Facile and clean synthesis of furopyridine derivatives via three-component reaction in aqueous media without catalyst

Article abstract of DOI:10.1080/00397910802656034

A series of furo[2′,1′:5,6]pyrido[2,3-d]pyrimidine derivatives were synthesized via the three-component reaction of an aldehyde, tetronic acid, and 6-amino-1,3-dimethyl-pyrimidine-2,4-dione in aqueous media without the use of catalyst. This protocol has t

Full text of DOI:10.1080/00397910802656034

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Facile and Clean Synthesis of
Furopyridine Derivatives via
Three-Component Reaction
in Aqueous Media Without
Catalyst
Da-Qing Shi a & Hao Yao b
a College of Chemistry, Chemical Engineering
and Materials Science, Key Laboratory of Organic
Synthesis of Jiangsu Province, Soochow University,
Suzhou, China
b College of Chemistry and Chemical Engineering,
Xuzhou Normal University, Xuzhou, China
Version of record first published: 16 Jun 2009
To cite this article: Da-Qing Shi & Hao Yao (2009): Facile and Clean Synthesis
of Furopyridine Derivatives via Three-Component Reaction in Aqueous Media
Without Catalyst, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 39:14, 2481-2491
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Synthetic Communications1, 39: 2481–2491, 2009
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397910802656034
Facile and Clean Synthesis of Furopyridine
Derivatives via Three-Component Reaction
in Aqueous Media Without Catalyst
Da-Qing Shi1 and Hao Yao2
1College of Chemistry, Chemical Engineering and Materials Science, Key
Laboratory of Organic Synthesis of Jiangsu Province, Soochow University,
Suzhou, China
2College of Chemistry and Chemical Engineering, Xuzhou Normal
University, Xuzhou, China
Abstract: A series of furo[20,10:5,6]pyrido[2,3-d]pyrimidine derivatives were
synthesized via the three-component reaction of an aldehyde, tetronic acid, and
6-amino-1,3-dimethyl-pyrimidine-2,4-dione in aqueous media without the use of
catalyst. This protocol has the advantages of better yields, less cost, reduced
environmental impact, and convenient procedure.
Keywords: Aqueous media, furo[2010:5,6]pyrido[2,3-d]pyrimidine, synthesis,
three-component reaction
Furopyridines are one of the most important privileged medicinal scaf-
folds, molecular frameworks used for the development of pharmaceutical
agents for diverse applications. Compounds with this motif show a wide
range of pharmacological activities such as antipsychotic,[1] antianaphlac-
tic,[2] antiproliferative,[3] anticonvulsant,[4] and anthelmintic[5] activities,
and they can be used as calcium influx promoters,[6] HIV-1 nonnucleoside
reverse transcriptase inhibitors,[7] and acetylcholinesterase inhibitors.[8]
Received September 8, 2008.
Address correspondence to Da-Qing Shi, College of Chemistry, Chemical
Engineering and Materials Science, Key Laboratory of Organic Synthesis of
Jiangsu Province, Soochow University, Suzhou 215123, China. E-mail:
dqshi@263.net
2481

2482
D.-Q. Shi and H. Yao
The pyrazolo[2,3-d]pyrimidine core of the pterin pigments was shared by
the vitamin folic acid and shows a diverse range of biological properties
and highly species-specific responses such as antitumor, antibacterial, anti-
hypertensive, anti-inflammatory, antifungal, and antileishma activity.
Likewise, pyrazole derivatives have been reported in the literature to be
versatile building blocks for the synthesis of a wide range of heterocyclic
motifs, such as pyrazolopyridines,[9] pyrazoloquinolines,[10] and pyrazolo-
pyrazoles.[11]
Reducing the amount of toxic waste and by-products arising from
chemical processes requires increasing emphasis on the use of less toxic
and environmentally compatible materials in the design of new synthetic
methods. One of the most promising approaches uses water as reaction
medium. Breslow et al.,[12] who showed that hydrophobic effects could
strongly enhance the rate of several organic reactions, rediscovered the
use of water as a solvent in organic chemistry in 1980s. In recent years,
there has been increasing recognition that water is an attractive medium
for many organic reactions.[13] The aqueous medium with respect to
organic solvent is less expensive, less dangerous, and environmentally
friendly, while it allows the control of the pH and the use of microaggre-
gates such as surfactants. Generally, the low solubility of most reagents in
water is not an obstacle to the reactivity, which, on the contrary, is
reduced with the use of cosolvents. The synthesis of new and important
types of heterocyclic compounds in water continues to attract wide atten-
tion among synthetic chemists. Based on our previous studies on the use
of water as solvent for the synthesis of heterocyclic compounds,[14] we
herein described a facile multicomponent reaction consisting of aldehyde,
tetronic acid, and 6-amino-1,3-dimethylpyrimidine-2,4-dione in aqueous
media to synthesize the furo[20,10:5,6]pyrido[2,3-d]pyrimidine deratives.
After some preliminary experiments, it was found that an equimolar
mixture of 6-amino-1,3-dimethylpyrimidine-2,4-dione (1), 4-chlorobenzal-
dehyde (2a), and tetronic acid (3) in a small amount of water without
catalyst stirred at 90ꢀC for 10h afforded 1,3-dimethyl-5-(4-chlorophenyl)-
8a-hydroxy-5,9,5a-trihydro-7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,
4,6-trione in good to excellent yields.
Scheme 1. The synthesis of 4.

Furopyridine Synthesis in Aqueous Media
2483
Table 1. Synthesis of 4a in different solvents
Entry
Solvent
Temperature (ꢀC)
Time (h)
Yield (%)
1
2
3
4
5
6
H2O
CH3CN
ClCH2CH2Cl,
EtOH
CH3COCH3
CH3COOEt
90
80
80
80
60
80
10
20
20
20
20
20
90
0
0
0
0
0
To find a solvent effective for the synthesis of the furo[20,10:5,6]
pyrido[2,3-d]pyrimidine-2,4,6-trione derivatives, we examined this con-
densation reaction in a different solvent. The best results were obtained
when water was used (Table 1).
Encouraged by this success, we extended this reaction of
6-amino-1,3-dimethylpyrimidine- 2,4-dione with a range of other
aromatic aldehydes and tetronic acid under similar condensations, fur-
nishing the respective furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione
4 in good yields. The results are summarized in Table 2.
As shown in Table 2, this protocol can be applied not only to the
aromatic aldehydes with electron-withdrawing groups (such as halide
groups) but also to aromatic aldehydes with electron-donating groups
(such as methoxyl, methyl groups) with excellent yields under the same
conditions. Therefore, we concluded that the electronic nature of the
substituents has no significant effect on this reaction. The further study
shows that the compounds containing 8a-hydroxy are stabile and final
products, and the 8a-hydroxy cannot be eliminated by adding 4-methyl-
benzenesulfonic acid (TsOH) or by extending the reaction time.
Table 2. Synthesis of furo[20,10:5,6]pyrido[2,3-d]pyrimidine 4 in aqueous media
Entry
Compound
Ar
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
9
4a
4b
4c
4d
4e
4f
4-ClC6H4
4-BrC6H4
4-FC6H4
4-OHC6H4
4-CH3C6H4
2-ClC6H4
4-CH3OC6H4
3,4-(CH3)2C6H3
3,4-(CH3O)2C6H3
3,4-Cl2C6H3
3,4-OCH2OC6H3
10
9
21
15
9
21
14
22
20
18
8
90
85
77
93
87
89
91
80
78
83
78
4g
4h
4i
10
11
4j
4k

2484
D.-Q. Shi and H. Yao
Figure 1. ORTEP diagram of 4h.
The structures of the compounds 4 were identified by their spectro-
scopic analysis. The structure of compound 4 h was further confirmed
by X-ray diffraction analysis.[15] The molecular structure of 4 h is shown
in Fig. 1.
Although the detailed mechanism of the reaction remains to be
fully clarified, the formation of furo[20,10:5,6]pyrido[2,3-d]pyrimidine
derivatives 4 could be explained by the reaction sequence presented in
Scheme 2. We proposed that the reaction proceeded via a reaction
Scheme 2. The possible mechanism.

Furopyridine Synthesis in Aqueous Media
2485
Scheme 3. The synthesis of 4a from 5a and 1.
sequence of condensation, addition, and cyclization. First, the condensa-
tion of aldehyde 2 and tetronic acid 3 gave the intermediate product 5.
The addition of 5 to 6-amino-1,3-dimethylpyrimidine-2,4-dione 1 then
furnished the product 4.
Evidence supporting this proposed mechanism came from the obser-
vation that when 5a and 1 were reacted under same conditions, the
expected product 4a was obtained in a yield similar to that obtained in
the one-pot reaction (Scheme 3).
In conclusion, we have developed
a simple three-component
reaction consisting of an aldehyde, tetronic acid, and 6-amino-1,3-
dimethylpyrimidine-2,4-dione for the synthesis of furo[20,10:5,6]pyrido
[2,3-d]pyrimidine derivatives in aqueous media. This new method has the
advantages of good yields, less cost, convenient procedure, and environmen-
tally friendly reaction conditions.
EXPERIMENTAL
Melting points are uncorrected. Infrared (IR) spectra were recorded on a
Tensor 27 spectrometer in KBr with absorption in cmꢁ1. 1H NMR spec-
tra were recorded on a Bruker DPX 400-MHz spectrometer as dimethyl
sulfoxide (DMSO-d6) solutions. J values are in hertz. Chemical shifts are
expressed in d downfield from internal tetramethylsilane (TMS).
High-resolution mass spectra (HRMS) were obtained using a time-of-
flight–mass spectra (TOF-MS) instrument. Elemental analysis was
carried out on a Vario EL III instrument.
General Procedure for the Synthesis of 1,3-Dimethyl-5-aryl-8a-hydroxy-5,9,
5a-trihydro-7-oxa-furo)20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4)
A suspension of a mixture of 1 (2 mmol), 2 (2 mmol), and 3 (2 mmol)
was stirred in water (10 mL) at 90ꢀC for 9–30 h, then cooled to room

2486
D.-Q. Shi and H. Yao
temperature. The crystalline powder formed was collected by filtration,
washed with water, and recrystallized from EtOH to give 4.
Spectral Data
1,3-Dimethyl-5-(4-chlorophenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4a)
Mp 225–227ꢀC; IR (KBr): 3503, 3260, 3071, 3024, 2939, 1785, 1679, 1606,
1543, 1488, 1441, 1397, 1341, 1320, 1267, 1231, 1211, 1148, 1119, 1090,
1
1059, 1043, 1018, 993, 962, 930, 869, 837, 822, 772, 754, 679 cmꢁ1; H
NMR (400 MHz, DMSO-d6): d 3.07 (s, 3H, CH3), 3.33 (s, 1H, CH),
3.38 (s, 3H, CH3), 4.07 (d, J ¼ 8.8 Hz, 1H, CH), 4.29 (s, 1H, CH), 4.50
(d, J ¼ 8.8 Hz, 1H, CH), 6.32 (s, 1H, OH), 7.26–7.30 (m, 4H, ArH),
7.62 (s, 1H, NH). Anal. calcd. for C17H16ClN3O5: C, 54.05; H, 4.27; N,
11.12; found: C, 53.90; H, 4.23; N, 11.03.
1,3-Dimethyl-5-(4-bromophenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido][2,3-d]pyrimidine-2,4,6-trione (4b)
Mp 237–238ꢀC; IR (KBr): 3512, 3267, 3068, 2960, 2934, 1780, 1679, 1606,
1544, 1485, 1440, 1388, 1370, 1341, 1320, 1230, 1211, 1149, 1119, 1079,
1606, 1544, 1485, 1440, 1388, 1370, 1341, 1320, 1230, 1211, 1149, 1119,
1
1074, 1058, 1042, 1020, 963, 929, 868, 836, 820, 771, 754, 619 cmꢁ1; H
NMR (400 MHz, DMSO-d6): d 3.08 (s, 3H, CH3), 3.32 (s, 1H, CH),
3.38 (s, 3H, CH3), 4.07 (d, J ¼ 8.4 Hz, 1H, CH), 4.27 (s, 1H, CH), 4.51
(d, J ¼ 8.4 Hz, 1H, CH), 6.34 (s, 1H, OH), 7.24 (d, J ¼ 8.4 Hz, 2H,
ArH), 7.42 (d, J ¼ 8.4 Hz, 2H, ArH), 7.64 (s, 1H, NH). HRMS calcd.
for C17H1679BrN3O5, m=z: 421.0273 (Mþ); found, m=z: 421.0278.
1,3-Dimethyl-5-(4-fluorophenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4c)
Mp 207–209ꢀC; IR (KBr): 3503, 3244, 3077, 2976, 2907, 1790, 1679, 1606,
1543, 1507, 1484, 1440, 1398, 1342, 1320, 1268, 1222, 1161, 1118, 1059,
1
1042, 1021, 837, 760, 680 cmꢁ1; H NMR (400 MHz, DMSO-d6): d 3.08
(s, 3H, CH3), 3.32 (s, 1H, CH), 3.38 (s, 3H, CH3), 4.08 (d, J ¼ 8.8 Hz,
1H, CH), 4.30 (s, 1H, CH), 4.51 (d, J ¼ 8.8 Hz, 1H, CH), 6.34 (s, 1H,
OH), 7.05 (t, J ¼ 8.4 Hz, 2H, ArH), 7.30 (t, J ¼ 8.4 Hz, A2H, rH), 7.64

Furopyridine Synthesis in Aqueous Media
2487
(s, 1H, NH). HRMS calcd. for C17H16FN3O5, m=z: 361.1074 (Mþ);
found, m=z: 361.1060.
1,3-Dimethyl-5-(4-hydroxyphenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4d)
Mp 238–240ꢀC; IR (KBr): 3627, 3380, 3351, 3269, 3017, 2959, 2902, 1760,
1698, 1616, 1584, 1548, 1517, 1484, 1397, 1374, 1318, 1266, 1233, 1174,
1
1121, 1021, 958, 833, 763, 692 cmꢁ1; H NMR (400 MHz, DMSO-d6):
d 3.08 (s, 3H, CH3), 3.24 (s, 1H, CH), 3.39 (s, 3H, CH3), 4.06
(d, J ¼ 8.8 Hz, 1H, CH), 4.22 (s, 1H, CH), 4.48 (d, J ¼ 8.4 Hz, 1H, CH),
6.23 (s, 1H, OH), 6.61 (d, J ¼ 8.0 Hz, 2H, ArH), 7.05 (d, J ¼ 8.0 Hz, 2H,
ArH), 7.56 (s, 1H, NH), 9.13 (s, 1H, OH). Anal. calcd. for C17H17N3O6:
C, 56.82; H, 4.77; N, 11.69; found: C, 56.71; H, 4.58; N, 11.19.
1,3-Dimethyl-5-(4-methylphenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4e)
Mp 214–216ꢀC; IR (KBr): 3380, 3233, 2917, 1776, 1700, 1626, 1604, 1546,
1513, 1483, 1438, 1393, 1372, 1302, 1270, 1255, 1229, 1181, 1160, 1114,
1
1021, 955, 866, 842, 818, 786, 758, 685, 579 cmꢁ1; H NMR (400 MHz,
DMSO-d6): d 2.24 (s, 3H, CH3), 3.07 (s, 3H, CH3), 3.27 (s, 1H, CH),
3.39 (s, 3H, CH3), 4.06 (d, J ¼ 8.8 Hz, 1H, CH), 4.28 (s, 1H, CH), 4.49
(d, J ¼ 8.4 Hz, 1H, CH), 6.23 (s, 1H, OH), 7.03 (d, J ¼ 8.0 Hz, 2H,
ArH), 7.15 (d, J ¼ 8.4 Hz, 2H, ArH), 7.58 (s, 1H, NH). Anal. calcd. for
C18H19N3O5: C, 60.50; H, 5.36; N, 11.76; found: C, 60.20; H, 5.40;
N, 11.61.
1,3-Dimethyl-5-(2-chlorophenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4f)
Mp 233–235ꢀC; IR (KBr): 3495, 3388, 3197, 3075, 3034, 3013, 2967, 2934,
1771, 1706, 1624, 1603, 1113, 1092, 1055, 1044, 939, 828, 782, 774, 749,
1
721, 693 cmꢁ1; H NMR (400 MHz, DMSO-d6): d 3.08 (s, 3H, CH3),
3.24 (s, 1H, CH), 3.41 (s, 3H, CH3), 4.10 (d, J ¼ 8.4 Hz, 1H, CH), 4.51
(d, J ¼ 8.8 Hz, 1H, CH), 4.71 (s, 1H, CH), 6.26 (s, 1H, OH), 7.15–7.23
(m, 3H, ArH), 7.43 (d, J ¼ 8.0 Hz, 1H, ArH), 7.69 (s, 1H, NH). Anal.
calcd. for C17H16ClN3O5: C, 54.05; H, 4.27; N, 11.12; found: C, 53.78;
H, 4.47; N, 11.50.

2488
D.-Q. Shi and H. Yao
1,3-Dimethyl-5-(4-methoxyphenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4g)
Mp 228–230ꢀC; IR (KBr): 3521, 3285, 2963, 2837, 1786, 1694, 1668, 1604,
1542, 1510, 1483, 1441, 1390, 1336, 1302, 1271, 1243, 1180, 1159, 1112,
1
1028, 963, 829, 786, 757, 681 cmꢁ1; H NMR (400 MHz, DMSO-d6):
d 3.07 (s, 3H, CH3), 3.27 (s, 1H, CH), 3.38 (s, 3H, CH3), 4.07
(d, J ¼ 8.8 Hz, 1H, CH), 4.26 (s, 1H, CH), 4.49 (d, J ¼ 8.8 Hz, 1H,
CH), 6.27 (s, 1H, OH), 6.79 (d, J ¼ 8.4 Hz, 2H, ArH), 7.18 (d, J ¼ 8.0 Hz,
Hz, 2H, ArH), 7.59 (s, 1H, NH). Anal. calcd. for C18H19N3O5: C, 57.90;
H, 5.13; N, 11.25; found: C, 57.69; H, 4.98; N, 11.39.
1,3-Dimethyl-5-(3,4-dimethylphenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4h)
Mp 216–218ꢀC; IR (KBr): 3505, 3233, 3068, 2919, 1781, 1696, 1651, 1622,
1552, 1483, 1436, 1391, 1373, 1302, 1272, 1238, 1186, 1156, 1107, 1023,
1
959, 889, 868, 825, 792, 758, 719, 686, 663 cmꢁ1; H NMR (400 MHz,
DMSO-d6): d 2.15 (s, 3H, CH3), 2.17 (s, 3H, CH3), 3.08 (s, 3H, CH3),
3.25 (s, 1H, CH), 3.39 (s, 3H, CH3), 4.05 (d, J ¼ 8.4 Hz, 1H, CH), 4.25
(s, 1H, CH), 4.49 (d, J ¼ 8.4 Hz, 1H, CH), 6.21 (s, 1H, OH), 6.93–6.98
(m, 2H, ArH), 7.05 (s, 1H, ArH), 7.59 (s, 1H, NH). HRMS calcd. for
C19H21N3O5, m=z: 371.1480(Mþ); found, m=z: 371.1490.
1,3-Dimethyl-5-(3,4-dimethoxyphenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4i)
Mp 247–249ꢀC; IR (KBr): 3475, 3282, 3013, 2936, 2837, 1782, 1692, 1619,
1541, 1516, 1486, 1397, 1374, 1348, 1263, 1268, 1179, 1149, 1114, 1028,
;
962, 867, 804, 789, 767, 684, 644, 599 cmꢁ1 1H NMR (400 MHz,
DMSO-d6): d 3.09(s, 3H, CH3), 3.32 (s, 1H, CH), 3.39 (s, 3H, CH3),
3.70 (s, 3H, OCH3), 3.74 (s, 3H, OCH3), 4.07 (d, J ¼ 8.4 Hz, 1H, CH),
4.27 (s, 1H, CH), 4.50 (d, J ¼ 8.8 Hz, 1H, CH), 6.25 (s, 1H, OH),
6.72–6.79 (m, 2H, ArH), 6.93 (s, 1H, ArH ), 7.56 (s, 1H, NH). Anal.
calcd. for C19H21N3O7: C, 56.57; H, 5.25; N, 10.42; found: C, 56.38; H,
5.39; N, 10.49.
1,3-Dimethyl-5-(3,4-dichlorophenyl)-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4j)
Mp 229–231ꢀC; IR (KBr): 3510, 3231, 3081, 2916, 1782, 1698, 1653, 1621,
1595, 1555, 1884, 1435, 1390, 1374, 1309, 1294, 1276, 1261, 1231, 1187,

Furopyridine Synthesis in Aqueous Media
2489
1
1157, 1108, 1063, 1020, 962, 950, 869, 825, 779, 753, 687, 665 cmꢁ1; H
NMR (400 MHz, DMSO-d6): d 3.10 (s, 3H, CH3), 3.37 (s, 1H, CH),
3.39 (s, 3H, CH3), 4.08 (d, 1H, J ¼ 8.8 Hz, CH), 4.29 (s, 1H, CH), 4.53
(d, 1H, J ¼ 8.8 Hz, CH), 6.46 (s, 1H, OH), 7.29 (d, J ¼ 7.2 Hz, 1H,
ArH), 7.50 (d, J ¼ 8.4 Hz, 1H, ArH), 7.53 (s, 1H, ArH), 7.69 (s, 1H,
NH). Anal. calcd. for C17H1535Cl2N3O5: C, 49.53; H, 3.67; N, 10.19;
found: C, 49.29; H, 3.69; N, 9.88.
1,3-Dimethyl-5-((benzo[d][1,3]dioxol-5-yl))-8a-hydroxy-5,9,5a-trihydro-
7-oxa-furo[20,10:5,6]pyrido[2,3-d]pyrimidine-2,4,6-trione (4k)
Mp 226–228ꢀC; IR (KBr): 3480, 3387, 3258, 2960, 2895, 1773, 1691, 1627,
1544, 1487, 1392, 1371, 1346, 1182, 1161, 1115, 1039, 1021, 955, 933, 906,
864, 822, 797, 765, 752, 693, 679, 653 cmꢁ1; 1H NMR (400 MHz, DMSO-
d6): d 3.07 (s, 3H, CH3), 3.28 (s, 1H, CH), 3.37 (s, 3H, CH3), 4.06 (d,
J ¼ 8.8 Hz, 1H, CH), 4.23 (s, 1H, CH), 4.48 (d, J ¼ 8.4 Hz, 1H, CH),
5.94 (d, J ¼ 6.4 Hz, 2H, ArH), 6.32 (s, 1H, OH), 6.72–6.78 (m, 2H,
ArH), 6.83 (s, 1H, ArH), 7.60 (s, 1H, NH). Anal. calcd. for
C18H17ClN3O7: C, 55.81; H, 4.42; N, 10.85; found: C, 55.92; H, 4.72;
N, 11.41.
Crystal Data for 6h
C
22 H30N4O7; M ¼ 462.50, colorless block crystals, 0.76ꢂ 0.75ꢂ 0.60mm,
˚ ˚
ꢀ
monoclinic, space group Cc, a ¼ 15.006(2) A, b ¼ 11.1263(17) A,
ꢀ
ꢀ
˚
c ¼ 14.0813(19) A, a ¼ 90.00 , b ¼ 90.337(5) , c ¼ 90.00 , V ¼ 2351.0(6)
A , Z ¼ 4, Dc ¼ 1.307 g ꢃ cmꢁ3. F(000) ¼ 984, m(MoKa) ¼ 0.085 mmꢁ1
.
3
˚
Intensity data were collected on Rigaku mercury diffractometer with
graphite monochromated MoKa radiation (k ¼ 0.71070 Aꢀ) using x scan
mode with 3.1ꢀ < h < 25.3ꢀ; 4114 unique reflections were measured and
3896 reflections with I > 2r(I) were used in the refinement. Structure
solved by direct methods and expanded using Fourier techniques. The final
cycle of full-matrix least squares technique was done to R ¼ 0.0613 and
wR ¼ 0.1654.
ACKNOWLEDGMENT
We are grateful to the Foundation of Key Laboratory of Organic
Synthesis of Jiangsu Province for financial support.

2490
D.-Q. Shi and H. Yao
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