Eco-friendly, one-pot multicomponent synthesis of pyran annulated heterocyclic scaffolds at room temperature using ammonium or sodium formate as non-toxic catalyst

Article abstract of DOI:10.1002/jhet.1974

A simple, facile, and convenient practical method for one-pot synthesis of pharmaceutically interesting diverse kind of pyran annulated heterocycles such as 4H-pyrano[3,2-c]coumarins, 4H-pyrano[3,2-c]-α-pyrones, 5,6,7,8-tetrahydro-5-oxo-4H-chromenes and b

Full text of DOI:10.1002/jhet.1974

Month 2014
Eco-friendly, One-Pot Multicomponent Synthesis of Pyran Annulated
Heterocyclic Scaffolds at Room Temperature Using Ammonium or
Sodium Formate as Non-toxic Catalyst
G. Brahmachari,* S. Laskar, and B. Banerjee
Department of Chemistry, Laboratory of Natural Products & Organic Synthesis, Visva-Bharati University, Santiniketan
7
31 235, West Bengal, India
*
E-mail: brahmg2001@yahoo.co.in
Received October 2, 2012
DOI 10.1002/jhet.1974
Published online in Wiley Online Library (wileyonlinelibrary.com).
In memory of Santosh Kr. Brahmachari.
A simple, facile, and convenient practical method for one-pot synthesis of pharmaceutically interesting
diverse kind of pyran annulated heterocycles such as 4H-pyrano[3,2-c]coumarins, 4H-pyrano[3,2-c]-a-
pyrones, 5,6,7,8-tetrahydro-5-oxo-4H-chromenes and benzo[h]-4H-chromenes in the presence of ammonium
or sodium formate as catalyst via three-component condensation reaction of aromatic aldehydes,
malononitrile, and CÀH activated acidic compounds in aqueous ethanol has been developed mostly at room
temperature. The salient features of the present method are mild reaction conditions, good to excellent yields,
high atom economy, environmentally benign, easy isolation of products, no column chromatographic
separation and reusability of reaction media.
J. Heterocyclic Chem., 00, 00 (2014).
INTRODUCTION
HIV [10,11], anti-inflammatory [12], antimalarial [13],
antimicrobial [14], antihyperglycemic and antidyslipidemic
[15], anti-neurodegenerative disorders such as Alzheimer’s
disease, Parkinson’s disease and Huntington’s disease [16],
and many more [17]. In addition to such pharmacological
potential, pyran annulated heterocycles find applications in
cosmetics and pigment industries [18], and are also useful
as photoactive materials [19]. Such wide applications of
pyran annulated heterocyclic scaffolds have drawn consid-
erable interest among the synthetic chemists for their
syntheses. Recently, few synthetic methods have appeared
in literature involving three-component reaction using 4-(N,
N-dimethylamino)pyridine [20], heteropolyacids [21], basic
ionic liquid [22], tetra-n-butylammonium bromide [23],
1,8-diazabicyclo[5.4.0]undec-7-ene [24], diammonium
hydrogen phosphate [25], nano ZnO [26], MgO [27],
KF/Al O [28], triethylbenzylammonium chloride [29],
In recent times, multicomponent reactions (MCRs) have
emerged as fascinating and well-accepted strategies [1] to
the scientific community at large for the construction of
novel and complex molecular structures because of the fact
that MRCs are usually associated with a number of benefits
such as procedural simplicity, shorter reaction times, high
atom economy, energy saving, lower costs, and avoidance
of time-consuming expensive purification processes [2].
In addition, MCRs have appeared to be much more envi-
ronment friendly [3] in comparison with conventional
multistep synthesis, and also capable to offer rapid and easy
access to libraries of heterocyclic “drug-like” scaffolds with
high structural diversity finding applications in the field of
drug discovery and development [4,5].
Pyran annulated heterocyclic scaffolds represent a
2
3
“
privileged” structural motif well-distributed in natural
TMGT [30], magnetic nanocatalyst [31], sulfonic acid
functionalized silica [32], and trisodium citrate [33] using
reflux conditions. Although these protocols reported by
products [6,7] with a broad spectrum of pharmacological
efficacies that include anticancer [8], cytotoxic [9], anti-
©
2014 HeteroCorporation

G. Brahmachari, S. Laskar, and B. Banerjee
Vol 000
Table 1
Optimization of reaction conditions.
others find certain usefulness, still there is further scope to
develop a more convenient and eco-friendly synthetic
methodology for such pharmacologically significant
heterocyclic scaffolds using cheap and non-toxic catalyst
under mild reaction conditions so as to attain considerable
a
a,b
Entry
Catalyst (mol%)
Time (h)
Yield (%)
1
2
3
4
5
6
7
b-Cyclodextrin (10)
5
45
46
85
90
51
32
86
ZrOCl
2
∙8H
4
2
O (10)
(10)
(20)
(20)
20
“
green credentials”.
HCOONH
HCOONH
HCOONH
No catalyst
HCOONa (20)
1.5
1.0
3.0
3.0
1.0
In continuation of our sincere effort to develop green
4
4
synthetic methodologies for organic transformations [34],
we have recently developed a straightforward and efficient
three-component one-pot synthesis of diverse pyran
annulated heterocyclic scaffolds in good yields using
commercially available ammonium or sodium formate as
inexpensive and environmentally benign catalyst, from
the reaction of aromatic aldehydes, malononitrile, and
various activated CÀH acidic compounds in aqueous etha-
nol, mostly at room temperature. The results are summarized
in Scheme 1 and Tables 1–3.
c
a
Experimental conditions: 4-chlorobenzaldehyde (1 mmol), malononitrile
(1.1 mmol), 4-hydroxycoumarin (1.1 mmol) and catalyst in 4 mL of
b
c
aqueous ethanol (1:1, v/v) at room temperature. Isolated yields. Under
neat condition. Product 4a.
First, we conducted a series of trial reactions using 4-
chlorobenzaldehyde (1; 1 mmol), malononitrile (2; 1.1 mmol),
and 4-hydroxycoumarin (3a; 1.1 mmol) in the absence or
presence of different catalysts in aqueous ethanol (1 : 1, v/v)
at room temperature for obtaining the best yield of the
desired product, 2-amino-3-cyano-4-(4-chlorophenyl)-5-
oxo-4,5-dihydropyrano[3,2-c]chromene (4a); the optimiza-
tion results are summarized in Table 1. It appeared that
20mol% of ammonium or sodium formate in aqueous etha-
nol at room temperature provides the best result in terms of
yield and time (Table 1, entries 4 and 7) for 4a, which was
characterized by its physical and spectral properties [24].
RESULTS AND DISCUSSION
We report in this paper ammonium and/or sodium
formate catalyzed highly efficient one-pot synthesis of a
wide range of structurally diverse pyran annulated heterocy-
cles such as 4H-pyrano[3,2-c]coumarins (4a–h), 4H-pyrano
[3,2-c]-a-pyrones (4i–m), 5,6,7,8-tetrahydro-5-oxo-4H-
chromenes (4n–t), and benzo[h]-4H-chromenes (4u–w) in
aqueous ethanol mostly at room temperature (Scheme 1).
Scheme 1. Synthesis of pyran annulated heterocycles.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
One-Pot Synthesis of Pyran Annulated Heterocyclic Scaffolds
Table 2
a
Synthesis of 4H-pyrano[3,2-c]coumarins (4a–h) and 4H-pyrano[3,2-c]-a-pyrones (4i–m).
b
ꢀ
Melting point ( C)
Yeild (%)
Activated
C–H acid
Substituent
(R)
Entry
Product
HCOONH
4
HCOONa
Found
Reported [Ref.]
1
2
3
4
5
6
7
8
9
4a
4b
4c
4d
4e
4f
4g
4h
4i
3a
3a
3a
3a
3a
3a
3a
3a
3b
3b
3b
3b
3b
4-Cl
H
4-F
4-NO
4-Me
3-NO
4-MeO
2-MeO
H
4-Me
4-Cl
4-NO
4-F
92
90
91
91
96
92
85
85
92
60
70
80
73
86
82
90
92
91
95
91
81
86
65
75
73
68
263–265
255–259
262–264
258–262
258–261
255–257
230–233
274–277
219–222
159–162
213–215
209–212
229–232
260–262 [24]
256–258 [24]
262–263 [24]
256–258 [24]
258–260 [20]
257–258 [28]
232–235 [33]
274–276 [32]
221–223 [24]
—
2
2
10
11
12
13
4j
4k
4l
—
2
210–212 [24]
—
4m
a
Experimental conditions: aldehyde (1 mmol), malononitrile (1.1 mmol), 4-hydroxycoumarin (3a) or 4-hydroxy-6-methylpyrone (3b) (1.1 mmol) and
2
4
0 mol% HCOONH
i–m. Isolated yields.
4
or HCOONa as the catalyst in 4 mL of aqueous ethanol (1:1, v/v) at room temperature. Stirred for 1.0 h for 4a–h and for 3.0 h for
b
Table 3
a
Synthesis of tetrahydrobenzo[b]-4H-pyrans (4n-t) and benzo[h]-4H-chromenes (4u–w).
b
ꢀ
Melting point ( C)
Yeild (%)
Activated
C–H acid
Substituent
(R)
Entry
Product
HCOONH
4
HCOONa
Found
Reported [Ref.]
1
2
3
4
5
6
7
4n
4o
4p
4q
4r
4s
3c
3c
3c
3c
3c
3c
3c
3d
3d
3d
H
4-NO
4-Me
3-NO
4-MeO
4-C1
4-F
4-NO
4-C1
4-F
90
80
81
87
91
93
80
87
82
70
83
74
76
92
80
80
74
82
79
72
225–228
185–187
203–207
208–212
196–198
211–213
188–190
236–238
230–234
233–235
225–227 [30]
184–186 [33]
204–205 [33]
205–208 [33]
191–193 [33]
213–214 [20]
—
237–238 [24]
232–234 [24]
236–237 [24]
2
2
4t
c
8
9
4u
4v
4w
2
c
c
10
a
4
Experimental conditions: aldehyde (1 mmol), malononitrile (1.1 mmol), 3c/3d (1.1 mmol) and 20 mol% HCOONH or HCOONa as the catalyst in 4 mL
c
b
of aqueous ethanol (1 : 1, v/v) at room temperature;. Isolated yields. Stirred for 2.0 h for 4n–t and refluxed for 3.0 h for 4u–w. Reflux condition.
After optimizing the reaction conditions, a number of aromatic
aldehydes having substituents such as methyl, methoxy,
nitro, and halogens were reacted with malononitrile and 4-
hydroxycoumarin using identical reaction conditions, and
all of them underwent the reaction smoothly affording the
corresponding 4H-pyrano[3,2-c]coumarins (4b–h) (Table 2,
entries 2–8 in 81–96% yields just within 1 h at room temper-
ature). To our delight, the reactions attempted by replacing 4-
hydroxycoumarin (3a) with 4-hydroxy-6-methylpyrone (3b)
Encouraged by these results, we attempted the reaction of
benzaldehyde, malononitrile, and dimedone (3c) under
similar reaction conditions. The desired product, 2-amino-
3-cyano-4-phenyl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-
chromene (4n) was obtained in 90% yield within 2 h at room
temperature (Table 3, entry 1). A variety of other aromatic
aldehydes substituted with methyl, methoxy, nitro, and
halogens reacted with malononitrile and dimedone smoothly
giving rise to the corresponding desired tetrahydrobenzo[b]-
4H-pyrans (4o–t) in good yields (74–93%) within 2 h at
room temperature (Table 3, entries 2–7). The scope of this
present protocol was further investigated with another C–H
activated acidic compound, 1-naphthol (3d); however, the
(
Scheme 1) also underwent successful condensation to
produce 4H-pyrano[3,2-c]-a-pyrones (4i–m) in good yields
60–92%) within 3 h under the similar reaction conditions
at room temperature (Table 2, entries 9–13).
(
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

G. Brahmachari, S. Laskar, and B. Banerjee
Vol 000
tedious separation procedures, clean reaction profiles, high
atom economy as well as the use of inexpensive and environ-
mentally benign catalyst are the key advantages of the
present method. Moreover, reusability of the reaction
media without significant loss of activity is an added advan-
tage. Keeping in view of the synthetic importance of such
pyran annulated heterocyclic molecules of pharmaceutical
interests, the present methodology offers the possibility of
its use with cost-effective and environmentally more friendly
ways for large-scale syntheses.
EXPERIMENTAL
General. Infrared spectra were recorded using a Shimadzu
(
FTIR-8400S) FTIR spectrophotometer (Shimadzu, Kyoto,
1
13
Japan) using KBr disk. H-and C-NMR spectra were obtained
at 300 and 400 MHz and 75 and 100 MHz, respectively, using
Bruker DRX spectrometer (Bruker Instruments, Billerica, MA,
Figure 1. ORTEP diagram of compound 4t (CCDC 873695).
USA) and DMSO-d as the solvent. Mass spectra (ESI-TOF-MS)
6
formate salt catalyzed three-component condensation reaction
between aromatic aldehydes, malononitrile, and 1-naphthol
in aqueous ethanol did not afford good result at room
temperature but required reflux condition. At reflux condi-
tion, the reaction took place smoothly affording the desired
products benzo[h]-4H-chromenes (4u–w) in moderately
good yields (Table 3, entries 8–10).
were measured on a quadrupole time-of-flight micro mass
spectrometer (Waters MS Technologies, Manchester, UK).
Elemental analyses were performed with an Elementar Vario EL III
Carlo Erba 1108 micro-analyzer instrument (Carlo Erba Reagenti
SpA, Rodano, Italy). Melting point was recorded on a Sunvic
melting point apparatus (Sunvic, Glasgow, UK) and is uncorrected.
Thin-layer chromatography was performed using silica gel 60 F254
2
0 Â 20 cm aluminum sheets (Merck, A.G., Germany).
The isolated products were fully characterized on the
basis of analytical data and detailed spectral studies
General procedure for the synthesis of pyran annulated
heterocyclic scaffolds. An oven-dried screw cap test tube was
charged with magnetic stir bar, aldehyde (1mmol),
malononitrile (1.1mmol), catalyst (HCOONH or HCOONa;
0mmol%), 4 mL aqueous ethanol (1: 1, v/v) in a sequential
1
including Fourier transform infrared (FTIR), H-NMR,
a
13
C-NMR and electrospray ionization time-of-flight mass
4
2
spectrometry (ESI-TOF-MS). All the known compounds
had physical and spectroscopic data identical to the literature
values [20,24,28,30,32,33]. Single crystal X-ray analysis
manner; the reaction mixture was then stirred vigorously at room
temperature for about 20min. After then, CÀH activated acid (3)
(
1.1mmol) was added to the stirred reaction mixture, and the
for
2-amino-3-cyano-4-(4-fluorophenyl)-7,7-dimethyl-5-
stirring was continued for appropriate range of time as indicated
in Tables 2 and 3. The progress of the reaction was monitored by
thin-layer chromatography. On completion of reaction, a solid
mass precipitated out, which was filtered off followed by washing
with cold aqueous ethanol to obtain crude product; 4 was purified
by its recrystallization from aqueous ethanol.
oxo-5,6,7,8-tetrahydro-4H-chromene (4t) (Table 3, entry 7)
was also documented in this present paper (Figure 1) [35].
It is worth noting that we reused the filtrate containing
residual solvent, catalyst, and substrates obtained upon filtra-
tion of the reaction mixture after completion of the reaction
up to fourth run, furnishing 4a in 80, 71, and 63% yields
respectively (not detailed in the Experimental section).
The spectral and analytical data of new entries are given later
in the text.
2
-Amino-3-cyano-4,5-dihydro-7-methyl-5-oxo-4-(4-methylphenyl)-
ο
pyrano[4,3-b]pyran (4j). White solid; mp 159–162 C; IR (KBr):
nmax /cm 3381, 3322, 3030, 2910, 2212, 1709, 1674, 1618, 1597,
1578, 1508, 1258, 1036, 773, 613, 530. H-NMR (300 MHz,
À1
1
CONCLUSIONS
DMSO-d
6
): d 7.11 (d, J = 8.1Hz, 2H, Ar-H), 7.06 (d, J = 8.1 Hz,
), 6.25 (s, 1H), 4.22 (s, 1H), 2.62
In conclusion, we have developed a very simple, facile,
and convenient practical method for one-pot synthesis of
pharmaceutically interesting diverse kind of pyran annulated
heterocycles such as 4H-pyrano[3,2-c]coumarins, 4H-pyrano
2
H, Ar-H), 7.15 (s, 2H, ÀNH
2
1
3
(
s, 3H, ÀCH ), 2.22 (s, 3H,ÀCH ). C-NMR (75 MHz,
3
3
DMSO-d ): d 162.72, 158.00, 140.63, 136.06, 128.9 (2C),
6
127.34 (2C), 119.28, 114.36, 113.40, 100.86, 97.87, 58.05,
+
3
5.87, 20.56, 19.24. ESI-TOF-MS: 317.11 [M + Na] ;
[3,2-c]-a-pyrones, 5,6,7,8-tetrahydro-5-oxo-4H-chromenes
elemental analysis calcd (%) for C H N O : C 69.38, H 4.79,
N 9.52; found: C 69.36, H 4.81, N 9.53.
1
7 14 2 3
and benzo[h]-4H-chromenes in the presence of ammonium
or sodium formate as catalyst via three-component conden-
sation reaction of aromatic aldehydes, malononitrile, and
CÀH activated acidic compounds in aqueous ethanol,
mostly at room temperature. Mild reaction conditions, good
to excellent yields, operational simplicity, and absence of
2
-Amino-3-cyano-4-(4-chlorophenyl)-4,5-dihydro-7-methyl-5-
ο
oxo-pyrano[4,3-b]pyran (4k). White solid;mp 213–215 C; IR
À1
(
KBr): nmax /cm 3375, 3321, 3145, 2910, 2197, 1703, 1672,
1636, 1605, 1485, 1258, 1144, 1095, 1040, 845, 771, 517
À1
1
cm ; H-NMR (300 MHz, DMSO-d ): d 7.37 (d, J = 8.1 Hz,
6
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2014
One-Pot Synthesis of Pyran Annulated Heterocyclic Scaffolds
2
6
H, Ar-H), 7.26 (s, 2H, ÀNH ), 7.23 (d, J = 8.7 Hz, 2H, Ar-H),
Acknowledgments. We are thankful to Bose Institute, Kolkata and
CDRI, Lucknow, India, for spectral measurements. Financial
assistance from both CSIR [Grant No. 02(0110)/12/EMR-II] and
UGC, New Delhi is also gratefully acknowledged. The authors
are grateful to Dr. Vivek K. Gupta, Post-Graduate Department of
Physics, University of Jammu, Jammu Tawi - 180 006, India for
collecting the X-ray data.
2
1
3
.28, (s, 1H), 4.33 (s, 1H), 2.44 (s, 3H, ÀCH ). C-NMR (75
3
MHz, DMSO-d
1
5
elemental analysis calcd (%) for C H ClN O : C 61.06, H
3
6
): d 162.74, 160.96, 157.91, 157.71, 142.22,
31.78, 131.20, 129.37, 129.13, 128.00, 118.82, 99.88, 97.60,
+
7.06, 35.38, 18.95. ESI-TOF-MS: 337.05 [M + Na] ;
1
6
11
2 3
.52, N 8.90; found: C 61.07, H 3.53, N 8.88.
-Amino-3-cyano-4-(4-fluorophenyl)-4,5-dihydro-7-methyl-
2
ο
5
-oxo-pyrano[4,3-b]pyran (4m). White solid; mp 229–232 C;
À1
IR (KBr): nmax /cm 3396, 3319, 3092, 2914, 2883, 2195, 1705,
REFERENCES AND NOTES
À1
1
1
(
7
634, 1607, 1504, 1259, 1040, 852, 515, 490 cm ; H-NMR
300 MHz, DMSO-d ), 7.22 (br s, 2H, Ar-H),
): d 7.26 (s, 2H, ÀNH
.13 (t, J= 8.7 Hz, 2H, Ar-H), 6.28 (s, 1H), 4.32 (s, 1H), 2.22 (s, 3H,
6
2
[1] (a) Cariou, C. C. A.; Clarkson, G. J.; Shipman, M. J Org Chem
2008, 73, 9762; (b) Armstrong, R. W.; Combs, A. P.; Tempest, P. A.;
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Brown, S. D.; Keating, T. A. Acc Chem Res 1996, 29, 123; (c) Zhou, L.;
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[2] (a) Elders, N.; van der Born, D.; Hendrickx, L. J. D.; Timmer,
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Synth Catal 2008, 350, 370; (c) Dömling, A. Chem Rev 2006, 106, 17; (d)
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[3] Anastas, P. T.; Warner, J. C. Green Chemistry Theory and
Practice; Oxford University Press: Oxford, UK, 1998, pp 1–152.
ÀCH ). C-NMR (75 MHz, DMSO-d ): d 163.01, 162.75, 161.33,
3
6
159.54, 158.15, 158.05, 139.77, 129.54, 129.43, 119.24, 115.26,
114.97, 100.54, 97.95, 57.73, 35.58, 19.30. ESI-TOF-MS: 321.09
+
[
3
M + Na] ; elemental analysis calcd (%) for C16
.72, N 9.39; found: C 64.42, H 3.77, N 9.41.
-Amino-3-cyano-4-(4-fluorophenyl)-7,7-dimethyl-5-oxo-5,6,7,8-
2 3
H11FN O : C 64.43, H
2
ο
tetrahydro-4H-chromene (4t).
White solid; mp 188–190 C; IR
À1
(KBr): nmax /cm 3354, 3321, 3082, 2957, 2187, 1672, 1636, 1603,
À1
1
1
502, 1218, 1028, 829, 491 cm ; H-NMR (400 MHz, DMSO-d
.21–7.17 (m, 2H, Ar-H), 7.14–7.09 (m, 2H, Ar-H), 7.03 (s, 2H,
ÀNH ), 4.22 (s, 1H), 2.51 (d, J= 0.8 Hz, 2H), 2.25 (d, J=16.4Hz,
6
):
7
2
1
H), 2.11 (d, J= 16 Hz, 1H), 1.04 (s, 3H, ÀCH ), 0.95 (s, 3H, ÀCH );
3
3
1
3
[4] (a) Liéby-Muller, F.; Simon, C.; Constantieux, T.; Rodriguez,
C-NMR (100 MHz, DMSO-d ): d 195.67, 162.47, 162.11, 159.70,
6
J. QSAR Comb Sci 2006, 25, 432; b) Sharma, G. V. M.; Reddy, K. L.;
Lakshmi, P. S.; Krishna, P. R. Synthesis 2006, 1, 55; (c) Wang, L. M.;
Sheng, J.; Zhang, L.; Han, J. W.; Fan, Z. Y.; Tian, H.; Qian, C. T.
Tetrahedron 2005, 61, 1539; (d) Nair, V.; Vinod, A. U.; Rajesh, C. J
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2008, 73, 9762; (b) Armstrong, R. W.; Combs, A. P.; Tempest, P. A.;
Brown, S. D.; Keating, T. A. Acc Chem Res 1996, 29, 123; (c) Zhou,
L.; Bohle, D. S.; Jiang, H. F.; Li, C. J. Synlett 2009, 937; (d) Brauch,
S.; Gabriel, L.; Westermann, B. Chem Commun 2010, 46, 3387.
158.50, 140.92, 129.09, 129.01, 119.63, 115.12, 114.91, 112.63, 58.14,
+
49.98, 34.93, 31.78, 28.32, 26.84.; ESI-TOF-MS: 335.13 [M + Na] ;
elemental analysis calcd (%) for C H FN O : C 69.22, H 5.49,
N, 8.97; found: C 69.23, H 5.48, N, 8.98.
Crystallographic studies. X-ray intensity data were
collected on Xcalibur CCD area detector diffractometer (Oxford
Diffraction Ltd., UK) equipped with graphite monochromated
MoKa radiation (l = 0.71073 Å). The crystal used for data
collection was of dimensions 0.30 Â 0.20 Â 0.20 mm. The cell
dimensions were determined by least squares fit of angular
1
8
17
2 2
[6] Feuer G. In Progress in Medicinal Chemistry; Ellis, G. P.;
West, G. P., Eds.; North-Holland Publishing Company: New York,
o
settings of 4247 reflections in the θ ranges 3.41–28.91 . The
1974, Vol 10, pp. 85–158.
intensities were measured by o scan mode for θ ranges 3.42–
[7] (a) Dean, F. M. Naturally Occurring Oxygen Ring
Compounds; Butter-worths: London, 1963, pp. 176–220; (b) Goel, A.;
Ram, V. J. Tetrahedron 2009, 65, 7865.
o
2
6.00 . 1513 reflections were treated as observed (I > 2s(I)).
Data were corrected for Lorentz, polarization and absorption
factors. The structure was solved by direct methods using
SHELXS97 [35a]. An ORTEP view of the title compound with
atomic labeling is shown in Figure 1 [35b]. The geometry of the
molecule was calculated using the WINGX [35c], PARST [35d],
and PLATON [35e] software. All non-hydrogen atoms of the
molecule were located in the best E-map. Full-matrix least-
squares refinement was carried out using SHELXL97 [35a]. All
the hydrogen atoms were geometrically fixed and allowed to
ride on the corresponding non-H atoms. The final refinement
cycles converged to an R = 0.0516 and wR (F2) = 0.1062 for the
observed data. Residual electron densities ranged from À0.207
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[
À3
to 0.152 eÅ . Compound 4t (Table 3, entry 7) empirical
[
formula C H FN O , white blocked shaped crystal, formula
18
17
2
2
wt: 312.34, space group P21/n with the unit cell parameters:
o
a = 9.4384(6), b = 17.1240(7), c = 10.4558(6) Å, b = 113.886(7) ,
and Z= 4. Complete crystallographic data of 2-amino-3-cyano-4-(4-
fluorophenyl)-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene
[
(
4t) (Table 3, entry 7) for the structural analysis have been deposited
with the Cambridge Crystallographic Data Centre, CCDC No.
73695. Copies of this information may be obtained free of
[
8
6
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
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