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S. Horn et al. / Tetrahedron Letters 50 (2009) 2562–2565
magnesium sulfate, the solvent was evaporated and the crude product was
purified by column chromatography on silica gel (CH2Cl2/n-hexane, 1:1, v/v).
14. All new compounds reported herein showed spectral data consistent with the
assigned structures. Selected data: compound 7: Yield: 6.2 mg (0.01 mmol,
21%); mp >300 °C; Rf = 0.52 (CH2Cl2/n-hexane, 1:1, v/v); 1H NMR (600 MHz,
CDCl3): d À2.68 (s, 2H, NH), 1.00 (t, 3H, 3J = 7.34 Hz, (CH2)4CH3), 1.59 (t, 2H,
3J = 7.70 Hz, (CH2)3CH2CH3), 1.83 (t, 2H, 3J = 7.70 Hz, (CH2)2CH2CH2CH3), 2.59 (t,
2H, 3J = 7.34 Hz, CH2CH2(CH2)2CH3), 2.73 (s, 3H, C6H4CH3), 2.75 (s, 6H,
C6H4CH3), 5.05 (t, 2H, 3J = 8.07 Hz, CH2(CH2)3CH3), 7.57 (d, 2H, 3J = 7.34 Hz,
HAr), 7.59 (d, 4H, 3J = 7.34 Hz, HAr), 8.10 (d, 2H, 3J = 8.07 Hz, HAr), 8.12 (d, 4H,
3J = 7.34 Hz, HAr), 8.83 (s, 4H, Hb), 8.96 (d, 2H, 3J = 4.40 Hz, Hb), 9.50 (d, 2H,
N
N
N
N
N
N
N
N
Ni
Ni
3J = 5.14 Hz, Hb) ppm; UV–vis (CH2Cl2): kmax (lg
e) = 419 nm (5.7), 517 (4.6), 553
(4.5), 593 (4.4), 649 (4.4); HRMS (ES+) [C46H42N4+H]: calcd 651.3488, found
651.3495. Compound 8: Yield: 7.8 mg (0.013 mmol, 29%); mp >300 °C;
Rf = 0.43 (CH2Cl2/n-hexane, 1:1, v/v); 1H NMR (400 MHz, CDCl3): d À2.63 (s,
2H, NH), 2.72 (s, 3H, C6H4CH3), 2.75 (s, 6H, C6H4CH3), 4.71 (s, 3H, CH3), 7.57 (d,
2H, 3J = 8.03 Hz, HAr), 7.59 (d, 4H, 3J = 7.78 Hz, HAr), 8.10 (d, 2H, 3J = 7.53 Hz,
HAr), 8.12 (d, 4H, 3J = 7.78 Hz, HAr), 8.84 (s, 4H, Hb), 8.96 (d, 2H, 3J = 4.77 Hz, Hb),
17 (10 %)
Figure 3. Bisporphyrin 17.
9.53 (d, 2H, 3J = 4.77 Hz, Hb) ppm; UV–vis (CH2Cl2): kmax (lg
e) = 419 nm (5.6),
517 (4.5), 552 (4.4), 593 (4.4), 651 (4.4); HRMS (ES+) [C42H34N4+H]: calcd
595.2862, found 595.2843. Compound 9: Yield: 21.1 mg (0.033 mmol, 73%);
mp >300 °C; Rf = 0.58 (CH2Cl2/n-hexane, 1:1, v/v); 1H NMR (600 MHz, CDCl3): d
À2.75 (s, 2H, NH), 2.72 (s, 3H, C6H4CH3), 2.76 (s, 6H, C6H4CH3), 3.56 (t, 2H,
3J = 8.07 Hz, CH2CN), 5.46 (t, 2H, 3J = 8.07 Hz, CH2CH2CN), 7.58 (d, 2H,
3J = 8.07 Hz, HAr), 7.60 (d, 4H, 3J = 7.34 Hz, HAr), 8.09 (d, 2H, 3J = 7.34 Hz, HAr),
8.11 (d, 4H, 3J = 8.07 Hz, HAr), 8.85 (s, 4H, Hb), 9.03 (d, 2H, 3J = 5.14 Hz, Hb), 9.46
material was recovered, a more reactive porphyrin, namely [5-
iodo-10,15,20-tris(4-methylphenyl)porphyrinato]nickel(II) 4, was
subjected to the same reaction conditions. Surprisingly, the only
product obtained was the directly meso–meso-linked bisporphyrin
17 in 10% yield (Fig. 3). The reaction mechanism remains unclear
but investigations are going on. Possibly, a radical dimerization
took place similar to that reported previously in oxidative coupling
reactions.7b,18
In conclusion, we have presented a detailed investigation of the
reaction of various potassium organotrifluoroborates with directly
brominated porphyrins. The method is generally applicable to the
meso- and b-position of the macrocycle as well as to aryl- and al-
kyl-substituted porphyrins with different substitution patterns.
The reaction conditions tolerate various functional groups and
depending on the nature of the potassium organotrifluoroborate,
the new compounds were obtained in moderate to good yields.
As potassium organotrifluoroborates offer a good alternative to
boronic acids or esters, many of which are commercially available,
we believe this method presents a useful tool for the synthesis of
novel porphyrins and we are currently expanding the scope of this
application.
(d, 2H, 3J = 4.40 Hz, Hb) ppm; UV–vis (CH2Cl2): kmax (lg
e) = 419 nm (5.7), 516
(4.6), 551 (4.5), 592 (4.5), 648 (4.4); HRMS (ES+) [C44H35N5+H]: calcd 634.2971,
found 634.3000. Compound 10: Yield: 7.9 mg (0.012 mmol, 26%); mp >300 °C;
Rf = 0.26 (ethyl acetate); 1H NMR (400 MHz, CDCl3): d À2.77 (s, 2H, NH), 1.82 (s,
4H, NCH2(CH2)2), 2.72 (s, 3H, C6H4CH3), 2.75 (s, 6H, C6H4CH3), 2.94 (s, 4H,
NCH2(CH2)2CH2), 6.00 (s, 2H, CH2N), 7.57 (d, 2H, 3J = 5.87 Hz, HAr), 7.59 (d, 4H,
3J = 6.85 Hz, HAr), 8.10 (d, 2H, 3J = 4.89 Hz, HAr), 8.12 (d, 4H, 3J = 7.83 Hz, HAr),
8.85 (d, 4H, 3J = 2.93 Hz, Hb), 8.98 (d, 2H, 3J = 4.89 Hz, Hb), 9.69 (d, 2H,
3J = 3.91 Hz, Hb) ppm; UV–vis (CH2Cl2): kmax (lg
e) = 421 nm (5.4), 519 (4.3), 554
(4.2), 594 (4.2), 651 (4.1); HRMS (ES+) [C46H41N5+H]: calcd 664.3461, found
664.3440. Compound 11: Yield: 4.9 mg (0.007 mmol, 16%); mp >300 °C;
Rf = 0.28 (CH2Cl2/n-hexane, 1:1, v/v); 1H NMR (600 MHz, CDCl3): d À2.72 (s,
2H, NH), 2.73 (s, 3H, C6H4CH3), 2.75 (s, 6H, C6H4CH3), 3.59 (t, 2H, 3J = 8.44 Hz,
CH2CH2OCH3), 3.80 (s, 3H, CH2CH2OCH3), 5.42 (t, 2H, 3J = 8.44 Hz,
CH2CH2OCH3), 7.57 (d, 2H, 3J = 8.07 Hz, HAr), 7.59 (d, 4H, 3J = 7.34 Hz, HAr),
8.09 (d, 2H, 3J = 8.80 Hz, HAr), 8.11 (d, 4H, 3J = 7.34 Hz, HAr), 8.84 (s, 4H, Hb), 8.98
(d, 2H, 3J = 4.40 Hz, Hb), 9.53 (d, 2H, 3J = 4.40 Hz, Hb) ppm; UV–vis (CH2Cl2):
kmax (lge) = 419 nm (5.6), 516 (4.5), 552 (4.3), 593 (4.2), 651 (4.2); HRMS (ES+)
[C45H38N4O2+H]: calcd 667.3073, found 667.3093. Compound 12: Yield: 6.7 mg
(0.009 mmol, 21%); mp 273 °C; Rf = 0.69 (ethyl acetate); 1H NMR (600 MHz,
CDCl3): d À2.70 (s, 2H, NH), 2.73 (s, 5H, C6H4CH3, CH2O), 2.76 (s, 6H, C6H4CH3),
2.91 (t, 2H, 3J = 4.40 Hz, NCH2), 3.47 (t, 2H, 3J = 4.77 Hz, OCH2), 3.57 (t, 2H,
3J = 8.07 Hz, CH2CH2CO), 3.66 (t, 2H, 3J = 4.40 Hz, CH2N), 5.47 (t, 2H,
3J = 9.17 Hz, CH2CH2CO), 7.58 (d, 2H, 3J = 8.80 Hz, HAr), 7.60 (d, 4H,
3J = 7.34 Hz, HAr), 8.10 (d, 2H, 3J = 4.40 Hz, HAr), 8.11 (d, 4H, 3J = 8.07 Hz, HAr),
8.85 (s, 4H, Hb), 8.99 (d, 2H, 3J = 4.40 Hz, Hb), 9.53 (d, 2H, 3J = 4.40 Hz, Hb) ppm;
Acknowledgement
This work was generously supported by a Science Foundation
Ireland Research Professorship grant (SFI/04/RP1/B482).
UV–vis (CH2Cl2): kmax (lge) = 419 nm (5.5), 518 (4.5), 552 (4.4), 592 (4.4), 647
(4.4); HRMS (ES+) [C48H43N5O2+H]: calcd 722.3495, found 722.3404.
Compound 13: Yield: 24.2 mg (0.034 mmol, 75%); mp >300 °C; Rf = 0.23
(ethyl acetate/n-hexane, 1:2, v/v); 1H NMR (600 MHz, CDCl3): d À2.73 (s, 2H,
NH), 2.73 (s, 3H, C6H4CH3), 2.74 (s, 6H, C6H4CH3), 3.72 (s, 3H, NCH3CH), 3.75 (s,
3H, CONCH3CO), 7.59 (m, 6H, HAr), 8.00 (s, 1H, CH), 8.12 (m, 6H, HAr), 8.87 (d,
4H, 3J = 3.67 Hz, Hb), 8.94 (d, 2H, 3J = 3.67 Hz, Hb), 9.06 (d, 2H, 3J = 4.40 Hz, Hb)
References and notes
1. Pandey, R. K.; Zheng, G. In The Porphyrin Handbook; Kadish, K. M., Smith, K. M.,
Guilard, R., Eds.; Academic Press: New York, 2000; pp 157–230.
2. Boyle, R. W.; Dolphin, D. Photochem. Photobiol. 1996, 64, 485–496.
3. Senge, M. O. Acc. Chem. Res. 2005, 38, 733–743.
4. (a) Sharman, W. M.; Van Lier, J. E. J. Porphyrins Phthalocyanines 2000, 4, 441–
453; (b) Miyaura, N.; Yamada, K.; Suzuki, A. Tetrahedron Lett. 1979, 36, 3437–
3440.
ppm; UV–vis (CH2Cl2): kmax (lge) = 420 nm (5.8), 516 (4.6), 551 (4.4), 591 (4.3),
648 (4.3); HRMS (ES+) [C47H38N6O2+H]: calcd 719.3126, found 719.3134.
15. (a) Senge, M. O.; Kalisch, W. W.; Runge, S. Tetrahedron 1998, 54, 3781–3798; (b)
Runge, S.; Senge, M. O. Z. Naturforsch. 1998, 53b, 1021–1030; (c) Kalisch, W. W.;
Senge, M. O. Angew. Chem., Int. Ed. 1998, 37, 1107–1109.
16. Liu, C.; Shen, D.-M.; Chen, Q.-Y. Chem. Commun. 2006, 770–772.
5. Zhou, X.; Zhou, Z.-Y.; Mak, T. C. W.; Chan, K. S. J. Chem. Soc., Perkin Trans. 1 1994,
2519–2520.
17. All new compounds reported herein showed spectral data consistent with the
assigned structures. Selected data: compound 14: Yield: 9.4 mg (0.016 mmol,
35%); mp >300 °C; Rf = 0.22 (CH2Cl2/n-hexane, 2:1, v/v); 1H NMR (400 MHz,
CDCl3): d À2.80 (s, 2H, NH), 2.77 (s, 6H, C6H4CH3), 3.56 (t, 4H, 3J = 7.89 Hz,
CH2CN), 5.41 (t, 4H, 3J = 7.89 Hz, CH2CH2CN), 7.61 (d, 4H, 3J = 7.60 Hz, HAr), 8.09
(d, 4H, 3J = 7.60 Hz, HAr), 9.00 (d, 4H, 3J = 4.68 Hz, Hb), 9.43 (d, 4H, 3J = 5.26 Hz,
6. Molander, G. A.; Ellis, N. Acc. Chem. Res. 2007, 40, 275–286.
7. (a) Horn, S.; Sergeeva, N. N.; Senge, M. O. J. Org. Chem. 2007, 72, 5414–5417; (b)
Feng, X.; Senge, M. O. J. Chem. Soc., Perkin Trans. 1 2001, 1030–1038; (c) Esdaile,
L. J.; Senge, M. O.; Arnold, D. P. Chem. Commun. 2006, 4192–4194; Fazekas, M.;
Pintea, M.; Senge, M. O.; Zawadzka, M. Tetrahedron Lett. 2008, 49, 2236–2239.
8. Horn, S.; Senge, M. O. Eur. J. Org. Chem. 2008, 4881–4890.
9. Tremblay-Morin, J.-P.; Ali, H.; van Lier, J. E. Tetrahedron Lett. 2006, 47, 3043–
3046.
Hb) ppm; UV–vis (CH2Cl2): kmax (lge) = 418 nm (5.6), 516 (4.4), 551 (4.4), 594
(4.4), 650 (4.4); HRMS (ES+) [C40H32N6+H]: calcd 597.2759, found 597.2767.
Compound 15: Yield: 7.1 mg (0.0115 mmol, 25%); mp 117 °C; Rf = 0.18 (CH2Cl2/
n-hexane, 1:1, v/v); 1H NMR (400 MHz, CDCl3): d À2.73 (s, 2H, NH), 0.99 (t, 9H,
3J = 7.28 Hz, CH3), 1.45 (m, 6H, (CH2)4CH2CH3), 1.55 (m, 6H, (CH2)3CH2CH2CH3),
1.84 (m, 6H, (CH2)2CH2(CH2)2CH3), 2.53 (m, 6H, CH2CH2(CH2)3CH3), 3.47 (t, 2H,
3J = 8.78 Hz, CH2CN), 4.94 (m, 6H, CH2(CH2)4CH3), 5.32 (t, 2H, 3J = 8.78 Hz,
CH2CH2CN), 9.39 (d, 2H, 3J = 4.77 Hz, Hb), 9.49 (d, 4H, 3J = 4.77 Hz, Hb), 9.53 (d,
10. Molander, G. A.; Ito, T. Org. Lett. 2001, 3, 393–396.
11. Molander, G. A.; Rivero, M. R. Org. Lett. 2002, 4, 107–109.
12. Shi, B.; Boyle, R. W. J. Chem. Soc., Perkin Trans. 1 2002, 1397–1400.
13. General procedure: A 20 mL Schlenk tube was flushed with argon and charged
with porphyrin (30 mg, 1 equiv) and Cs2CO3 (20 equiv) in THF/H2O (10:1, v/v).
The solution was degassed via three freeze-pump-thaw cycles and was placed
under argon. Potassium organotrifluoroborate (10 equiv) and Pd(dppf)Cl2
(0.25 equiv) were added and the reaction mixture was heated to 80 °C
overnight. The solvent was removed and the residue was dissolved in
dichloromethane. The crude product was washed with a saturated solution
of sodium bicarbonate, water and brine. The organic phase was dried over
2H, 3J = 5.02 Hz, Hb) ppm; UV–vis (CH2Cl2): kmax (lg
e) = 418 nm (5.6), 518 (4.5),
554 (4.4), 600 (4.3), 656 (4.3); HRMS (ES+) [C41H53N5+H]: calcd 616.4379,
found 616.4367. Compound 16: Yield: 20.2 mg (0.03 mmol, 70%); mp 123 °C;
Rf = 0.22 (CH2Cl2/n-hexane, 1:1, v/v); 1H NMR (400 MHz, CDCl3): d À2.75 (s, 2H,
NH), 2.78 (t, 2H, 3J = 7.31 Hz, CH2CN), 3.22 (t, 2H, 3J = 7.60 Hz, CH2CH2CN), 7.79
(m, 12H, HAr), 8.15 (d, 2H, 3J = 7.02 Hz, HAr), 8.24 (m, 6H, HAr), 8.68 (d, 1H,
3J = 4.68 Hz, Hb), 8.71 (s, 1H, Hb), 8.81 (d, 1H, 3J = 4.68 Hz, Hb), 8.83 (d, 1H,