Compound Number 1 2 3 4 5 Synthetic Procedure Compound 1, KY1220, (Z)-5-((1-(4-nitrophenyl)-1H-pyrrol-2-yl)methylene)-2-thioxoimidazolidin-4-one was purchased from Chemdiv, Catalog #3229-2677, 97% HPLC purity. Compound 2, KYA1797, (Z)-3-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-4-oxo-2-thioxothiazolidin-3- yl)propanoic acid was purchased from TimTec Compound Collection ST004998, 97% HPLC purity. Compound 3, KYA1690, (Z)-4-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-4-oxo-2-thioxothiazolidin-3- yl)butanoic acid was purchased from TimTec Compound Collection ST056849, 97% HPLC purity. To a solution of bis(carboxymethyl)trithiocarbonate (2000 mg, 8.84 mmol) in 1,2-Dimethoxyethane (35.3 ml), triethylamine (894.34 mg, 8.84 mmol) and 5-Aminovaleric acid (1035.40 mg, 8.84 mmol) were added. The reaction mixture was heated at 100 C for 10 min under microwave irradiation. The solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel. The desired compound was dried in vacuo to give as a yellow solid with a 41.21% yield. 1 H NMR (500MHz, DMSO-d 6 ) δ 12.02 (s, 1H), 4.24 (s, 2H), 3.85 (t, 2H, J=7.0Hz), 2.23 (t, 2H, J=7.0Hz), 1.59-1.54 (m, 2H), 1.51-1.45 (m, 2H). Rhodanine-3-butaonic acid (110.86 mg, 0.48 mmol) and sodium acetate (116.94 mg, 1.43 mmol) were added to 5-(4-Nitrophenyl)furfural (86 mg, 0.4 mmol) in ethanol (3.9 ml). The mixture was heated at 90 C for 6 h. After cooled to ambient temperature, the resulting crystals was collected by filtration, washed with ethanol and dried in vacuo to give (Z)-5-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-4-oxo-2- thioxothiazolidin-3-yl)pentanoic acid 4 as an orange powder with a 63.58% yield. ESI (m/z) 433 (MH + ) 455 (MNa + ); 1 H NMR (500MHz, DMSO-d 6 ) δ 12.05 (s, 1H), 8.38 (d, 2H, J=8.5Hz), 8.03 (d, 2H, J=8.5Hz), 7.68 (s, 1H), 7.59 (d, 1H, J=4.0Hz), 7.40 (d, 1H, J=3.5Hz), 4.02 (t, 2H, J=7.2Hz), 2.26 (t, 2H, J=7.2Hz), 1.68-1.63 (m, 2H), 1.55-1.49 (m, 2H); HRMS (m/z): [M]- calcd. for C 19 H 16 N 2 O 6 S 2, 431.0377; found, 431.0394; Purity: 100% (254 nm, RT = 14.946 min). Potassium hydroxide (1 M, 3.36 ml) in methanol was added to KYA1797 (800 mg, 1.98 mmol) in methanol (98.90 ml). The mixture was stirred for 2 h, and the resulting crystals were collected by filtration, washed with methanol and dried in vacuo to give potassium (Z)-3-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-4- oxo-2-thioxothiazolidin-3-yl)propanoate 5 orange powder with a 71.44% yield. ESI (m/z) 405 (MH+); 1 H NMR (500MHz, DMSO-d 6 ) δ 8.41 (d, 2H, J=9.0Hz), 8.06 (d, 2H, J=8.5Hz), 7.69 (s, 1H), 7.61 (d, 1H, J=3.5Hz), 7.40 (d, 1H, J=4.0Hz), 4.14-4.10 (m, 2H), 2.20 (m, 2H); HRMS (m/z): [M] + calcd. for C 17 H 12 KN 2 O 6 S 2, 403.0064; found, 403.0070
6 2,4-thiazolidinedione (800 mg, 6.83 mmol) was dissolved in DMF (0.1 M), and ethyl 4-bromobutanoate (3.2 g, 16.39 mmol) was then added. The reaction mixture was heated at 120 C for 30 min under microwave irradiation, and the solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel. The desired compound, 4-(2,4-dioxo-thiazolidin-3-yl)-butyric acid ethyl ester, was dried in vacuo to give a yellow oil with a 53.81% yield. 1 H NMR (500MHz, DMSO-d 6 ) δ 4.15 (s, 2H), 4.06-4.02 (m, 2H), 3.52 (t, 2H, J=6.7 Hz), 2.30 (t, 2H, J=7.2 Hz), 1.78-1.72 (m, 2H), 1.17 (t, 2H, J=7.0 Hz). Next, 4-(2,4-dioxo-thiazolidin-3-yl)-butyric acid ethyl ester (455.5 mg, 1.96 mmol) was dissolved in 35% HCl solution, and the reaction mixture was refluxed overnight. After the reaction was completed, saturated sodium bicarbonate solution was added until the ph of the mixture reached neutral. The solution was then evaporated and extracted using ethyl acetate (50 ml 3). The organic layer was washed with brine, dried over anhydrous MgSO 4, and concentrated. The crude product was purified by flash column chromatography on silica gel. 4-(2,4-Dioxo-thiazolidin-3-yl)-butyric acid was dried in vacuo to give as a brown solid with a 15.49% yield. 1 H NMR (500MHz, DMSO-d 6 ) δ 12.10 (s, 1H), 4.15 (s, 2H), 3.52 (t, 2H, J=6.8 Hz), 2.22 (t, 2H, J=7.2 Hz), 1.75-1.68 (m, 2H). Next, 5-(4-nitrophenyl)furan-2-carbaldehyde (65 mg, 0.3 mmol) and sodium acetate (73 mg, 0.9 mmol) were added to a solution of 4-(2,4-dioxo-thiazolidin-3-yl)-butyric acid (62 mg, 0.3 mmol) in ethanol (0.1 M). The mixture was stirred and heated at 90 C for 6 h. The precipitate was collected by filtration and washed with ethanol (50 ml). The desired compound, 4-{5-[1-[5-(4-Nitro-phenyl)-furan-2-yl]-meth-(Z)- ylidene]-2,4-dioxo-thiazolidin-3-yl}c-butyric acid, was dried in vacuo to give as an orange solid with a 32.48% yield. ESI (m/z): 403 (MH + ), 425 (MNa + ). Next, 4-{5-[1-[5-(4-Nitro-phenyl)-furan-2-yl]-meth-(Z)-ylidene]-2,4-dioxo-thiazolidin-3-yl}-butyric acid (23 mg, 0.057 mmol) was dissolved in anhydrous dichloromethane (0.05 M) at room temperature under an Ar atmosphere. Amine-PEG2-biotin (Thermo Scientific, 25.69 mg, 0.069 mmol), EDC (21.92 mg, 0.114 mmol), and DMAP (13.97 mg, 0.114 mmol) were added and the mixture was stirred overnight at room temperature, after which 10% HCl was added and the mixture was extracted three times with dichloromethane, washed with brine. The organic layer was dried over anhydrous Na 2 SO 4, filtered and concentrated. The precipitate was collected by filtration and washed with ethanol. The desired compound, (Z)-N-(2-(2-(2-(4-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-2,4-dioxothiazolidin-3- yl)butanamido)ethoxy)ethoxy)ethyl)-5-(2-oxohexahydro-1h-thieno[3,4-d]imidazol-4-yl)pentanamide 6, was dried in vacuo to give an orange solid with a 17.29% yield. ESI (m/z): 759 (MH + ), 781 (MNa + ).
7 2,4-thiazolidinedione (800 mg, 6.83 mmol) was dissolved in acetone or DMF (0.1 M), and ethyl 4- bromobutanoate (3.2 g, 16.39 mmol) was added. The reaction mixture was then heated at 120 C for 30 min under microwave irradiation. The solvent was removed in vacuo. The residue was purified by flash chromatography on silica gel. The desired compound, 4-(2,4-dioxo-thiazolidin-3-yl)-butyric acid ethyl ester, was dried in vacuo to give as a yellow oil with a 53.81% yield. 1 H NMR (500MHz, DMSO-d 6 ) δ 4.15 (s, 2H), 4.06-4.02 (m, 2H), 3.52 (t, 2H, J = 6.7 Hz), 2.30 (t, 2H, J = 7.2 Hz), 1.78-1.72 (m, 2H), 1.17 (t, 2H, J = 7.0 Hz). Next, 4-(2,4-dioxo-thiazolidin-3-yl)-butyric acid ethyl ester (455.5 mg, 1.97 mmol) was dissolved in 35% HCl solution, and the reaction mixture was refluxed overnight. After the reaction was completed, saturated sodium bicarbonate solution was added until the ph of the mixture reached neutral. The solution was then evaporated and extracted using ethyl acetate (50 ml 3). The organic layer was washed with brine, dried over anhydrous MgSO 4, and concentrated. The crude product was purified by flash column chromatography on silica gel. 4-(2,4-Dioxo-thiazolidin-3-yl)-butyric acid was dried in vacuo to give a brown solid with a 15.49% yield. 1 H NMR (500MHz, DMSO-d 6 ) δ 12.10 (s, 1H), 4.15 (s, 2H), 3.52 (t, 2H, J = 6.8 Hz), 2.22 (t, 2H, J = 7.2 Hz), 1.75-1.68 (m, 2H). Next, 5-Phenyl-2-furaldehyde (149.96 mg, 0.87 mmol) and piperidine (148.33 mg, 1.74 mmol) were added to a solution of 4-(2,4-dioxo-thiazolidin-3-yl)-butyric acid (177 mg, 0.87 mmol) in ethanol (0.1 M). The mixture was stirred and heated at 90 C for 6 h. The resulting precipitate was collected by filtration and washed with ethanol (50 ml). The desired compound, (Z)-4-(2,4-dioxo-5-((5-phenylfuran-2- yl)methylene)thiazolidin-3-yl)butanoic acid, was dried in vacuo to give as a yellow solid with a 35.34% yield. 1 H NMR (400MHz, DMSO-d 6 ) δ 12.11 (s, 1H), 7.80 (d, 2H, J=8.0 Hz), 7.73 (s, 1H), 7.51 (t, 2H, J=7.6 Hz), 7.38 (t, 1H, J=7.4 Hz), 7.28-7.24 (m, 2H), 3.65 (t, 2H, J=6.6 Hz), 2.24 (t, 2H, J=7.2 Hz), 1.81-1.74 (m, 3H). Next, (Z)-4-(2,4-dioxo-5-((5-phenylfuran-2-yl)methylene)thiazolidin-3-yl)butanoic acid (20 mg, 0.055 mmol) was dissolved in anhydrous dichloromethane (0.05 M) at room temperature under an Ar atmosphere. Amine-PEG2-biotin (Thermo Scientific, 25.15 mg, 0.067 mmol), EDC (1-ethyl-3-[3- dimethylaminopropyl]carbodiimide hydrochloride, 21.46 mg, 0.11 mmol) and DMAP (4- dimethylaminopyridine, 13.67 mg, 0.11 mmol) were added and the mixture was stirred overnight at room temperature, after which 10% HCl was added and the mixture was extracted three times using dichloromethane, and washed with brine. The organic layer was dried over anhydrous Na 2 SO 4, filtered and concentrated. The precipitate was collected by filtration and washed with ethanol. The desired compound, (Z)-N-(2-(2-(2-(4-(2,4-dioxo-5-((5-phenylfuran-2-yl)methylene)thiazolidin-3- yl)butanamido)ethoxy)ethoxy)ethyl)-5-(2-oxohexahydro-1h-thieno[3,4-d]imidazol-4-yl)pentanamide 7, was dried in vacuo to give an orange solid with an 16.11% yield. ESI (m/z): 714 (MH + ), 736 (MNa + ).
Potassium hydroxide (1 M, 0.29 ml) in methanol was added to KYA1690 (109 mg, 0.26 mmol) in methanol (13.13 ml). The mixture was stirred for 2 h, and the resulting crystals were collected by filtration, washed with methanol and dried in vacuo to give potassium (Z)-4-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-4- oxo-2-thioxothiazolidin-3-yl)butanoate 8 as a red powder with a 75.15% yield. APCI (m/z) 419 (MH+); 1 H NMR (500MHz, DMSO-d 6 ) δ 8.37 (d, 2H, J=8.0Hz), 8.03 (d, 2H, J=8.5Hz), 7.67 (s, 1H), 7.60 (s, 1H), 7.39 (d, 1H, J=2.5Hz), 4.01 (t, 2H, J=7.2Hz), 1.93 (t, 2H, J=7.5Hz), 1.80-1.73 (m, 2H); HRMS (m/z): [M] + 8 calcd. for C 18 H 14 KN 2 O 6 S 2, 417.0221; found, 417.0218. Potassium hydroxide (1 M, 0.20 ml) in methanol was added to KYA2370 (77 mg, 0.18 mmol) in methanol (9.10 ml). The mixture was stirred for 2 h, and the resulting crystals were collected by filtration, washed with methanol and dried in vacuo to give potassium (Z)-5-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-4- oxo-2-thioxothiazolidin-3-yl)pentanoate 9 as an orange powder with a 67.45 % yield. ESI (m/z) 433 (MH + ) 455 (MNa + ); 1 H NMR (500MHz, DMSO-d 6 ) δ 8.38(m, 2H), 8.02(m, 2H), 7.68(s, 1H), 7.58(m 1H), 7.40(m, 1H), 4.0-3.97(m, 2H), 1.90-1.88(m, 2H), 1.16-1.57(m, 2H), 1.45-1.42(m, 2H); HRMS (m/z): [M] - calcd. for 9 C 19 H 15 KN 2 O 6 S 2, 431.0377; found, 431.0394. KYA1797 (14 mg) was dissolved in anhydrous dichloromethane (0.05 M) at room temperature under an Ar atmosphere. Amine-PEG2-biotin (Thermo Scientific, 15.56 mg), EDC (13.27 mg), and DMAP (8.46 mg) were added and the mixture was stirred overnight at room temperature, after which 10% HCl was added and the mixture was extracted three times with dichloromethane, washed with brine. The organic layer was dried over anhydrous Na 2 SO 4, filtered and concentrated. The precipitate was collected by filtration and washed with ethanol. The desired compound, (Z)-N-(2-(2-(2-(3-(5-((5-(4-nitrophenyl)furan-2- yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)propanamido)ethoxy)ethoxy)ethyl)-5-(2-oxohexahydro-1hthieno[3,4-d]imidazol-4-yl)pentanamide 10, was dried in vacuo to give an orange solid with a 22.78% 10 yield. ESI (m/z): 761 (MH+), 763 (MNa+). KYA1797 (27 mg) was dissolved in anhydrous dichloromethane (0.05 M) at room temperature under an Ar atmosphere. Amine-PEG3-biotin (Thermo Scientific, 33.53 mg), EDC (25.6 mg) and DMAP (16.31 mg) were added and the mixture was stirred for overnight at room temperature, after which 10% HCl was added and the mixture was extracted three times with dichloromethane, and washed with brine. The organic layer was dried over anhydrous Na 2 SO 4, filtered and concentrated. The precipitate was collected by filtration and washed with ethanol. The desired compound, (Z)-N-(15-(5-((5-(4-nitrophenyl)furan-2-yl)methylene)-4-oxo- 2-thioxothiazolidin-3-yl)-13-oxo-3,6,9-trioxa-12-azapentadecyl)-5-(2-oxohexahydro-1H-thieno[3,4- d]imidazol-4-yl)pentanamide 11, was dried in vacuo to give an orange solid with a 17.79% yield. ESI 11 12 13 14 15 16 17 18 19 20 (m/z): 805 (MH + ), 827 (MNa + ).
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