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Synlett 2005(19): 2893-2898  
DOI: 10.1055/s-2005-918957
LETTER
© Georg Thieme Verlag Stuttgart · New York

Metal-Dependent Halogenation and/or Coupling Reactions of Porphyrins with PhIX2 (X = Cl, F)

Li-Mei Jina, Juan-Juan Yinb, Liang Chenc, Chan-Cheng Guo*c, Qing-Yun Chen*a,c
a Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, P. R. of China
b Nanobiology Medicine Department, Shanghai Applied Physical Institute, Chinese Academy of Sciences, 2019 Jialuo Road, Shanghai 201800, P. R. of China
c College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. of China
Fax: +86(21)64166128; e-Mail: Chenqy@mail.sioc.ac.cn;
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Publication History

Received 22 August 2005
Publication Date:
27 October 2005 (online)

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Abstract

Treatment of zinc(II)-5,10,15-trisubstituted porphyrins with PhICl2 afforded the corresponding meso-chlorinated porphyrins and meso,meso-linked bisporphyrins in almost 50% yield. The reaction of copper(II), nickel(II), or free-base 5,10,15-trisubstituted porphyrins with PhICl2 gave only meso-chlorinated products without any coupling bisporphyrins. Similarly, the reaction of nickel(II) or free-base 5,15-diphenylporphyrins solely yielded meso-chlorinated products, whereas that of the zinc(II)-5,15-diphenylporphyrin with PhICl2, produced only coupling products. Interestingly, β-chloroporphyrins were exclusively formed not only for copper(II) or free-base 5,10,15,20-tetraarylporphyrins, but also for the zinc complexes. In contrast to the reaction of PhICl2, the reaction of PhIF2 with 5,10,15-trisubstituted metalloporphyrins gave the coupling bisporphyrins in high yields, without any fluorinated product. However, in the presence of I2, the meso-iodination of free-base 5,10,15-trisubstituted porphyrins proceeded smoothly.

Key words

chlorination - iodination - coupling reaction - porphyrinoids - synthetic methods

8

Reaction of Zinc(II)-5,10,15-trisubstituted Porphyrin with PhICl 2 . A mixture of zinc(II)-5-(4-trifluoromethyl-phenyl)-10,20-diphenylporphyrin (Zn1b, 100 mg, 0.15 mmol) and PhICl2 (41 mg, 0.15 mmol) was stirred in CH2Cl2 (50 mL) at r.t. for 1 h and filtered through a short column of silica gel. The filtrate was treated with 36% HCl (1 mL) at r.t. for 10 min, washed with H2O, dried over Na2SO4, and evaporated in vacuo to give a purple solid. The residue was purified by flash chromatography (silica gel, 300-400 mesh, CH2Cl2-hexanes, 1:5) to afford 2b (48 mg, 50%) as the first fraction and 3b (45 mg, 50%) as the second fraction. 2b: 1H NMR (CDCl3): δ = 9.65 (d, J = 4.7 Hz, 2 H), 8.91 (d, J = 4.6 Hz, 2 H), 8.82 (d, J = 4.6 Hz, 2 H), 8.70 (d, J = 5.1 Hz, 2 H), 8.29 (d, J = 7.8 Hz, 2 H), 8.20-8.17 (m, 4 H), 8.01 (d, J = 8.2 Hz, 2 H), 7.80-7.73 (m, 6 H), -2.74 (s, 2 H). MS (ESI): m/z = 641.35 (MH+). UV-vis (log ε, CH2Cl2): λmax = 414 (5.67), 513 (4.37), 548 (4.05), 591 (3.81), 648 (3.74). Anal. calcd for C39H24ClF3N4·0.5H2O: C, 72.05; H, 3.88; N, 8.62. Found: C, 71.71; H, 3.97; N, 8.14. 3b: 1H NMR (CDCl3): δ = 8.97 (d, J = 4.9 Hz, 4 H), 8.88 (d, J = 5.0 Hz, 4 H), 8.63 (d, J = 4.8 Hz, 4 H), 8.45 (d, J = 8.0 Hz, 4 H), 8.26-8.23 (m, 8 H), 8.13-8.09 (m, 8 H), 7.72-7.70 (m, 12 H), -2.18 (s, 4 H). 19F NMR (CDCl3): δ = -61.99 (s, 6 F). MS (MALDI): m/z = 1211.4 (MH+). UV-vis (relative intensity, CH2Cl2): λmax = 415 (1), 450 (1.1), 523 (0.24), 560 (0.06), 594 (0.07), 651 (0.03). Anal. calcd for C78H48F6N83·CH3OH: C, 74.41; H, 4.63; N, 8.57. Found: C, 74.52; H, 5.14; N, 8.15. HRMS (MALDI): m/z calcd for C78H48N8F6·H+, 1211.3979; found, 1211.3981.

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Chlorination of 5,10,15-Trisubstituted Porphyrins with PhICl 2 . A sample of nickel(II)-5,10,15-triphenylporphyrin (Ni1a, 50 mg, 0.08 mmol) and PhICl2 (23 mg, 0.08 mmol) was stirred in CH2Cl2 (50 mL) at r.t. for 2 h. Then the mixture was purified by flash chromatography (silica gel, CH2Cl2-hexanes, 1:3) to give Ni2a (47 mg, 90%). 1H NMR (300 MHz, CDCl3): δ = 9.48 (d, J = 4.8 Hz, 2 H), 8.79 (d, J = 4.8 Hz, 2 H), 8.68 (s, 4 H), 7.97 (m, 6 H), 7.67 (m, 9 H). UV-vis (relative intensity, CH2Cl2): λmax = 529 (1), 414 (14). MS (MALDI): m/z = 628.1. Anal. calcd for C38H23N4ClNi·0.5H2O: C, 71.58; H, 3.72; N, 8.48; Cl, 5.57. Found: C, 71.49; H, 3.76; N, 8.64; Cl, 5.87.

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Crystallographic data for Zn3b·2CHCl3: C80H46F6N8Cl6Zn2, MW = 1576.69, crystal system monoclinic, space group P2 (1)/n, a = 11.755 (3), b = 19.839 (4), c = 32.115 (8) Å, V = 7484 Å3, Z = 4, dc = 1.415 mgm-3, µ(Mo - Kα) = 0.921 mm-1, crystal size 0.516 × 0.275 × 0.221 mm, R1 = 0.0981, wR2 = 0.2829, GOF = 0.963 [I > 2σ(I)]. Crystallographic data have been deposited with the Cambridge Crystallo-graphic Data Centre (CCDC 281147). These data can be obtained free of charge at www.ccdc.cam.ac.uk/Data_request/cif or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44 (1223)336033; E-mail: deposit@ccdc.cam.ac.uk.

12

Chlorination of 5,15-Diphenylporphyrins; General Procedure. A sample of 5,15-diphenylporphyrin (4, 50 mg, 0.11 mmol) and PhICl2 (30 mg, 0.11 mmol) was stirred in CH2Cl2 (50 mL) at r.t. for 2 h. Then the mixture was purified by flash chromatography (silica gel, CH2Cl2-hexanes, 1:3) mainly to give 8a (43 mg, 80%). Treating 4 with PhICl2 (60 mg, 0.22 mmol, 2 equiv) under similar conditions, yielded 9a (52 mg) in 90% yield. 8a: 1H NMR (CDCl3): δ = 10.16 (s, 1 H), 9.73 (d, J = 5.1 Hz, 2 H), 9.29 (d, J = 4.9 Hz, 2 H), 8.98 (d, J = 4.8 Hz, 2 H), 8.97 (d, J = 4.8 Hz, 2 H), 8.24-8.21 (m, 4 H), 7.82-7.80 (m, 6 H), -2.94 (s, 2 H). MS (MALDI): m/z = 496 (M+). UV-vis (relative intensity, CH2Cl2): λmax = 413 (1), 510 (0.05), 545 (0.015), 587 (0.013), 642 (0.007). Anal. calcd for C32H21ClN4·H2O: C, 74.63; H, 4.5; N, 10.88. Found: C, 74.70; H, 4.39; N, 10.65. 9a: 1H NMR (CDCl3): δ = 9.60 (d, J = 4.5 Hz, 4 H), 8.87 (d, J = 4.3 Hz, 4 H), 8.19-8.17 (m, 4 H), 7.81-7.78 (m, 6 H), -2.68 (s, 2 H). MS (MALDI): m/z = 531.1 (MH+). UV-vis (relative intensity, CH2Cl2): λmax = 418 (1), 520 (0.05), 554 (0.03), 599 (0.015), 658 (0.017). HRMS (MALDI): m/z calcd for C32H20N4Cl2·H+, 531.1138; found, 531.1136.

13

Reaction of Zinc(II)-5,15-diphenylporphyrin with PhICl 2 . To a solution of zinc(II)-5,15-diphenylporphin (Zn4, 0.25 mmol, 130 mg) in CH2Cl2 (100 mL) was added PhICl2 (68 mg, 0.25 mmol) at r.t., and the mixture was stirred for 6 h. Then the mixture was concentrated to dryness, purified by dry powder chromatography (silica gel, THF-hexanes, 1:5), and the second brown band was collected (the first red-purple band was the starting porphyrin). The crude product was treated with 36% HCl (1 mL) in CH2Cl2 for 10 min, washed with H2O, and purified by flash chromatography (silica gel, CH2Cl2-hexanes, 1:3) to afford 7 (18 mg, 15%), 6 (24 mg, 20%), and 5 (11 mg, 10%). 7: 1H NMR (CDCl3): δ = 9.73 (d, J = 4.5 Hz, 4 H), 8.95 (d, J = 4.4 Hz, 4 H), 8.53 (d, J = 4.5 Hz, 4 H), 8.19-8.16 (m, 8 H), 8.01 (d, J = 4.7 Hz, 4 H), 7.68-7.64 (m, 12 H), -2.16 (s, 4 H). MS (MALDI): m/z = 991.3 (MH+). UV-vis (relative intensity, CH2Cl2): λmax = 417 (1), 449 (1), 525 (0.2), 561 (0.07), 599 (0.06), 658 (0.03). HRMS (MALDI): m/z calcd for C64H40N8Cl2·H+, 991.2816; found, 991.2811. 6: 1H NMR (CDCl3): δ = 10.33 (s, 1 H), 9.73 (d, J = 4.5 Hz, 2 H), 9.41 (d, J = 4.2 Hz, 2 H), 9.06 (d, J = 4.8 Hz, 2 H), 8.95 (d, J = 5.0 Hz, 2 H), 8.63 (d, J = 4.9 Hz, 2 H), 8.51 (d, J = 5.0 Hz, 2 H), 8.24-8.16 (m, 8 H), 8.09 (d, J = 4.8 Hz, 2 H), 7.98 (d, J = 5.0 Hz, 2 H), 7.70-7.65 (m, 12 H), -2.12 (s, 2 H), -2.44 (s, 2 H). MS (MALDI): m/z = 957.3 (MH+). UV-vis (relative intensity, CH2Cl2): λmax = 415 (1), 446 (1), 521 (0.21), 559 (0.06), 596 (0.06), 656 (0.02). HRMS (MALDI): m/z calcd for C64H41N8Cl·H+, 957.3216; found, 957.3238. 5: 1H NMR (CDCl3): δ = 10.35 (s, 2 H), 9.42 (d, J = 4.3 Hz, 4 H), 9.07 (d, J = 4.2 Hz, 4 H), 8.61 (d, J = 4.4 Hz, 4 H), 8.23-8.21 (m, 8 H), 8.06 (d, J = 4.8 Hz, 4 H), 7.68-7.67 (m, 12 H), -2.41 (s, 4 H). MS (MALDI): m/z = 923.4 (MH+). UV-vis (relative intensity, CH2Cl2): λmax = 409 (1), 443 (0.9), 518 (0.2), 588 (0.06), 643 (0.01). HRMS (MALDI): m/z calcd for C64H42N8·H+, 923.3605; found, 923.3614.

15

Chlorination of 5,10,15,20-Tetraarylporphyrins. A sample of copper(II)-5,10,15,20-tetra(4-methoxy-phenyl)porphyrin (Cu10c, 50 mg, 0.06 mmol) and PhICl2 (17 mg, 0.06 mmol) was stirred in CH2Cl2 (50 mL) at r.t. for 1 h. H2SO4 (1 mL) was added, and the reaction was stirred for another 10 min. Then the mixture was washed with H2O, dried over Na2SO4, and purified by flash chromatography (silica gel, CH2Cl2-hexanes, 1:2) to give 11c (43 mg, 90%). 1H NMR (CDCl3): δ = 8.92-8.92 (m, 7 H), 8.13-7.95 (m, 8 H), 7.30-7.24 (m, 8 H), 4.10 (m, 12 H), 2.84 (s, 2 H). MS (MALDI): m/z = 769.3 (MH+). UV-vis (relative intensity, CH2Cl2): λmax = 424 (1), 521 (0.05), 556 (0.025), 595 (0.015), 653 (0.017). HRMS (MALDI): m/z calcd for C48H37N4O4Cl·H+, 769.2576; found, 769.2585.

16

The one-electron oxidation potentials of the porphyrins were detected in CH2Cl2-MeCN (4:1) using 0.1 M TBAPF6 as supporting electrolyte at r.t. [Glass-carbon working electrode, Pt disk (2 mm diameter) reference electrode, Pt wire counter electrode.]

18

Coupling Procedure Using PhIF 2 A sample of nickel(II)-5-chloro-10,20-diphenylporphyrin (Ni1d, 30 mg, 0.054 mmol) and PhIF2 (13 mg, 0.054 mmol) in CH2Cl2 (30 mL) was stirred at r.t. for 30 min. Then the resulting yellow-brown mixture was washed with H2O several times, the organic layer was dried over anhydrous Na2SO4, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography (silica gel, CH2Cl2-hexanes, 1:1) to give Ni13d (28 mg, 93%).1H NMR (CDCl3): δ = 9.56 (d, J = 5.1 Hz, 4 H), 8.84 (d, J = 4.7 Hz, 4 H), 8.47 (d, J = 4.8 Hz, 4 H), 8.00-7.96 (m, 12 H), 7.64-7.61 (m, 12 H). MS (MALDI): m/z = 1102.1 (M+). UV-vis (CH2Cl2): λmax 420-450 (br), 537. HRMS (MALDI): m/z calcd for C64H36N8Cl2Ni2, 1102.1142; found, 1102.1187.

19

meso -Iodination of Free Base 1 A sample of 5-(4-trifluoromethylphenyl)-10,20-diphenylporphyrin (1b, 50 mg, 0.08 mmol), I2 (20 mg, 0.08 mmol), and PhIF2 (20 mg, 0.08 mmol) in CH2Cl2 (30 mL) was stirred at r.t. for 1 h. Then the resulting mixture was washed with H2O several times, the organic layer was dried over anhydrous Na2SO4, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography (silica gel, CH2Cl2-hexanes, 1:3) to give 12b (46 mg, 80%). 1H NMR (CDCl3): δ = 9.69 (d, J = 5.0 Hz, 2 H), 8.89 (d, J = 4.8 Hz, 2 H), 8.83 (d, J = 4.8 Hz, 2 H), 8.74 (d, J = 4.8 Hz, 2 H), 8.32 (d, J = 7.7 Hz, 2 H), 8.18 (m, 4 H), 8.03 (d, J = 9.0 Hz, 2 H), 7.80 (m, 6 H), -2.73 (s, 2 H). MS (MALDI): m/z = 732.1 (M+). HRMS (MALDI): m/z calcd for C39H24N4F3I·H+, 733.10705; found, 733.1091.