Synthesis of 3-substituted imidazo[1,5-a]pyridines having 1-(N-picolinamidin-2-yl) group

Article abstract of DOI:10.1016/j.tet.2012.03.095

The 3-substituted imidazo[1,5-a]pyridine compounds having 1-(N-picolinamidin-2-yl) group (1a-h) were synthesized by heating 1 equiv of an aldehyde (eight examples), 2 equiv of 2-cyanopyridine and ammonium acetate in PEG-400. By heating 2 equiv of the aldehyde and 1 equiv of 2-cyanopyridine under the same experimental conditions, 2,4,5-trisubstituted imidazoles (2a-c) were isolated. All the reported compounds were thoroughly characterized and the molecular structures of 1a and 2b were established by single crystal X-ray diffraction studies.

Full text of DOI:10.1016/j.tet.2012.03.095

Tetrahedron 68 (2012) 3927e3931
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Synthesis of 3-substituted imidazo[1,5-a]pyridines having 1-(N-picolinamidin-
2-yl) group
*
Vijendra Kumar Fulwa, Vadivelu Manivannan
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The 3-substituted imidazo[1,5-a]pyridine compounds having 1-(N-picolinamidin-2-yl) group (1aeh)
were synthesized by heating 1 equiv of an aldehyde (eight examples), 2 equiv of 2-cyanopyridine and
ammonium acetate in PEG-400. By heating 2 equiv of the aldehyde and 1 equiv of 2-cyanopyridine under
the same experimental conditions, 2,4,5-trisubstituted imidazoles (2aec) were isolated. All the reported
compounds were thoroughly characterized and the molecular structures of 1a and 2b were established
by single crystal X-ray diffraction studies.
Received 10 February 2012
Received in revised form 23 March 2012
Accepted 26 March 2012
Available online 30 March 2012
Keywords:
Imidazo[1,5-a]pyridine
Imidazole
Ó 2012 Elsevier Ltd. All rights reserved.
2-Cyanopyridine
Diamidine
1. Introduction
2. Results and discussion
Imidazo[1,5-a]pyridine is a class of fused bicyclic 5:6 system
having two nitrogen atoms.1 Some of its derivatives are shown to be
active as thromboxane A2 synthetase inhibitors2 and positive ion-
otropic agents.3 The de novo synthesis of imidazo[1,5-a]pyridine
nucleus having different substituents at pyridine2e5 and at 3- and/
or 1-positions of the imidazole6e25 rings have been reported.
This nucleus is generally generated from imines or methylamines
derived from di-2-pyridyl ketone and 2-aminomethylpyridine or
2-cyanopyridine.
Heating a mixture of 1 equiv of an aldehyde and 2 equiv of 2-
cyanopyridine along with ammonium acetate (as a source of free
ammonia) in PEG-400 at 100 ꢀC, yielded a viscous liquid, which on
pouring into water precipitated the product (Scheme 1) as solid.
Thorough characterization of the solid confirmed the presence of
1,3-disubstitued imidazo[1,5-a]pyridine nucleus in which the 3-
substituent arise from the aldehyde and 1-substituent arise from
the 2-cyanopyridine (Scheme 1). It is important to note that 1 equiv
of 2-cyanopyridine is required to form the imidazo[1,5-a]pyridine
nucleus while the second equivalent becomes part of amidine
group. Our attempts to isolate the 1-amino substituted imidazo
[1,5-a]pyridine by using a 1:1 equiv of the reactants (attempted
only in the case of salicylaldehyde with 2-cyanopyridine) could not
succeed and led to 2,4,5-trisubstituted imidazole compound (vide
infra).
However, under the same experimental conditions performing
the reaction with 2 equiv of an aldehyde and 1 equiv of 2-
cyanopyridine yielded 2,4,5-trisubstitued imidazole compounds.
In this case, the 4- and 5-substituents arise from the aldehyde
group while that at 2-position arise from the nitrile reactant
(Scheme 2). It is pertinent to note that the synthesis of 2,4,5-
trisubstitued imidazole from 2:1 mixture of an aldehyde and 2-
cyanopyridine has been reported by heating in microwave27 and
as well as by using various ratios28 in hot acetic acid. We have
provided the synthetic details of 2aec and their spectroscopic data
were not provided here as they were identical.
We recently reported26 the synthesis of some 2,4,5-trisubstituted
imidazoles and formation of imidazo[1,5-a]pyridine nucleus from
a reaction between2-cyanopyridineandpicolylamines. Thisreaction
is limited to N-(3-(2-pyridyl)imidazo[1,5-a]pyridine)picolinami-
dines and they were obtained in low yields as minor product along
with 2,4,6-tris(2-pyridyl)1,3,5-triazine, hence required further
chromatographic separation. As its continuation, we examined the
reaction of 2-cyanopyridine with some aldehydes in presence of
ammonium acetate. This reaction afforded 3-substituted imidazo
[1,5-a]pyridine compounds having 1-(N-picolinamidin-2-yl) group,
as clean unique product in good yields and the results are described
here.
* Corresponding author. Tel.: þ91 361 258 2306; fax: þ91 361 269 0762; e-mail
address: mani@iitg.ernet.in (V. Manivannan).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.03.095

3928
V.K. Fulwa, V. Manivannan / Tetrahedron 68 (2012) 3927e3931
A plausible mechanism for the formation of 1a is shown in
Scheme 3. Salicylaldehyde is known to form an imine (I) with
ammonia, which can react further with 2-cyanopyridine to form an
amidine (II). The amidine nitrogen of intermediate II can attack the
carbon atom of another molecule of 2-cyanopyridine to form the
diamidine intermediate III. The lone pair of electron on nitrogen
atom-4 can attack carbon-3 of the diamidine group resulting in the
formation of the fused five-membered rings in IV. Subsequent
proton removal and delocalization of the negative charge will lead
to the final product 1a.
R
N
N
R
H
N
O
PEG 400
100 oC
N
HN
NH
NH3
N
N
N
H
H
N
OH
NH
1a-1h
OH
O
8 Examples
N
I
NH3
Scheme 1. Synthesis of 3-substituted imidazo[1,5-a]pyridine compounds having
1-(N-picolinamidin-2-yl) group.
4
H
H
3
R
N
N
R
OH
2 N
OH
N
1
N
N
NH
NH
N
N
II
H
N
N
III
N
H
N
N
OH
N
OH
N
N
NH
N
NH2
2a-2c
Scheme 2. General structure of compound 2.
N
N
Hence by having control over stoichiometric ratio of aldehyde
and 2-cyanopyridine, imidazo[1,5-a]pyridine or imidazole nuclei
can be generated in PEG-400. To explore the scope of this re-
action, we have used eight aldehydes for the synthesis of imidazo
[1,5-a]pyridine compounds. With aldehydes having heterocyclic
or aromatic rings, the reaction afforded the expected products in
very good yields. But only to test the use of PEG-400 for synthesis
of imidazoles, three aldehydes were employed, in which their
yields were good (Table 1) and we have not examined any
further.
IV
1a
Scheme 3. Plausible mechanism for the formation of 1a.
A plausible mechanism for the formation of 2a is shown in
Scheme 4. The amidine nitrogen in II can attack the carbon atom of
another molecule of imine (I) to generate the intermediate V. Attack
by C(4)eH bond pair of electron on carbon-5 lead to formation of the
sigma bond between them. This results in the generation of five-
membered ring as in VI. Elimination of one molecule of ammonia
will yield the final product 2a that contain the imidazole ring.
All the compounds have been thoroughly characterized using
various techniques. 1H and 13C NMR spectra of 1aeh are consistent
with the expected structures. Characteristically, compounds 1a, 1b,
Table 1
Synthesis of 3-substituted imidazo[1,5-a]pyridine compounds having 1-(N-picoli-
namidin-2-yl) group and 2,4,5-trisubstitued imidazole compounds
1d-h exhibit two distinct triplet at
spectra for the fused pyridine ring of imidazo[1,5-a]pyridine nu-
cleus, but 1c exhibit a multiplet at
d
¼6.5e7.0 ppm in their 1H NMR
Entry
R group
Product
Yield (%)
1
2
3
4
5
6
7
8
2-Hydroxyphenyl
Phenyl
2-Thienyl
4-Methoxyphenyl
2-Pyrenyl
9-Anthracenyl
4-Methylphenyl
2-Bromophenyl
2-Hydroxyphenyl
Phenyl
1a
1b
1c
1d
1e
1f
1g
1h
2a
2b
2c
83
80
65
75
82
70
78
60
65
70
60
d
¼6.7 ppm. The molecular ion
MþþH peak in the HRMS/ESI-MS of 1aeh, were found at respective
m/z values with good agreement. The molecular structure of 1a has
been determined by single crystal X-ray diffraction method,29
which reveals the presence of 3-(2-hydroxyphenyl) substituted
imidazo[1,5-a]pyridine compound having 1-(N-picolinamidin-2-yl)
group. The molecular structure 2b has also been determined30 and
perspective views of 1a and 2b are shown in Figs. 1 and 2,
respectively.
9
10
11
2-Thienyl

V.K. Fulwa, V. Manivannan / Tetrahedron 68 (2012) 3927e3931
3929
HO
HO
H
H
H
HN
NH
5
NH2
4
OH
N
H
3
OH
1 N
N
2
N
N
V
II
HO
H
NH2
OH
NH3
HO
N
N
H
OH
N
NH
Fig. 2. ORTEP (30% probability ellipsoids) plot of 2b. Hydrogen atoms in the aromatic
ꢀ
rings are omitted for clarity. Selected distances (A): N1eC1 1.3620(18), N2eC1
N
N
1.3180(19), N2eC2 1.384(2), C2eC3 1.387(2), N1eC3 1.374(2).
experimental conditions. We believe that this method can be useful
for the synthesis of different imidazo[1,5-a]pyridines and 2,4,5-
trisubstituted imidazoles using PEG as solvent.
2a
VI
Scheme 4. A plausible mechanism for the formation of 2a.
4. Experimental section
4.1. General methods
2-Cyanopyridine, all the aldehydes (Aldrich, USA); PEG-400
NH4OAc (Merck India Ltd) and solvents were used as received
without further purification.
X-ray crystallographic data were collected using a Bruker SMART
ꢀ
APEX-CCD diffractometer with Mo K
a
radiation (
l
¼0.71073 A). The
intensity data were corrected for Lorentz and polarization effects
and empirical absorption corrections were applied using the SAINT
program.31,32 All the structures were solved by direct methods using
SHELXS-97.32 Non-hydrogen atoms located from the difference
Fourier maps were refined anisotropically by full-matrix least-
squares on F2, using SHELXL-97.33 All hydrogen atoms were included
in the calculated positions and refined isotropically using a riding
model.
4.2. Syntheses
4.2.1. N-(3-(2-Hydroxyphenyl)H-imidazo[1,5-a]pyridin-1-yl)picoli-
namidine (1a). A mixture of salicylaldehyde (0.500 g, 4.13 mmol),
2-cyanopyridine (0.860 g, 8.26 mmol) and ammonium acetate
(0.636 g, 8.26 mmol) in PEG-400 (2.0 g) was heated at 100 ꢀC in an
oil-bath for 12 h. The mixture was cooled and then added to water
(50 mL) with stirring. After stirring for 1 h, the greenish-yellow
precipitate was filtered washed with water and dried in vacuum
over P4O10 and recrystallized from dichloromethane. Crystals
suitable for X-ray studies were obtained by slow evaporation of
dichloromethane solution of 1a. Yield: 1.13 g (83%). Mp 198 ꢀC;
HRMS-Mass: calcd for C19H15N5Oþ 329.1277 found (MþþH)
Fig. 1. ORTEP (30% probability ellipsoids) plot of 1a. Hydrogen atoms in the aromatic
rings are omitted for clarity. Selected distances (A): N2eC7 1.369(3), N2eC8 1.390(3),
C8eC9 1.338(3), C10eC9 1.421(3), C11eC10 1.348(3), C12eC11 1.397(3), N2eC12
1.405(3), C12eC13 1.380(3), N1eC13 1.378(3), N1eC7 1.344(3), N3eC13 1.391(3),
N3eC14 1.291(3), N4eC14 1.344(3).
ꢀ
330.1288. 400 MHz 1H NMR (
d (J, Hz), CDCl3): 10.10 (1H, s), 8.60 (2H,
3. Conclusion
d, 7.2), 8.35 (1H, d, 7.2), 8.13 (1H, s), 7.93 (1H, d, 8.8), 7.82 (1H, t, 8.8),
7.71 (1H, d, 7.6), 7.50 (1H, s), 7.34 (2H, m), 7.16 (1H, d, 9.2), 7.04 (1H,
In conclusion, we have described a simple and efficient method
for the synthesis of 3-substituted 1-(N-2-picolinamidinyl)imidazo
[1,5-a]pyridine by reacting an aldehyde and 2-cyanopyridine in 1:2
ratio with ammonium acetate in PEG-400 at 100 ꢀC. On the other
hand, 2,4,5-trisubstituted imidazoles were obtained by reacting an
aldehyde and 2-cyanopyridine in 2:1 ratio under the same
t, 8.8), 6.75 (1H, t, 6.4), 6.68(1H, t, 6.0). 100 MHz 13C NMR (
d, CDCl3):
155.5, 152.5, 150.7, 148.2, 138.7, 136.6, 130.2, 130.0, 125.4, 125.0,
125.0, 121.7, 121.0, 120.0, 120.0, 118.0, 117.5, 115.5, 115.0. FTIR (KBr,
cmꢁ1): 3080, 3046, 1625, 1580, 1563, 1533, 1508, 1467, 1436, 1396,
1369, 1314, 1283, 1249, 1230, 1158, 1140, 1089, 1039, 994, 957, 870,
826, 796, 770, 747, 731, 703, 689, 656, 488, 470. Anal. Calcd for

3930
V.K. Fulwa, V. Manivannan / Tetrahedron 68 (2012) 3927e3931
C19H15N5O: C, 69.29; H, 4.59; N, 21.26. Found: C, 69.20; H, 4.54; N,
21.19.
Compounds 1beh were synthesized by adopting the same
procedure described for 1a, using 8.26 mmol of 2-cyanopyridine.
129.0, 129.0, 127.3, 127.0, 127.0, 126.0, 126.0, 126.0, 125.4, 123.0,
122.0, 120.4, 118.6, 114.0. FTIR (KBr, cmꢁ1): 3048, 1621, 1550, 1505,
1441, 1365, 1314, 1294, 1230, 1134, 1096, 1051, 1014, 990, 955, 914,
888, 849, 787, 760, 728, 707, 590, 571, 538, 512. Anal. Calcd for
C27H19N5: C, 78.43; H, 4.63; N, 16.94. Found: C, 78.30; H, 4.57; N,
16.91.
4.2.2. N-(3-PhenylH-imidazo[1,5-a]pyridin-1-yl)picolinamidine
(1b). Yield: 1.03 g (80%). Mp 188 ꢀC; HRMS-Mass: calcd for
C19H15N5 þ 313.1327 found (MþþH) 314.1328. 400 MHz 1H NMR (
d
4.2.7. N-(3-p-TolylH-imidazo[1,5-a]pyridin-1-yl)picolinamidine
(J, Hz), CDCl3): 9.30 (1H, s), 8.60 (2H, t, 8), 8.22 (1H, d, 7.2), 7.85 (4H,
(1g). Yield: 1.05 g (78%). Mp 164 ꢀC; HRMS-Mass: calcd for
m), 7.53 (2H, t, 8.0), 7.42 (2H, t, 7.2), 7.33 (1H, t, 7.6), 6.78 (1H, t, 6.4),
C20H17N5 327.1484 found (MþþH) 328.1643. 400 MHz 1H NMR (
d (J,
6.60 (1H, t, 7.2). 100 MHz 13C NMR (
d, CDCl3): 153.0, 151.0, 148.1,
Hz), CDCl3): 9.30 (1H, s), 8.60 (2H, m), 8.16 (1H, d, 10.8), 7.90 (1H, d,
8.4), 7.79 (1H, t, 12.0), 7.73 (2H, d, 8.0), 7.33 (4H, m), 6.64 (1H, t, 6.4),
141.0, 136.4, 133.0, 131.0, 129.1, 128.3, 127.8, 125.5, 124.3, 122.0,
120.5, 120.0, 117.0, 115.0. FTIR (KBr, cmꢁ1): 3048, 1620, 1584, 1563,
1531, 1515, 1506, 1468, 1415, 1380, 1324, 1307, 1252, 1235,1177, 1156,
1137, 1077, 1044, 996, 954, 816, 795, 761, 775, 736, 707, 660, 623,
599, 571, 493, 475. Anal. Calcd for C19H15N5: C, 72.83; H, 4.82; N,
22.35. Found: C, 72.75; H, 4.80; N, 22.32.
6.55 (1H, t, 6.8), 2.43 (3H, s). 100 MHz 13C NMR (
d, CDCl3): 153.0,
150.6, 148.0, 140.4, 138.2, 136.4, 133.0, 130.0, 128.0, 128.0, 125.3,
124.2, 121.5, 120.4, 119.6, 116.5, 114.4, 21.5. FTIR (KBr, cmꢁ1): 3423,
3278, 3054, 2994, 2912, 2851, 1633, 1621, 1587, 1559, 1523, 1504,
1469, 1446, 1388, 1311, 1297, 1251, 1185, 1135, 1108, 1033, 995, 954,
824, 801, 748, 727, 714, 626, 577, 503. Anal. Calcd for C20H17N5: C,
73.37; H, 5.23; N, 21.39. Found: C, 73.25; H, 5.20; N, 21.32.
4.2.3. N-(3-(Thiophen-2-yl)H-imidazo[1,5-a]pyridin-1-yl)picolina-
midine (1c). Yield: 0.86 g (65%). Mp 170 ꢀC; HRMS-Mass: calcd for
C17H13N5Sþ 319.0892 found (MþþH) 320.0893. 400 MHz 1H NMR (
d
4.2.8. N-(3-(2-Bromophenyl)H-imidazo[1,5-a]pyridin-1-yl)picolina-
midine (1h). Yield: 0.97 g (60%). Mp 174 ꢀC; HRMS-Mass: calcd for
C19H14BrN5 391.0433 found (Mþþ23Na) 414.0693. 400 MHz 1H NMR
(J, Hz), CDCl3): 9.23 (1H, s), 8.60 (2H, m), 8.26 (1H, d, 8.4), 7.92 (1H, t,
8.0), 7.80 (1H, t, 7.6), 7.50 (1H, d, 4.4), 7.50 (1H, s), 7.40 (1H, d, 6),
7.34 (1H, t, 6.4), 7.20 (1H, t, 3.2), 6.70 (2H, m). 100 MHz 13C NMR (
d
,
(d (J, Hz), CDCl3): 9.20 (1H, s), 8.60 (2H, m), 7.94 (1H, d, 8.8), 7.81
CDCl3): 153.0, 151.0, 148.2, 148.1, 140.6, 136.4, 133.0, 128.0, 126.0,
125.2, 124.4, 124.0, 121.6, 121.0, 120.0, 117.0, 115.2. FTIR (KBr, cmꢁ1):
1635,1619, 1591, 1562, 1530, 1497, 1472,1447,1410, 1391, 1320, 1300,
1245, 1146, 1097, 1048, 1030, 997, 908, 843, 797, 742, 729, 714, 684,
648, 625, 572, 523, 489. Anal. Calcd for C17H13N5S: C, 63.93; H, 4.10;
N, 21.93. Found: C, 63.88; H, 4.08; N, 21.85.
(1H, t, 7.6), 7.76 (1H, d, 8.4), 7.64 (1H, d, 7.6), 7.57 (1H, d, 7.2), 7.48
(1H, t, 7.6), 7.36 (3H, m), 6.73 (1H, t, 6.4), 6.61 (1H, t, 7.2). 100 MHz
13C NMR (
d, CDCl3): 153.0, 151.0, 148.0, 140.0, 136.5, 133.5, 133.1,
131.6, 131.5, 131.0, 128.0, 125.0, 124.3, 124.2, 121.5, 121.2, 119.3, 117.0,
114.0. FTIR (KBr, cmꢁ1): 3459, 3324, 3192, 2976, 2919, 1618, 1587,
1562,1504,1428,1370,1295,1266,1248,1204,1180,1135,1059, 992,
891, 812, 796, 752, 732, 694, 640, 570, 524, 456. Anal. Calcd for
C19H14BrN5: C, 58.18; H, 3.60; N, 17.85. Found: C, 58.05; H, 3.52; N,
17.76.
4.2.4. N-(3-(4-Methoxyphenyl)H-imidazo[1,5-a]pyridin-1-yl)picoli-
namidine (1d). Yield: 1.06 g (75%). Mp 165 ꢀC; HRMS-Mass: calcd
for C20H17N5O 343.1433, found 344.1576 (MþþH). 400 MHz 1H NMR
(d
(J, Hz), CDCl3): 9.30 (1H, s), 8.60(2H, d, 8.8), 8.13 (1H, d, 7.2), 7.90
4.2.9. 2-(2-Pyridyl)-4,5-bis(2-hydroxyphenyl)imidazole (2a). A mix-
ture of salicylaldehyde (1.0 g, 8.26 mmol), 2-cyanopyridine (0.430 g,
4.13 mmol) and ammonium acetate (1.27 g,16.52 mmol) in PEG-400
(2.0 g) was heated at 100 ꢀC in an oil-bath for 12 h. The mixture was
cooled and then added to water (50 mL) with stirring. After stirring
for 1 h, the yellow precipitate was filtered washed with water, dried
in vacuum over P4O10 and recrystallized from dichloromethane.
Yield of 2a: 0.89 g (65%).
(1H, d, 9.2), 7.80 (3H, m), 7.38 (1H, s), 7.32 (1H, t, 7.2), 7.06 (2H, d,
8.4), 6.63 (1H, t, 9.2), 6.65 (1H, t, 11.2), 3.09 (3H, s). 100 MHz 13C
NMR (d, CDCl3): 159.8, 153.0, 150.70, 150.64, 148.1, 136.5, 133.0,
129.3, 125.2, 124.3, 123.2, 121.6, 120.4, 119.7, 116.5, 114.5, 114.4, 55.6.
FTIR (KBr, cmꢁ1): 1636, 1625, 1584, 1562, 1523, 1470, 1382, 1312,
1284, 1247, 1235, 1186, 1176, 1135, 1111, 1049, 1036, 1017, 994, 954,
838, 802, 749, 723, 707, 681, 616, 579, 501, 486, 446, 429. Anal. Calcd
for C20H17N5O: C, 69.96; H, 4.99; N, 20.40. Found: C, 69.82; H, 4.93;
N, 20.33.
Compounds 2-(2-pyridyl)-4,5-bis(phenyl)imidazole (2b) and 2-
(2-pyridyl)-4,5-bis(2-thienyl)imidazole (2c) were synthesized by
adopting the same procedure described for 2a.
4.2.5. N-(3-(Pyren-2-yl)H-imidazo[1,5-a]pyridin-1-yl)picolinamidine
(1e). Yield: 1.48 g (82%). Mp 214 ꢀC; HRMS-Mass: calcd for
Acknowledgements
C29H19N5 þ 437.1640, found (MþþH) 438.1929. 400 MHz 1H NMR (
d
(J, Hz), CDCl3): 9.35 (1H, s), 8.70(1H, d, 8.0), 8.60 (1H, d, 4.8), 8.20
We are grateful to Department of Science and Technology (DST)
New Delhi for financial grant and for establishing single crystal
X-ray diffractometer facility under FIST scheme. Authors are
thankful Mr. Babulal Das for the X-ray data.
(10H, m), 7.85 (1H, t, 7.6), 7.70 (1H, d, 7.6), 7.42 (1H, s), 7.40 (1H, t,
5.6), 6.76 (1H, t, 6.4), 6.55 (1H, t, 7.2). 100 MHz 13C NMR (
d, CDCl3):
153.0, 151.0, 148.1, 141.0, 136.5, 132.2, 132.0, 131.4, 131.0, 131.0, 129.0,
128.4, 128.0, 127.4, 126.4, 126.0, 125.6, 125.4, 125.1, 125.0, 124.7,
124.5, 124.3, 122.0, 121.0, 119.5, 117.2, 114.4. FTIR (KBr, cmꢁ1): 1619,
1586, 1563, 1532, 1500, 1467, 1443, 1385, 1316, 1253, 1179, 1141,
1096, 1064, 994, 950, 847, 832, 801, 746, 729, 715, 682, 642. Anal.
Calcd for C29H19N5: C, 79.60; H, 4.38; N, 16.01. Found: C, 79.42; H,
4.28; N, 15.94.
Supplementary data
CIF for 1a, 2b and 1H NMR, 13C NMR and HRMS of 1aeh and
2aec. Crystallographic data (excluding structure factors) for the
structure 1a and 2b in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publi-
cation no. CCDC # 848475 and 848476. Copies of the data can be
obtained, free of charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK, (fax: þ44 (0) 1223 336033 or e-mail:
deposit@ccdc.cam.ac.uk). Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.tet.2012.03.095.
4.2.6. N-(3-(Anthracen-9-yl)H-imidazo[1,5-a]pyridin-1-yl)picolina-
midine (1f). Yield: 1.19 g (70%). Mp 240 ꢀC; HRMS-Mass: calcd for
C27H19N5 413.1640 found (MþþH) 414.1781. 400 MHz 1H NMR (
d (J,
Hz), CDCl3): 10.70 (1H, s), 9.10 (2H, d, 8.8), 8.70 (1H, s), 8.52 (1H, s),
8.13 (3H, m), 8.05 (2H, d, 8.0), 7.70 (2H, d, 8.4), 7.54 (4H, m), 7.15
(1H, d, 6.8), 7.00 (1H, t, 6.4), 6.50 (1H, t, 6.8). 100 MHz 13C NMR (
d,
CDCl3): 153.1, 140.0, 134.0, 132.0, 132.0, 132.0, 131.0, 130.0, 130.0,

V.K. Fulwa, V. Manivannan / Tetrahedron 68 (2012) 3927e3931
17. Crawforth, J. M.; Paoletti, M. Tetrahedron Lett. 2009, 50, 4916e4918.
3931
References and notes
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29. X-ray diffraction data: 1a: (296(2) K, Mo K
a
): C19H15N5O, 329.34, P21/n, a¼8.
3
ꢀ
ꢀ
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ꢀ
9812(7), b¼12.1712(11), c¼15.0575(13) A, ¼100.863(6) , V¼1616.5(2) A , Z¼4,
b
Dcalcd¼1.345 g cmꢁ3
,
m
¼0.88 mmꢁ1, F(000)¼688, Rint¼0.0487, R1 (I > 2
)¼0.
s
0399, wR2 (I > 2
s
)¼0.1030 (227 param., 1213 obsd refl., 1473 unique).
30. X-ray diffraction data: 2b: (296(2) K, Mo K
a
): C20H14N3, 296.34, C2/c, a¼23.
3
ꢀ
ꢀ
ꢀ
5453(12), b¼11.1287(7), c¼13.0794(7) A, ¼116.320(5) , V¼3071.9 (3) A , Z¼8,
b
Dcalcd¼1.282 g cmꢁ3
,
m
¼0.77 mmꢁ1, F(000)¼1248, Rint¼0.0598, R1 (I > 2
)¼0.
s
0423, wR2 (I > 2
s
)¼0.1150 (212 param., 2049 obsd refl., 2684 unique).
€ €
31. Sheldrick, G. M. SADABS; University of Gottingen: Gottingen, Germany, 1996.
32. SMART and SAINT; Siemens Analytical X-ray Instruments: Madison, WI, 1996.
33. Sheldrick, G. M. SHELXS-97 and SHELXL-97; University of Gottingen: Gottingen,
€
€
16. Shibahara, F.; Sugiura, R.; Yamaguchi, E.; Kitagawa, A.; Murai, T. J. Org. Chem.
2009, 74, 3566e3568.
Germany, 1997.