Feasibility of sigmatropic rearrangement on electron-deficient coumarinyl ketones

Article abstract of DOI:10.1139/V08-037

Different alkyl/aryl 7-hydroxy-8-coumarinyl ketones were converted to 7-O-allyl and 7-O-cyclohexenyl ethers and the study of hitherto unreported sigmatropic rearrangement on 7-O-allyl and 7-O-cyclohex-2'-ene-1'-ylcoumarinyl ketones prepared is accounted h

Full text of DOI:10.1139/V08-037

401
Feasibility of sigmatropic rearrangement on
electron-deficient coumarinyl ketones
Lakshmi Narayan Dutta, Banani De, Godhuli Pal, and Amarendra Patra
Abstract: Different alkyl/aryl 7-hydroxy-8-coumarinyl ketones were converted to 7-O-allyl and 7-O-cyclohexenyl ethers
and the study of hitherto unreported sigmatropic rearrangement on 7-O-allyl and 7-O-cyclohex-2′-ene-1′-ylcoumarinyl ke-
tones prepared is accounted herein. The rearrangement yielded alkyl/aryl 6-allyl-7-hydroxy-8-coumarinyl ketones 3 and
alkyl/aryl 6-cyclohex-2′-en-1′-yl-7-hydroxy-8-coumarinyl ketones 7 as the major products. Interestingly, unusual selectivity
was observed in the case of alkyl 7-O-allylcoumarinyl ketones. Thus alkyl 3-allyl-7-hydroxy-8-coumarinyl ketones 4 and
alkyl 8-allyl-7-hydroxy-6-coumarinyl ketones 5 were the outcome from alkyl 7-O-allyl-8-coumarinyl ketones and alkyl 4-
methyl-7-O-allyl-8-coumarinyl ketones, respectively, albeit in minor yields.
Key words: allyloxycoumarinyl ketones, 7-O-cyclohex-2′-en-1′-ylcoumarinyl ketones, sigmatropic rearrangement, 3-
allylcoumarinyl ketones, 8-allylcoumarinyl ketones.
Résumé : On a transformé diverses alkyl/aryl 7-hydroxy-8-coumarinylcétones en leurs éthers, les oxydes de 7-O-allyle et 7-
O-cyclohexényle correspondants, et on rapporte les résultats obtenus lors des réarrangements sigmatropiques qui n’avaient ja-
mais été rapportés antérieurement et qui ont été effectués sur les 7-O-allyl- et 7-O-cyclohex-2′-én-1′-ulcoumarinylcétones ainsi
préparées. Les produits principaux de ces réactions sont les alkyl/aryl 6-allyl-7-hydroxy-8-coumarinylcétones, 3, et les al-
kyl/aryl 6-cyclohex-2′-én-1′-yl-7-hydroxy-8-coumarinylcétones, 7. On a observé une sélectivité inhabituelle intéressante dans
le cal des alkyl 7-O-allylcoumarinylcétones. Même s’ils n’ont été obtenus qu’avec de faibles rendements, les alkyl 3-allyl-7-
hydroxy-8-coumarinylcétones, 4, et alkyl 8-allyl-7-hydroxy-6-coumarinylcétones, 5, sont les produits obtenus à partir respecti-
vement des 7-O-allyl-8-coumarinylcétones et alkyl 4-méthyl-7-O-allyl-8-coumarinylcétones.
Mots-clés : allyloxycomarinylcétones, 7-O-cyclohex-2′-én-1′-ylcoumarinylcétones, réarrangement sigmatropique, 3-
allylcoumarinylcétones, 8-allylcoumarinylcétones.
[Traduit par la Rédaction] Dutta et al. 409
Introduction
bearing further electron-rich and electron-deficient
functionalities. Herein we report the findings of an intense
investigation on Claisen rearrangement restricting the
functionalisation to the electron-deficient coumarinyl ke-
tones.
Coumarins (1, 2) have attracted the attention of synthetic
organic chemists (3–5) throughout the globe for building up
new exotic molecules owing to their well-established range
of biological activities (6–10). In quest of newer synthetic
methodologies we have successfully carried out a series of
systematic studies on the selectivities of different
organometallics (11, 12) and ylids (13) involving typical
non-concerted processes on coumarinyl ketones and
coumarincarboxaldehydes. Under the scope of concerted
process we have extensively applied a sigmatropic reaction
in the form of thermal Claisen rearrangement for the synthe-
sis of various natural and unnatural coumarins. In spite of a
flurry of activity in the synthesis of coumarin employing
Claisen rearrangement (14–20), there is virtually no report
on the efficacy of the rearrangement on the coumarin moiety
Discussion
The starting materials selected for this study, viz. 7-
allyloxy-8-coumarinyl alkyl/aryl ketones 2a–2h and 7-
cyclohex-2′-en-1′-yloxy-8-coumarinyl alkyl/aryl ketones 6a–
6h were prepared from 7-hydroxy-8-coumarinyl alkyl/aryl
ketones 1a–1h. The hydroxycoumarinyl ketones could be
procured from 7-hydroxycoumarin and 4-methyl-7-
hydroxycoumarin, as appropriate, exploiting Fries rearrange-
ment (21). The aforesaid allyl coumarinyl ethers have thus
been successfully prepared in good yield by following the
usual protocol of refluxing the compounds for 8 h in dry
acetone with allyl bromide in the presence of anhydrous
K2CO3. An initial sigmatropic rearrangement study revealed
that the allyl ethers failed to record any positive result in sol-
vents like chlorobenzene and polyethylene glycol 400. Con-
sequent to that, the rearrangement was tried and ultimately
became successful in N,N-diethylaniline. The C–C bond for-
mations showed typical selectivities by yielding 6-allyl sub-
Received 26 November 2007. Accepted 22 February 2008.
Published on the NRC Research Press Web site at
canjchem.nrc.ca on 3 April 2008.
L.N. Dutta,1 B. De, G. Pal. Department of Chemistry,
Jadavpur University, Kolkata 700 032, India
A. Patra. Centre of Advanced Studies on Natural Products,
Department of Chemistry, University College of Science,
Kolkata 700 009, India.
stituted coumarinyl ketones
3 and 3-allyl substituted
1Corresponding author (e-mail: amarendra@satyam.net.in).
coumarinyl ketones 4 with 7-allyloxy-8-coumarinyl ketones
Can. J. Chem. 86: 401–409 (2008)
doi:10.1139/V08-037
© 2008 NRC Canada

402
Can. J. Chem. Vol. 86, 2008
, anhyd. K2CO3, dry Me2CO, 14 h, and reflux; (ii) PhNEt2, 195 °C, and 8 h.
Scheme 1. Reagents and conditions: (i)
Scheme 2. Reagents and conditions: (i)
, NEt3, dry Me2CO, 4 h, and reflux. (ii) Ph2O, reflux for 10 min.
Table 1. Yields of the compounds 2 to 7.
2a, 2c, and 2e, whereas the 4-methyl-7-allyloxy-8-
coumarinyl ketones 2b, 2d, and 2f resulted in 6-allyl substi-
tuted coumarinyl ketones 3 along with 8-allyl substituted 6-
coumarinyl ketones 5 as a consequence of unusual acyl mi-
gration. The allyl ethers having benzoyl coumarinyl func-
tionality, 2g and 2h, did produce only the usual 6-allyl
substituted coumarinyl ketones without any trace of other re-
arranged products (Scheme 1).
It should be noted that attempted cyclohexenylation of
hydroxycoumarinyl ketones following the usual protocol of
refluxing in dry acetone with 3-bromocyclohexene in the
presence of anhydrous K2CO3 (22) turned out to be entirely
unsuccessful. Finally the problem was overcome through the
judicious selection of a base, viz. triethylamine instead of
anhydrous K2CO3 (Scheme 2). It should be emphasized that
the study of Claisen rearrangement turned out to be remark-
ably successful in diphenyl ether as solvent, while the yield
was extremely poor when carried out in chlorobenzene
(<5%) and N,N-diethylaniline (~10%). The cyclohexenyl
ethers on Claisen rearrangement underwent regioselective
formation of 6-cyclohex-2′-ene-1′-yl-8-coumarinyl alkyl/aryl
ketones 7a–7h in good yields (Table 1). No unusual acyl mi-
gration or Claisen rearrangement on other positions of
coumarin moiety was observed with cyclohexenyl ethers.
The formation of 6-allyl and 6-cyclohexenyl substituted
coumarinyl ketones turned out to be quite obvious via an in-
Substituents
R1
Yield (%)
Entry
R2
2
3
4
5
6
7
1
2
3
4
5
6
7
8
a
b
c
d
e
f
H
Me
H
Me
H
Me
H
Me
Me
Et
83
83
84
85
84
84
85
85
44
46
41
42
43
43
47
44
40
—
26
—
24
—
—
—
—
33
—
26
—
26
—
—
66
93
76
63
70
78
76
89
60
62
62
65
59
61
59
58
Et
n-Pr
n-Pr
Ph
g
h
Me
Ph
7-allyloxy-8-coumarinyl ketones may be rationalized from
the intermediate C formed via a [3,3] sigmatropic shift,
which further underwent Cope rearrangement with the trans-
fer of allyl functionality at the 4a position, leading to the in-
termediate C. The intermediate C follows an itinerary of
further [3,3] Cope rearrangement followed by [1,7] tauto-
meric shift to afford the 3-allyl substituted coumarinyl ke-
tones. The 4-methyl-7-allyloxycoumarinyl ketones prefer to
follow from the intermediate B as an alternative pathway
leading to the anionic intermediate D, along with the ejected
acylium ion R-CϵO+ that may exist, most plausibly enjoying
the character of an intimate ion pair though the feasibility of
a concerted mechanism cannot be ruled out. On further
chemical mutation to intermediate F, the 6-acyl-8-
allylcoumarinyl ketones are being derived via the [1,3] tau-
tomeric shift.
termediate
A (Scheme 3). In the formation of 3-
allylcoumarinyl ketones, the intermediate C may be visual-
ized as a consequence of a [3,3] Cope rearrangement of the
intermediate B produced via a [3,3] sigmatropic shift. Alter-
natively, the genesis of 3-allylcoumarinyl ketones from alkyl
© 2008 NRC Canada

Dutta et al.
403
Scheme 3.
Table 2. Chemical shift (δ) values of C-5 protons and C-6, C-8
carbon signals.
The structures of the compounds were unequivocally set-
tled from elemental analyses and extensive spectroscopic in-
vestigations. Assignment of the structures of 6-allyl and 8-
allylsubstituted coumarinyl ketones posed an interesting prob-
lem and could be unequivocally solved by critical analysis of
δ Value
Location of
ketoalkyl
C-5 proton C-6 carbon C-8 carbon
1
the H NMR and 13C NMR spectra, with particular emphasis
Compound functionality signal
signal
signal
on the proton signals of C-5 and carbon signals of C-6 and C-
8. The proton signals at the 5-position enjoy more deshielding
because of the anisotropic effect offered by the newly arrived
adjacent ketocarbonyl functionality. On the contrary, the C-6
carbon signal of 8-allyl substituted compounds are more
shielded than those of the 6-allyl substituted compounds (23)
(Table 2), and the C-8 signals varied oppositely.
3b
5b
3d
5d
3f
C-8
C-6
C-8
C-6
C-8
C-6
7.48
7.88
7.43
7.95
7.49
7.95
126.1
112.4
126.2
112.5
126.1
112.5
108.6
116.3
108.7
116.0
108.7
116.2
5f
Conclusion
moiety may be rationalized either from steric or electronic
considerations. The plausible explanation of such selectivity
in favor of the electronic and (or) steric effect of methyl
group can only be confirmed on further study of Claisen re-
arrangement on 7-allyloxy-8-coumarinyl ketones with vary-
ing substituents (Et, n-Pr, i-Pr, t-Bu, CHO, CN, CO2Me,
CH2OH) at the 4-position.
In conclusion, it is worth mentioning that an unusual se-
lectivity was observed in the product formation with the in-
troduction of a methyl group at the 4-position of the 7-
allyloxy-8-coumarinyl ketone moiety. The changeover in the
character of the minor products with the introduction of
methyl group at the 4-position of the 8-coumarinyl ketone
© 2008 NRC Canada

404
Can. J. Chem. Vol. 86, 2008
OCH2CH=CHAHB), 5.37 (d,
J
=
17.0 Hz, 1H,
Experimental
OCH2CH=CHAHB), 5.98 (m, 1H, OCH2CH=CH2), 6.24 (d,
J = 9.0 Hz, 1H, 3-H), 6.84 (d, J = 9.0 Hz, 1H, 6-H), 7.43 (d,
J = 9.0 Hz, 1H, 5-H), 7.63 (d, J = 9.0 Hz, 1H, 4-H). Anal.
calcd. for C15H14O4: C 69.75, H 5.46; found: C 69.70, H
5.41.
All melting points were determined in open capillaries
and are uncorrected. IR spectra (νmax in cm–1) were recorded
in KBr with a PerkinElmer 883-IR and RXI FT IR spectro-
photometers. The UV spectra were measured in 95% ethanol
using an Hitachi U 2000 and Lamda 20 ELMER spectropho-
tometers. The elemental analyses were carried out in a
Compound 2d
PerkinElmer 240C elemental analyzer. The 1H NMR and 13
C
Mp 70 °C. IR (cm–1): 3090, 2990, 1745, 1710, 1605,
1
NMR spectra were recorded in a Bruker AV300 supercon
NMR spectrometer operating at 300.13 MHz for proton and
75.47 MHz for carbon, using CDCl3 as solvent and TMS as
an internal standard. Mass spectra were recorded on a
Finnigan Mat 1020 C, Shimadzu Model GEMS QP1000A,
and LC-MS MS Q-TOF-micro spectrometers and a Q TRAP
LC/MS/MS system operative at 70 eV. The column chro-
matographic separation and filtration were performed with
silica gel (mesh size 60–120) prepared by Glaxo (India) Ltd
and Merck (India) Ltd. Petroleum ether used had a boiling
point 60–80 °C.
1570, 1495, 1380. H NMR δ: 1.21 (t, J = 7.0 Hz, 3H, 2′-
CH3), 2.39 (d, J = 1.0 Hz, 3H, 4-CH3), 2.91 (q, J = 7.0 Hz,
2H, 1′-CH2), 4.60 (d, J = 5.0 Hz, 2H, OCH2CH=CH2), 5.45
(d, J = 10.0 Hz, 1H, OCH2CH=CHAHB), 5.52 (d, J =
16.0 Hz, 1H, OCH2CH=CHAHB), 6.02 (m, 1H,
OCH2CH=CH2), 6.15 (q, J = 1.0 Hz, 1H, 3-H), 6.88 (d, J =
7.2 Hz, 1H, 6-H), 7.51 (d, J = 7.2 Hz, 1H, 5-H). Anal. calcd.
for C16H16O4: C 70.57, H 5.92; found: C 70.60, H 5.88.
Compound 2e
Mp 52 °C. IR : 3080, 2970, 1760, 1710, 1610, 1560,
1
1490, 1410. H NMR δ: 0.93 (t, J = 5.1 Hz, 3H, 3′-CH3),
Preparation of 7-allyloxycoumarinyl ketones 2a–2h
1.68 (tq, J = 5.1 Hz, 5.1 Hz, 2H, 2′-CH2), 2.77 (t, J = 5.1 Hz,
2H, 1′-CH2), 4.56 (d, J = 6.0 Hz, 2H, OCH2CH=CH2), 5.23
(d, J = 12.0 Hz, 1H, OCH2CH=CHAHB), 5.28 (d, J =
18.0 Hz, 1H, OCH2CH=CHAHB), 5.90 (ddt, J = 18.0, 12.0,
6.0 Hz, 1H, OCH2CH=CH2), 6.17 (d, J = 9.0 Hz, 1H, 3-H),
6.78 (d, J = 9.0 Hz, 1H, 6-H), 7.36 (d, J = 9.0 Hz, 1H, 5-H),
7.57 (d, J = 9.0 Hz, 1H, 4-H). Anal. calcd. for C16H16O4: C
70.57, H 5.92; found: C 70.52, H 5.99.
General procedure
7-Hydroxycoumarinyl ketones (4.3 mmol) dissolved in
dry acetone (50 mL) were treated with allyl bromide
(4.9 mmol) and anhydrous K2CO3 (4.3 mmol) and refluxed
under anhydrous conditions on water bath for ~14 h. Excess
acetone was distilled off and the residual solid cakelike mass
was treated with water (150 mL). The mixture was acidified
in cold conditions with cold dil HCl (4 N). The solid sepa-
rated was filtered out and washed with cold water until it
was neutral. The resultant solid was dried and crystallized
from EtOAc/petroleum ether to obtain crystals of 7-
allyloxycoumarinyl ketones 2a–2h.
Compound 2f
Mp 70 °C. IR (cm–1): 3060, 2950, 1735, 1720, 1600,
1
1560, 1485, 1370. H NMR δ: 0.98 (t, J = 7.0 Hz, 3H, 3′-
CH3), 1.73 (tq, J = 7.0 Hz, 7.0 Hz, 2H, 2′-CH2), 2.38 (d, J =
1.0 Hz, 3H, 4-CH3), 2.83 (t, J = 7.0 Hz, 2H, 1′-CH2), 4.63
(d, J = 6.0 Hz, 2H, OCH2CH=CH2), 5.28 (d, J = 10.0 Hz,
1H, OCH2CH=CHAHB), 5.37 (d, J = 18.0 Hz, 1H,
OCH2CH=CHAHB), 5.97 (ddt, J = 18.0, 10.0, 6.0 Hz, 1H,
OCH2CH=CH2), 6.13 (q, J = 1.0 Hz, 1H, 3-H), 6.85 (d, J =
9.0 Hz, 1H, 6-H), 7.52 (d, J = 9.0 Hz, 1H, 5-H). Anal. calcd.
for C17H18O4: C 71.31, H 6.34; found: C 71.34, H 6.30.
Compound 2a
Mp 68 °C. IR (cm–1): 3080, 2980, 1740, 1700, 1620,
1
1590, 1490, 1400. H NMR δ: 2.57 (sharp s, 3H, 1′-CH3),
4.73 (d, J = 5.0 Hz, 2H, OCH2CH=CH2), 5.34 (d, J =
10.0 Hz, 1H, OCH2CH=CHAHB), 5.39 (d, J = 17.0 Hz, 1H,
OCH2CH=CHAHB), 5.95 (m, 1H, OCH2CH=CH2), 6.27 (d,
J = 9.0 Hz, 1H, 3-H), 6.91 (d, J = 7.2 Hz, 1H, 6-H), 7.45 (d,
J = 7.2 Hz, 1H, 5-H), 7.70 (d, J = 9.0 Hz, 1H, 4-H). Anal.
calcd. for C14H12O4: C 68.84, H 4.95; found: C 68.79, H
4.90.
Compound 2g
Mp 102 °C. IR : 3065, 2980, 1725, 1675, 1610, 1565, 1495,
1
1405. H NMR δ: 4.58 (d, J = 5.0 Hz, 2H, OCH2CH=CH2),
5.16 (d, J = 11.0 Hz, 1H, OCH2CH=CHAHB), 5.18 (d, J =
17.0 Hz, 1H, OCH2CH=CHAHB), 5.83 (m, 1H, OCH2CH=CH2),
6.24 (d, J = 8.0 Hz, 1H, 3-H), 6.92 (d, J = 8.0 Hz, 1H, 6-H),
7.52 (m, 5H, C6H5), 7.77 (d, J = 8.0 Hz, 1H, 5-H), 7.88 (d,
J = 8.0 Hz, 1H, 4-H). Anal. calcd. for C19H14O4: C 74.50, H
4.60; found: C 74.45, H 4.65.
Compound 2b
Mp 108 °C. IR (cm–1): 3060, 2995, 1730, 1710, 1605, 1565,
1
1495, 1380. H NMR δ: 2.32 (d, J = 1.0 Hz, 3H, 4-CH3), 2.53
(sharp s, 3H, 1′-CH3), 4.58 (d,
J = 6.0 Hz, 2H,
OCH2CH=CH2), 5.23 (d, J = 10.0 Hz, 1H, OCH2CH=CHAHB),
5.32 (d, J = 17.0 Hz, 1H, OCH2CH=CHAHB), 5.96 (m, 1H,
OCH2CH=CH2), 6.08 (q, J = 1.0 Hz, 1H, 3-H), 6.80 (d, J =
9.0 Hz, 1H, 6-H), 7.47 (d, J = 9.0 Hz, 1H, 5-H). Anal. calcd.
for C15H14O4: C 69.75, H 5.46; found: C 69.72, H 5.41.
Compound 2h
Mp 151 °C. IR : 3090, 2990, 1725, 1680, 1595, 1560,
1
1490, 1370. H NMR δ: 2.44 (d, J = 1.2 Hz, 3H, 4-CH3),
4.60 (br d, J = 7.0 Hz, 2H, OCH2CH=CH2), 5.15 (d, J =
10.0 Hz, 1H, OCH2CH=CHAHB), 5.18 (d, J = 17.0 Hz, 1H,
OCH2CH=CHAHB), 5.81 (ddt, J = 17.0, 10.0, 7.0 Hz, 1H,
OCH2CH=CH2), 6.14 (q, J = 1.2 Hz, 1H, 3-H), 6.94 (d, J =
9.0 Hz, 1H, 6-H), 7.43 (t, J = 7.8 Hz, 2H, 3′-H and 5′-H),
7.58 (br t, J = 7.8 Hz, 1H, 4′-H), 7.65 (br d, J = 7.8 Hz, 2H,
Compound 2c
Mp 65 °C. IR (cm–1): 3080, 2970, 1750, 1715, 1610,
1
1570, 1490, 1405, 1300. H NMR δ: 1.16 (t, J = 7.0 Hz, 3H,
2′-CH3), 2.86 (q, J = 7.0 Hz, 2H, 1′-CH2), 4.63 (d, J =
6.0 Hz, 2H, OCH2CH=CH2), 5.30 (d, J = 10.0 Hz, 1H,
© 2008 NRC Canada

Dutta et al.
405
2′-H and 6′-H), 7.85 (d, J = 9.0 Hz, 1H, 5-H). Anal. calcd.
3.40 (q, J = 7.0 Hz, 2H, 1′-CH2), 3.47 (br d, J = 7.0 Hz, 2H,
CH2CH=CH2), 5.04 (d, J = 7.0 Hz, 1H, CH2CH=CHAHB),
5.10 (d, J = 17.0 Hz, 1H, CH2CH=CHAHB), 5.96 (m, 1H,
CH2CH=CH2), 6.24 (d, J = 10.0 Hz, 1H, 3-H), 7.38 (s, 1H, 5-
H), 7.62 (d, J = 10.0 Hz, 1H, 4-H), 14.20 (s, 1H, 7-OH). MS-
EI (70 eV) m/z: 258 (62.4), 243 (2.9), 229 (100), 212 (3.4), 201
(33.3), 185 (3.8), 173 (8.9), 145 (3.4), 128 (2.9), 115 (7.2).
Anal. calcd. for C15H14O4: C 69.75, H 5.46; found: C 69.71,
H 5.49.
for C20H16O4: C 74.99, H 5.03; found: C 74.94, H 4.98.
Preparation of 6-allyl-8-coumarinyl alkyl/aryl ketones
3a–3h
General Procedure
The allyloxycoumarinyl ketones 2a–2h (2.0 mmol) dis-
solved in distilled PhNEt2 (30 mL) were heated at 195 °C
for 8 h under anhydrous conditions. PhNEt2 was then dis-
tilled off and the residual mass left was dissolved in CHCl3
(30 mL). The CHCl3 solution of the mass was washed suc-
cessively with cold dil. HCl (3 × 15 mL), a saturated brine
solution (1x15 mL), followed by a saturated aqueous solu-
tion of NaHCO3 (2 × 15 mL), and again with a saturated
brine solution (2 × 15 mL). Removal of solvent after drying
over anhydrous Na2SO4 afforded a semi-solid mass, which
was found to be a mixture of three components. Column
chromatographic resolution over silica gel yielded the 6-
allyl-8-coumarinyl ketones 3a–3h from petroleum ether and
EtOAc (99:1) eluate fractions. The products were crystal-
lized from EtOAc/petroleum ether.
Compound 3d
Mp 125 °C. IR (cm–1): 3080, 2960, 1740, 1710, 1610,
1
1560, 1450, 1395. H NMR δ: 1.17 (t, J = 7.0 Hz, 3H, 2′-
CH3), 2.34 (d, J = 1.0 Hz, 3H, 4-CH3), 3.30 (q, J = 7.0 Hz,
2H, 1′-CH2), 3.35 (br d, J = 6.5 Hz, 2H, CH2CH=CH2), 5.04
(d, J = 17.0 Hz, 1H, CH2CH=CHAHB), 5.05 (d, J = 10.0 Hz,
1H, CH2CH=CHAHB), 5.91 (m, 1H, CH2CH=CH2), 6.06 (q,
J = 1.0 Hz, 1H, 3-H), 7.43 (s, 1H, 5-H), 14.00 (s, 1H, 7-
OH). 13C NMR δ: 8.2 (1°, 2′-CH3), 19.2 (1°, 4-CH3), 33.5
(2°, CH2CH=CH2), 39.7 (2°, 1′-CH2), 108.7 (4°, C-8), 111.0
(3°, C-3), 111.3 (4°, C-4a), 116.8 (2°, CH2CH=CH2), 126.2
(4°, C-6), 130.3 (3°, CH2CH=CH2), 135.3 (3°, C-5), 153.2
(4°, C-4), 153.7 (4°, C-8a), 159.7 (4°, C-2), 164.7 (4°, C-7),
207.8 (4°, C-1′). MS-EI (70 eV) m/z: 272 (49.1), 257 (5.9),
243 (100), 215 (19.6), 201 (2.3), 117 (4.7), 115 (2.5). Anal.
calcd. for C16H16O4: C 70.57, H 5.92; found: C 70.60, H
5.87.
Compound 3a
Mp 121 °C. UV–vis (EtOH) λmax (log ⑀): 321.7 (4.78),
270.5 (4.76), 254.5 (4.75). IR (cm–1): 3080, 2920, 1730,
1
1710, 1610, 1560, 1400, 1365. H NMR δ: 2.89 (sharp s, 3H,
1′-CH3), 3.35 (br d, J = 6.5 Hz, 2H, 6-CH2CH=CH2), 5.071
(d, J = 10.0 Hz, 1H, CH2CH=CHAHB), 5.072 (d, J = 18.0 Hz,
1H, CH2CH=CHAHB), 6.01 (m, 1H, CH2CH=CH2), 6.20 (d,
J = 9.5 Hz, 1H, 3-H), 7.33 (s, 1H, 5-H), 7.57 (d, J = 9.5 Hz,
1H, 4-H), 14.02 (s, 1H, 7-OH). 13C NMR δ: 33.0 (2°,
CH2CH=CH2), 33.7 (1°, 1′-CH3), 108.7 (4°, C-8), 110.3 (4°,
C-4a), 112.0 (3°, C-3), 116.9 (2°, CH2CH=CH2), 126.7 (4°,
C-6), 133.9 (3°, CH2CH=CH2), 135.1 (3°, C-5), 144.2 (3°, C-
4), 154.4 (4°, C-8a), 159.6 (4°, C-2), 165.1 (4°, C-7), 204.3
(4°, C-1′). MS-EI (70 eV) m/z: 244 (49.5, M+), 229 (57.2),
216 (19.6), 211 (25.6), 201 (100), 183(12.8), 173 (41.8), 155
(16.6), 145 (29.4), 131 23.5), 115 (92.5). Anal. calcd. for
C14H12O4: C 68.84, H 4.95; found: C 68.89, H 4.99.
Compound 3e
Mp 84 °C. IR (cm–1): 3085, 2970, 1735, 1720, 1625,
1
1565, 1455, 1400. H NMR δ: 1.05 (t, J = 7.2 Hz, 3H, 3′-
CH3), 1.81 (tq, J = 7.2 Hz, 7.2 Hz, 2H, 2′-CH2), 3.35 (t, J =
7.2 Hz, 2H, 1′-CH2), 3.42 (br d, J = 6.6 Hz, 2H,
CH2CH=CH2), 5.13 (d, J = 16.0 Hz, 1H, CH2CH=CHAHB),
5.14 (d, J = 10.0 Hz, 1H, CH2CH=CHAHB), 5.99 (ddt, J =
16.0, 10.0, 6.6 Hz, 1H, CH2CH=CH2), 6.27 (d, J = 9.5 Hz,
1H, 3-H), 7.38 (s, 1H, 5-H), 7.62 (d, J = 9.5 Hz, 1H, 4-H),
14.16 (s, 1H, 7-OH). MS-EI (70 eV) m/z: 272 (43), 257 (8),
244 (1), 229 (100), 201 (10), 173 (3), 115 (5). Anal. calcd.
for C16H16O4: C 70.57, H 5.92; found: C 70.55, H 5.99.
Compound 3b
Mp 122 °C. IR (cm–1): 3080, 2980, 1740, 1715, 1610,
Compound 3f
1
Mp 98 °C. IR (cm–1): 3080, 2960, 1740, 1725, 1620,
1560, 1450, 1395. H NMR δ: 2.36 (d, J = 1.0 Hz, 3H, 4-
1
CH3), 2.90 (sharp s, 3H, 1′-CH3), 3.38 (br d, J = 6.5 Hz, 2H,
CH2CH=CH2), 5.06 (d, J = 16.0 Hz, 1H, CH2CH=CHAHB),
5.07 (d, J = 10.0 Hz, 1H, CH2CH=CHAHB), 5.93 (m, 1H,
CH2CH=CH2), 6.10 (q, J = 1.0 Hz, 1H, 3-H), 7.48 (s, 1H, 5-
H), 8.86 (s, 1H, 7-OH). 13C NMR δ: 19.2 (1°, 4-CH3), 33.4
(2°, CH2CH=CH2), 33.9 (1°, 1′-CH3), 108.6 (4°, C-8), 111.1
(3°, C-3), 111.3 (4°, C-4a), 116.8 (2°, CH2CH=CH2), 126.1
(4°, C-6), 130.6 (3°, CH2CH=CH2), 135.3 (3°, C-5), 153.2
(4°, C-4), 153.7 (4°, C-8a), 159.6 (4°, C-2), 164.8 (4°, C-7),
204.7 (4°, C-1′). MS-EI (70 eV) m/z: 258 (60.3), 243 (54.4),
230 (21.5), 215 (34.3), 187 (13.2), 115 (27.4), 91 36.7), 77
(41.6), 65 (43.6), 43 (100). Anal. calcd. for C15H14O4: C
69.75, H 5.46; found: C 69.71, H 5.43.
1560, 1450, 1390. H NMR δ: 1.03 (t, J = 7.0 Hz, 3H, 3′-
CH3), 1.78 (tq, J = 7.0 Hz, 7.0 Hz, 2H, 2′-CH2), 2.40 (d, J =
1.0 Hz, 3H, 4-CH3), 3.32 (t, J = 7.0 Hz, 2H, 1′-CH2), 3.43
(br d, J = 6.5 Hz, 2H, CH2CH=CH2), 5.08 (d, J = 9.0 Hz,
1H, CH2CH=CHAHB), 5.11 (d,
J = 16.0 Hz, 1H,
CH2CH=CHAHB), 5.98 (m, 1H, CH2CH=CH2), 6.13 (q, J =
1.0 Hz, 1H, 3-H), 7.49 (s, 1H, 5-H), 14.07 (s, 1H, 7-OH).
13C NMR δ: 13.6 (1°, 3′-CH3), 17.7 (2°, 2′-CH2), 19.2 (1°, 4-
CH3), 33.4 (2°, CH2CH=CH2), 46.8 (2°, 1′-CH2), 108.7 (4°,
C-8), 111.0 (3°, C-3), 111.2 (4°, C-4a), 116.7 (2°,
CH2CH=CH2), 126.1 (4°, C-6), 130.2 (3°, CH2CH=CH2),
135.3 (3°, C-5), 153.0 (4°, C-4), 153.6 (4°, C-8a), 159.6 (4°,
C-7), 164.7 (4°, C-2), 207.3 (4°, C-1′). MS-EI (70 eV) m/z:
286 (61.1), 271 (12.8), 258 (2.9), 253 (8.5), 243 (100), 225
(2.9), 215 (14.5), 201 (2.1), 187 (4.3), 115 (9.8). Anal.
calcd. for C17H18O4: C 71.31, H 6.34; found: C 71.25, H
6.30.
Compound 3c
Mp 110 °C. IR (cm–1): 3060, 2960, 1730, 1710, 1620, 1580,
1465, 1400, 1310. 1H NMR δ: 1.21 (t, J = 7.0 Hz, 3H, 2′-CH3),
© 2008 NRC Canada

406
Can. J. Chem. Vol. 86, 2008
CH2), 3.61 (br d, J = 6.3 Hz, 2 H, 3-CH2CH=CH2), 5.02 (d, J
= 10.0 Hz, 1H, 3-CH2CH=CHAHB), 5.12 (d, J = 17.0 Hz, 1H,
3-CH2CH=CHAHB), 5.97 (ddt, J = 17.0, 10.0, 6.3 Hz, 1H, 3-
CH2CH=CH2), 6.27 (d, J = 9.6 Hz, 1H, 6-H), 7.63 (d, J =
9.6 Hz, 1H, 5-H), 7.83 (s, 1H, 4-H), 13.16 (s, 1H, 7-OH). MS-
EI (70 eV) m/z: 272 (40), 257 (10), 244 (1.5), 229 (100), 201
(18), 173 (2), 145 (1), 115 (5). Anal. calcd. for C16H16O4: C
70.57, H 5.92; found: C 70.53, H 5.94.
Further elution of the silica column of Claisen product
mixture from compounds 2b, 2d, and 2f afforded the 8-allyl-
6-coumarinyl ketones 4b, 4d, and 4f, respectively, from later
petroleum ether/EtOAc (96:4, v/v) eluate fractions and sub-
sequent crystallization from the appropriate solvent–solvent
mixture.
Compound 3g
Mp 119 °C. IR (cm–1): 3060, 1730, 1710, 1620, 1575,
1
1450, 1400, 1345. H NMR δ: 3.49 (br d, J = 6.6 Hz, 2H,
CH2CH=CH2), 5.17 (d, J = 12.0 Hz, 1H, CH2CH=CHAHB),
5.18 (d, J = 15.0 Hz, 1H, CH2CH=CHAHB), 6.02 (ddt, J =
15.0, 12.0, 6.6 Hz, 1H, CH2CH=CH2), 6.16 (d, J = 9.0 Hz,
1H, 3-H), 7.43 (s, 1H, 5-H), 7.46 (t, J = 9.0 Hz, 2H, 3′-H
and 5′-H), 7.59 (d, J = 9.0 Hz, 1H, 4-H), 7.61 (br t, J =
9.0 Hz, 1H, 4′-H), 7.67 (br d, J = 9.0 Hz, 2H, 2′-H and 6′-H),
11.56 (s, 1H, 7-OH). Anal. calcd. for C19H14O4: C 74.50, H
4.60; found: C 74.48, H 4.56.
Compound 3h
Mp 180 °C. IR (cm–1): 3060, 1710, 1695, 1590, 1555,
1
1425, 1365. H NMR δ: 2.26 (d, J = 1.0 Hz, 3H, 4-CH3),
Compound 5b
3.68 (br d, J = 6.5 Hz, 2H, CH2CH=CH2), 5.06 (dq, J =
10.0, 1.0 Hz, 1H, CH2CH=CHAHB), 5.17 (dq, J = 16.0,
1.0 Hz, 1H, CH2CH=CHAHB), 5.96 (m, 1H, CH2CH=CH2),
6.16 (q, J = 1.0 Hz, 1H, 3-H), 7.68 (s, 1H, 5-H), 7.71 (m,
5H, C6H5), 12.76 (s, 1H, 7-OH). Anal. calcd. for C20H16O4:
C 74.99, H 5.03; found: C 74.97, H 5.02.
Mp 98 °C. IR (cm–1): 3080, 2960, 1730, 1710, 1620, 1590,
1395, 1270. 1H NMR δ: 2.43 (d, J = 1.0 Hz, 3H, 4-CH3), 2.69
(sharp s, 3H, 1′-CH3), 3.58 (br d, J = 7.0 Hz, 2H, 8-
CH2CH=CH2), 5.00 (d, J = 10.0 Hz, 1H, 8-CH2CH=CHAHB),
5.08 (d, J = 17.0 Hz, 1H, 8-CH2CH=CHAHB), 5.94 (m, 1H,
8-CH2CH=CH2), 6.16 (q, J = 1.0 Hz, 1H, 3-H), 7.88 (s, 1H,
5-H), 12.96 (s, 1H, 7-OH). 13C NMR δ: 18.6 (1°, 4-CH3),
26.4 (2°, 8-CH2CH=CH2), 26.5 (1°, 1′-CH3), 112.4 (q, C-6),
112.6 (3°, C-3), 115.7 (2°, 8-CH2CH=CH2), 116.1 (4°, C-4a),
116.3 (4°, C-8), 125.7 (3°, 8-CH2CH=CH2), 134.2 (3°, C-5),
151.9 (4°, C-4), 156.1 (4°, C-8a), 159.9 (4°, C-2), 163.1 (4°,
C-7), 203.5 (4°, C-1′). Anal. calcd. for C15H14O4: C 69.75, H
5.46; found: C 69.72, H 5.44.
Subsequent elution of the silica column of crude Claisen
products from compounds 2a, 2c, and 2e with petroleum
ether/EtOAc (96:4, v/v) afforded the 3-allyl-8-coumarinyl
ketones 4a, 4c, and 4e, as appropriate. The products were
crystallized from EtOAc/petroleum ether.
Compound 4a
Mp 147 °C. IR (cm–1): 3080, 2960, 1730, 1710, 1610,
1
1400, 1325. H NMR δ: 2.62 (sharp s, 3H, 1′-CH3), 3.55 (br
Compound 5d
d, J = 7.0 Hz, 2H, 3-CH2CH=CH2), 4.99 (d, J = 13.0 Hz,
1H, 3-CH2CH=CHAHB), 5.00 (d, J = 16.0 Hz, 1H, 3-
CH2CH=CHAHB), 5.90 (ddt, J = 16.0, 13.0, 7.0 Hz, 1H, 3-
CH2CH=CH2), 6.22 (d, J = 9.5 Hz, 1H, 6-H), 7.57 (d, J =
9.5 Hz, 1H, 5-H), 7.74 (s, 1H, 4-H), 12.93 (s, 1H, 7-OH).
13C NMR δ: 26.3 (2°, 3-CH2CH=CH2), 26.5 (1°, 1′-CH3),
111.3 (4°, C-8), 113.6 (3°, C-6), 115.9 (2°, 3-CH2CH=CH2),
116.5 (4°, C-4a), 116.7 (4°, C-3), 129.2 (t, 3-CH2CH=CH2),
134.2 (3°, C-5), 143.2 (3°, C-4), 156.7 (4°, C-8a), 159.8 (4°,
C-2), 163.5 (4°, C-7), 203.4 (4°, C-1′). MS-EI (70 eV) m/z:
244 (82.1), 229 (100), 211 (5.9), 201 (55.9), 187 (20.9), 173
(17.9), 155 (3.4), 145 (7.7), 127 (6.4), 115 (29.9). Anal.
calcd. for C14H12O4: C 68.84, H 4.95; found: C 68.82, H
4.91.
Mp 110 °C. IR (cm–1): 3080, 2960, 1740, 1710, 1620,
1
1590, 1450, 1395. H NMR δ: 1.32 (t, J = 7.0 Hz, 3H, 2′-
CH3), 2.45 (d, J = 1.0 Hz, 3H, 4-CH3), 3.15 (q, J = 7.0 Hz,
2H, 1′-CH2), 3.68 (br d, J = 7.0 Hz, 2H, 8-CH2CH=CH2),
5.06 (d, J = 10.0 Hz, 1H, 8-CH2CH=CHAHB), 5.15 (d, J =
18.0 Hz, 1H, 8-CH2CH=CHAHB), 5.99 (m, 1H, 8-
CH2CH=CH2), 6.20 (s, 1H, 4-H), 7.95 (s, 1H, 5-H), 13.20
(s, 1H, 7-OH). 13C NMR δ: 8.2 (1°, 2′-CH3), 18.4 (1°, 4-
CH3), 26.5 (2°, 8-CH2CH=CH2), 31.5 (2°, 1′-CH2), 112.5
(4°, C-6), 112.6 (3°, C-3), 115.8 (2°, 8-CH2CH=CH2), 116.0
(4°, C-8), 116.6 (4°, C-4a), 124.8 (3°, 8-CH2CH=CH2),
134.5 (3°, C-5), 151.7 (4°, C-4), 156.2 (4°, C-8a), 159.7 (4°,
C-2), 163.4 (4°, C-7), 206.2 (4°, C-1′). MS-EI (70 eV) m/z:
272 (58.5),. 257 (10.6), 243 (100), 215 (29.9), 201 (1.6), 187
(7.2), 159 (1.7), 115 (2.5). Anal. calcd. for C16H16O4: C
70.57, H 5.92; found: C 70.95, H 5.90.
Compound 4c
Mp 130 °C. IR (cm–1): 3080, 2970, 1735, 1710, 1620,
1
1560, 1450, 1400, 1360. H NMR δ: 1.24 (t, J = 7.0 Hz, 3H,
Compound 5f
2′-CH3), 3.08 (q, J = 7.0 Hz, 2H, 1′-CH2), 3.60 (br d, J =
Mp 128 °C. IR (cm–1): 3080, 2960, 1740, 1715, 1620,
7.0 Hz, 2H, 3-CH2CH=CH2), 5.02 (d, J = 10.0 Hz, 1H, 3-
1
1570, 1450, 1390. H NMR δ: 1.10 (t, J = 8.0 Hz, 3H, 3′-
CH2CH=CHAHB), 5.10 (d,
J
=
17.0 Hz, 1H, 3-
CH3), 1.80 (tq, J = 8.0 Hz, 8.0 Hz, 2H, 2′-CH2), 2.50 (d, J =
1.0 Hz, 3H, 4-CH3), 3.08 (t, J = 8.0 Hz, 2H, 1′-CH2), 3.68
(br d, J = 7.0 Hz, 2H, 8-CH2CH=CH2), 5.08 (d, J = 11.0 Hz,
1H, CH2CH=CHAHB), 5.18 (d, J = 18.0 Hz, 1H, 8-
CH2CH=CHAHB), 6.00 (m, 1H, 8-CH2CH=CH2), 6.24 (s,
1H, 4-H), 7.95 (s, 1H, 5-H), 13.24 (s, 1H, 7-OH). 13C NMR
δ: 13.7 (1°, 3′-CH3), 18.0 (2°, 2′-CH2), 18.7 (1°, 4-CH3), 26.5
(2°, 8-CH2CH=CH2), 40.1 (2°, 1′-CH2), 112.5(q, C-6), 112.8
(3°, C-3), 115.8 (2°, 8-CH2CH=CH2), 116.2 (4°, C-8), 116.6
(4°, C-4a), 125.0 (3°, 8-CH2CH=CH2), 134.5 (3°, C-5),
151.7 (4°, C-4), 156.3 (4°, C-8a), 159.8 (4°, C-2), 163.5 (4°,
CH2CH=CHAHB), 5.95 (m, 1H, 3-CH2CH=CH2), 6.28 (d,
J = 10.0 Hz, 1H, 6-H), 7.64 (d, J = 10.0 Hz, 1H, 5-H), 7.84
(s, 1 H, 4-H), 13.12 (s, 1 H, 7-OH). MS-EI (70 eV) m/z: 258
(35.5), 243 (5.1), 229 (100), 201 (54.7), 185 (2.1), 173 (8.5),
145 (3.8), 128 (4.7), 115 (13.6). Anal. calcd. for C15H14O4:
C 69.75, H 5.46; found: C 69.70, H 5.42.
Compound 4e
Mp 132 °C. IR (cm–1): 3090, 2975, 1740, 1725, 1620, 1570,
1
1470, 1400. H NMR δ: 1.04 (t, J = 7.2 Hz, 3H, 3′-CH3), 1.80
(tq, J = 7.2 Hz, 7.2 Hz, 2H, 2′-CH2), 3.00 (t, J = 7.2 Hz, 2H, 1′-
© 2008 NRC Canada

Dutta et al.
407
C-7), 205.8 (4°, C-1′). MS-EI (70 eV) m/z: 286 (63.2), 271
(21.3), 258 (3.4), 243 (100), 215 (12.8), 201 (2.5), 187 (8.5),
115 (6.8). Anal. calcd. for C17H18O4: C 71.31, H 6.34;
found: C 71.27, H 6.29.
3.2 Hz, 1H, 3′-H), 6.20 (d, J = 9.6 Hz, 1H, 3-H), 6.89 (d, J =
8.7 Hz, 1H, 6-H), 7.40 (d, J = 8.7 Hz, 1H, 5-H), 7.61 (d, J =
9.6 Hz, 1H, 4-H). 13C NMR δ: 7.55 (1°, 8-COCH2CH3),
13.73 (3°, C-3), 18.65 (2°, C-5′), 24.93 (2°, C-4′), 28.42 (2°,
C-6′), 38.00 (2°, 8-COCH2CH3), 72.74 (3°, C-1′), 110.14 (3°,
C-6), 112.84 (4°, C-4a), 120.85 (4°, C-8), 124.90 (3°, C-2′),
129.10 (3°, C-5), 133.28 (3°, C-3′), 142.85 (3°, C-4), 151.52
(4°, C-8a), 157.54 (4°, C-2), 159.72 (4°, C-7), 201.98 (4°, 8-
COCH2CH3). Anal. calcd. for C18H18O4: C 72.47, H 6.08;
found: C 72.42, H 6.09.
7-O(Cyclohex-2′-ene-1′-yl)-8-coumarinyl ketones 6a–6h
General procedure
Pure and dried 7-hydroxy-8-coumarinyl ketone 1a–1h
(2.5 mmol) taken in dry acetone (50 mL) were refluxed with
3-bromocyclohexene (0.4 mL, 0.003 mole) and NEt3 (1 mL,
0.726 g, 0.007 mole) for 4 h. After distilling off acetone, wa-
ter (10 mL) was added, and the content was acidified with
cold dil HCl (4 N, 15 mL). The organic part of the mixture
was then extracted with CHCl3 (50 mL), which was washed
successively with a saturated brine solution (15 mL), a satu-
rated NaHCO3 solution (2 × 15 mL), and again with a satu-
rated brine solution (3 × 15 mL). The CHCl3 layer was dried
over anhydrous Na2SO4 for 30 min, filtered, and excess
CHCl3 was distilled off to obtain an oily mass. TLC experi-
ment showed that the oily mass was more polar than the
starting material on using 5% EtOAc/benzene as developer
Compound 6d
Mp 89 °C. IR (cm–1): 3035, 2958, 1726, 1668, 1607,
1
1568, 1490, 1484, 1377. H NMR δ: 1.18 (t, J = 7.2 Hz, 3H,
8-COCH2CH3), 1.67–1.61 (br m, 1H, 6′-Hax), 1.96–1.90
(br m, 3H, 5′-H2, 6′-Heq), 2.14–2.03 (br m, 2H, 4′-H2), 2.37
(d, J = 1.0 Hz, 3H, 4-CH3), 2.83 (q, J = 7.2 Hz, 2H, 8-
COCH2CH3), 4.44 (br s, 1H, 1′-H), 5.80 (br d, J = 10.5 Hz,
1H, 2′-H), 5.98 (br d, J = 10.0 Hz, 1H, 3′-H), 6.11 (q, J =
1.0 Hz, 1H, 3-H), 6.91 (d, J = 8.8 Hz, 1H, 6-H) 7.52 (d, J =
8.8 Hz, 1H, 5-H). Anal. calcd. for C19H20O4: C 73.06, H
6.45; found: C 73.09, H 6.44.
solvent.
The
oily
mass
was
then
column
chromatographically filtered. Crystals of 6a–6h were ob-
tained on eluting with 10% EtOAc/petroleum ether and sub-
sequent crystallization of the products.
Compound 6e
Mp 72 °C. IR (cm–1): 3047, 2929, 1727, 1702, 1607,
1
1560, 1485, 1458. H NMR δ: 0.96 (t, J = 7.4 Hz, 3H, 8-
COCH2CH2CH3), 1.67–1.63 (br m, 1H, 6′-Hax), 1.72 (tq, J =
7.3 Hz, 7.3 Hz, 2H, 8-COCH2CH2CH3), 1.84–1.82 (br m,
3H, 5′-H2, 6′-Heq), 2.07–2.01 (br m, 2H, 4′-H), 2.81 (t, J =
7.2 Hz, 2H, 8-COCH2CH2CH3), 4.87 (br s, 1H, 1′-H), 5.79
(br dt, J = 10.0 Hz, 2.8 Hz, 1H, 2′-H), 5.97 (br dt, J =
10.0 Hz, 3.4 Hz, 1H, 3′-H), 6.20 (d, J = 9.5 Hz, 1H, 3-H),
6.87 (d, J = 8.7 Hz, 1H, 6-H), 7.39 (d, J = 8.7 Hz, 1H, 5-H),
7.60 (d, J = 9.5 Hz, 1H, 4-H). 13C NMR δ: 13.64 (1°, 8-
COCH2CH2CH3), 16.92 (2°, 8-COCH2CH2CH3), 18.66 (2°,
C-5′), 24.93 (2°, C-4′), 28.40 (2°, C-6′), 46.76 (2°, 8-
COCH2CH2CH3), 72.70 (3°, C-1′), 110.08 (3°, C-6), 112.81
(4°, C-4a), 113.71 (3°, C-3), 120.95 (4°, C-8), 124.90 (3°, C-
2′), 129.98 (3°, C-5), 133.23 (3°, C-3′), 142.85 (3°, C-4),
151.54 (4°, C-8a), 157.55 (4°, C-2), 159.71 (4°, C-7), 201.41
(4°, 8-COCH2CH2CH3). Anal. calcd. for C19H20O4: C 73.06,
H 6.45; found: C 73.05, H 6.48.
Compound 6a
Mp 118 °C. IR (cm–1): 3071, 2925, 1722, 1666, 1607,
1
1560, 1489, 1436, 1400. H NMR δ: 1.66–1.63 (br m, 1H,
6′-Hax), 1.93–1.82 (br m, 3H, 5′-H2, 6′-Heq), 2.18–2.01 (br m,
2H, 4′-H2), 2.54 (sharp s, 3H, 8-COCH3), 4.89 (br s, 1H, 1′-
H), 5.78 (br d, J = 12.3 Hz, 1H, 2′-H), 5.98 (br dt, J =
11.1 Hz, 3.8 Hz, 1H, 3′-H), 6.21 (d, J = 9.6 Hz, 1H, 3-H),
6.90 (d, J = 8.7 Hz, 1H, 6-H), 7.41 (d, J = 8.7 Hz, 1H, 5-H),
7.76 (d, J = 9.6 Hz, 1H, 4-H). 13C NMR δ: 18.67 (2°, C-5′),
24.90 (2°, C-4′), 28.39 (2°, C-6′), 32.13 (1°, 8-COCH3),
72.81 (3°, C-1′), 110.16 (3°, C-6), 112.83 (4°, C-4a), 113.72
(3°, C-3), 120.87 (4°, C-8), 124.85 (3°, C-2′), 129.29 (3°, C-
5), 133.34 (3°, C-3′), 142.85 (3°, C-4), 151.49 (4°, C-8a),
157.53 (4°, C-2), 159.68 (4°, C-7), 198.53 (4°, 8-COCH3).
Anal. calcd. for C17H16O4: C 71.82, H 5.67; found: C 71.85,
H 5.66.
Compound 6f
Mp 64 °C. IR (cm–1): 2952, 1735, 1718, 1611, 1570,
Compound 6b
Mp 90 °C. IR (cm–1): 3418, 3029, 2939, 1724, 1601,
1
1491, 1434, 1408. H NMR δ: 0.95 (t, J = 7.4 Hz, 3H, 8-
1
1488, 1378, 1282. H NMR δ: 1.70–1.62 (br m, 1H, 6′-Hax),
COCH2CH2CH3), 1.67–1.63 (br m, 2H, 6′-H2), 1.71 (tq, J =
7.3 Hz, 7.3 Hz, 2H, 8-COCH2CH2CH3), 1.92–1.86 (br m,
2H, 5′-H2), 2.07–2.01 (br m, 2H, 4′-H2), 2.36 (d, J = 1.0 Hz,
3H, 4-CH3), 2.77 (t, J = 7.2 Hz, 2H, 8-COCH2CH2CH3),
4.86 (br d, J = 2.0 Hz, 1H, 1′-H), 5.78 (br dt, J = 10.0 Hz,
2.7 Hz, 1H, 2′-H), 5.96 (br dt, J = 10.0 Hz, 3.2 Hz, 1H, 3′-
H), 6.07 (q, J = 1.0 Hz, 1H, 3-H), 6.89 (d, J = 8.9 Hz, 1H, 6-
H), 7.50 (d, J = 8.9 Hz, 1H, 5-H). Anal. calcd. for C20H22O4:
C 73.60, H 6.79; found: C 73.62, H 6.81.
1.81–1.75 (br m, 3H, 5′-H2, 6′-Heq), 2.08–2.02 (br m, 2H, 4′-
H2), 2.36 (d, J = 1.0 Hz, 3H, 4-CH3), 2.60 (sharp s, 3H, 8-
COCH3), 4.88 (br s, 1H, 1′-H), 5.79 (br dt, J = 11.1 Hz,
2.7 Hz, 1H, 2′-H), 5.97 (br dt, J = 10.0 Hz, 2.7 Hz, 1H, 3′-
H), 6.09 (q, J = 1.0 Hz, 1H, 3-H), 6.90 (d, J = 8.7 Hz, 1H, 6-
H), 7.52 (d, J = 8.7 Hz, 1H, 5-H). Anal. calcd. for C18H18O4:
C 72.47, H 6.08; found: C 72.48, H 6.05.
Compound 6c
Mp 104 °C. IR (cm–1): 3031, 2937, 1725, 1714, 1605,
Compound 6g
1
1560, 1484, 1406. H NMR δ: 1.17 (t, J = 7.2 Hz, 3H, 8-
Mp 99 °C. IR (cm–1): 2934, 1728, 1674, 1605, 1560,
1
COCH2CH3), 1.64–1.59 (br m, 1H, 6′-Hax), 1.84–1.73 (br m,
3H, 5′-H2, 6′-Heq), 1.92–1.85 (br m, 2H, 4′-H2), 2.82 (q, J =
7.2 Hz, 2H, 8-COCH2CH3), 4.87 (s, 1H, 1′-H), 5.78 (br dt,
J = 7.2 Hz, 3.1 Hz, 1H, 2′-H), 5.97 (br dt, J = 7.2 Hz,
1486, 1448, 1402. H NMR δ: 1.43–1.36 (br m, 1H, 6-H′ax),
1.76–1.66 (br m, 3H, 5′-H2, 6′-Heq), 1.90–1.85 (br m, 2H, 4′-
H2), 4.82 (br d, J = 3.3 Hz, 1H, 1′-H), 5.69 (br dt, J =
11.0 Hz, 3.5 Hz, 1.55 Hz, 1H, 2′-H), 5.83 (br dt, J =
© 2008 NRC Canada

408
Can. J. Chem. Vol. 86, 2008
10.2 Hz, 3.24 Hz, 1H, 3′-H), 5.85 (d, J = 9.5 Hz, 1H, 3-H),
6.20 (d, J = 8.7 Hz, 1H, 6-H), 7.38 (t, J = 7.4 Hz, 2H, 3′′-H
and 5′′-H), 7.50 (d, J = 8.7 Hz, 1H, 5-H), 7.54 (br t, J =
7.5 Hz, 1H, 4′′-H), 7.65 (d, J = 9.5 Hz, 1H, 4-H), 7.83 (br d,
J = 7.18 Hz, 2H, 2′′-H and 6′′-H). Anal. calcd. for C22H18O4:
C 76.29, H 5.24; found: C 76.32, H 5.22.
5), 131.81 (3°, C-3′), 153.07 (4°, C-4), 153.80 (4°, C-8a),
159.45 (4°, C-2), 164.61 (4°, C-7), 200.00 (4°, 8-COCH3).
MS m/z: 299.2 [M + H]+, 321.1 [M + Na]. Anal. calcd. for
C18H18O4: C 72.47, H 6.08; found: C 72.45, H 6.09.
Compound 7c
Mp 132 °C. IR (cm–1): 3020, 2975, 1735, 1715, 1610,
Compound 6h
1
1560, 1445, 1400. H NMR δ: 1.25 (t, J = 7 Hz, 3H, 8-
Mp 130 °C. IR (cm–1): 3063, 2905, 1730, 1665, 1608,
COCH2CH3), 1.62–1.48 (br m, 4H, 6′-H2, 5′-H2), 2.09–1.99
(br m, 2H, 4′-H2), 3.41 (q, J = 7.0 Hz, 2H, 8-COCH2CH3),
3.87 (q, J = 2.7 Hz, 1H, 1′-H), 5.62 (br dt, J = 7.7 Hz,
2.3 Hz, 1H, 2′-H), 6.00 (br dt, J = 10.0 Hz, 3.4 Hz, 1H, 3′-
H), 6.25 (br d, J = 9.5 Hz, 1H, 3-H), 7.40 (s, 1H, 5-H) 7.64
(d, J = 9.5 Hz, 1H, 4-H), 14.28 (s, 1H, 7-OH). 13C NMR δ:
8.2 (1°, 8-COCH2CH3), 20.41 (2°, C-5′), 25.10 (2°, C-4′),
29.37 (2°, C-6′), 33.67 (3°, C-1′), 38.52 (2°, 8-COCH2CH3),
108.64 (4°, C-4a), 110.27 (4°, C-8), 111.61 (3°, C-3), 128.74
(3°, C-2′), 129.90 (3°, C-5), 132.44 (4°, C-6), 132.91 (3°, C-
3′), 144.35 (3°, C-4), 154.35 (4°, C-8a), 159.64 (4°, C-2),
165.03 (4°, C-7), 207.63 (4°, 8-COCH2CH3). MS m/z: 299.2
[M + H]+, 321.2 [M + Na]. Anal. calcd. for C18H18O4: C
72.47, H 6.08; found: C 72.43, H 6.07.
1
1575, 1491, 1440, 1381. H NMR δ: 1.46–1.41 (br m, 2H,
6′-H2), 1.78–1.66 (br m, 2H, 5′-H2), 1.88–2.00 (br m, 2H, 4′-
H2), 2.44 (d, J = 1.0 Hz, 3H, 4-CH3), 4.86 (br s, 1H, 1′-H),
5.72 (br d, J = 9.8 Hz, 1H, 2′-H), 5.88 (br d, J = 9.9 Hz, 1H,
3′-H), 6.13 (q, J = 1.0 Hz, 1H, 3-H), 7.00 (d, J = 8.7 Hz, 1H,
6-H), 7.42 (t, J = 7.4 Hz, 2H, 3′′-H and 5′′-H), 7.57 (br t, J =
7.18 Hz, 1H, 4′′-H), 7.64 (d, J = 8.7 Hz, 1H, 5-H), 7.83 (br
d, J = 7.4 Hz, 2H, 2′′-H and 6′′-H). Anal. calcd. for
C23H20O4: C 76.65, H 5.59; found: C 76.68, H 5.58.
6-(Cyclohex-2′-ene-1′-yl)-7-hydroxy-8-coumarinyl ketones
7a–7h
General procedure
Pure and dry 7-(cyclohex-2′-ene-1′-yloxy)-8-coumarinyl
ketones 6a–6h (1.8 mmol) were taken in Ph2O (10 mL) and
refluxed for 10 min. The brown viscous liquid formed was
less polar than the starting material (as shown by TLC ex-
periment on using 5% EtOAc/benzene as developer). The
brown liquid was then charged on a column of silica gel and
eluted with petroleum ether and then with EtOAc/petroleum
ether (1:9 v/v). The crystals of pure Claisen products 7a–7h
were obtained from the later eluate fraction.
Compound 7d
Mp 114 °C. IR (cm–1): 3033, 2980, 1735, 1710, 1610,
1
1550, 1400, 1320. H NMR δ: 1.24 (t, J = 7.0 Hz, 3H, 8-
COCH2CH3), 1.49–1.44 (br m, 1H, 6′-Hax), 1.66–1.51 (br m,
3H, 5′-H2, 6′-Heq), 2.09–2.03 (br m, 2H, 4′-H2), 2.38 (d, J =
1.0 Hz, 3H, 4-CH3), 3.41 (q, J = 7.0 Hz, 2H, 8-COCH2CH3),
3.89 (br s, 1H, 1′-H), 5.63 (br d, J = 9.0 Hz, 1H, 2′-H), 6.00
(br dt, J = 10.0 Hz, 2 Hz, 1H, 3′-H), 6.13 (sharp q, J =
1.0 Hz, 1H, 3-H), 7.53 (s, 1H, 5-H), 14.20 (s, 1H, 7-OH).
13C NMR δ: 8.29 (1°, 8-COCH2CH3), 19.14 (1°, 4-CH3),
20.57 (2°, C-5′), 25.10 (2°, C-4′), 29.51 (2°, C-6′), 33.92 (3°,
C-1′), 38.67 (2°, 8-COCH2CH3), 108.47 (4°, C-4a), 110.93
(3°, C-3), 111.15 (4°, C-8), 128.86 (3°, C-2′), 129.34 (3°, C-
5), 129.84 (4°, C-6), 131.92 (3°, C-3′), 153.19 (4°, C-4),
153.73 (4°, C-8a), 159.63 (4°, C-2), 164.64 (4°, C-7), 208.00
(4°, 8-COCH2CH3). MS-EI (70 eV) m/z: 312 (100, M), 283
(81.8), 258 (39), 229 (13.2), 215 (25.5), 203 (9.1), 187 (10),
128 (10), 115 (10), 91 (8.2), 77 (8.2). Anal. calcd. for
C19H20O4: C 73.06, H 6.45; found: C 73.09, H 6.46.
Compound 7a
Mp 120 °C. IR (cm–1): 3080, 2920, 1745, 1725, 1610,
1
1560, 1440, 1400, 1360. H NMR δ: 1.62–1.48 (br m, 4H,
5′-H2, 6′-H2), 2.09–2.00 (br m, 2H, 4′-H2), 2.95 (sharp s, 3H,
8-COCH3), 3.86 (sextet, J = 2.8 Hz, 1H, 1′-H), 5.60 (br dt,
J = 8 Hz, 2.7 Hz, 1H, 2′-H), 5.99 (br dt, J = 10.0 Hz, 2.1 Hz,
1H, 3′-H), 6.24 (br d, J = 9.5 Hz, 1H, 3-H), 7.42 (s, 1H, 5-
H), 7.64 (d, J = 9.5 Hz, 1H, 4-H), 14.17 (s, 1H, 7-OH). 13C
NMR δ: 20.40 (2°, C-5′), 25.10 (2°, C-4′), 29.36 (2°, C-6′),
33.57 (1°, 8-COCH3), 33.64 (3°, C-1′), 108.87 (4°, C-4a),
110.27 (4°, C-8), 111.93 (3°, C-3), 128.67 (3°, C-2′), 129.94
(3°, C-5), 132.36 (4°, C-6), 133.19 (3°, C-3′), 144.24 (3°, C-
4), 154.45 (4°, C-8a), 159.59 (4°, C-2), 165.03 (4°, C-7),
Compound 7e
Mp 114 °C. IR (cm–1): 3040, 2970, 1730, 1715, 1610,
204.42 (4°, 8-COCH3). MS m/z: 285.4 [M + H]+ Anal.
.
1
1550, 1445, 1405, 1310. H NMR δ: 1.05 (t, J = 7.4 Hz, 3H,
calcd. for C17H16O4: C 71.82, H 5.67; found: C 71.85, H
5.66.
8-COCH2CH2CH3), 1.59–1.53 (br m, 1H, 6′-Hax), 1.64–1.60
(br m, 3H, 5′-H2, 6′-Heq), 1.81 (tq, J = 7.2 Hz, 7.2 Hz, 2H, 8-
COCH2CH2CH3), 2.10–2.02 (br m, 2H, 4′-H2), 3.35 (t, J =
7.0 Hz, 2H, 8-COCH2CH2CH3), 3.86 (br d, J = 2.6 Hz, 1H,
1′-H), 5.62 (br dd, J = 10.0 Hz, 3.6 Hz, 1H, 2′-H), 5.99 (br
dt, J = 10.2 Hz, 3.4 Hz, 1H, 3′-H), 6.25 (br d, J = 9.5 Hz,
1H, 3-H), 7.41 (s, 1H, 5-H), 7.64 (d, J = 9.5 Hz, 1H, 4-H),
14.00 (s, 1H, 7-OH). 13C NMR δ: 13.70 (1°, 8-
COCH2CH2CH3), 17.95 (2°, 8-COCH2CH2CH3), 20.41 (2°,
C-5′), 25.10 (2°, C-4′), 29.37 (2°, C-6′), 33.70 (3°, C-1′), 46.92
(2°, 8-COCH2CH2CH3), 108.79 (4°, C-4a), 110.27 (4°, C-8),
111.88 (3°, C-3), 128.78 (3°, C-2′), 129.93 (3°, C-5), 132.46
(4°, C-6), 132.97 (3°, C-3′), 144.34 (3°, C-4), 154.32 (4°, C-
8a), 159.60 (4°, C-2), 165.15 (4°, C-7), 207.28 (4°, 8-
Compound 7b
Mp 132 °C. IR (cm–1): 3060, 2920, 1736, 1710, 1610,
1
1555, 1430, 1390, 1360. H NMR δ: 1.53–1.44 (br m, 1H,
6′-Hax), 1.62–1.54 (br m, 3H, 5′-H2, 6′-Heq), 2.1–1.99 (br m,
2H, 4′-H2), 2.40 (d, J = 1.0 Hz, 3H, 4-CH3), 2.93 (sharp s,
3H, 8-COCH3), 3.89 (q, J = 3.0 Hz, 1H, 1′-H), 5.62 (br d,
J = 8.1 Hz, 1H, 2′-H), 5.99 (br dd, J = 10.0 Hz, 2.2 Hz, 1H,
3′-H), 6.12 (q, J = 1.0 Hz, 1H, 3-H), 7.53 (s, 1H, 5-H), 14.70
(s, 1H, 7-OH). 13C NMR δ: 19.04 (1°, 4-CH3), 20.53 (2°, C-
5′), 25.05 (2°, C-4′), 29.46 (2°, C-6′), 33.87 (1°, 8-COCH3),
33.97 (3°, C-1′), 108.93 (4°, C-4a), 110.96 (3°, C-3), 111.12
(4°, C-8), 128.76 (3°, C-2′), 129.60 (4°, C-6), 129.87 (3°, C-
© 2008 NRC Canada

Dutta et al.
409
COCH2CH2CH3). MS m/z: 313.6 [M + H]+ Anal. calcd. for
C19H20O4: C 73.06, H 6.45; found: C 73.05, H 6.44.
References
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1. (a) R.D.H. Murray. In Fortschritte der Chem. Org. Naturstoffe.
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Murray, J. Mendez, and S.A. Brown. In The natural
coumarins, occurrence, chemistry and biochemistry. Wiley,
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Publishing, New York. 2000. p. 181.
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Pharm. Sci. 30, 379 (1989).
Compound 7f
Mp 89 °C. IR (cm–1): 2958, 1724, 1711, 1603, 1563,
1
1490, 1448, 1372. H NMR δ: 1.04 (t, J = 7.4 Hz, 3H, 8-
COCH2CH2CH3), 1.54–1.50 (br m, 1H, 6′-Hax), 1.68–1.55
(br m, 3H, 5′-H2, 6′-Heq), 1.80 (tq, J = 7.0 Hz, 7.0 Hz, 2H, 8-
COCH2CH2CH3), 2.19–2.04 (br m, 2H, 4′-H2), 2.40 (d, J =
1.0 Hz, 3H, 4-CH3), 3.34 (t, J = 7.05 Hz, 2H, 8-
COCH2CH2CH3), 3.90 (br s, 1H, 1′-H), 5.63 (br d, J =
8.1 Hz, 1H, 2′-H), 6.01 (br dt, J = 8.0 Hz, 2.2 Hz, 1H, 3′-H),
6.14 (q, J = 1.0 Hz, 1H, 3-H), 7.54 (sharp s, 1H, 5-H), 14.17
(s, 1H, 7-OH). 13C NMR δ: 13.67 (1°, 8-COCH2CH2CH3),
18.02 (2°, 8-COCH2CH2CH3), 19.10 (1°, 4-CH3), 20.60 (2°,
C-5′), 25.12 (2°, C-4′), 29.54 (2°, C-6′), 47.04 (2°, 8-
COCH2CH2CH3), 108.94 (3°, C-1′), 108.95 (4°, C-4a),
111.00 (3°, C-3), 111.17 (4°, C-8), 128.91 (3°, C-2′), 129.36
(3°, C-5), 129.86 (3°, C-3′), 131.93 (4°, C-6), 153.09 (4°, C-
4), 153.71 (4°, C-8a), 159.74 (4°, C-2), 164.71 (4°, C-7),
207.60 (4°, 8-COCH2CH2CH3). MS m/z: 327.3 [M + H]+.
Anal. calcd. for C20H22O4: C 73.60, H 6.79; found: C 73.63,
H 6.77.
Compound 7g
Mp 138 °C. IR (cm–1): 3060, 2950, 1730, 1680, 1565,
1
1440, 1400, 1340. H NMR δ: 1.67–1.54 (m, 3H, 5′-H2, 6′-
Hax), 2.13–2.05 (br m, 3H, 6′-Heq, 4′-H2), 3.93 (br s, 1H, 1′-
H), 5.69 (br d, J = 9.8 Hz, 1H, 2′-H), 6.04 (br dt, J =
10.1 Hz, 2.1 Hz, 1H, 3′-H), 6.16 (br d, J = 9.5 Hz, 1H, 3-H),
7.46 (t, J = 7.4 Hz, 2H, 3′′-H and 5′′-H), 7.46 (s, 1H, 5-H),
7.61 (br t, J = 7.3 Hz, 1H, 4′′-H), 7.62 (d, J = 9.3 Hz, 1H, 4-
H), 7.68 (br d, J = 7.3 Hz, 2H, 2′′-H and 6′′-H), 11.64 (s,
1H, 7-OH). MS m/z: 347.4 [M + H]+. Anal. calcd. for
C22H18O4: C 76.29, H 5.24; found: C 76.33, H 5.22.
11. (a) L.N. Dutta, N.C. Sinha, and A.K. Sarkar. Indian J. Chem.
30B, 1112, (1991); (b) L.N. Dutta, N.C. Sinha, and A.K.
Sarkar. Indian J. Chem, 27B, 801 (1988).
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Chem. 73, 1556 (1995); (b) L.N. Dutta and M. Bhattacharyya.
J. Indian Chem. Soc. 80, 953 (2003).
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hedron Lett. 11, 243 (1970); (b) R.D.H. Murray, M.M.
Ballantyne, T.C. Hogg, and P.H. McCabe. Tetrahedron, 31,
2960 (1975).
Compound 7h
Mp 175 °C. IR (cm–1): 3444, 2926, 1735, 1685, 1617,
1
1560, 1498, 1449, 1399. H NMR δ: 1.84–1.62 (br m, 3H,
5′-H2, 6′-Hax), 2.29–2.15 (br m, 3H, 6′-Heq, 4′-H2), 2.43 (d, J
= 1.0 Hz, 3H, 4-CH3), 3.97 (br s, 1H, 1′-H), 5.73 (br d, J =
10.0 Hz, 1H, 2′-H), 6.07 (br d, J = 10.0 Hz, 1H, 3′-H), 6.16
(q, J = 1.0 Hz, 1H, 3-H), 7.48 (t, J = 7.4 Hz, 2H, 3′′-H and
5′′-H), 7.59 (s, 1H, 5-H), 7.61 (br t, J = 7.3 Hz, 1H, 4′′-H),
7.70 (br d, J = 7.3 Hz, 2H, 2′′-H and 6′′-H), 11.39 (s, 1H, 7-
OH). MS-EI (70 eV) m/z: 360 (100, M), 339 (12.7), 332
(14.1), 317 (10.9), 306 (22.7), 279 (13.6), 263 (63.6), 215
(8.2), 165 (8.2), 115 (10.4), 105 (38.2), 77 (34.1) Anal.
calcd. for C23H20O4: C 76.65, H 5.59; found: C 76.63, H
5.61.
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23, 2049 (1982); (b) V.K. Ahluwalia, C. Prakash, and R.
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(1999).
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Commun. 19, 917 (1989); (b) K.C. Majumdar, A.T. Khan,
A.K. Gupta, and K. Dey. Synth. Commun. 20, 1249 (1990);
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3633 (1998).
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43, 7781 (2002).
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3621 (2003).
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Vol. 3. Edited by G.A. Olah. Wiley, New York. 1964. p. 499.
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Acknowledgement
Sincere thanks are accorded to the Department of Chemis-
try, J.U. for IR spectra, CAS Instrumentation Centre, Depart-
ment of Chemistry, C.U. for various NMR spectra, Indian
Institute of Chemical Biology, Kolkata 700032 for mass
spectral data, and Indian Association for the Cultivation of
Science, Kolkata 700032 for elemental analyses.
© 2008 NRC Canada