3140 Kumari et al.
Asian J. Chem.
reaction mixture was left overnight and mixed with crushed
ice to get a solid product, filtered, dried and crystallized from
methanol to get VI, yield 80 %, m.p. 253-255 °C (lit. 251-253
°C)12. IR (nujol, νmax, cm-1): 3390 (OH), 1685 (C=O), 1365
4-Methyl-2-oxo-2H-1-benzopyran-7-yl phenylcar-
bamate (XIII):Yield 76 %, m.p. 138-140 °C. IR (nujol, νmax
,
cm-1): 3400 (NH), 1695 (NH-CO), 1680 (C=O). 1H NMR (400
MHz, DMSO-d6): 2.45 (s, 3H, C4-CH3); 5.94 (s, 1H, C3-H);
6.89 (s, 1H, C8-H); 6.97 (s, 1H, C6-H); 6.92-7.48 (m, 5H, Ar-
H); 8.49 (s, 1H, NH). Analysis found: C, 69.34; H, 4.40; N,
4.69 %; C17H13NO4 Required: C, 69.15; H, 4.44; N, 4.74 %.
4-Methyl-2-oxo-2H-1-benzopyran-7,8-diyl bis(phenyl-
carbamate) (XIV): Yield 74 %, m.p. 226-227 °C. IR (nujol,
νmax, cm-1): 3392 (NH), 1695 (NH-CO), 1670 (C=O). 1H NMR
(400 MHz, DMSO-d6): 2.39 (s, 3H, C4-CH3); 5.88 (s, 1H, C3-
H); 6.93 (s, 1H, C5-H); 7.09-7.51 (m, 10H,Ar-H); 7.98 (s, 1H,
NH).Analysis found: C, 66.47; H, 4.20; N, 6.36 %. C24H18N2O6
Required: C, 66.97; H, 4.22; N, 6.51 %.
1
(C-CH3). H NMR (400 MHz, DMSO-d6): 2.28 (s, 3H, C4-
CH3); 2.56 (s, 3H, C5-CH3); 5.91(s, 1H, C3-H); 6.51(s, 1H, C8-
H); 6.56 (s, 1H, C6-H). Analysis found: C, 69.61; H, 5.29 %;
C11H10O3 Required: C, 69.46; H, 5.30 %.
Compounds VII-IX were prepared similarly from II-IV
and V respectively.
7-Hydroxy-4-methyl-2H-1-benzopyran-2-one (VII):
Yield 78 %, m.p. 183 °C (lit. 185-186 °C)13. IR (nujol, νmax
,
cm-1): 3400 (OH), 1671 (C=O), 1390 (C-CH3). 1H NMR (400
MHz, DMSO-d6): 2.38 (s, 3H, C4- CH3); 6.03(s, 1H, C3-H);
6.71 (s, 1H, C8-H); 6.80 (d, J = 7.5 Hz, 1H, C6-H); 7.48 (d, J =
7.5 Hz, 1H, C5-H). Analysis found: C, 68.12; H, 4.55 %.
C10H8O3 Required: C, 68.18; H, 4.58 %.
6-Chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl
phenylcarbamate (XV): Yield 78 %, m.p. 268-269 °C. IR
(nujol, νmax, cm-1): 3400 (NH), 1700 (NH-CO), 1668 (C=O),
754 (C-Cl). 1H NMR (400 MHz, DMSO-d6): 2.36 (s, 3H, C4-
CH3); 6.09 (s, 1H, C3-H); 6.87 (s, 1H, C8-H); 6.93 (s, 1H, C5-
H); 6.96-7.59 (m, 5H,Ar-H); 8.55 (s, 1H, NH).Analysis found:
C, 61.71; H, 3.66; N, 4.27 %. C17H12NO4Cl Required: C, 61.92;
H, 3.67; N, 4.25 %.
7,8-Dihydroxy-4-methyl-2H-1-benzopyran-2-one
(VIII):Yield 78 %, m.p. 239 °C (lit.235-237 °C)14. IR (nujol,
νmax, cm-1): 3231(OH), 1651 (C=O), 1371 (C-CH3). 1HNMR
(400 MHz, DMSO-d6): 2.30 (s, 3H, C4-CH3); 6.05 (s, 1H, C3-
H); 6.95-7.75 (m, 4H, Ar-H). Analysis found: C, 62.23; H,
4.22 %. C10H8O4 Required: C, 62.50; H, 4.20 %.
2-Oxo-2H-1-benzopyran-4-yl phenylcarbamate (XVI):
Yield 80 %, m.p. 187-188 °C. IR (nujol, νmax, cm-1): 3380 (NH),
1710 (NH-CO), 1695 (C=O). Analysis found: C, 68.28; H,
3.69; N, 4.94 %. C16H11NO4 Required : C, 68.32; H, 3.94; N,
4.98%.
6-Chloro-7-hydroxy-4-methyl- 2H-1-benzopyran-2-
one (IX):Yield 82 %, m.p. 268-270 °C. IR (nujol, νmax, cm-1):
3370 (OH), 1678 (C=O), 844 (C-Cl), 1605 (C=C), 1390 (C-
1
CH3) H NMR (400 MHz, DMSO-d6): 2.37(s, 1H, C4-CH3);
6.08 (s, 1H, C3-H); 6.89 (s, 1H, C5-H); 7.55 (s, 1H, C8-H).
Analysis found: C, 57.36; H, 3.37. C10H7O3Cl Required: C,
57.03; H, 3.35.
Nematicidal bioevaluation: The plant parasitic nematode
Meloidogyne javanica was used as test organism. Stock solutions
of 2000 mg L-1 of all the compounds were prepared by
dispersing these in acetone. Nematicidal activity was evaluated
against second stage juveniles (J2) of M. javanica.A suspension
of juveniles (1 mL) was poured into 5 cm Petri-dishes.
Measured quantities of stock solution were added to these Petri-
dishes to make final concentrations of 1000, 500, 250 and 125
ppm. Acetone and water were used as control. Each treatment
was replicated three times. These Petri-dishes were kept in
BOD incubator at 28 1 °C. Observations were recorded after
24 h and 48 h by counting live (active) and dead (inactive) J2s
under a stereoscopic binocular microscope and the per cent
mortality was counted16. The revival of immobilized nematodes
was examined by randomly transferring ten J2s to water for 24
h. None of those immobilized J2s revived. The experimental
data was statistically analyzed using two factorial completely
randomized design; the compounds and the concentrations
constituting the two factors.
4-Hydroxy 2H-1-benzopyran-2-one (X)15:A mixture of
malonic acid monophenyl ester (180 mg, 1 mmol) and Eaton's
reagent (3 mL) was stirred at 70 °C for 1 h and then water was
added to this mixture while stirring vigorously. Completion
of the reaction was monitored by TLC. The precipitate was
filtered, washed with water and dried to give a solid. It was
recrystallized from ethanol to afford X.Yield 80 %, m.p. 209-
1
210 °C. IR (nujol, νmax, cm-1): 3380 (OH), 1680 (C=O). H
NMR (400 MHz, DMSO-d6): 5.56 (s, 1H, C3-H); 7.19-7.25
(m, 2H); 7.48-7.53 (m, 1H); 7.72 (d, 1H, J = 8.0 Hz); 11.95 (s,
1H, OH). Analysis found: C, 66.17; H, 3.76 %. C9H6O3
Required : C, 66.67; H, 3.73 %.
4,5-Dimethyl-2-oxo-2H-1-benzopyran-7-yl phenyl-
carbamate (XII): A mixture of 7-hydroxy-4,5-dimethyl-2H-
1-benzopyran-2-one (VI, 3.80 g, 20 mmol) and phenyliso-
cyanate (XI, 2.38 g, 20 mmol) in dry benzene (20 mL) was
refluxed for 12 h on steam bath. Completion of the reaction
was monitored by TLC. It was then concentrated under vacuum,
to give solid residue which was crystallized from methanol to
afford XII,Yield: 78 %, m.p. 218-220 °C. IR (nujol, νmax, cm-1):
3370 (NH), 1690 (NH-CO), 1680 (C=O). 1H NMR (400 MHz,
DMSO-d6): 2.29 (s, 3H, C4-CH3); 2.55 (s, 3H, C5-CH3); 5.93
(s, 1H, C3-H) 6.53 (s, 1H, C6-H); 6.92 (s, 1H, C8-H); 7.22-
7.46 (m, 5H,Ar-H); 8.50 (s, 1H, NH).Analysis found: C, 69.54;
H, 4.82; N, 4.51 %. C18H15NO4 Required: C, 69.89; H, 4.89;
N, 4.53 %.
RESULTS AND DISCUSSION
Pechmann condensation of orcinol (I), resorcinol (II),
pyrogallol (III) and 4-chlororesorcinol (IV) with benzyl
acetoacetate (V), gave their corresponding 7-hydroxy-4, 5-
dimethyl-2H-1-benzopyran-2-one (VI), 7-hydroxy-4-methyl-
2H-1-benzopyran-2-one (VII), 7, 8-dihydroxy-4-methyl-2H-
1-benzopyran-2-one (VIII) and 6-chloro-7-hydroxy-4-methyl-
2H-1-benzopyran-2-one (IX) (Scheme-I).
1
Their H NMR spectra were in accordance with the
proposed structures. In the spectrum (400 MHz) of 7-hydroxy-
4-methyl-2H-1-benzopyran-2-one (VII), the diagnostic proton
Other compounds XIII-XVI were prepared similarly from
VII-X and XI respectively.