Job/Unit: O43524
/KAP1
Date: 30-01-15 13:22:40
Pages: 8
K. Sudarshan, M. K. Manna, I. S. Aidhen
FULL PAPER
(3 mL), and the mixture was stirred for 2 h under a hydrogen atmo-
sphere at room temperature. After stirring, the solvent was evapo-
rated under reduced pressure, and the obtained residue was purified
by silica gel column chromatography to obtain the desired product
as a pale yellow solid, yield 92% (0.055 g). Rf = 0.41 (EtOAc/hex-
anes = 2:3), m.p. 243–245 °C (ref.[13c] 241–244 °C). 1H NMR
(500 MHz, [D6]DMSO): δ = 6.86 (d, J = 8.0 Hz, 1 H), 6.91 (d, J
= 8.0 Hz, 1 H), 7.21–7.23 (m, 2 H), 7.28 (s, 1 H), 7.08 (d, J =
7.5 Hz, 1 H), 7.67 (t, J = 7.5 Hz, 1 H), 9.34 (s, 1 H, OH), 9.61 (s,
1 H, OH), 10.84 (s, 1 H, OH) ppm. 13C NMR (125 MHz, CDCl3):
δ = 100.7, 105.3, 112.3, 114.1, 116.1, 116.7, 117.1, 122.4, 137.7,
Supporting Information (see footnote on the first page of this arti-
1
cle): Experimental details and copies of the H NMR, 13C NMR,
and HRMS spectra of all new compounds.
Acknowledgments
The authors thank the Department of Science and Technology
(DST), New Delhi, for funding towards the 400 MHz NMR spec-
trometer to the Department of Chemistry, Indian Institute of Tech-
nology Madras (IIT-Madras), under the Intensification of Re-
search in High Priority Areas (IRPHA) Scheme and the ESI-MS
facility under the Fund for Improvement of Science & Technology
Infrastructure (FIST) program. The Board of Research in Nuclear
Sciences (BRNS) is acknowledged for funding of project-2013.
K. S. acknowledges the University Grants Commission (UGC),
New Delhi for a Senior Research Fellowship.
138.6, 145.7, 147.9, 152.8, 160.5, 165.3 ppm. IR (KBr): ν = 2980,
˜
2851, 1669, 1612, 1525, 1172 cm–1. HRMS (ESI): calcd. for
C15H10O5Na [M + Na]+ 293.0426; found 293.0420.
Synthesis of O-Prenyl Ether 24: Under a nitrogen atmosphere, an-
hydrous K2CO3 (0.495 g, 3.58 mmol) and prenyl bromide (0.12 mL,
1.07 mmol) were added to a stirred solution of isocoumarin 23
(0.240 g, 0.89 mmol) in dry DMF (8 mL). After 5 h, the mixture
was diluted with water (10 mL) and extracted with EtOAc (3ϫ
15 mL). The combined organic layer was washed with water (3ϫ
20 mL) and brine (15 mL) and was finally dried with Na2SO4. The
solvent was evaporated, and the obtained residue was purified by
silica gel column chromatography (EtOAc/hexanes = 1:4) to yield
title compound 24, yield 85% (0.255 g). Rf = 0.54 (EtOAc/hexanes
= 1:4). Colorless solid, m.p. 117–119 °C (ref.[11b] 123–124 °C). 1H
NMR (500 MHz, CDCl3): δ = 1.77 (s, 3 H, OCH3), 1.79 (s, 3 H,
OCH3), 3.89 (s, 3 H, OCH3), 4.70 (d, J = 6.3 Hz, 2 H), 5.55–5.59
(m, 1 H), 6.45 (s, 2 H), 6.76 (s, 1 H), 7.40–7.44 (m, 3 H), 7.84–7.87
(m, 2 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 18.5, 25.9, 55.7,
66.5, 100.2, 100.6, 102.0, 103.9, 119.4, 125.4, 128.8, 130.0, 132.1,
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137.9, 142.2, 154.3, 158.7, 162.7, 165.3 ppm. IR (KBr): ν = 3022,
˜
2926, 1591, 1424, 1213 cm–1. HRMS (ESI): calcd. for C21H20O4Na
[M + Na]+ 359.1259; found 359.1252.
Synthesis of Cajanolactone A (2): Montmorillonite K10 (0.300 g)
was added to a solution of O-prenyl ether 24 (0.100 g, 0.29 mmol)
in dry CH2Cl2 (4 mL) at 0 °C. The mixture was stirred for 1.5 h at
room temperature. After this, the mixture was filtered through a
pad of Celite, and the residue was washed with CH2Cl2. The sol-
vent was evaporated, and the obtained residue was purified by silica
gel column chromatography (EtOAc/hexanes = 1:4) to yield title
compound 2 (30%), along with 25 (18%) and 23 (20%). Data for
2: Yield: 30% (0.030 g). Rf = 0.44 (EtOAc/hexanes = 1:4). Colorless
[9] a) Q. Wang, H. Matsuda, K. Matsuhira, S. Nakamura, D.
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1
solid, m.p. 125–127 °C (ref.[11b] 127–129 °C). H NMR (400 MHz,
CDCl3): δ = 1.69 (s, 3 H, CH3), 1.85 (s, 3 H, CH3), 3.45 (d, J =
6.8 Hz, 2 H, allylic CH2 of prenyl group), 3.89 (s, 3 H, OCH3),
5.05–5.09 (m, 1 H, vinylic CH of prenyl group), 6.52 (s, 1 H, C7-
H), 7.03 (s, 1 H, C4-H), 7.42–7.49 (m, 3 H), 7.81–7.85 (m, 2 H),
11.29 (s, 1 H, OH) ppm. 13C NMR (100 MHz, CDCl3): δ = 18.1,
23.7, 25.8, 56.0, 98.3, 99.7, 100.1, 116.1, 122.7, 125.3, 129.0, 130.1,
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Tang, Chin. Chem. Lett. 2014, 25, 749.
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Soehano, X.-W. Liu, Z.-X. Liang, J. Am. Chem. Soc. 2012, 134,
11924; b) T. N. Trotter, A. M. M. Albury, M. P. Jennings, J.
Org. Chem. 2012, 77, 7688; c) K. Cherry, J.-L. Parrain, J. Thi-
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d) F. Bellina, D. Ciucci, P. Vergamini, R. Rossi, Tetrahedron
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X. Guo, J. Org. Chem. 2013, 78, 1660; f) L. Ackermann, J.
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R. K. Chinnagolla, M. Jeganmohan, Chem. Commun. 2012, 48,
2030; h) M. P. Pavan, M. Chakravarty, K. C. K. Swamy, Eur.
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D. Hill, R. C. Larock, J. Comb. Chem. 2009, 11, 1128; j) K.
Ueura, T. Satoh, M. Miura, J. Org. Chem. 2007, 72, 5362; k)
K. Ueura, T. Satoh, M. Miura, Org. Lett. 2007, 9, 1407; l) Y.
Liang, Y.-X. Xie, J.-H. Li, Synthesis 2007, 400; for 3,4-dihy-
droisocoumarins, see: m) P. Zhao, D. Chen, G. Song, K. Han,
X. Li, J. Org. Chem. 2012, 77, 1579; n) S. K. Mandal, S. C.
132.0, 132.1, 136.1, 152.6, 162.6, 164.4, 166.5 ppm. IR (KBr): ν =
˜
3684, 3025, 2926, 2854, 1516 cm–1. HRMS (ESI): calcd. for
C21H21O4 [M + H]+ 337.1440; found 337.1433. Data for 25: Yield:
18% (0.018 g). Rf = 0.41 (EtOAc/hexanes = 1:4). Colorless solid,
m.p. 152–154 °C. 1H NMR (400 MHz, CDCl3): δ = 1.68 (s, 3 H,
CH3), 1.80 (s, 3 H, CH3), 3.40 (d, J = 7.0 Hz, 2 H, allylic CH2 of
prenyl group), 3.93 (s, 3 H, OCH3), 5.19–5.24 (m, 1 H, Vinylic CH
of prenyl group), 6.45 (s, 1 H, C5-H), 6.88 (s, 1 H, C4-H), 7.43–
7.47 (m, 3 H), 7.83 (d, J = 7.8 Hz, 2 H), 11.22 (s, 1 H, OH) ppm.
13C NMR (100 MHz, CDCl3): δ = 17.9, 22.2, 25.9, 56.0, 98.3,
100.5, 103.1, 116.9, 121.6, 125.2, 128.9, 130.0, 131.7, 132.3, 137.2,
152.8, 160.0, 164.4, 166.2 ppm. IR (KBr): ν = 3684, 3025, 2926,
˜
2854, 1516 cm–1. HRMS (ESI): calcd. for C21H21O4 [M + H]+
337.1440; found 337.1429.
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