## 2 Materials and Methods
### Preparation and Characterization of Target Compounds
#### 2.2.3 General Procedure for the Synthesis of 6a-j  
To a mixture of isatin monohydrazone (1 mmol) and substituted aryl aldehyde (1 mmol) in 10 mL ethanol, a few drops of glacial acetic acid was added. The reaction mixture was refluxed for 4 h. The precipitate solid was filtered, washed with cold ethanol and air dried to obtain the target compounds (6a-j), which was then further purified by recrystallization using methanol. \({}^{13}\)CNMR spectra for 6a-j is available in the Supplementary Materials file. 1-Benzyl-3-((4-(dimethylamino)benzylidene)hydrazono)indolin-2-one (6a)  
Dark red solid (53%) mp = 183-184 \({}^{\circ}\)C. IR (KBr): \(\
u_{\max}\) (cm\({}^{-1}\)): 2926 (C-H aliphatic), 1707 (C=O), 1606 (C=N), 1558 (C=N). \({}^{1}\)H NMR (DMSO-d6, 600 MHz: \(\delta\) 3.06 (s, 6H, N(CH\({}_{3}\))\({}_{2}\)), 4.97 (s, 2H, N-CH\({}_{2}\)-Ph),  
Figure 1: Isatin moiety containing active & potential drugs and gefitinib. 6.84 (d, \(J\) = 7.8, 2H, ArH), 6.98 (d, \(J\) = 7.2, 1H, ArH), 7.15 (t, 1H, ArH), 7.26 (s, 1H, ArH), 7.34 (m, 5H, ArH), 7.85 (d, \(J\) = 7.8, 2H, ArH), 8.30 (d, \(J\) = 7.2, 1H, ArH), 8.67 (s, 1H, N=CH) ppm. \({}^{13}\)C NMR (DMSO-d6, 150 MHz: \(\delta\) 166.41, 164.43, 153.76, 149.56, 144.80, 136.70, 133.09, 131.97, 129.18, 129.08, 127.99, 127.68, 123.35, 120.76, 117.04, 112.30, 110.22, 43.11 and 40.14 ppm. ESI mass m/z = 383 [M + H]\({}^{+}\). 1-Benzyl-3-(((4-chlorocyclohexa\({}^{-1}\), 5-dien-1-yl) methylene)hydrazano)indolin-2-one (**6b**)  
Dark red solid (30%) mp = 210-211 \({}^{\circ}\)C. IR (KBr): \(\
u_{\rm max}\) (cm\({}^{-1}\)): 2918 (C-H aliphatic), 1718 (C=O), 1591 (C=N). \({}^{1}\)H NMR (DMSO-d6, 600 MHz: \(\delta\) 4.97 (s, 2H, N-CH\({}_{2}\)-Ph), 7.00 (d, \(J\) = 7.8, 1H, ArH), 7.08 (t, 1H, ArH), 7.24-7.44 (m, 6H, ArH), 7.64 (d, \(J\) = 7.8, 2H, ArH), 7.92 (d, \(J\) = 6.6, 1H, ArH), 8.05 (d, \(J\) = 7.8, 2H, ArH), 8.66 (s, 1H, N=CH) ppm. \({}^{13}\)C NMR (DMSO-d6, 150 MHz: \(\delta\) 163.69, 159.86, 150.00, 145.57, 137.31, 136.45, 134.18, 132.66, 131.03, 129.87, 129.20, 128.00, 127.72, 123.60, 116.30, 110.63 and 43.23 ppm. ESI mass m/z = 374 [M(\({}^{35}\)Cl) + H]\({}^{+}\), 376 [M(\({}^{37}\)Cl) + H]\({}^{+}\). 1-Benzyl-3-((4-hydroxybenzylidene)hydrazano)indolin-2-one (**6c**)  
Orange solid (50%) mp = 235-236 \({}^{\circ}\)C. IR (KBr): \(\
u_{\rm max}\) (cm\({}^{-1}\)): 3329 (O-H), 3022 (C-H aliphatic), 1705 (C=O), 1608 (C=N), 1589 (C=N). \({}^{1}\)H NMR (DMSO-d6, 600 MHz: \(\delta\) 4.97 (s, 2H, N-CH\({}_{2}\)-Ph), 6.92 (d, \(J\) = 7.8, 2H, ArH), 6.98 (d, \(J\) = 7.2, 1H, ArH), 7.08 (t, 1H, ArH), 7.22-7.4 (m, 6H, ArH), 7.73 (bs, 1H, OH), 7.86 (d, \(J\) = 7.2, 2H, ArH), 8.15 (d, \(J\) = 7.8, 1H, ArH), 8.65 (s, 1H, N=CH) ppm. \({}^{13}\)C NMR (DMSO-d6, 150 MHz: \(\delta\) 164.32, 164.11, 162.32, 150.79, 150.31, 145.17, 136.56, 133.62, 132.08, 129.29, 129.18, 127.96, 127.49, 124.88, 123.49 and 43.14 ppm. ESI mass m/z = 356 [M + H]\({}^{+}\). 1-Benzyl-3-((2-bromobenzylidene)hydrazano)indolin-2-one (**6d**)  
Orange solid (65%) mp = 173-174 \({}^{\circ}\)C. IR (KBr): \(\
u_{\rm max}\) (cm\({}^{-1}\)): 2935(C-H aliphatic), 1722 (C=O), 1606 (C=N). \({}^{1}\)H NMR (DMSO-d6, 600 MHz: \(\delta\) 4.95 (s, 2H, N-CH\({}_{2}\)-Ph), 6.99 (d, \(J\) = 4.8, 1H, ArH), 7.06 (t, 1H, ArH), 7.25 (m, 1H, ArH), 7.3-7.37 (m, 4H, ArH), 7.4 (t, 1H, ArH), 7.51 (t, 1H, ArH), 7.58 (t, 1H, ArH), 7.78 (d, \(J\) = 8.4, 1H, ArH), 7.86 (d, \(J\) = 7.2, 1H, ArH), 8.22 (d, \(J\) = 7.2, 1H, ArH), 8.75 (s, 1H, N=CH) ppm. \({}^{13}\)C NMR (DMSO-d6, 150 MHz: \(\delta\) 163.57, 158.38, 149.98, 145.68, 136.37, 134.37, 134.28, 134.15, 132.16, 129.31, 129.19, 129.15, 129.10, 128.00, 127.71, 125.68, 123.64, 116.16, 116.16, 110.68 and 43.22 ppm. ESI mass m/z = 418 [M(\({}^{79}\)Br) + H]\({}^{+}\), 420 [M(\({}^{81}\)Br) + H]\({}^{+}\). 1-Benzyl-3-((E)-(3-bromobenzylidene)hydrazano)indolin-2-one (**6e**)  
Orange solid (52%) mp = 173-174 \({}^{\circ}\)C. IR (KBr): \(\
u_{\rm max}\) (cm\({}^{-1}\)): 2920 (C-H aliphatic), 1720 (C=O), 1624 (C=N), 1573 (C=N).