A green method for the synthesis of novel benzo[b]pyran derivatives in an ionic liquid

Article abstract of DOI:10.3184/030823409X431373

A series of novel 2-amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-5-oxo-4-aryl- 4H-benzo[b]pyran-3-carbonitriles was obtained from the reaction of 2-(1-arylethylidene)malononitrile and 5,5-dimethylcyclohexane-1,3-dione in an ionic liquid at 90°C. This method h

Full text of DOI:10.3184/030823409X431373

234 RESEARCH PAPER
APRILꢄꢀꢊꢅꢋ±ꢊꢅꢌ
JOURNAL OF CHEMICAL RESEARCH 2009
A green method for the synthesis of novel benzo[b]pyran derivatives in
an ionic liquid
Xiang-Shan Wanga,b*, Jian-Rong Wua, Qing Lia and Shu-Jiang Tua,b
aSchool of Chemistry and Chemical Engineering, Xuzhou Normal University, Xuzhou Jiangsu 221116, P. R. China
bThe Key Laboratory of Biotechnology for Medical Plant, Xuzhou Jiangsu 221116, P. R. China
A
series of novel 2-amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-5-oxo-4-aryl-4H-benzo[b]pyran-3-carbonitriles was
obtained from the reaction of 2-(1-arylethylidene)malononitrile and 5,5-dimethylcyclohexane-1,3-dione in an
ionic liquid at 90ꢀ°C. This method had the advantages of operational simplicity, mild reaction conditions and an
environmentally benign procedure.
Keywords: benzopyran, ionic liquid, 5,5-dimethylcyclohexane-1,3-dione
Ar
CH3
CN
In recent times, room temperature ionic liquids (RTILs),
especially those based on the 1,3-dialkylimidazolium salts,
have shown great promise as attractive alternatives to
conventional solvents. They possess the unique advantages of
highthermalstability, negligiblevapourpressure, immiscibility
with a number of organic solvents and recyclability. In many
cases, the products are weakly soluble in the ionic phase so
that the products can be easily separated by simple extraction.
Ionic liquids have been used as solvents for a large number of
organic transformations.1-5
Benzopyran and its derivatives are very useful compounds
LQꢀ YDULRXVꢀ ¿HOGVꢀ RIꢀ FKHPLVWU\ꢀ DQGꢀ LQꢀ PHGLFLQHꢁꢀ 7KLVꢀ
heterocyclic moiety has found broad application in drug
development for the treatment of bone defects and injuries,6
smooth muscle cell-rich vascular lesions,7 cancer in
animals8 and infectious diseases.9 2-Aminobenzo[b]pyran
is one of a number of important benzopyrans, which have
received considerable attention due to their wide range of
useful biological properties, which include antimicrobial
activity,10,11 antibacterial activity,12 antiapoptotic13 activity
and molluscicidal activity.14 Accordingly, novel strategies
for the synthesis of 2-aminobenzopyran derivatives continue
WRꢀ UHFHLYHꢀ PXFKꢀ DWWHQWLRQꢀ LQꢀ WKHꢀ ¿HOGꢀ RIꢀ V\QWKHWLFꢀ RUJDQLFꢀ
chemistry.15-21 They have mainly been synthesised from the
reactions of active compounds such as those containing 1,3-
dicarboxyl groups and naphthalenol, with an D,E-unsaturated
dinitrile or cyanoacetate, or by three component reactions of
benzaldehyde, malonodinitrile (or cyanoacetate) and active
compounds.
O
O
NC
Ar
CN
IL, 90 oC
+
O
NH2
CH3
O
3
2
1
Scheme 1
with 2. The desireds product were obtained in good yields.
The optimisation of the reaction conditions, including reaction
temperature and solvent, was investigated using 2-(1-(4-nitro-
phenyl)ethylidene)malononitrile and 2 as model reactants.
As summarised in Table 1, the results showed that at room
temperature only trace amounts of product were found by
TLC (Table 1, entry 1). To our delight, the reaction proceeded
smoothly in good yield at 90°C. Moreover, different ionic
liquids were tested as reaction media and it was observed that
-
[bmim+] [BF4 ] was the preferred ionic liquid for the reaction
ꢂ7DEOHꢀꢃꢄꢀHQWULHVꢀꢅ±ꢆꢇꢁꢀ,QꢀDGGLWLRQꢄꢀ(W2+ꢀDQGꢀ'0)ꢀZHUHꢀDOVRꢀ
tested as solvents for this reaction. It was found that only a
trace amount of product was obtained when EtOH alone
was used and that only 52% was isolated in DMF (Table 1,
HQWULHVꢀꢈ±ꢃꢉꢇꢁꢀ$ꢀOLWWOHꢀSLSHULGLQHꢀZDVꢀDGGHGꢀWRꢀWKHꢀ(W2+ꢀRUꢀ
-
[bmim+][BF4 @ꢀ VROYHQWVꢀ WRꢀ VLJQL¿FDQWO\ꢀ LQFUHDVHꢀ RUꢀ VOLJKWO\ꢀ
GHFUHDVHꢀWKHꢀ\LHOGVꢀUHVSHFWLYHO\ꢀꢂ7DEOHꢀꢃꢄꢀHQWULHVꢀꢃꢃ±ꢃꢊꢇꢁ
After the reaction was completed, the reaction mixtures were
cooled to room temperature. Water (5 mL) was then added to
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LQꢀWKHꢀ¿OWUDWHꢀZDVꢀUHPRYHGꢀE\ꢀHYDSRUDWLRQꢀDWꢀUHGXFHGꢀSUHVVXUHꢀ
at 80°&ꢀIRUꢀꢋꢀKꢀDQGꢀWKHꢀLRQLFꢀOLTXLGꢀLQꢀWKHꢀ¿OWUDWHꢀFRXOGꢀEHꢀ
recycled. The recovered ionic liquid could be directly used for
reactions involving the same substrate. Alternatively, if the
However, it should be noted that the known 2-
aminobenzopyrans from the above-mentioned reactions only
contained one non-hydrogen group such as a phenyl group on
the 4-position, the other group was always a hydrogen atom.
In order to solve the problem of obtaining two non-hydrogen
groups on the 4-position, we report here the synthesis of 2-
amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-5-oxo-4-aryl-4H-
benzo[b] pyran-3-carbonitrile in an ionic liquid.
Table 1 Synthesis of 3a under different reaction conditionsa
Entry
Temp./ꢀ°C
Ionic liquidb
Yieldc/%
-
1
2
R.t.
50
[bmim+][BF4-]
Trace
58
[bmim+][BF4-]
[bmim+][BF4 ]
[emim+] Br-
[pmim+] Br-
[bmim+]Br-
3
90
85
Results and discussion
4
90
77
5
90
79
2-(1-Arylethylidene)malononitrile
1
and 5,5-dimethyl
6
90
78
cyclohexane-1,3-dione 2 were treated in an ionic liquid at
90°C and 2-amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-5-oxo-
4-aryl-4H-benzo[b]pyran-3-carbonitrile derivatives 3 were
obtained in good yields (Scheme 1).
-
7
90
[emim+][BF4-]
82
8
90
[pmim+][BF4 ]
EtOH
80
9
Reflux
90
Reflux
Trace
52
10
11
12
DMF
Piperidine/EtOH
72
78
Firstly, we tried to perform the three component
reaction between acetophenone, malonodinitrile and 5,5-
dimethylcyclohexane-1,3-dione, but failed. Subsequently,
we synthesised the 2-(1-arylethylidene)malononitriles 1 from
acetophenones and malonodinitrile and then reacted them
-
90
Piperidine/[bmim+][BF4 ]
aReaction conditions: ionic liquid (2 mL), 2-(1-(4-nitrophenyl)
ethylidene)malononitrile (0.426 g, 2 mmol) and 2 (0.280 g,
2 mmol).
= 1-butyl-3-methylimidazolium; emim = 1-ethyl-3-
methylimidazolium; pmim = 1-methyl-3- propylimidazolium.
bbmim
cIsolated yields.
* Correspondent. E-mail: xswang1974@yahoo.com

JOURNAL OF CHEMICAL RESEARCH 2009 235
1411, 1349, 1317, 1212, 1167, 1112, 1049, 1012, 862; HRMS [Found:
m/z 376.1254, Calcd for C19H19N3NaO4: (M + Na+) 376.1273].
2-Amino-5,6,7,8-tetrahydro-4-(3-methoxyphenyl)-4,7,7-trimethyl-
5-oxo-4H-benzo[b]pyran-3-carbonitrile (3bꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢃꢈ±ꢊꢊꢃ°C; 1H
NMR (DMSO-d6, G, ppm): 1.01 (s, 3H, CH3), 1.03 (s, 3H, CH3), 1.73
(s, 3H, CH3), 2.09 (d, J = 15.6 Hz, 1H, CH), 2.18 (d, J = 15.6 Hz, 1H,
&+ꢇꢄꢀꢊꢁꢍꢉ±ꢊꢁꢍꢍꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 3.72 (s, 3H, CH32ꢇꢄꢀꢌꢁꢐꢊ±ꢌꢁꢐꢋꢀꢂPꢄꢀꢊ+ꢄꢀ
ArH), 6.78 (s, 2H, NH2), 6.82 (d, Jꢀ ꢀꢆꢁꢉꢀ+]ꢄꢀꢃ+ꢄꢀ$U+ꢇꢄꢀꢐꢁꢃꢐ±ꢐꢁꢊꢊꢀꢂPꢄꢀ
1H, ArH); 13C NMR (DMSO-d6, G, ppm): 25.4, 27.3, 27.6, 31.4, 37.6,
40.1, 51.3, 54.8, 65.9, 110.2, 112.9, 115.9, 118.8, 128.7, 149.6, 156.4,
158.8, 161.3, 195.7. IR (KBr, Q, cm-1): 3409, 3329, 3007, 2954, 2833,
2193, 1656, 1601, 1493, 1467, 1428, 1406, 1389, 1352, 1318, 1288,
1254, 1208, 1168, 1044, 986, 965, 857, 776, 764,704; HRMS [Found:
m/z 361.1514, Calcd for C20H22N2NaO3: (M + Na+) 361.1528].
2-Amino-4-(4-fluorophenyl)-5,6,7,8-tetrahydro-4,7,7-trimethyl-
5-oxo-4H-benzo[b]pyran-3-carbonitrile (3cꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢃꢈ±ꢊꢊꢃ°C; 1H
NMR (DMSO-d6, G, ppm): '0.98 (s, 3H, CH3), 1.01 (s, 3H, CH3),
1.74 (s, 3H, CH3), 2.07 (d, J = 15.6 Hz, 1H, CH), 2.16 (d, J = 15.6
+]ꢄꢀꢃ+ꢄꢀ&+ꢇꢄꢀꢊꢁꢋꢌ±ꢊꢁꢍꢌꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 6.86 (s, 2H, NH2ꢇꢄꢀꢐꢁꢉꢌ±ꢐꢁꢃꢉꢀ
ꢂPꢄꢀ ꢊ+ꢄꢀ$U+ꢇꢄꢀ ꢐꢁꢊꢌ±ꢐꢁꢊꢈꢀ ꢂPꢄꢀ ꢊ+ꢄꢀ$U+ꢇꢑꢀ 13C NMR (DMSO-d6, G,
ppm): 25.7, 27.4, 30.8, 31.4, 37.4, 40.1, 51.3, 65.7, 114.1, 114.3,
115.8, 128.2, 128.3, 144.1 156.4, 159.0, 161.3 162.4. IR (KBr, Q,
cm-1): 3400, 3327, 3009, 2960, 2874, 2195, 1664, 1640, 1508, 1471,
1408, 1350, 1316, 1212, 1164, 1087, 1047, 984, 962, 917, 892, 845;
HRMS [Found: m/z 349.1320, Calcd for C19H19FN2NaO2: (M + Na+)
349.1328].
2-Amino-4-(4-chlorophenyl)-5,6,7,8-tetrahydro-4,7,7-trimethyl-
5-oxo-4H-benzo[b]pyran-3-carbonitrile (3dꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢉꢍ±ꢊꢉꢌ°C;
1H NMR (DMSO-d6, G, ppm): 0.99 (s, 3H, CH3), 1.02 (s, 3H, CH3),
1.74 (s, 3H, CH3), 2.08 (d, J = 15.6 Hz, 1H, CH), 2.17 (d, J = 15.6 Hz,
ꢃ+ꢄꢀ&+ꢇꢄꢀꢊꢁꢍꢉ±ꢊꢁꢍꢍꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 6.86 (s, 2H, NH2), 7.27 (d, J = 8.8
Hz, 2H, ArH), 7.32 (d, J = 8.8 Hz, 2H, ArH); 13C NMR (DMSO-d6,
G, ppm): 25.5, 27.4, 30.7, 31.4, 37.6, 40.1, 51.2, 65.4, 115.7, 118.7,
127.6, 128.3, 130.3, 147.0, 156.5, 161.5, 195.7. IR (KBr, Q, cm-1):
3392, 3323, 3013, 2946, 2888, 2195, 1715, 1694, 1682, 1660, 1651,
1645, 1634, 1605, 1493, 1463, 1409, 1351, 1317, 1277, 1211, 1169,
1093, 1047, 1011, 985, 963, 844; HRMS [Found: m/z 365.1012,
Calcd for C19H1935ClN2NaO2: (M + Na+) 365.1033]. The expected
MS intensity pattern due to Cl isotopes was observed.
Table 2 The reactions of 2-(1-arylethylidene) malononitrile
and 5,5-dimethyl cyclohexane-1,3-dione in an ionic liquida
Entry
Ar
Products
Time/h Yields/%b
1
2
4-NO2C6H4
3-OMeC6H4
4-FC6H4
3a
3b
3c
3d
3e
3f
3g
3h
3i
12
14
12
15
14
16
16
15
15
15
14
85
82
88
81
85
78
79
83
81
80
87
3
4
4-ClC6H4
5
2-naphthoyl
4-benzyloxyphenyl
4-OMeC6H4
4-MeC6H4
3-BrC6H4
4-BrC6H4
C6H5
6
7
8
9
10
11
3j
3k
aReaction conditions: ionic liquid (2 mL), 1 (2 mmol) and 2
(0.280 g, 2 mmol).
bIsolated yields.
ionic liquid was used for reactions with different substrates,
it was washed with ethyl acetate, followed by evaporation
at 80°C under reduced pressure for 3 h. Investigations using
2-(1-(4-nitrophenyl)ethylidene)malononitrile and 2 as model
substrates proved the successful reuse of the ionic liquid.
Even in the fourth cycle the yield (83%) of product 3a was
fairly good.
According to the optimised conditions, we next examined
the utility of this process (Scheme 3) to synthesise a range of
benzo[b]pyrans 3. Various 2-(1-arylethylidene) malononitriles
1, bearing either electron-withdrawing groups (such as halide
or nitro) or electron-donating groups (such as alkyl or alkoxyl),
were subjected to reaction with 2 to give the corresponding
benzo[b]pyran derivatives 3 in good yields (Table 2).
Conclusion
In conclusion, we have reported a green method of synthesising
novel 2-aminobenzo[b]pyran derivatives bearing two non-
hydrogen groups on the 4-position from the reaction of
2-(1-arylethylidene)malononitrile and 5,5-dimethylcyclohexane-
1,3-dione in an ionic liquid at 90°C. The noteworthy features
of this procedure are mild reaction conditions, reaction in one-
pot, good yields, operational simplicity and an environmentally
2-Amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-4-(naphthalen-2-yl)-
5-oxo-4H-benzo[b]pyran-3-carbonitrile (3e):ꢀ 0ꢁSꢁꢀ ꢊꢌꢈ±ꢊꢐꢉ°C;
1H NMR (DMSO-d6, G, ppm): 1.01 (s, 3H, CH3), 1.04 (s, 3H, CH3),
1.88 (s, 3H, CH3), 2.06 (d, J = 15.6 Hz, 1H, CH), 2.17 (d, J = 15.6 Hz,
ꢃ+ꢄꢀ &+ꢇꢄꢀ ꢊꢁꢍꢉ±ꢊꢁꢍꢍꢀ ꢂPꢄꢀ ꢊ+ꢄꢀ &+2), 6.87 (s, 2H, NH2ꢇꢄꢀ ꢐꢁꢅꢐ±ꢐꢁꢀ ꢅꢈꢀ
ꢂPꢄꢀ ꢃ+ꢄꢀ$U+ꢇꢄꢀ ꢐꢁꢋꢐ±ꢐꢁꢍꢉꢀ ꢂPꢄꢀ ꢊ+ꢄꢀ$U+ꢇꢄꢀ ꢐꢁꢐꢈ±ꢐꢁꢆꢍꢀ ꢂPꢄꢀ ꢅ+ꢄꢀ$U+ꢇꢄꢀ
ꢐꢁꢈꢃ±ꢐꢁꢈꢌꢀ ꢂPꢄꢀ ꢃ+ꢄꢀ $U+ꢇꢑꢀ 13C NMR (DMSO-d6, G, ppm): 25.5,
27.3, 27.7, 31.5, 38.0, 40.2, 51.3, 65.6, 115.8, 118.8, 123.9, 125.6,
125.7, 126.0, 127.2, 127.3, 128.0, 131.3, 132.5, 145.1, 156.5, 161.5,
195.8. IR (KBr, Q, cm-1): 3390, 3325, 3053, 3026, 2957, 2873, 2193,
1656, 1606, 1509, 1458, 1410, 1391, 1373, 1352, 1316, 1210, 1168,
1129, 1048, 986, 888, 855, 820, 791, 739, 693; HRMS [Found: m/z
381.1558, Calcd for C23H22N2NaO2: (M + Na+), 381.1579].
-
friendly procedure. Also, [bmim+] [BF4 ] could be reused
VHYHUDOꢀWLPHVꢀZLWKRXWꢀVLJQL¿FDQWꢀORVVꢀRIꢀDFWLYLW\ꢁ
Experimental
Melting points were determined in open capillaries and are
uncorrected. IR spectra were recorded on a TENSOR 27 spectrometer
in KBr pellets. 1H NMR spectra were obtained from solution in
DMSO-d6 with Me4Si as an internal standard using a Bruker-400
spectrometer. HRMS analyses were carried out using a Bruker-micro-
TOF-Q-MS analyser.
2-Amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-4-(4-benzyloxy-
phenyl)-5-oxo-4H-benzo[b]pyran-3-carbonitrile (3fꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢅꢉ±
232°C; 1H NMR (DMSO-d6, G, ppm): 0.98 (s, 3H, CH3), 1.02 (s,
3H, CH3), 1.74 (s, 3H, CH3), 2.07 (d, J = 15.6 Hz, 1H, CH), 2.16 (d,
Jꢀ ꢀꢃꢍꢁꢌꢀ+]ꢄꢀꢃ+ꢄꢀ&+ꢇꢄꢀꢊꢁꢍꢉ±ꢊꢁꢍꢍꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 5.05 (s, 2H, CH2),
6.74 (s, 2H, NH2), 6.91 (d, J = 8.8 Hz, 2H, ArH), 7.16 (d, J = 8.8 Hz,
ꢊ+ꢄꢀ$U+ꢇꢄꢀꢐꢁꢅꢆ±ꢐꢁꢋꢊꢀꢂPꢄꢀꢅ+ꢄꢀ$U+ꢇꢄꢀꢐꢁꢋꢌꢀꢂGꢄꢀJ = 7.2 Hz, 2H, ArH); 13
C
General procedure for the syntheses of 2-amino-5,6,7,8-tetrahydro-
4,7,7- trimethyl-5-oxo-4-aryl-4H-benzo[b]pyran-3-carbonitrile 3
$ꢀGU\ꢀꢍꢉꢀP/ꢀÀDVNꢀZDVꢀFKDUJHGꢀZLWKꢀꢊꢎꢂꢃꢎDU\OHWK\OLGHQHꢇPDORQRQLWULOHꢀ
(2.0 mmol), 5,5-dimethylcyclohexane-1,3-dione (0.280 g, 2.0 mmol),
NMR (DMSO-d6,G, ppm): 25.6, 27.4, 27.5, 31.4, 37.2, 40.2, 51.4, 66.2,
69.2, 113.7, 116.0, 118.9, 127.5, 127.7, 127.8, 128.4, 137.2, 140.3,
156.26, 156.29, 161.0, 195.7. IR (KBr, Q, cm-1): 3304, 3327, 2953,
2902, 2862, 2193, 1666, 1604, 1508, 1468, 1456, 1408, 1370, 1350,
1316, 1238, 1238, 1177, 1066, 1046, 1014, 983, 962, 918, 865, 837;
HRMS [Found: m/z 437.1841, Calcd for C26H26N2NaO3: (M + Na+)
437.1841].
-
and [bmim+][BF4 ] (2 mL). The reaction mixture was stirred at 90°C
IRUꢀ ꢃꢊ±ꢃꢌꢀ Kꢄꢀ DQGꢀ WKHQꢀ FRROHGꢀ WRꢀ URRPꢀ WHPSHUDWXUHꢁꢀ 7KHꢀ JHQHUDWHGꢀ
\HOORZꢀVROLGꢀZDVꢀ¿OWHUHGꢀRIIꢄꢀDQGꢀWKHꢀLRQLFꢀOLTXLGꢀLQꢀWKHꢀ¿OWUDWHꢀZDVꢀWKHQꢀ
recovered for reuse by heating at 80°C for several hours under reduced
pressure. The crude yellow products were washed with water and
SXUL¿HGꢀE\ꢀUHFU\VWDOOLVDWLRQꢀIURPꢀ'0)ꢀDQGꢀZDWHUꢄꢀIROORZHGꢀE\ꢀEHLQJꢀ
dried at 80°C for several hours under reduced pressure to give 3.
2-Amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-4-(4-nitrophenyl)-5-
oxo-4H-benzo[b]pyran-3-carbonitrile (3aꢇꢏꢀ0ꢁSꢁꢀꢊꢉꢃ±ꢊꢉꢊ°C (Lit.21
2-Amino-5,6,7,8-tetrahydro-4-(4-methoxyphenyl)-4,7,7-trimethyl-
5-oxo-4H-benzo[b]pyran-3-carbonitrile (3gꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢋꢅ±ꢊꢋꢍ°C; 1H
NMR (DMSO-d6, G, ppm): 0.99 (s, 3H, CH3), 1.02 (s, 3H, CH3), 1.75
(s, 3H, CH3), 2.06 (d, J = 15.6 Hz, 1H, CH), 2.16 (d, J = 15.6 Hz, 1H,
&+ꢇꢄꢀꢊꢁꢍꢉ±ꢊꢁꢍꢍꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 3.73 (s, 3H, CH3O), 6.69 (s, 2H, NH2),
6.82 (d, J = 8.4 Hz, 2H, ArH), 7.16 (d, J = 8.4 Hz, 2H, ArH); 13C
NMR (DMSO-d6, G, ppm): 25.6, 27.3, 27.6, 31.4, 37.1, 40.2, 51.4,
54.9, 66.2, 112.9, 116.0, 118.9, 127.4, 140.1, 156.3, 157.0, 160.9,
195.7. IR (KBr, Q, cm-1): 3396, 3327, 2969, 2931, 2903, 2843, 2192,
1661, 1605, 1511, 1463, 1440, 1408, 1390, 1371, 1351, 1319, 1295,
1256, 1208, 1179, 1067, 1046, 1030, 981, 837; HRMS [Found: m/z
361.1526, Calcd for C20H22N2NaO3: (M + Na+) 361.1528].
1
ꢃꢈꢍ±ꢃꢈꢌ°C). H NMR (DMSO-d6, G, ppm): 1.05 (s, 3H, CH3), 1.03
(s, 3H, CH3), 1.79 (s, 3H, CH3), 2.10 (d, J = 15.6 Hz, 1H, CH), 2.18
(d, Jꢀ ꢀꢃꢍꢁꢌꢀ+]ꢄꢀꢃ+ꢄꢀ&+ꢇꢄꢀꢊꢁꢍꢉ±ꢊꢁꢍꢍꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 7.02 (s, 2H, NH2),
7.55 (d, J = 8.8 Hz, 2H, ArH), 8.15 (d, J = 8.8 Hz, 2H, ArH); 13C
NMR (DMSO-d6, G, ppm): 25.5, 27.4, 27.5, 30.7, 31.5, 38.2, 51.0,
64.4, 115.4, 118.5, 122.9, 127.8, 145.4, 155.7, 156.8, 162.0, 195.8.
IR (KBr, Q, cm-1): 3397, 3329, 2963, 2194, 1659, 1603, 1519, 1459,

236 JOURNAL OF CHEMICAL RESEARCH 2009
2-Amino-5,6,7,8-tetrahydro-4,7,7-trimethyl-5-oxo-4-p-tolyl-4H-
benzo[b]pyran-3-carbonitrile (3hꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢃꢅ±ꢊꢃꢍ°C; 1H NMR
(DMSO-d6, G, ppm): 0.99 (s, 3H, CH3), 1.02 (s, 3H, CH3), 1.74 (s,
3H, CH3), 2.06 (d, J = 15.6 Hz, 1H, CH), 2.16 (d, J = 15.6 Hz, 1H,
CH), 2.25 (s, 3H, CH3ꢇꢄꢀꢊꢁꢍꢃ±ꢊꢁꢍꢆꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 6.74 (s, 2H, NH2),
7.06 (d, J = 8.4 Hz, 2H, ArH), 7.13 (d, J = 8.4 Hz, 2H, ArH); 13C
NMR (DMSO-d6, G, ppm): 20.5, 27.3, 27.6, 31.4, 37.4, 40.1, 51.4,
66.1, 116.0, 118.8, 126.2, 128.3, 134.5, 145.0, 156.3, 161.0, 195.7.
IR (KBr, Q, cm-1): 3396, 3326, 3017, 2962, 2195, 1715, 1655,
1605, 1511, 1460, 1408, 1391, 1351, 1282, 1211, 1169, 1064, 1047,
1018, 986, 963, 918, 835; HRMS [Found: m/z 345.1579, Calcd for
C20H22N2NaO2: (M + Na+) 345.1579].
2-Amino-4-(3-bromophenyl)-5,6,7,8-tetrahydro-4,7,7-trimethyl-
5-oxo-4H-benzo[b]pyran-3-carbonitrile (3iꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢊꢊ±ꢊꢊꢋ°C;
1H NMR (DMSO-d6, G, ppm): 1.00 (s, 3H, CH3), 1.03 (s, 3H,
CH3), 1.73 (s, 3H, CH3), 2.10 (d, J = 15.6 Hz, 1H, CH), 2.19 (d,
Jꢀ ꢀꢃꢍꢁꢌꢀ+]ꢄꢀꢃ+ꢄꢀ&+ꢇꢄꢀꢊꢁꢋꢆ±ꢊꢁꢍꢈꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 6.90 (s, 2H, NH2),
7.26 (d, Jꢀ ꢀꢌꢁꢆꢀ+]ꢄꢀꢊ+ꢄꢀ$U+ꢇꢄꢀꢐꢁꢅꢍ±ꢐꢁꢅꢐꢀꢂPꢄꢀꢊ+ꢄꢀ$U+ꢇꢑꢀ13C NMR
(DMSO-d6, G, ppm): 25.4, 27.3, 27.5, 31.5, 37.8, 40.1, 51.2, 65.2,
115.5, 118.6, 121.2, 125.6, 128.6, 129.0, 129.9, 150.7, 156.6, 161.7,
195.7. IR (KBr, Q, cm-1): 3393, 3327, 2967, 2890, 2194, 1656, 1605,
1569, 1468, 1416, 1389, 1371, 1350, 1317, 1272, 1211, 1166, 1123,
1048, 986, 966, 961, 880, 804, 764, 713, 698; HRMS [Found: m/z
409.0518, Calcd for C19H1979BrN2NaO2: (M + Na+) 409.0528].
The expected MS intensity pattern due to Br isotopes was observed.
2-Amino-4-(4-bromophenyl)-5,6,7,8-tetrahydro-4,7,7-trimethyl-
5-oxo-4H-benzo[b]pyran-3-carbonitrile (3jꢇꢏꢀ 0ꢁSꢁꢀ ꢊꢃꢅ±ꢊꢃꢋ°C;
1H NMR (DMSO-d6, G, ppm): 0.99 (s, 3H, CH3), 1.02 (s, 3H,
CH3), 1.73 (s, 3H, CH3), 2.08 (d, J = 15.6 Hz, 1H, CH), 2.17 (d,
Jꢀ ꢀꢃꢍꢁꢌꢀ+]ꢄꢀꢃ+ꢄꢀ&+ꢇꢄꢀꢊꢁꢍꢃ±ꢊꢁꢍꢌꢀꢂPꢄꢀꢊ+ꢄꢀ&+2), 6.88 (s, 2H, NH2),
7.21 (d, J = 8.4 Hz, 2H, ArH), 7.46 (d, J = 8.4 Hz, 2H, ArH); 13C
NMR (DMSO-d6, G, ppm): 25.4, 27.4, 27.5, 31.4, 37.6, 40.1, 51.2,
65.3, 115.6, 118.7, 118.8, 128.7, 130.5, 147.4, 156.5, 162.4, 195.7.
IR (KBr, Q, cm-1): 3393, 3325, 3013, 2963, 2872, 2194, 1715, 1656,
1604, 1488, 1464, 1410, 1396, 1351, 1317, 1276, 1211, 1169, 1078,
1048, 1008, 986, 963, 841; HRMS [Found: m/z 409.0519, Calcd for
C19H1979BrN2NaO2: (M + Na+) 409.0528]. The expected MS intensity
pattern due to Br isotopes was observed.
3060, 3008, 2962, 2871, 2196, 1681, 1605, 1491, 1447, 1407, 1350,
1316, 1267, 1211, 1167, 1047, 984, 961, 917, 808, 741, 699; [Found:
m/z 331.1417, Calcd for C19H20NaN2O2: (M + Na+) 331.1422].
We are grateful to the Foundation of National Natural Science
Foundation of China (no. 20802061) and Natural Science
Foundation of the Education Committee of Jiangsu Province
ꢂꢉꢆ.-'ꢃꢍꢉꢉꢃꢈꢇꢀIRUꢀ¿QDQFLDOꢀVXSSRUWꢁ
Received 24 November 2008; accepted 19 February 2009
Paper 08/0304 doi: 10.3184/030823409X431373
Published online: 29 April 2009
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