Supplementary Material (ESI) for Chemical Communication Syntheses and Characterization of Polymer-Supported Organotrifluoroborates: Applications in Radioiodination Reactions Li Yong; Min-Liang Yao; James F. Green; Hall Kelly; George W. Kabalka* Departments of Chemistry and Radiology, University of Tennessee, Knoxville, Tennessee 37996-16 Fax: (+1)865-9742997: E-mail: kabalka@ion.chem.utk.edu General comments: All glassware was dried in an oven at 12 o C and flushed with dry argon prior to use. All solvents and chemicals were purchased from commercial sources and used as received. Dowex 1-X 1 (Bio.Rad Laboratories, 1-2 mesh, chloride form. Control number, MM617). DI water (Barnstead E-pure) was used in all solution preparation and reactions. Potassium organotrifluoroborates were prepared from organoboronic acids or esters according to the reported procedures or obtained from commercial sources. 11 B and 13 C solid-state NMR spectroscopy was performed on a Varian INOVA 4 MHz solid state NMR. IR spectroscopy was carried out using a Nicolet 67 FT/IR with a continuum microscope. UV/vis spectroscopy was performed using an Evolution 6 UV-vis. The ph value of the solutions was measured using an Accumet Basic ph Meter. No-carrier-added Na (in.1% aqueous NaOH) was purchased from MDS Nordion, Inc. 1. Preparation of the Dowex resin bearing quaternary ammonium hydroxide moieties through chloride-hydroxide anion exchange Dowex 1-X 1 (1 grams) was washed sequentially with 1 N aqueous HCl (3 x 4 ml), 1 N aqueous NaOH (3 x 4 ml), water (1 ml) of water and then dried overnight prior to use. 1
[When aqueous AgNO 3 is added to the second (NaOH) wash, a white precipitate (AgCl) forms, confirming that chloride-hydroxide anion exchange occurred] 2. Synthesis of Dowex-supported 2-naphthylenyltrifluoroborate salt To a suspension of the base form of the Dowex resin (1 g) in H 2 O (1 ml), a solution of 2- naphthylenyltrifluoroborate (1 mmol) in MeOH (1 ml) was added in one portion. The ph of the reaction mixture was then monitored. Reaction time versus ph was measured as a means of monitoring the formation of the Dowexsupported 2-naphthylenyltrifluoroborate salt. The reactions were generally complete in less than 3 hours. Time (Min.) PH value Time (Min.) PH value Time (Min.) PH value 6.1 2 6.45 9 7.26 2 6.13 22 6.49 1 7.29 4 6.15 24 6.52 11 7.32 6 6.18 26 6.58 12 7.35 8 6.22 28 6.6 13 7.38 1 6.25 4 6.93 14 7.4 12 6.29 5 7.5 2 7.4 14 6.33 6 7.18 26 7.4 16 6.39 7 7.2 18 6.41 8 7.23 2
7.5 7.3 7.1 6.9 Ph Value 6.7 6.5 6.3 6.1 5.9 5 1 15 2 25 3 Reaction time (minute) 3. IR study: A, IR spectrum of Dowex resin bearing quaternary ammonium hydroxide moieties 3
B. IR spectrum of Dowex-supported 2-naphthylenyltrifluoroborate salt 4
4. NMR study A.. Solid-state 13 C-NMR of Dowex resin bearing quaternary ammonium hydroxide moieties: 23.4 172.74 152.86 133.87 122.73 13.42 53.77 45.34 29.81 17.77 5 4 5 4 3 5 3 2 5 2 1 5 1 5-5 3 2 9 2 8 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 1 9 1 8 1 7 1 6 1 5 1 4 1 3 1 2 f1 ( p p m ) 1 1 1 9 8 7 6 5 4 3 2 1-1 - 2-3 - 4-5 B. Solid-state 13 C-NMR study of Dowex-supported 3,4,5-trimethoxyphenyl BF 3 K salt (57.8 ppm and 65.6 ppm, which confirms the presence of the OMe group in the polymer supported material) 23.9 183.5 172.25 153.2 129.86 123.36 17.93 13.74 85.45 79.83 73.52 53.7 45.31 38.11 33.29 29.37 16.8 3 8 3 6 3 4 3 2 3 2 8 2 6 2 4 2 2 2 1 8 1 6 1 4 1 2 1 8 6 4 2-2 - 4-6 3 2 9 2 8 2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 1 9 1 8 1 7 1 6 1 5 1 4 1 3 1 2 f 1 ( p p m ) 1 1 1 9 8 7 6 5 4 3 2 1-1 - 2-3 - 4-5 5
C. Solid-state 11 B NMR of Dowex-supported 3,4,5-trimethoxyphenyl BF 3 K salt 2 6 2 4 2 2 2 1 8 1 6 1 4 1 2 1 8 6 4 2-2 2E + 5 2 E + 5 2 E+ 5 2 E+ 5 2E + 5 2E + 5 2E + 5 2E + 5 f1 (p p m ) 2E + 5 2 E + 5 2 E + 5 2 E+ 5 2 E+ 5 2E + 5 2E + 5 6
5. Determination of the maximum loading of Ar-BF 3 - on the Dowex surface through an UV/vis spectorsopic analysis. To determine the maximum loading of Ar-BF 3 - on the Dowex surface, two series of experiments were carried out using two different potassium organotrifluoroborates. A.. Study A using potassium 2-naphthelenyltrifluoroborate: Potassium 2-naphthelenyltrifluoroborate 234 mg (1. mmol) was dissolved in methanol (4 ml). The solution was carefully to a 1 ml volumetric flask. Then DI water (4 ml) was added to this solution. DI water and methanol (v/v 1:1) were added to attain a total volume of 1 ml. Afterwards,.25 ml,.5 ml, 1 ml, 1.5 ml and 2 ml of the solution was taken and placed in 5 volumetric flasks (5 ml) separately. To all of flasks co-solvent [DI water and methanol (v/v 1:1)] was added to reach the volume of 5 ml. Five standard samples obtained were then subjected to the UV/vis study. 7
3 2.5 2 Std1, 5x1^-5 M Std2, 1x1^-4 M Std3, 2x1^-4 M Std4, 3x1^-4 M Std5, 4x1^-5 M Absorbance 1.5 1.5 2 25 21 215 22 225 23 235 24 245 25 wavelength (nm) 3 2.5 Absorbance 2 1.5 1 R 2 =.9998.5 1 2 3 4 Napthyl-BF 3 K concentration x1-4 M Calibration plot: y =.4656x +.649 Control experiment: Dowex (1. g) was added to potassium 2-naphthelenyltrifluoroborate (1. mmol) in methanol-water (v/v 1:1, 2 ml). After completion of the reaction (monitored by ph 8
meter), the Dowex-supported aryltrifluoroborate was filtered off and washed thoroughly with methanol-water (v/v 1:1, 6 ml). The filtrate was diluted to 1 ml using 5% aqueous methanol and 2 µl of this solution was taken and again diluted to 1 ml using 5% aqueous methanol and analyzed by UV/vis spectroscopy. 3 2.5 sample 2 absorption 1.5 1.5 2 21 22 23 24 25 wavelength Based on the UV absorbance (1.21Å) of the diluted reaction sample, based on the calibration plot the quantity of unreacted potassium 2-naphthelenyltrifluoroborate in the original filtrate (from the control experiment) was calculated to be.59 mmol. Therefore, the maximum loading amount is.41 mmole of organotrifluoroborate per 1 g of Dowex polymer. 5b. Study B using phenyltrifluoroborate: For the preparation of the five standard samples and the control experiment, see study A in 5a. Absorbance 4 3.5 3 2.5 2 1.5 Std1., 3x1^-4 M Std2., 4x1^-4 M Std3., 5x1^-4 M Std4., 6x1^-4 M Std5, 7x1^-4 M 1.5 9 19 2 21 22 23 24 25 wavelength
.7.6.5 Absorption.4.3.2 y =.886x -.288 R 2 =.9829 Series1 Linear (Series1).1 2 3 4 5 6 7 8 Ph-BF3K concentration [M] Calibration plot: y =.886x.288 Control experiment: Dowex (1. g) was added to potassium 2-phenyltrifluoroborate (1. mmol) in methanol-water (v/v 1:1, 2 ml). After completion of the reaction (monitored by ph meter), the Dowex-supported aryltrifluoroborate was filtered off and washed thoroughly with methanol-water (v/v 1:1, 6 ml). The filtrate was diluted to 1 ml using 5% aqueous methanol and 1 ml of this solution was taken and again diluted to 1 ml using 5% aqueous methanol and analyzed by UV/vis spectroscopy. 1
4 3.5 3 2.5 Absorption 2 1.5 sample 1 1.5 19 2 21 22 23 24 25 Wavelength Based on the UV absorbance (.497Å) of the diluted reaction sample and the calibration plot, the quantity of unreacted potassium phenyltrifluoroborate in the original filtrate (from the control experiment) was calculated to be.61 mmol. Therefore, the maximum loading amount is.39 mmole of organotrifluoroborate per 1 g of Dowex polymer. 11
6. The appearance of Dowex-supported BF 3 salts under a microscope (enlarged 7 times). The diameter of these beads are approcimately.1 mm. The face of Dowex 12
7. Radioiodination of resin-supported ArBF 3 salts Z. NMeR1 R 2 BF 3 + NaI-123 Chloramine-T THF-H 2 O, 6 o C 2-3 min Z A suspension of Dowex supported organotrifluoroborate (1 mg in.5 ml of 33% aqueous THF) was placed in a 2 ml Wheaton vial containing no-carrier-added Na (1. mci in.1% aqueous NaOH). Chloramine-T (1. mg) was added to the reaction vial which was sealed and covered with aluminum foil. The reaction mixture was stirred for 2-3 min at 6 o C and then aqueous sodium thiosulfite (1 μl of a 1. x 1-4 M solution) was added to destroy residual molecular iodine. The product was extracted into hexane-ethyl acetate (v/v, 2:1, 1 ml) and then purified by passing it through a silica gel cartridge using hexanes as eluant. The total synthesis time was about 4-5 min. The radiochemical yield is shown below. 29% t Bu 46% Ph 45% MeO OMe OMe 37% F 3 C 34% 33% 31% 13