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Synlett 2007(13): 2096-2100  
DOI: 10.1055/s-2007-984888
LETTER
© Georg Thieme Verlag Stuttgart · New York

Fluoroalkylation of Porphyrins: Synthesis of Porphyrins Bearing Double meso,β-Fused Fluoroalkyl Rings via Radical Cyclization

Liang Chena, Li-Mei Jinb, Ji-Chang Xiaob, Can-Cheng Guo*a, Qing-Yun Chen*a,b
a 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;
b Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, 200032, P. R. of China
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Publikationsverlauf

Received 2 February 2007
Publikationsdatum:
12. Juli 2007 (online)

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Abstract

A series of fluorinated meso,β-fused 5,15-diphenyl­porphyrins have been synthesized by the reaction of 5,15-di­phenylporphyrins with fluoroalkyl halides under modified sulfinatodehalogenation reaction conditions through radical cyclization.

Key words

fluoroalkylation - fused porphyrins - radical cyclization - fluoroalkyl iodides - sulfinatodehalogenation

10

Preparation of 5,15-Diphenyl-2,20-(hexafluoropropan-ediyl)porphyrin (5) Porphyrin 1 (0.2 mmol) was dissolved in the mixture of DMSO-CH2Cl2 (v/v, 15 mL/15 mL), then ICF2CF2CF2I (0.2 mmol), Na2S2O4 (0.6 mmol), and NaHCO3 (0.6 mmol) were added in order. The mixture was stirred for 5 h at 65 °C. The course of the reaction was monitored by TLC. After adding 30 mL of CH2Cl2 the mixture was washed with H2O (3×). The organic layer was dried over anhyd Na2SO4 and evaporated to dryness. The crude products were purified by column chromatography, using PE-CH2Cl2 (v/v, 4:1) as eluent. The first red-purple band was dug out and washed with CH2Cl2 to give 5 (40%). The red-purple band was further purified by flash chromatography [300-400 mesh silica gel, PE-CH2Cl2 (v/v, 5:1)] to yield a light-purple solid. Compound 5: 1H NMR (300 MHz, CDCl3): δ = -3.36 (br d, J = 31.2 Hz, 2 H), 7.78-7.89 (m, 6 H), 8.15-8.22 (m, 4 H), 8.83 (d, J = 4.8 Hz, 2 H), 9.04 (d, J = 5.4 Hz, 2 H), 9.09 (d, J = 4.8 Hz, 1 H), 9.19 (d, J = 5.4 Hz, 1 H), 9.28 (d, J = 4.8 Hz, 1 H) 9.47 (t, J = 2.4 Hz, 1 H), 9.98 (br s, 1 H), 10.08 (s, 1 H) ppm. 19F NMR (282 MHz, CDCl3): δ = -82.03 (br s, 2 F), -104.48 (br s, 2 F), -131.83 (br s, 2 F) ppm. UV/Vis (relative intensity, CH2Cl2): λmax = 633 (1.0), 582 (2.3), 514 (5.5), 412 (117.6). MS (MALDI-TOF): m/z = 611 [MH+]. Anal. Calcd for C35H20H6N4×0.5H2O: C, 67.85; H, 3.42; N, 9.04. Found: C, 68.05; H, 3.39; N, 8.89.
Preparation of 5,15-Diphenyl-2,20:10,12-di(hexafluoro-propanediyl)porphyrin (6)
Porphyrin 1 (0.2 mmol) was dissolved in the mixture of DMSO-CH2Cl2 (v/v, 15 mL/15 mL), then ICF2CF2CF2I (0.6 mmol), Na2S2O4 (3 mmol), and NaHCO3 (3 mmol) was added in order. The mixture was stirred for 8-10 h at 65 °C. The course of the reaction was monitored by TLC. After adding 30 mL of CH2Cl2 the mixture was washed with H2O (3×). The organic layer was dried over anhyd Na2SO4 and evaporated to dryness. The crude products were purified by column chromatography, using PE-CH2Cl2 (v/v, 5:1) as eluent. The first red-purple band was dug out and washed with CH2Cl2 to give 6 (25%). The red-purple band was further purified by flash chromatography [300-400 mesh silica gel, PE-CH2Cl2 (v/v, 10:1)] to yield a light-purple solid. Compound 6: 1H NMR (300 MHz, CDCl3): δ = -3.12 (s, 2 H), 7.85-7.93 (m, 6 H), 8.21-8.24 (m, 4 H), 9.25 (d, J = 5.4 Hz, 2 H), 9.40 (t, J = 2.4 Hz, 2 H), 9.99-10.02 (m, 2 H) ppm. 19F NMR (282 MHz, CDCl3): δ =-82.96 (br s, 2 F), -104.97 (br s, 2 F), -131.60 (br s, 2 F) ppm. UV/Vis (relative intensity, CH2Cl2): λmax = 640 (1.3), 586 (1.0), 560 (1.3), 521 (1.9), 414 (44.3). MS (MALDI): m/z = 759 [MH+]. HRMS (MALDI): m/z calcd for for C38H19N4F12 +: 759.1418; found: 759.1427.

11

Crystal Data of 6
CCDC no. 635096, C38H18F12N4, MW = 758.56, T = 293 (2) K, l = 0.71073 Å, monoclinic, space group P2(1)/c, a = 14.531 (2) Å, b = 10.9219 (18) Å, c = 10.1624 (17) Å, α = 90°, β = 95.964 (4)°, γ = 90°, V = 1604.1 (5) Å3, Z = 2, D = 1.571 g/cm3, µ = 0.143 mm-1, F(000) = 764, crystal size: 0.365 × 0.332 × 0.130 mm, 9244 reflections collected, 3493 independent reflections [R(int) = 0.0660]; refinement method: full-matrix least-squares on F 2; goodness-of-fit on F2 = 0.920, final R indices [I > 2 σ(I)] R1 = 0.0627, wR2 = 0.1834; R indices (all data) R1 = 0.1202, wR2 = 0.2067.
Crystal Data of 6·Zn
CCDC no. 635097, C38H16F12N4Zn, MW = 821.92, T = 293 (2) K, l = 0.71073 Å, monoclinic, space group P2(1)/c, a = 14.4919 (15) Å, b = 11.1408 (12) Å, c = 9.9987 (11) Å, α = 90°, β = 95.509 (2)°, γ = 90°, V = 1606.8 (3) Å3, Z = 2, D = 1.699 g/cm3, µ = 0.872 mm-1, F(000) = 820, crystal size: 0.292 × 0.231 × 0.051 mm, 8214 reflections collected, 2987 independent reflections [R(int) = 0.0581]; refinement method: full-matrix least-squares on F 2; goodness-of-fit on F 2 = 1.036, final R indices [I > 2 σ(I)] R1 = 0.0668, wR2 = 0.1788; R indices (all data) R1 = 0.0888, wR2 = 0.1937.

13

Mixture of 5,15-Diphenyl-2,20:10,12-di(hexafluoro-propanediyl)porphyrin(6) and 5,15-Diphenyl-2,20:8,10-di(hexafluoropropanediyl)porphyrin (7)
1H NMR (300 MHz, CDCl3): δ = 7.81-7.96 (m, 12 H, 6 + 7), 8.16-8.25 (m, 8 H, 6 + 7), 9.03 (d, J = 5.4 Hz, 2 H, 7), 9.25 (d, J = 5.4 Hz, 2 H, 6), 9.40 (t, J = 2.4 Hz, 2 H, 6), 9.45 (t, J = 2.4 Hz, 2 H, 7), 9.80 (s, 2 H, 7), 9.98-10.02 (m, 2 H, 6) ppm. 19F NMR (282 MHz, CDCl3): δ = -83.07 (br s, 4 F, 6 + 7), -104.89 (br s, 4 F, 6 + 7), -131.42 (br s, 4 F, 6 + 7). MS (MALDI): m/z = 759 [MH+].

16

General Procedure for the Preparation of 5,15-Diphenyl-2,20:10,12-di(tetrafluoroethanediyl)porphinato Zinc(II) (Zn·11) and 5,15-Diphenyl-2,20:8,10-di(tetrafluoro-ethanediyl)porphinato Zinc(II) (Zn·12)
Zinc porphyrin Zn·9 (0.1 mmol) was dissolved in the 20 mL DMSO, then Na2S2O4 (1 mmol) and NaHCO3 (1 mmol) were added in order. The mixture was stirred for 8 h at 120 °C. The course of the reaction was monitored by TLC. After adding 40 mL CH2Cl2, the mixture was washed with H2O several times. The organic layer was dried over anhyd Na2SO4 and evaporated to dryness. The crude products were purified by flash chromatography [300-400 mesh silica gel, PE-CH2Cl2 (v/v, 1:1)], the main purple band was the mixture of Zn·11 and Zn·12 (40%). The ratio of two isomers was 1:1.3.
Mixture of 5,15-Diphenyl-2,20:10,12-di(tetrafluoro-ethanediyl)porphinato Zinc(II) (Zn·11) and 5,15-Diphenyl-2,20:8,10-di(tetrafluoroethanediyl)porphinato Zinc(II) (Zn·12)
1H NMR [300 MHz, (CD3)2SO]: δ = 7.90-7.95 (m, 13.8 H, Zn·11 + Zn·12), 8.27-8.44 (m, 9.2 H, Zn·11 + Zn·12), 9.13 (d, J = 4.2 Hz, 2 H, Zn·12), 9.16 (d, J = 4.2 Hz, 2.6 H, Zn·11), 9.41 (s, 2.6 H, Zn·11), 9.47 (s, 2 H, Zn·12), 9.64 (d, J = 4.2 Hz, 2.6 H, Zn·11), 9.69 (d, J = 4.2 Hz, 2 H, Zn·12) ppm. 19F NMR [282 MHz, (CD3)2SO]: δ = -78.79 (s, 2 F, Zn·12), -79.11 (s, 2.6 F, Zn·11), -95.31 (s, 2 F, Zn·12), -95.80 (s, 2.6 F, Zn·11) ppm. UV/Vis (relative intensity, CH2Cl2): λmax = 550 (1.0), 416 (30.4). MS (MALDI): m/z = 720.1 [M+]. HRMS (MALDI): m/z calcd for for C36H17N4F8Zn+: 721.0611; found: 721.0595.
General Procedure for the Preparation of 5,15-Diphenyl-10-(2-chlorotetrafluoroethyl)-2,20-tetrafluoro-ethanediylporphinato Zinc(II) (Zn·13)
Zinc porphyrin Zn·9 (0.1 mmol) was dissolved in 20 mL DMSO, then Na2S2O4 (0.5 mmol) and NaHCO3 (0.5 mmol) were added in order. The mixture was stirred for 8 h at 120 °C. The course of the reaction was monitored by TLC. After adding 40 mL CH2Cl2, the mixture was washed with H2O several times. The organic layer was dried over anhyd Na2SO4 and evaporated to dryness. The crude products were purified by flash chromatography [300-400 mesh silica gel, PE-CH2Cl2 (v/v, 1:1)]. The first red-purple band was Zn·13 (40%). The second red-purple band was the mixture of Zn·11 and Zn·12 (10%).
5,15-Diphenyl-10-(2-chlorotetrafluoroethyl)-2,20-tetrafluoroethanediylporphinato Zinc(II) (Zn·13)
1H NMR [300 MHz, (CD3)2SO]: δ = 7.85-7.92 (m, 6 H,), 8.22-8.29 (m, 4 H), 8.97 (d, J = 4.8 Hz, 1 H), 9.03 (d, J = 4.8 Hz, 1 H), 9.07 (d, 1 H), 9.23 (d, J = 1.8, 1 H), 9.61 (d, J = 4.8Hz, 1 H), 9.64 (s, 1 H) ppm. 19F NMR [282 MHz, (CD3)2SO]: δ = -62.98 (s, 2 F), -72.56 (s, 2 F), -79.93 (br s, 2 F), -95.36 (br s, 2 F) ppm. UV/Vis (relative intensity, CH2Cl2): λmax = 553 (1.0), 416 (30.1). MS (MALDI): m/z = 756.0 [M+]. HRMS (MALDI): m/z calcd for for C36H18N4F8ClZn+: 757.0378; found: 757.0351.

17

Hydrolysis of 5,15-Diphenyl-2,20-(hexafluoropropane-diyl)porphinato Zinc(II) (Zn·5) and 5,15-Diphenyl-2,20-(tetrafluoroethanediyl)porphinato Zinc(II) (Zn·10)
A sample of Zn·5 or Zn·10 (15 mg) was dissolved in 10 mL CH2Cl2, then silica gel (300-400 mesh) was added. The solvent was evaporated to dryness. The powder was exposed to air for 1 h, then directly subjected to chromatography (silica, CH2Cl2). The green band was collected to yield Zn·14 or Zn·15.
5,15-Diphenyl-2,20-(20′-oxo)-(tetrafluoropropanediyl) porphinato Zinc(II) (Zn·14)
1H NMR (300 MHz, CDCl3): δ = 7.79-7.88 (m, 6 H), 8.14-8.22 (m, 4 H), 8.92 (d, J = 4.2 Hz, 1 H), 8.95 (d, J = 4.8 Hz, 1 H), 9.05 (d, J = 4.8 Hz, 1 H), 9.28 (d, J = 1.8 Hz, 1 H), 9.29 (d, J = 1.8 Hz, 1 H), 9.52 (s, 1 H), 10.21 (s, 1 H), 10.31 (d, J = 4.8 Hz, 1 H) ppm. 19F NMR (282 MHz, CDCl3): δ = -102.20 (t, J = 13.0 Hz, 2 F, β-CF2), -121.58 (t, J = 13.8 Hz, 2 F, CF2CO) ppm. UV/Vis (relative intensity, CH2Cl2): λmax = 607 (2.0), 561 (1.0), 426 (29.8). IR (KBr): 1637 (C=O) cm-1. MS (MALDI): m/z = 650 [M+]. Anal. Calcd for C35H18F4N4OZn: C, 64.48; H, 2.78; N, 8.59. Found: C, 64.47; H, 3.06; N, 8.34.