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Synlett 2005(8): 1306-1310  
DOI: 10.1055/s-2005-868484
LETTER
© Georg Thieme Verlag Stuttgart · New York

General and Efficient Synthesis of meso- and β-Perfluoroalkylated Porphyrins via Pd-Catalyzed Cross-Coupling Reaction

Chao Liu, Qing-Yun Chen*
Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, 200032 Shanghai, P. R. China
Fax: +86(21)64166128; e-Mail: Chenqy@mail.sioc.ac.cn;
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Publication History

Received 8 March 2005
Publication Date:
21 April 2005 (online)

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Abstract

A general and efficient method has been developed for the synthesis of meso- and β-perfluoroalkyl-substituted porphyrins via Pd-catalyzed cross-coupling reaction of meso- and β-brominated porphyrins with perfluoroalkyl iodides and copper.

Key words

brominated porphyrins - AsPh3 - perfluoroalkylation - Pd2(dba)3·CHCl3

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General Procedure for the Preparation of MDPP(Rf) 2 (M3) (M = Ni or Cu).
Porphyrin (40 mg), Pd2(dba)3·CHCl3/AsPh3 (10 mol%/80 mol%) and Cu (20 equiv to porphyrin) were added to a 50 mL Schlenk flask. The flask was then evacuated and backfilled with argon (three cycles). DMSO (8 mL) and RfI (10 equiv to porphyrin) were charged with a syringe at r.t. The reaction mixture was stirred at 100 °C for 4-48 h, and then allowed to reach r.t. The reaction mixture was diluted with CH2Cl2 and filtered through Celite. The solvent was washed three times with H2O. The organic layer was dried over Na2SO4 and evaporated to dryness. The resulting solid was purified by flash chromatography to yield the desired products in good yields. All the products gave satisfactory spectra. For example, NMR, mass spectra, elemental analysis and UV/Vis spectroscopy data of Ni3a are as follows: 1H NMR (300 MHz, CDCl3): δ = 7.64-7.74 (m, 6 H, Ph-H), 7.91 (s, 4 H, Ph-H), 8.76-8.80 (m, 4 H, β-H), 9.24-9.28 (m, 4 H, β-H) ppm. 19F NMR (282 MHz, CDCl3): δ = -67.37 (t, J = 14.4 Hz, 4 F, CF2Cl), -83.13 (br, 4 F, Por-CF2), -113.37 (s, 4 F, CF 2CF2Cl), -119.19 (t, J = 11.3 Hz, 4 F, Por-CF2CF 2) ppm. MS (MALDI): m/z = 986.0 [M+]. UV/Vis (CH2Cl2): λmax = 411, 543, 585 nm. Anal. Calcd for C48H18N4F16Cl2Ni: C, 48.62; H, 1.84; N, 5.67. Found: C, 48.45; H, 2.04; N, 5.57.

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The perfluoroalkylation of β-bromo-substituted porphyrins were carried out with the starting porphyrin (50 mg), Pd2(dba)3·CHCl3/AsPh3 (10 mol%/80 mol%), Cu (10 equiv per Br) and IC4F8Cl (5 equiv per Br) in 10 mL DMSO at 100 °C for 1-14 h. The procedure was essentially similar to that of perfluoroalkylation of meso-bromo-substituted porphyrins, see ref. 11; the products were characterized on the basis of NMR, mass spectrometry, elemental analysis and UV/Vis spectra. For example, spectroscopic data of Ni8 are as follows: 19F NMR (282 MHz, CDCl3): δ = -68.21 (t, J = 12.4 Hz, 4 F, CF2Cl), -98.23 (m, 4 F, Por-CF2), -117.44 (m, 4 F, CF 2CF2Cl), -119.57 (t, J = 13.5 Hz, 4 F, Por-CF2CF 2) ppm. MS (MALDI): m/z = 1138.1 [M+]. UV/Vis (CH2Cl2): λmax = 428, 547, 588 nm. Anal. Calcd for C52H26N4F16Cl2Ni·H2O: C, 53.92; H, 2.44; N, 4.84. Found: C, 54.13; H, 2.38; N, 4.77.

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For the details of this reaction, see ref. 4a; spectroscopic data of Ni11 are as follows: 1H NMR (300 MHz, CDCl3): δ = 7.70-7.75 (m, 12 H, Ph-H), 8.01-8.09 (m, 8 H, Ph-H), 8.41 (s, 4 H, β-H) ppm. 19F NMR (282 MHz, CDCl3): δ = -131.45 (d, J = 18.6 Hz, 4 F, Por-CF), -156.61 (d, J = 20.0 Hz, 4 F, Por-CF=CF) ppm. MS (MALDI): m/z = 914.1 [M+]. UV/Vis (CH2Cl2): λmax = 452, 572, 614 nm. Anal. Calcd for C52H24N4F8Ni: C, 68.22; H, 2.64; N, 6.12. Found: C, 68.51; H, 2.71; N, 6.21.