SUPPORTING INFORMATION Drastically Decreased Reactivity of Thiols and Disulfides Complexed by Cucurbit[6]uril Lidia Strimbu Berbeci, Wei Wang and Angel E. Kaifer* Center for Supramolecular Science and Department of Chemistry, University of Miami, Coral Gables, FL 33124-0431 akaifer@miami.edu TABLE OF CONTENTS Synthetic details Pages SI2-SI3. Synthetic route to obtain 1 (Scheme SI1) Page SI4 Products of thiol scrambling reaction (Scheme SI2) Page SI4 Additional NMR data (Figures SI1-SI8) Page SI5-SI8. Page SI1
Synthesis All compound structures are shown in Scheme SI1. Bis-(2-hydroxy-ethyl)-carbamic acid tert-butyl ester (5). 2-(2-Aminoethylamino)ethanol (10 ml, 0.104 mol) was taken into 200 ml CH 3 CN. Ditert-butyl dicarbonate (25g, 0.1145 mol) was dissolved in 140 ml of CH 3 CN and added dropwise to the 2-(2-aminoethylamino)ethanol solution at room temperature. The reaction was stirred for 3 hours and the solvent was evaporated. The product was obtained as a viscous oil and used without further purification. Yield was quantitative. 1 H NMR (400 MHz, MeOD-d 4 ): δ 1.46-1/51 (m, t-boc), 3.39 (t, J = 6 Hz, CH 2, 4H), 3.7 (t, J = 6 Hz, CH 2, 4H). FAB MS: m/z 206 (M +, calc. 205), 150 (M + -Boc). [2-(3, 5-Dimethoxy-benzyloxy)-ethyl]-(2-hydroxy-ethyl)-carbamic acid tert-butyl ester (4) Compound 5 (6.0 g, 29.3 mmol) was dissolved in 100 ml of DMF under N 2. Sodium hydride (1 equiv. 5.86 mmol) was added and the mixture was stirred for 15 min at room temperature. The reaction was cooled for 15 min at 0 o C, and 3, 5-dimethoxybenzylbromide (1.35 g, 5.86 mmol) dissolved in 20 ml of dry DMF, was added dropwise. Stirring was continued for 1 h at 0 o C, and product formation was followed by TLC. At the end of the reaction, 20 ml of saturated NH 4 Cl was added. The DMF was removed under vacuum and the product purified by column chromatography. Compound 4 was obtained as a pale yellow oil in 61% yield. 1 H-NMR (400 MHz, MeOD-d 4 ): 1.39-1.45 (m, t-boc, 9H); 3.40 (t, J = 6 Hz, CH 2, 2H), 3.48-3.49 (m, CH 2, 2H); 3.57-3.60 (m, CH 2, 2H); 3.64 (t, J = 6 Hz, CH 2, 2H), 3.76 (s, CH 3, 6H); 4.45 (s, CH 2 -benzylic, 2H); 6.38 (t, J = 2.4 Hz, Bz, 1H); 6.48 (d, J = 2 Hz, Bz, 2H). FAB MS: m/z 356 (MH +, M calc. 355); 256 (M + -Boc). Thiolacetic acid 2-{tert-butoxycarbonyl-[2-(3, 5-dimethoxy-benzyloxy)-ethyl]- amino}-ethyl ester (3) Triphenylphosphine (1.89 g, 7.2 mmol) and DIAD (7.2 mmol, 1.42 ml) were mixed in 27 ml of THF under N 2 at 0 o C for 30 min solution A. In a separate flak compound 4 (1.273 g, 3.6 mmol) and thiolacetic acid (0.542 ml, 7.2 mmol) were mixed together in 40 ml of dry THF under N 2 solution B. After 30 min solution B was added dropwise to solution A and stirred for 1h at 0 o C. The reaction was followed by TLC. When the Page SI2
reaction is finished, quenching was accomplished by adding 20 ml of MeOH and the solvent was removed. The product was dissolved in CHCl 3 and purified by column chromatography. Compound 3 was obtained as an oil in 59% yield. 1 H-NMR (400 MHz, MeOD-d 4 ): 1.40-1.47 (m, t-boc, 9H); 3.40 (t, J = 6 Hz, CH 2, 2H), 3.48-3.49 (m, CH 2, 2H); 3.57-3.60 (m, CH 2, 2H); 2.32 (s, CH 3, 3H), 3.0-3.1 (t, CH 2, 2H); 3.40-3.46 (m, CH 2 - N(boc)-CH 2, 4H); 3.58 (t, J = 5.4 Hz, CH 2, 2H); 3.76 (s, CH 3, 6H); 4.45 (s, CH 2 -benzylic, 2H); 6.38 (t, J = 2.4 Hz, Bz, 1H); 6.48 (d, J = 2.4 Hz, Bz, 2H). FAB MS: m/z 414 (MH+, M calc. 413); 314 (M+ - Boc). [2-(3, 5-Dimethoxy-benzyloxy)-ethyl]-(2-mercapto-ethyl)-ammonium (1) Compound 3 (110 mg, 0.266 mmol) was taken into 10 ml of dry MeOH under N 2. The reaction was cooled to -78 o C in an acetone/dry ice bath. CH 3 COCl (1.9 ml, 26.6 mmol) was added dropwise and the reaction mixture was stirred overnight. A small portion was taken and analyzed by 1 H-NMR before the reaction was stopped to make sure that the reaction was finished. At the end of the reaction, the solvent was removed and the compound was dried under vacuum. Compound 1 was obtained as an air sensitive white powder, which was kept under a N 2 atmosphere. 1 H-NMR (400 MHz, D 2 O): 2.83 (t, J = 6.8 Hz, CH 2 SH, 2H); 3.23 (t, CH 2, 4H), 3.58 (t, J = 5.4 Hz, CH 2, 2H); 3.79-3.81 (m, CH 2, 2H); 3.84 (s, CH 3, 6H), 4.57 (s, CH 2 -benzylic, 2H); 6.60 (t, J = 2.4 Hz, Bz, 1H); 6.68 (d, J = 2.4 Hz, Bz, 2H). 13 C (75 MHz, D 2 O): 160.8, 140.3, 107.2, 100.5, 73.0, 64.6, 56.0, 49.8, 47.0, 20.1. FAB MS: m/z 272 (MH +, M calc. 271). 2,2 -disulfanediylbis(n-(2-(3,5-dimethoxybenzyloxy)ethyl)ethanaminium) (2) Compound 1 was oxidized with a slight excess of trichloronitromethane in acetonitrile solution. After 2h, the solvent was evaporated and the residue was recrystallized from EtOH to yield pure disulfide 2. 1 H-NMR (500 MHz, D 2 O): 2.989 (t, J = 7.0 Hz, CH 2 S, 4H); 3.326 (m, CH 2, 4H), 3.406 (t, J = 7.0 Hz, CH 2, 4H); 3.796-3.830 (m, CH 2, 16H); 4.555 (s, CH 2 -Benzylic, 2H); 6.552 (s, Bz, 2H); 6.670 (s, Bz, 4H). 13 C (100 MHz, DMSO-d 6 ): 160.48, 140.16, 105.43, 99.34, 72.05, 64.92, 55.20, 46.25, 46.00, 32.07. FAB MS: m/z 542 (MH +, M calc. 541). Anal. Calcd for(c 26 H 40 N 2 O 6 S 2 2HCl H 2 O): C: 49.44, H: 7.02, N: 4.43. Found: C: 49.08, H: 6.88, N: 4.39. Page SI3
Scheme SI1. Structures of thiol 1 and disulfide 2 and the synthetic route to 1. + H 3 N NH 3 + S S NH 3 + SH O O NH + 3 + H 3 N S S O HS NH + 3 O NH + O 3 + NH 3 S O O S SH O NH + 3 O O + H 3 N S S NH3 Scheme SI2. Products of the thiol/disulfide scrambling reaction between cystamine and cysteine methyl ester. Page SI4
Figure SI1. Partial 1 H NMR spectra (500 MHz, D 2 O, 0.2 M NaCl, pd = 2.0) of 2.0 mm cysteamine in the presence of variable concentrations of CB6: (a) 0 equiv, (b) 0.2 equiv, (c) 0.4 equiv, (d) 0.6 equiv, (e), 0.8 equiv, (f) 1.0 equiv, (g) 1.2 equiv, (h) 1.4 equiv, (i) 1.6 equiv, (j) 1.8 equiv, (k) 2.0 equiv. The symbol * labels the acetone residue. Figure SI2. 1 H NMR chemical shift of the CH 2 N protons of cysteamine as a function of the added concentration of CB6. The continuous line through the data points corresponds to the best fit to a 1:1 binding isotherm. Page SI5
Figure SI3. Partial 1 H-NMR spectra (500 MHz, D 2 O, 0.2 M NaCl, pd = 2) of 1.0 mm thiol 1 in the presence of variable concentrations of CB6: (a) 0 equiv, (b) 0.1 equiv, (c) 0.2 equiv, (d) 0.4 equiv, (e) 0.6 equiv, (f) 0.8 equiv, (g) 1.0 equiv, (h) 1.2 equiv, (i) 1.4 equiv, (j) 1.6 equiv, (k) 1.8 equiv, (l) 2.0 equiv. The symbol * labels the acetone residue Figure SI4. 1 H NMR chemical shift of the c methylene protons of thiol 1 (1.0 mm) as a function of the added concentration of CB6. The continuous line through the data points corresponds to the best fit to a 1:1 binding isotherm. Page SI6
Figure SI5. A comparison of the 1 H-NMR spectra (500 MHz, D 2 O, 0.2 M NaCl, pd = 2) for (A) thiol 1 and (B) disulfide 2. The symbol * labels the residual acetone peak. Figure SI6. Partial 1 H-NMR spectra (500 MHz, D 2 O, 0.2 M NaCl, pd = 1.1) of 1.0 mm disulfide 2 in the presence of variable concentrations of CB6: (a) 0 equiv, (b) 0.4 equiv, (c) 0.8 equiv, (d) 1.2 equiv, (e) 1.4 equiv, and (f) 2.2 equiv. The symbol * labels the residual acetone peak. Page SI7
Figure SI7. Partial 1 H-NMR spectra (500 MHz, D 2 O, 0.2 M NaCl, pd = 2) of (a) 1.0 mm cystamine + 1.0 mm CB6, (b) 0.5 mm cystamine + 0.5 mm CB6, and (c) 0.1 mm cystamine + 0.1 mm CB6. The symbol * labels the residual acetone peak. Figure SI8. Partial 1 H-NMR spectra (500 MHz, D 2 O, 0.2 M NaCl, pd = 7) of (a) 1.0 mm cystamine in the presence of 1.05 equiv of CB6, (b) 5 min after addition of 1.5 equiv DTT, (c) 30min, (d) 12 h, (e) 36 h after DDT addition. The symbol * labels the residual acetone peak. Page SI8