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DOI: 10.1055/s-2007-967967
Synthesis of New Strapped Porphyrins via a Bisdipyrromethane Condensation
Publication History
Publication Date:
21 February 2007 (online)
Abstract
Two new cationic strapped meso-porphyrins were synthesized via a new route, which consists of the condensation of a bisdipyrromethane with an aldehyde under acidic conditions. One of the strapped porphyrins binds to G-quadruplex DNA.
Key words
strapped porphyrins - condensation - synthesis - meso - bisdipyrromethane
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References and Notes
Preparation of Compound 4.
To a flask containing 3 (1.5 g, 3.69 mmol) and pyrrole (118 g, 1.65 mol) was added 1.4 equiv of TFA and the flask was left to stir in open air for 15 min. The reaction was quenched with TEA (7.22 g, 71.4 mmol) and then the unreacted pyrrole was evaporated. The resulting brown oil was purified by column chromatography on silica gel (CHCl3-MeOH, 10:1), yielding 4 quantitatively as a light brown oil. 1H NMR (500 MHz, CDCl3): δ = 8.49 (br s, 4 H), 7.21-7.24 (m, 4 H), 6.95-6.92 (m, 2 H), 6.91-6.89 (m, 2 H), 6.87 (s, 4 H), 6.58-6.60 (m, 4 H), 6.06-6.09 (m, 4 H), 5.89-5.90 (m, 4 H), 5.61 (s, 2 H), 4.21-4.23 (m, 4 H), 4.03-4.05 (m, 4 H) ppm. 13C NMR (500 MHz cryo, CDCl3): δ = 155.8, 153.1, 145.7, 132.5, 130.2, 128.2, 121.6, 116.8, 116.6, 112.5, 108.0, 106.4, 67.4, 66.8, 40.4 ppm. HRMS: m/z calcd 639.2971; found: 639.2943 [M + H+].
Preparation of Compound 9.
To a flask containing 8 (2.4 g, 4.12 mmol) and pyrrole (236 g, 3.30 mol) was added 1.4 equiv of TFA and the flask was left to stir in open air for 15 min. The reaction was quenched with TEA (7.22 g, 71.4 mmol) and then the unreacted pyrrole was evaporated. The resulting brown oil was purified by column chromatography on silica gel (CHCl3-MeOH, 10:1), yielding 9 quantitatively as a light green oil. 1H NMR (500 MHz, CDCl3): δ = 7.24 (dd, J = 1.6, 7.6 Hz, 2 H), 7.18 (dt, J = 1.6, 7.6, 8.0 Hz, 2 H), 6.91 (dt, J = 0.9, 7.6, 7.6 Hz, 2 H), 6.83 (dd, J = 0.9, 8.0 Hz, 2 H), 6.76 (s, 4 H), 6.62-6.65 (m, 4 H), 6.08-6.10 (m, 4 H), 5.93-5.94 (m, 4 H), 5.66 (s, 2 H), 4.04-4.06 (m, 4 H), 3.94-3.96 (m, 4 H), 3.77-3.79 (m, 4 H), 3.75-3.76 (m, 4 H), 3.70-3.72 (m, 4 H), 3.65-3.67 (m, 4 H) ppm. 13C NMR (500 MHz cryo, CDCl3): δ = 155.8, 152.9, 132.6, 132.0, 130.1, 128.0, 121.4, 116.5, 115.5, 112.4, 107.8, 106.2, 70.8, 70.7, 69.9, 69.7, 67.8, 67.1, 40.5 ppm. HRMS: m/z calcd: 815.3942; found: 815.4121 [M + H+].
Preparation of Porphyrin 6.
To a stirred solution of 4 (0.50 g, 1.03 mmol) and 4-pyridinecarboxaldehyde (0.22 g, 2.06 mmol) in CH2Cl2 (500 mL), under nitrogen at r.t. and in the dark, was added TCA (2.20 g, 13.46 mmol) dissolved in CH2Cl2 (10 mL). After reacting for 90 min, TEA (7.22 g, 71.4 mmol) was added followed by DDQ (0.15 g, 0.66 mmol) and the reaction was stirred for an additional 30 min. The solvent was then evaporated in vacuo and purified by preparative TLC (CH2Cl2-MeOH, 10:1), yielding 0.9% of porphyrin 6 (7.5 mg) as a purple solid. UV/Vis: λmax = 418, 518, 556, 602 nm. 1H NMR (500 MHz, CDCl3): δ = 8.97 (br s, 4 H), 8.86 (d, J = 4.8 Hz, 4 H), 8.74 (d, J = 4.8 Hz, 4 H), 7.95 (br s, 4 H), 7.83-7.85 (m, 2 H), 7.77-7.81 (m, 2 H), 7.50-7.55 (m, 2 H), 7.20-7.25 (m, 2 H), 3.87-3.85 (m, 4 H), 3.55 (s, 4 H), 2.82-2.84 (m, 4 H), -2.74 (br s, 2 H) ppm. 13C NMR (500 MHz cryo, CDCl3): δ = 159.4, 152.3, 148.2, 134.1, 131.8, 130.2, 129.6, 120.4, 113.4, 69.3, 68.6, 58.6 ppm. As is usual in porphyrin chemistry, many of the quaternary carbon NMR signals are too weak to be seen. HRMS: m/z calcd: 811.3033; found: 811.3044 [M + H+].
Preparation of Porphyrin 10.
To a stirred solution of 9 (0.59 g, 0.60 mmol) and 4-pyridinecarboxaldehyde (0.13 g, 1.20 mmol) in CH2Cl2 (500 mL), under nitrogen at r.t. and in the dark, was added TCA (2.20 g, 13.46 mmol) dissolved in CH2Cl2 (10 mL). After reacting for 90 min, TEA (7.22 g, 71.4 mmol) was added followed by DDQ (0.30 g, 1.32 mmol) and the reaction was stirred for an additional 30 min. The solvent was then evaporated in vacuo and purified by preparative TLC (CH2Cl2-MeOH, 10:1), yielding 19% of porphyrin 10 (92.4 mg) as a purple solid. UV/Vis: λmax = 414, 510, 546, 592 nm. 1H NMR (500 MHz, CDCl3): δ = 9.00 (br s, 4 H), 8.83 (d, J = 4.6 Hz, 4 H), 8.74 (d, J = 4.6 Hz, 4 H), 8.13 (br d, 4 H), 7.86 (dd, J = 1.1, 7.9 Hz, 2 H), 7.76 (td, J = 1.6, 7.6, 7.9 Hz, 2 H), 7.43 (d, J = 7.8 Hz, 2 H), 7.38 (td, J = 1.1, 7.8, 7.6 Hz, 2 H), 5.79 (s, 4 H), 4.06 (t, J = 5.2 Hz, 4 H), 3.19 (t, J = 5.2 Hz, 4 H), 2.88-2.90 (m, 4 H), 2.83-2.84 (m, 4 H), 2.79-2.81 (m, 4 H), 2.74-2.77 (m, 4 H) and -2.79 (br s, 2 H) ppm. 13C NMR (500 MHz cryo, CDCl3): δ = 158.4, 152.1, 148.1, 136.1, 130.8, 130.1, 129.3, 119.9, 117.2, 116.5, 115.2, 112.7, 70.2, 70.1, 69.0, 68.6, 67.4 ppm. HRMS: m/z calcd: 987.4081; found: 987.4041 [M + H+].
Preparation of Porphyrin 7.
The quaternization of the pyridyl groups of porphyrin 6 was achieved by methylation with a large excess of MeI in DMF, at 40 °C for 5 h, yielding quantitatively porphyrin 7.
Preparation of Porphyrin 11.
The quaternization of the pyridyl groups of porphyrin 10 was achieved by methylation with a large excess of MeI in DMF, at 40 °C for 5 h, yielding quantitatively porphyrin 11.
Preparation of Porphyrin 1.
Porphyrin 7 was then submitted to an anion-exchange resin with Dowex 1X2-200 in the chloride form, by shaking the dissolved porphyrin in a mixture of acetone-H2O (3:2) with the exchange resin for approximately 3 h. The resin was then filtered off and washed with H2O, giving porphyrin 1 in quantitative yields and without any further purification. UV/vis λmax = 424, 518, 556, 602 nm. 1H NMR (500 MHz, CD3CN 80% CD3OD 20%): δ = 9.06 (d, J = 5.3 Hz, 4 H), 9.02-8.72 (br m, 12 H), 8.51 (dd, J = 1.4, 7.1 Hz, 2 H), 8.88-8.92 (m, 2 H), 7.59 (t, J = 7.1, 8.0 Hz, 2 H), 7.37 (d, J = 8.0 Hz, 2 H), 4.64 (s, 6 H), 3.89-3.91 (m, 4 H), 3.64 (s, 4 H), 2.91-2.90 (m, 4 H) ppm. The NH signals are not present due to exchange with the solvent. 13C NMR (500 MHz cryo, CD3CN 80% CD3OD 20%): δ = 159.5, 153.2, 144.9, 134.8, 131.9, 121.3, 115.9, 114.4, 69.8, 69.2, 49.2 ppm. HRMS: m/z calcd: 420.1706 [(M - 2 Cl)/2]; found: 420.1709.
Preparation of Porphyrin 2.
Porphyrin 11 was then submitted to an anion-exchange resin with Dowex 1X2-200 in the chloride form, by shaking the dissolved porphyrin in a mixture of acetone-H2O (3:2) with the exchange resin for approximately 3 h. The resin was then filtered off and washed with H2O, giving porphyrin 2 in quantitative yields and without any further purification. UV/vis λmax = 426, 510, 546, 592 nm. 1H NMR (500 MHz, CD3NO2): δ = 9.19 (d, J = 6.7 Hz, 4 H), 9.03 (br s, 4 H), 8.92 (br s, 4 H), 8.89 (br s, 4 H), 7.86-7.91 (m, 4 H), 7.60 (d, J = 7.8 Hz, 2 H), 7.41 (td, J = 0.9, 7.0, 7.8 Hz, 2 H), 5.53 (s, 4 H), 4.81 (s, 6 H), 4.18-4.20 (m, 4 H), 3.30-3.32 (m, 4 H), 2.96-2.97 (m, 4 H), 2.87-2.89 (m, 4 H), 2.79-2.81 (m, 4 H), 2.69-2.71 (m, 4 H), -2.82 (br s, 2 H) ppm. 13C NMR (500 MHz cryo, CD3NO2): δ = 159.5, 152.8, 144.6, 137.0, 133.8, 131.6, 120.9, 115.9, 113.9, 70.8, 70.7, 69.7, 69.5, 69.4, 69.1 ppm. HRMS: m/z calcd: 508.2231 [(M - 2 Cl)/2]; found: 508.2064.