Table 2 UV-vis spectra of 3, 5a and 11
Notes and references
z Crystallographic data for bis(1-imidazo[1,5-a]pyridyl)(4-chlorophenyl)-
methane (3g) C31H21ClN6, monoclinic space group P21/c, a = 11.262(6),
b = 10.562(6), c = 20.766(12) A, b = 96.078(7)1, V = 2456(2) A3, Z = 4,
Dcalcd = 1.387 Mg mꢁ3, 19 735 reflections measured, 5616 unique (Rint
=
0.0806). R1 = 0.1074 (I 4 2s(I)), wR2 = 0.2600 (all data), GOF(F2) = 1.
1 For recent examples, see: (a) D. Velasco, S. Castellanos, M. Lopez,
F. Lpez-Calahorra, E. Brillas and L. Julia, J. Org. Chem., 2007, 72,
7523; (b) N. Crivillers, M. Mas-Torrent, J. Vidal-Gancedo, J. Veciana
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D. Velasco, F. Lopez-Calahorra, E. Brillas and L. Julia, J. Org.
Chem., 2008, 73, 3759; (d) M. Lopez, D. Velasco, F. Lopez-Calahorra
and L. Julia, Tetrahedron Lett., 2008, 49, 5196.
2 For reviews, see: (a) D. F. Duxbury, Chem. Rev., 1993, 93, 381;
(b) M. S. Shchepinov and V. A. Korshun, Chem. Soc. Rev., 2003, 32, 170.
3 For recent examples, see: (a) V. Dang, J. Wang, S. Feng, C. Buron,
F. A. Villamena, P. G. Wang and P. Kuppusamy, Bioorg. Med.
Chem. Lett., 2007, 17, 4062; (b) T. T. Kucukkilinc and I. Ozer,
Chem. Biol. Interact., 2008, 175, 309; (c) M. K. Parai, G. Panda,
V. Chaturvedi, Y. K. Manju and S. Sinha, Bioorg. Med. Chem.
Lett., 2008, 18, 289; (d) B. Moazed, D. Quest and
V. Gopalakrishnan, Eur. J. Pharmacol., 2009, 604, 79.
Entry 3 Ar1
Ar2
Ph
l/nm (log e)a
1
2
3a Ph
3b Ph
242(4.35), 329(4.28), 604(2.97)
C6H4OMe-4 244(4.27), 320(4.18), 465(3.66),
602(4.14)
C6H4Cl-4
3
4
5
3c Ph
3d Ph
3e 4-MeOC6H4 C6H4OMe-4 254(4.54), 317(4.52), 464(3.19),
255(4.15), 320(4.85), 611(3.50)
C6H4Me-4 244(4.21), 327(4.17), 604(3.26)
618(3.56)
6
7
8
9
10
3f 2-Pyridyl
3g 2-Pyridyl
3h 2-Thienyl
3i 2-Thienyl
C6H4OMe-4 250(4.39), 363(4.50), 621(2.79)
C6H4Cl-4 249(4.35), 360(4.40), 630(2.89)
C6H4OMe-4 229(4.37), 347(4.35), 633(2.54)
C6H4Cl-4
253(4.41), 345(4.32), 644(2.53)
248(4.33), 317(4.51), 495(3.19),
618(3.56)
5a 4-MeOC6H4 Ph
11
11 Ph
240, 265, 338b
4 For recent examples of triarylmethanes bearing furans and
thiophenes: (a) A. V. Butin, S. K. Smirnov and I. V. Trushkov,
Tetrahedron Lett., 2008, 49, 20; (b) R. E. Chen, Y. L. Wang,
Z. W. Chen and W. K. Su, Can. J. Chem., 2008, 86, 875;
(c) A. V. Butin, V. T. Abaev, V. V. Mel’chin, A. S. Dmitriev,
A. S. Pilipenko and A. S. Shashkov, Synthesis, 2008, 1798.
5 For syntheses, see: (a) G. Hajos and Z. Riedl, Sci. Synth., 2002, 12,
613; (b) S. Chuprakov, F. W. Hwang and V. Gevorgyan, Angew.
Chem., Int. Ed., 2007, 46, 4757; (c) C. Richardson and P. J. Steel,
Tetrahedron Lett., 2007, 48, 4553; (d) A. Moulin, S. Garchia,
J. Martinez and J.-A. Fehrentz, Synthesis, 2007, 2667; (e) J. J. Li,
J. J. Li, J. Li, A. K. Trehan, H. S. Wong, S. Krishnananthan,
L. J. Kennedy, Q. Gao, A. Ng, J. A. Robl, B. Balasubramanian and
B.-C. Chen, Org. Lett., 2008, 10, 2897; (f) F. Colombo, G. Cravotto,
G. Palmisano, A. Penoni and M. Sisti, Eur. J. Org. Chem., 2008, 2801.
6 (a) M. E. Bluhm, C. Folli, D. Pufky, M. Kroger, O. Walter and
M. Doring, Organometallics, 2005, 24, 4139; (b) L. Salassa,
C. Garino, A. Albertino, G. Volpi, C. Nervi, R. Gobetto and
K. I. Hardcastle, Organometallics, 2008, 27, 1427.
a
b
Measured in CHCl3. Ref. 7.
is red-shifted by more than 150 nm compared with that of the
parent imidazo[1,5-a]pyridine 5a, despite the fact that no
conjugation exists between the two imidazo[1,5-a]pyridyl
groups in the former substance. More interesting is the fact
that compound 11, in which the two imidazo[1,5-a]pyridyl
groups are fully conjugated, shows its longest wavelength
absorption maximum at only 338 nm (entry 11).7 Similarly,
the longest wavelength absorption maximum of 10, consisting
of two phenyl groups and one imidazo[1,5-a]pyridyl group, is
at 328 nm. The introduction of a methoxy or a chlorine
substituent to the aromatic ring attached to the central sp3
carbon atom has almost no effect on the absorption maxima of
these substances (entries 2–4). In contrast, the introduction of
a methoxy group to the aromatic ring connected to the
imidazo[1,5-a]pyridyl group causes a slight red shift (entry 5).
Furthermore, substitution of these same aromatic groups by a
2-pyridyl or a 2-thienyl moiety brings about a red-shift of
ca. 20 and 30 nm, respectively.
7 C.-M. Liu, H.-Y. Gao, D.-Q. Zhang and D.-B. Zhu, Lett. Org.
Chem., 2005, 2, 712.
8 (a) J. D. Kendall, G. W. Rewcastle, R. Frederick, C. Mawson,
W. A. Denny, E. S. Marshall, B. C. Baguley, C. Chaussade,
S. P. Jackson and P. R. Shepherd, Bioorg. Med. Chem., 2007, 15,
7677; (b) R. Gozalbes, L. Simon, N. Froloff, E. Sartori,
C. Monteils and R. Baudelle, J. Med. Chem., 2008, 51, 3124.
9 (a) F. Shibahara, A. Kitagawa, E. Yamaguchi and T. Murai, Org.
Lett., 2006, 8, 5621; (b) F. Shibahara, R. Sugiura, E. Yamaguchi,
A. Kitagawa and T. Murai, J. Org. Chem., 2009, 74, 3566;
(c) F. Shibahara, E. Yamaguchi, A. Kitagawa, A. Imai and
T. Murai, Tetrahedron, 2009, 65, 5062.
10 (a) W. Oi, M. Nishiki and K. Ito, Lett. Org. Chem., 2007, 4, 112;
(b) F. M. Moghaddam, G. R. Bardajee and H. Ismail, Asian J.
Chem., 2008, 20, 1063; (c) I. Alonso, J. Esquivias, R. Gomez-Arrayas
and J. C. Carretero, J. Org. Chem., 2008, 73, 6401; (d) M. R. Sheets,
A. Li, E. A. Bower, A. R. Weigel, M. P. Abbott, R. M. Gallo,
A. A. Mitton and D. A. Klumpp, J. Org. Chem., 2009, 74, 2502.
11 T. Murai, H. Aso, Y. Tatematsu, Y. Itoh, H. Niwa and S. Kato,
J. Org. Chem., 2003, 68, 8514.
In summary, the results of this effort demonstrate that
sequential, iodine and pyridine promoted cyclization–
condensation reactions of N-thioacyl-1-(2-pyridyl)-1,2-amino-
alcohols, derived from secondary thioamides and aromatic
aldehydes, take place to produce triarylmethanes that bear
nitrogen-containing 10 p-electron, imidazo[1,5-a]pyridyl
groups. The synthesis of unsymmetrically substituted members
of this family can be achieved by the reaction of N-thioacyl-
1,2-aminoalcohols in the presence of imidazo[1,5-a]pyridines
that contain different substituents from those present in the
alcohols. The bis(1-imidazo[1,5-a]pyridyl)arylmethanes formed
in this manner are green substances that have longest
wavelength absorption maxima at ca. 600 nm. Additional
applications of this chemistry to produce new classes of
triarylmethanes are under current investigation.
12 (a) L.-T. An, F.-Q. Ding and J. P. Zou, Dyes Pigm., 2008, 77, 478;
(b) S. Ajaikumar and A. Pandurangan, J. Mol. Catal. A: Chem., 2008,
286, 21; (c) Z. Li, Z. Duan, J. Kang, H. Wang, L. Yu and Y. Wu,
Tetrahedron, 2008, 64, 1924; (d) M. Kodomari, M. Nagamatsu,
M. Akaike and T. Aoyama, Tetrahedron Lett., 2008, 49, 2537;
(e) G. K. S. Prakash, F. Paknia, S. Chacko, T. Mathew and
G. A. Olah, Heterocycles, 2008, 76, 783; (f) Y. Yamamoto and
K. Itonaga, Chem.–Eur. J., 2008, 14, 10705.
This work was supported in part by Grant-in-Aid for
Scientific Research on Priority Area (No. 20036020, ‘‘Synergy
of Elements’’) from the Ministry of Education, Culture,
Sports, Science and Technology, Japan.
13 P. Srihari, D. C. Bhunia, P. Screedhar and J. S. Yadav, Synlett,
2008, 1045.
14 Cyclization of a compound similar to 9 derived from acetophenone
resulted in the formation of 5 and acetophenone.
ꢀc
This journal is The Royal Society of Chemistry 2009
Chem. Commun., 2009, 7009–7011 | 7011