [M + H] + 456.51.…”