meso-Oxidation of Porphyrins: Convenient Iron(III)-Mediated Synthesis of Dioxoporphyrins

Abstract

Iron(III)-mediated meso-oxidation reactions of 5,15-di­arylporphyrins resulted in a variety of dioxoporphyrins in high yields. In the case of meso-amino-substituted diarylporphyrins, a variety of products was produced.

Key words

FeCl₃˙6H₂O - oxidation - dioxoporphyrin

References and Notes

• 1a Fuhrhop J.-H. In Porphyrins and Metalloporphyrins   Smith KM. Elsevier Scientific Publications; Amsterdam: 1975.  p.593-623  
• 1b Inhoffen HH. Fuhrhop J.-H. von der Haar F. Liebigs Ann. Chem.  1966,  700:  92 
• 1c Fuhrhop J.-H. J. Chem. Soc., Chem. Commun.  1970,  781 
• 1d Barnett GH. Evans B. Smith KM. Tetrahedron  1975,  31:  2711 
• 2a Watson ZC. Bampos N. Sanders JKM. New J. Chem.  1998,  1135 
• 2b Marty M. Watson ZC. Twyman LJ. Nakash M. Sanders JKM. Chem. Commun.  1998,  2265 
• 2c McCallien DWJ. Sanders JKM. J. Am. Chem. Soc.  1995,  117:  6611 
• 3a Shen D.-M. Liu C. Chen X.-G. Chen Q.-Y. J. Org. Chem.  2009,  74:  206 
• 3b Liu C. Shen D.-M. Chen Q.-Y. J. Am. Chem. Soc.  2007,  129:  5814 
• 3c Jin L.-M. Chen L. Yin J.-J. Guo C.-C. Chen Q.-Y. Eur. J. Org. Chem.  2005,  3994 
• 3d Jin L.-M. Yin J.-J. Chen L. Guo C.-C. Chen Q.-Y. Synlett  2005,  2893 
• 5 Esdaile LJ. Jensen P. McMurtrie JC. Arnold DP. Angew. Chem. Int. Ed.  2007,  46:  2136 
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4

Typical Procedure for the Fe(III)-Mediated Synthesis of Dioxoporphyrins Zn2 A mixture of Zn1a (100 mg, 0.19 mmol, 1.0 equiv) and FeCl₃˙6H₂O (513 mg, 10 equiv) was stirred in DMF (20 mL) in air at 130 ˚C for 5 h. After cooling to r.t., the reaction mixture was diluted with CH₂Cl₂ (20 mL) and washed with H₂O three times. The organic layer was passed through dry SiO₂ and evaporated to dryness. The resulting solid was crystallized from CH₂Cl₂-MeOH or purified by flash column chromatography (SiO₂, 300-400 mesh, PE-EtOAC 4:1) to produce the desired dioxoporphyrin Zn2a (90 mg, 85% yield).

Characterization Data for Selected Representative CompoundsDioxoporphyrin Zn2a
^¹H NMR (300 MHz, acetone-d ₆ ): δ = 6.28-6.31 (m, 4 H,
β-H), 6.87-6.90 (m, 4 H, β-H), 7.33 (d, J = 3.6 Hz, 4 H, PhH), 7.40-7.42 (m, 6 H, PhH). MS (MALDI): m/z = 555.1 [M + H⁺]. UV/vis (CH₂Cl₂): λ_max (%) = 403 (13.0), 450 (6.7), 509 (2.6), 546 (5.6), 708 (1.0) nm. Anal. Calcd for C₃₂H₁₈N₄O₂Zn˙2MeOH: C, 65.86; H, 4.23; N, 9.04. Found: C, 65.14; H, 4.07; N, 8.86.
Dioxoporphyrin H ₂ 2a
^¹H NMR (300 MHz, CDCl₃): δ = 6.51 (br s, 4 H, β-H), 7.17 (d, J = 4.2 Hz, 4 H, β-H), 7.42-7.53 (m, 10 H, PhH), 14.02 (s, 2 H, NH). MS (MALDI): m/z = 493.2 [M + H⁺]. UV/vis (CH₂Cl₂): λ_max (%) = 408 (3.1), 472 (1.0), 499 (1.2) nm. Anal. Calcd for C₃₂H₂₀N₄O₂˙0.5EtOH: C, 76.88; H, 4.50; N, 10.87. Found: C, 76.37; H, 4.31; N, 10.45.
Dioxoporphyrin Ni2a
^¹H NMR (300 MHz, CDCl₃): δ = 6.20 (d, J = 4.2 Hz, 4 H,
β-H), 6.45 (d, J = 4.5 Hz, 4 H, β-H), 7.45 (s, 10 H, PhH).
MS (MALDI): m/z = 549.1 [M + H⁺]. UV/vis (CH₂Cl₂):
λ_max (%) = 358 (14.4), 445 (35.4), 524 (8.1), 660 (1.0) nm. Anal. Calcd for C₃₂H₁₈N₄O₂Ni: C, 68.85; H, 3.43; N, 10.04. Found: C, 68.63; H, 3.49; N, 9.67. Crystal data: C₃₄H₂₆NiO₄, M = 613.30, triclinic, space group P-1, a = 7.6032 (11), b = 8.6684 (12), c = 11.3434 (16) Å, α = 94.136 (2), β = 100.890 (2), γ = 108.289 (2)˚, V = 690.11 (17) Å^³, T = 293 (2) K, Z = 1, D _c = 1.476 g/cm^-³, 4091 reflections measured, 2937 unique which were used in all calculations. R(int) = 0.0734; R ₁ = 0.0465. The final wR(F ^²) was 0.0465 (all data). CCDC 711638 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.