Et
Bu
pyridine)/nm 425, 622; For Cu-4: lmax(solid)/nm 420, 663; lmax(THF–
pyridine)/nm 416, 61. For Zn-5a: dH(CDCl3) 1.44 (16 H, m), 3.39 (8 H, m),
6.45 (8 H, m), 7.78–7.8 (12 H, m), 8.24 (8 H, m); lmax(CHCl3)/nm (log e)
425 (6.45), 550 (5.15); m/z (FAB) 988 (M++1). For Zn-6a: dH(CDCl3) 7.17
(8 H, dd, J 6.35, 3.42), 7.28 (8 H, dd, J 6.35, 2.92), 7.87 (8 H, t, J 7.33), 7.95
(4 H, t, J 7.81), 8.30 (8 H, d, J 6.84); lmax(CHCl3)/nm (log e) 463 (6.44),
609 (5.09), 652 (5.68); m/z (FAB) 876 (M+ +1). For 8: dH(CDCl3) 23.99 (2
H, s), 1.18 ( 6 H, t, J 7.3), 1.48 (6 H, s), 1.79 (6 H, t, J 7.3 ), 2.1–2.3 (8 H,
m), 4.07 (4 H, t, J 7.3 ), 4.13 (4 H, q, J 7.3 ), 5.72 (2 H, s), 7.20 (2 H, m),
10.12 (2 H, s), 10.17 (2 H, s); lmax(CHCl3)/nm 398 (6.21), 497 (5.15), 529
(4.89), 566 (4.73), 620 (4.54); m/z (FAB) 585 (M++1). For 9: dH(CDCl3)
23.64 (2 H, m), 1.14 (6 H, t, J 7.3), 1.52 (6 H, s), 1.80 (4 H, m), 1.89 (6 H,
t, J 7.3), 2.30 (4 H, m), 4.02 (4 H, q, J 7.3), 4.16 (4 H, t, J 7.3), 8.08 (2 H,
dd, J 1.1), 9.34 (2 H, dd, J 1.1). 10.08 (2 H, s), 10.39 (2 H, s); lmax(CHCl3)/
nm (log e) 404 (6.48), 504 (5.12), 541 (5.40), 574 (4.91), 629 (5.17); m/z
(FAB) 557 (M++1).
+
2
ButO2C
CH2OAc
N
H
NH
2
i
Bu
Me
NH
CO2But
NH
NH
CO2But
Bu
Bu
Me
Et
Me
7
NH
N
N
ii, iii
Bu
Me
Et
NH
N
iv
HN
N
1 N. Ono, H. Hironaga, K. Simidzu, K. Ono and T. Ogawa, J. Chem. Soc.,
Chem. Commun., 1994, 1019; N. Ono, C. Tsukamura, Y. Nomura, H.
Hironaga, T. Murashima and T. Ogawa, Adv. Mater., 9, 1997, 149.
Polypyrroles fused with aromatic rings have been little studied, while the
corresponding polythiophenes have been well-studied, see F. Wudl, M.
Kobayashi and A. J. Heager, J. Org. Chem., 1984, 49, 3382; M. Hanack,
U. Schmid, S. Echingerr, F. Teichert and J. Heiber, Syntheis, 1993,
634.
2 N. Ono, H. Hironaga, K. Ono, S. Kaneko, T. Murashima, T. Ueda, C.
Tsukamura and T. Ogawa, J. Chem. Soc., Perkin Trans. 1, 1996, 417;
T. D. Lash and B. H. Novak, Angew. Chem., Int. Ed. Engl., 1995, 34, 683;
P. Chandrasekar and T. D. Lash, Tetrahedron Lett., 1996, 28, 4873 and
references cited therein.
3 R. Bonnett and R. C. Brown, J. Chem. Soc., Chem. Commun., 1972, 393;
R. Bonnett and S. A. North, in Advances in heterocyclic chemistry, ed.
A. R. Katritzky and A. J. Boulton, Academic Press, New York, 1981, vol.
29, pp. 341–399; R. Kreher, N. Kohl and G. Use, Angew. Chem., Int. Ed.
Engl, 1982, 21, 621; M. Lee, H. Morimoto and K. Kanematsu, J. Chem.
Soc., Chem. Commun., 1994, 1535.
Et
NH
Bu
Bu
Me
Et
Me
9
8
Scheme 3 Reagents and conditions: i, AcOH–EtOH, reflux, 16 h; ii,
3,4-diethylpyrrole-2,5-dicarbaldehyde, TFA, room temp., 2 h; iii, DDQ,
CHCl3, room temp., 1 h, 11% for three steps; iv, 200 °C, 10 min, quant.
spectrum of 8 (lmax 398, 497, 529, 566, 619 nm; band strength
IV > III > II > I) indicated that 8 was readily converted to 9
(lmax 404, 504, 541, 574, 629 nm; band strength III > I > IV
> II); these were in good agreement with those reported in the
literature.7,9
In conclusion, we have described a new synthesis of
benzoporphyrins using 1 or 2 as insoindole synthons which is
superior to the existing methods in its simplicity and generality.
It should be emphasized that formation of benzoporphyrns 4, 6
and 9 can be achieved by simple heating. This process is a very
clean reaction and purification of products is not usually
necessary if precursors 3, 5 and 8 are pure. This method could
be extended to the preparation of other p-extended molecules
including polypyrroles fused with aromatic rings, which is now
in progress in our laboratory.
4 S. Ito, T. Murashima and N. Ono, J. Chem. Soc., Perkin Trans. 1, 1997,
3161.
5 The retro-Diels–Alder reaction of 1 or 2 takes place at 200–230 °C, the
bridged moiety of 1 and 2 being stable during de-ethoxycarbonylation of
1 at 170 °C. The formation of isoindoles from 1 or 2 by heating was
monitored via NMR spectroscopy.
6 K. M. Smith, Porphyrins and Metalloporphyrins, Elsevier, Amsterdam,
1975.
The work was partly supported by Grants-in aid for Scientific
Research from the Ministry of Education, Science, Sports and
Culture of Japan.
7 Existing methods for benzoporphyrin synthesis are summarized in R.
Bonnett and K. A. McManus, J. Chem. Soc., Perkin Trans. 1, 1996, 2461;
for a recent synthesis of benzoporphyrins, see M. G. H. Vicente, A. C.
Tome, A. Walter and J. A. S. Cavaleiro, Tetrahedron Lett., 1997, 38,
3639 and references cited therein.
8 T. D. Lash, Chem. Eur. J., 1996, 2, 1197; A. Boudif and M. Momenteau,
J. Chem. Soc., Perkin Trans. 1, 1996, 1235; L. T. Nguyen, M. O. Senge
and K. M. Smith, J. Org. Chem., 1996, 61, 998 and references cited
therein.
Notes and References
† E-mail: ononbr@dpc.ehime-u.ac.jp
‡ All new compounds gave satisfactory elementary analyses. Selected data
for 2: mp 130–131 °C, dH(CDCl3) 1.54 (4 H, m), 3.85 (2 H, m), 6.45 (2 H,
d, J 2.1), 6.50 (1 H, d, J 4.27), 6.52 (1 H, d, J 4.27), 7.53 (1 H, NH); m/z (EI)
145 (M+, 7), 117 (100). For Zn-3: lmax(solid on glass)/ nm 405, 525, 560;
lmax(CHCl3)/nm 400, 534, 561. For Cu-3: lmax(solid)/nm 402, 520, 560.
For 4: lmax(solid)/nm 454, 617, 696; lmax[(CHCl3+CF3CO2H)]/nm 431,
605, 660 nm. For Zn-4: lmax(solid on glass)/nm 450, 690; lmax(THF–
9 P. S. Clezy and A. H. Mirza, Aust. J. Chem., 1982, 35, 197; T. D. Lash,
Energy Fuels, 1993, 7, 166.
Received in Cambridge, UK, 15th May 1998; 8/03656J
1662
Chem. Commun., 1998