Synthesis of 7-(furan-2-yl)-7,8,10,10a-tetrahydro-6H-benzo[c]-chromen-6, 9(6aH)-diones

Article abstract of DOI:10.1134/S1070428010110187

Methods of synthesis were developed for 7-(furan-2-yl)-substituted 7,8,10,10a-tetrahydrobenzo[c] chromen-6,9-diones by regioselective [4+2]-cycloaddition of coumarin-3-carboxylic acids to 2-(3-trimethylsiloxybuta- 1,3-dien-1-yl)furans. The [4+2]-cycloaddi

Full text of DOI:10.1134/S1070428010110187

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 11, pp. 1709−1718. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © E.E. Shults, S.P. Bondarenko, M.M. Shakirov, I.Yu. Bagryanskaya, G.A. Tolstikov, 2010, published in Zhurnal Organicheskoi Khimii,
2010, Vol. 46, No. 11, pp. 1701−1709.
Synthesis of 7-(Furan-2-yl)-7,8,10,10a-tetrahydro-6H-benzo[с]-
chromen-6,9(6aH)-diones
E. E. Shults, S. P. Bondarenko, M. M. Shakirov, I. Yu. Bagryanskaya, and G. A. Tolstikov
Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences,
Novosibirsk, 630090 Russia
е-mail: schultz@nioch.nsc.ru
Received December 22, 2009
Abstract—Methods of synthesis were developed for 7-(furan-2-yl)-substituted 7,8,10,10a-tetrahydrobenzo[с]
chromen-6,9-dionesbyregioselective[4+2]-cycloadditionofcoumarin-3-carboxylicacidsto2-(3-trimethylsiloxybuta-
1,3-dien-1-yl)furans. The [4+2]-cycloaddition was efficiently catalyzed with L-proline.
DOI: 10.1134/S1070428010110187
Versatile benzo[с]chromen derivatives attract atten-
tion as pharmacologically valuable agents. First of all
it is ellagic acid (I) that is tested as an antitumor drug
[1]. An important group of analgesics and agents for the
treatment of neurogenic diseases consists of natural and
synthetic cannabinoids, tetrahydrobenzo[c]chromens, for
instance, dronabinol (Δ9-tetrahydrocannabinol, TНС) (II)
[2] and ajulemic acid (III) [3]. A wide series of cannabi-
noid derivatives was synthesized and the substituents in
the benzo[с]chromen frame were shown to significantly
affect the analgesic action [2, 4].
The aim of this research is the development of syn-
thesis methods for furyl-substituted 7,8,10,10a-benzo-[с]
chromen-6,9-diones based on the [4+2]-cycloaddition
of coumarin-3-carboxylic acids to 1-(furan-2-yl)-3-
trimethylsiloxybutadienes.
Coumarin-3-carboxylic acids are traditionally pre-
pared by Knoevenagel condensation of salicylic alde-
hydes with malonic acid and its esters, sometimes under
the catalysis with organic bases [5, 6]. In 1988 a two-
stage synthesis of the coumarin-3-carboxylic acids was
developed involving a condensation of 2-methoxybenz-
aldehydes with the Meldrum’s acid in DMF followed by
cyclization in the presence of sulfuric acid [7]. Various
modification of this method were developed including the
performance of the condensation of o-hydroxyaldehydes
with the Meldrum’s acid in the presence of a solid-phase
catalyst [8], pyridinium acetate in ethanol [9], in water
[10], in ionic liquids [11].
OH
O
O
OH
OH
H
H
O
HO
O
O
OH
We showed that coumarin-3-carboxylic acids IV–VII
formed at heating a mixture of o-hydroxybenzaldehydes
with the Meldrum’s acid (VIII) to 90–100°С in water
(yield 65–90%). The reaction of 3-(tert-butyl)-2-hydroxy-
5-(2-methoxyethyl)benzaldehyde or 5-(3-acetoxypropyl)-
3-(tert-butyl)-2-hydroxybenzaldehyde with Meldrum’s
acid in the mentioned conditions provided a low yield of
compounds IX, X (20–25%). In order to increase the yield
of the condensation products we carried out the reactions
II
I
CO2H
OH
H
H
O
III
1709

SHULTS et al.
1710
Scheme 1.
R1
H
H2O, 90_100°C
or
R1
R3
O
O
R2
R2
CHO
OH
COOH
O
_
5
4
CH3
CH3
O
O
CHCl3 H2O
6
7
3
2
+
1
O
8
R3
VIII
IV_VII, IX, X
O
H
CH3
CH3
O
6
5'
1
CHO
5
2
H2O, 90_100°C
1'
3
4
O
VIII
+
O
OH
OH
3'
OCH3
OCH3
XI
R1 = OCH3, R2 = R3 = H (IV); R1 = R2 = H, R3 = OCH3 (V); R1 = H, R2 = R3 = Cl (VI); R1 = R3 = H, R2 = NO2 (VII);
R1 = H, R3 = C(CH3)3, R2 = CH3OCH2CH2, (IX), Ac(O)CH2CH2CH2 (X).
in the system chloroform–water. As a result compounds
IX, X were obtained in 79 and 85% yield respectively.
In reaction of 2-hydroxy-3-methoxybenzaldehyde with
compound VIII in water (90°С, 30 min) we succeeded
to obtain 5-(2-hydroxy-3-methoxybenzylidene)-1,3-
dioxane-4,6-dione (ХI). At the same time the initial
aldehyde was also isolated from the reaction mixture.
The conversion was 20%.
dicarboxylic acid, and intramolecular esterification.
We established that the reaction of 5-methoxy-
coumarin-3-carboxylic acid (IV) with 1-(α-furyl)-3-
trimethylsiloxybutadienes XIIa, XIIb in the presence
of ZnCl2 in dichloromethane occurred in each case with
the formation of two compounds: 7-furyl-substituted
1-methoxy-7,8,10,10a-tetrahydro-6H-benzo[c]chromen-
6,9(6аH)-diones XIII, XIV and 1-methoxy-7,8-dihydro-
6H-benzo[c]chromen-6,9(6аH)-dione XV, XVI. The main
reaction products are compounds XIII, XIV [the ratio
(XIII):(XV) = 6 : 1, (XIV) : (XVI) = 5 : 1] (Scheme 2).
Compounds XIII, XIV, XVI were isolated by column
chromatography in the yields 28, 30, and 5% respectively.
We did not aim to isolate the primary reaction products
containing the carboxy group and trimethylsilyl sub-
stituent since the final target were the tetrahydrobenzo[c]
chromendiones. It is characteristic that the reaction of
[4+2]-cycloaddition in the presence of excess ZnCl2
(1.2 equiv) is accompanied by a considerable tarring.
Diels–Alder reaction of 1,3-dienes with the 3-sub-
stituted coumarins is a convenient way to versatile
chromens, but the low reactivity of the coumarins as
dienophiles somewhat restricts their synthetic application.
The 3-alkoxy- and 3-cyanocoumarins are known to react
with isoprene at boiling in xylene furnishing benzo[с]
chromens in fair yields [12]. In [13] the [4+2]-cycload-
dition of 3-(8-phenyl-menthyloxycarbonyl)coumarin
with 2,3-dimethyl-1,3-butadiene at room temperature
was described with the use of diene excess (44 equiv)
and equimolar amount of ZnCl2. Recently various ways
were developed for the intensification of this cycloaddi-
tion reaction: The catalysis of the reaction between the
ethyl coumarin-3-carboxylates and 1,3-butadienes with
HfCl4·2THF [14], performing the reaction in water [15]
or at elevated pressure [15, 16]. According to [15] the
reaction of 2,3-dimethylbutadiene with ethyl coumarin-
3-carboxylates in water at heating yields tetrahydro-6Н-
benzo[с]chromenones. Girotti et al. suggested a scheme
of these products formation involving the hydrolysis of
the lactone ring, the decarboxylation of the intermediate
We showed formerly that 5-arylidene-1,3-dioxanedio-
nes readily reacted with siloxy-substituted dienes XIIa,
XIIb with the formation in high yield and regioselectiv-
ity spiroadducts in the presence of L-proline [17]. In the
reaction of 5-methoxycoumarin-3-carboxylic acid (IV)
with dienes XIIa, XIIb in CH3CN c in the presence
of L-proline (10 mol%, 60°С, 12–15 h) we obtained
tetrahydro-6H-benzo[c]chromen-6,9(6аH)-diones XIII,
XIV in 68 and 62% yield respectively. The reaction of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 11 2010

SYNTHESIS OF 7-(FURAN-2-YL)-7,8,10,10a-TETRAHYDRO-...
1711
Scheme 2.
Me3SiO
O
O
9
H3CO
8
10
OCH3
H
H
ZnCl2,
CH2Cl2, 20°C
H
7
6a
10a
1
+
+
IV
2
H
O
H
O
3
O
6
O
5
O
4
O
O
R4
R4
R4
XIIa, XIIb
XIII, XIV
XV, XVI
O
R1
R1
H
L-proline, MeCN,
or MeCN_DMF
H
H
R2
R2
COOH
XIIa, XIIb +
H
O
O
O
O
O
R4
R3
R3
IV_VII, IX, X
XIII, XIV, XVII_XXIII
H
OSiMe3
OSiMe3
H3CO
H
H3CO
L-proline, MeCN,
25°C
O
HO
O
HO
+
O
O
O
O
O
O
H
O
H3C
H
O
N
C
CH3
HO
O
XIIa
XI
A
H
H3CO
OSiMe3
H3CO
O
O
HO
_Me3SiH, _(CH3)2CO,
_CO2,
O
+
O _
_L-proline
O
O
H
O
H
O
O
N
C
XVII
HO
O
B
the mixture CH3CN–DMF, 2 : 1, in the presence of L-
proline at 80°С made it possible to increase the yield of
compound XVII to 73%. The reactions of substituted
coumarin-3-carboxylic acids VI, VII, IX with diene
XIIa or of compound X with dienes XIIa, XIIb in the
dienes XIIa, XIIb with 8-methoxycoumarin-3-carboxylic
acid (V) in these conditions resulted in the formation of
tetrahydro-6H-benzo[c]chromen-6,9(6аH)-diones XVII,
XVIII in 60 and 56% yield respectively. The performance
of the reaction between coumarin V and diene XIIa in
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 11 2010

SHULTS et al.
1712
spectra. The cis-position of Н6а proton with respect to
protons Н7,10а follows from the values of the coupling
constants with the mentioned protons (J 3.8–5.3 Hz).
The syn-orientation of Н6а,7,10a protons is confirmed by
the data of NOESY experiment for compound XIV by
the existence of the NOE-effect between the protons Н10а
and Н6а, Н7.
1
The characteristic feature of Н NMR spectra of
compounds XV, XVI is the singlet signal of proton Н10
at 6.52 and 6.55 ppm respectively. The cis-position of
protons Н6а,7 follows from the values of the coupling
constants between these protons (J 5.8–6.1 Hz) (δ 3.96
and 4.08 ppm for compound XVI). In the 13С NMR the
signal of atom С9 of the conjugated carbonyl group is
observed at δ 195.88 ppm.
The structure of 7,8,10,10a-tetrahydro-6Н-benzo[с]
chromendione (XVII) was additionally proved by XRD
analysis. The spatial arrangement of the molecule of com-
pound XVII is shown on the figure. The six-membered
ring joined to the chromen skeleton has a chair form. The
furan ring is flat, the mean-square deviation of atoms from
the plane is 0.002 Å. The orientation of the furan ring
with respect to the chromen skeleton is characterized by
the torsion angle С3’C2’C7C6a 64.2(4)°. The pyran ring
exists in the semichair conformation, the torsion angle
С10аС1аС4аО5 equals 6.6(4)°. Atoms О1 and С11 are lo-
cated in the plain of the benzene fragment (mean-square
deviation from the plane through the atoms of the benzene
Spatial arrangement of (6aR,7S,10aR)-4-methoxy-7-(furan-2-
yl)-7,8,10,10a-tetrahydro-6H-benzo[c]chromen-6,9(6aH)-dione
(XVII) according to XRD data.
found conditions afforded tetrahydrobenzo[c]chromen-
6,9(6aH)-diones XIX–XXIII in 46–63% yield.
We also obtained compound XVII (yield 87%) in the
reaction of 5-arylidenedioxanedione XI with diene XIIa
in acetonitrile at room temperature (Scheme 2). The pos-
sible route to dione XVII formation involves as the main
stage the opening of the dioxanedione ring of the spiroad-
duct A accompanied by acetone and CO2 elimination and
the hydrolysis of the trimethylsilyl group.
ring and О1, С11 is 0.018
Å).
The structure of compounds obtained is unambigu-
ously proved by spectral data. The characteristic feature of
the 1Н NMR spectra of tetrahydro-6Н-benzo[c]chromen-
6,9-diones is the presence of seven one-proton signals in
the region 2.3–3.8 ppm. The chemical shifts of protons
were obtained from the analysis of 2D 1Н–1Н correlation
The bond lengths and bond angles in molecule XVII
within the 3σ range coincide with the average values
[18]. We did not find in the Cambridge Crystallographic
Database [19] structures with analogous skeleton and
substituents, namely, benzo[с]chromen frame with a
Scheme 3.
Me3SiO
H
OSiMe3
OSiMe3
R
C
R1
O
.
.
.
R2
O
R1
H
HO
O...
R1
H
O
OH...
.
O
C
R2
R
R2
O
.
.
R
.
OH
C
.
.
H
C
O
N
O
O
OH
.
O
.
O
.
.
.
O
.
.
.
.
.
C
R3
HO
O
O
.
O
.
.
.
.
H
O
C
H
R3
ZnCl2
R3
HO
N
N
D
C
E
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 11 2010

SYNTHESIS OF 7-(FURAN-2-YL)-7,8,10,10a-TETRAHYDRO-...
1713
furan ring as a substituent. The geometry of the benzo[с]
chromen within 3σ limits coincides with the analogous
values of the molecule (6aRS,10aSR)-3-methoxy-
6а,7,8,9,10,10а-hexahydro-6Н-dibenzo[b,d]pyran-6-one
[20], the nearest analog of compound XVII.
In experiments freshly distilled solvents and reagents
of “pure” grade were used.
Meldrum’s acid (VIII) was obtained as described in
[21], 2-(3-trimethylsiloxybuta-1,3-dien-1-yl)furans XIIа,
XIIb, by procedure [22].
It is clear arom the data obtained that the reaction of
siloxybutadienes XIIа, XIIb with coumarin-3-carboxylic
acids proceeds stereo- and regioselectively. Considering
the probable transition states C–E arising during the
formation of the reaction products (Scheme 3) it is pos-
sible to conclude that the approach of the diene from the
above is preferable; the regioselectivity is governed by
the stabilization of the interactions arising in this case
between the substituents of the diene and the dienophile,
and also with the catalyst.
Coumarin-3-carboxylic acids IV–VII, IX, X. To
a solution of 1.44 g (10 mmol) of Meldrum’s acid (VIII)
in 40 ml of water was added at stirring 10 mmol of an
aromatic aldehyde. The reaction mixture was heated to
100°С and stirred for 2 h. On cooling the precipitate was
filtered off and washed in succession with hot water and
ether, dried in a vacuum to obtain compounds IV–VII.
To a solution of 10 mmol of an aromatic aldehyde
in 40 ml of chloroform was added 1.44 g (10 mmol) of
Meldrum’s acid (VIII). The reaction mixture was boiled
for 8 h, cooled, and washed with 10 ml of water. The
chloroform solution was evaporated, the residue was
crystallized from ethanol to obtain compounds IX, X.
The furan substituent in compounds XIII, XIV, XVII–
XXIII is located obviously prevailingly in the equatorial
position, and in compounds XV, XVI, pseudoequatorial,
since the spatial interactions arising at the 1,3-diaxial
orientation between the fused aryl and furan substituents
of the chromen skeleton in this conformation result in
a more thermodynamically stable product.
5-Methoxy-2-oxo-2Н-chromen-3-carboxylic acid
(IV). Yield 90%, mp 214–216°С (215–216°С [7]). UV
spectrum, λmax, nm (log ε): 208 (4.56), 246 (3.85), 322
1
(4.26). Н NMR spectrum [(CD3)2SO], δ, ppm: 3.91 s
(3Н, ОСН3), 6.88 d (1Н, Н3, J 8.6 Hz), 6.92 d (1Н, Н1,
J 8.2 Hz), 7.62 d.d (1Н, Н2, J 8.0, 8.2 Hz), 8.60 s (1Н,
Н4), 11.93 s (1Н, ОН). 13С NMR spectrum, δ, ppm: 59.87
(ОСН3), 109.57 (С6), 111.55 (С8), 116.75 (С4а), 119.24
(С3), 139.08 (С7), 146.17 (С4), 158.79 (С8а), 159.96 (С2),
160.34 (С5), 167.20 (СООН). Mass spectrum, m/z (Irel,
%): 221 (6), 220 (45) [M]+, 203 (4), 188 (3), 177 (22),
176 (100), 148 (50), 133 (66), 105 (26), 77 (40), 51 (33).
C11H8O5. Calculated M 220.03717.
EXPERIMENTAL
NMR spectra were registered on spectrometers
Bruker AV-300 [operating frequencies 300.13 (1Н) and
75.47 MHz (13С)],AV-400 [operating frequencies 400.13
(1Н) and 100.78 MHz (13С)], and DRX-500 [operating
frequencies 500.13 (1Н) and 125.76 MHz (13С)] from
solutions of compounds in CDCl3. The assignment of
signals in the NMR spectra was performed with the use
of various types of proton-proton and carbon-proton cor-
relation spectra (СOSY, COXH, COLOC). For recording
mass spectra, evaluation of molecular mass and elemen-
tal composition mass spectrometer of high resolution
DFS Thermo Scientific was applied (energy of ionizing
electrons 70 eV, vaporizer temperature 230–280°С). IR
spectra were recorded on a spectrophotometer Vector-22
from pellets with KBr. UV absorption spectra were taken
on a spectrophotometer HР 8453 UV-Vis in ethanol. The
XRD experiment was performed with a diffractometer
Bruker P4 (MoKα-radiation, graphite monochromator,
2θ/θ-scanning with varied rate, 2.5 deg/min in the range
2.29 < θ < 26.00°).
8-Methoxy-2-oxo-2Н-chromen-3-carboxylic acid
(V). Yield 86%, mp 214–216°С (218–219°С [6]). UV
spectrum, λmax, nm, (log ε): 207 (4.22), 256 (4.45), 324
(3.94). 1Н NMR spectrum (CDCl3), δ, ppm: 3.88 s (3Н,
ОСН3), 7.29 d.d (1Н, Н6, J 8.0 Hz), 7.33 d.d (1Н, Н5,
J 1.2, 8.1 Hz), 7.35 d.d (1Н, Н7, J 1.2, 8.0 Hz), 8.66 s (1Н,
Н4), 11.48 s (1Н, ОН). 13С NMR spectrum, δ, ppm: 56.54
(ОСН3), 116.55 (С7), 118.81 (С3), 121.47 (С4а), 122.66
(С4), 124.19 (С5), 125.14 (С6), 146.62 (С8a), 149.06 (С8),
156.85 (С2), 164.41 (СООН).
2-Oxo-6,8-dichloro-2Н-chromen-3-carboxylic
acid (VI). Yield 65%, mp 196–199°С (198–202°С [5]).
1Н NMR spectrum (CDCl3), δ, ppm: 7.42 d (1Н, Н7,
J 1.9 Hz), 7.54 d (1Н, Н5, J 1.9 Hz), 8.36 s (1Н, Н4),
12.08 s (1Н, ОН). Found, %: С 46.65; Н 1.81; Cl 27.81.
C10H4Cl2O4. Calculated, %: С 46.37; Н 1.56; Cl 27.37.
The reaction products were isolated applying column
chromatography on silica gel (Acros, 0.035–0.070 mm),
eluents benzene–ethyl acetate, chloroform–ethanol.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 11 2010

SHULTS et al.
1714
170.98 (С=О). Mass spectrum, m/z (Irel, %): 346 [M]+
(30), 314 (16), 313 (86), 287 (21), 286 (100), 272 (18),
271 (98), 243 (20), 128 (16), 57 (17), 43 (56). C19H22O6.
Calculated M 346.14163.
6-Nitro-2-oxo-2Н-chromen-3-carboxylic acid
(VII). Yield 72%, mp 235–237°С (237–238°С [5]). IR
spectrum, ν, cm–1: 3262, 1745, 1680, 1618, 1571, 1536,
1523, 1330, 1260, 1079, 1010, 855, 828, 801, 752, 730.
UV spectrum, λmax, nm (log ε): 207 (4.66), 268 (4.45),
324 (3.56). 1Н NMR spectrum [(CD3)2SO], δ, ppm: 7.55 d
(1Н, Н8, J 8.1 Hz), 8.40 d.d (1Н, Н7, J 8.1, 2.0 Hz), 8.45 s
(1Н, Н4), 8.72 d (1Н, Н5, J 2.0 Hz), 11.85 s (1Н, ОН).
13С NMR spectrum, δ, ppm: 122.72 (С3), 123.35 (С8),
125.30 (С4), 130.95 (С4а), 133.34 (С5), 143.70 (С7),
148.64 (С8а), 152.15 (С6), 160.45 (С2), 163.06 (СООН).
Mass spectrum, m/z (Irel, %): 235 [M]+ (29), 191 (100),
133 (15), 117 (19), 105 (14), 89 (22), 88 (11), 77 (14),
63 (20), 62 (18), 51 (16), 28 (14). Found, % С 50.88;
Н 1.78; N 5.84. C10H5NO6. Calculated, %: С 51.06;
Н 2.13; N 5.96. Calculated M 235.01168.
5-(2-Hydroxy-3-methoxybenzylidene)-2,2-dimeth-
yl-1,3-dioxane-4,6-dione (XI). To a solution of 1.44 g
(10 mmol) of Meldrum’s acid (VIII) in 40 ml of water
was added at stirring 1.52 g (10 mmol) of 2-hydroxy-3-
methoxybenzaldehyde. The reaction mixture was stirred
for 30 min at 100°С and was left standing at room temper-
ature for 1 h. The separated precipitate was filtered off and
washed in succession with water and ether to obtain 1.49 g
of a mixture of compound XI and the initial aldehyde.
Compound XI was isolated by recrystallization from
ethanol. Conversion was 20%. mp 214–217°С. 1Н NMR
spectrum (CDCl3), δ, ppm: 1.79 s (6Н, 2 СН3), 3.90 s
(3Н, ОСН3), 6.87 t (1Н, Н5’, J 8.1 Hz), 6.97 d.d (1Н, Н4’,
J 1.9, 8.1 Hz), 7.52 d.d (1Н, Н6’, J 1.9, 8.1 Hz), 8.68 s
(1H, СН=), 12.01 s (1H, OH). Found [M]+ 278.29990.
C14H14O6. Calculated M 278.29976.
8-(tert-Butyl)-6-(2-methoxyethyl)-2-oxo-2Н-
chromen-3-carboxylic acid (IX). Yield 79%, mp
105–106°С. IR spectrum, cm–1: 3230, 2965, 2638, 1755,
1735, 1704, 1621, 1581, 1491, 1273, 1211, 1202, 1167,
1134, 1099, 960, 803, 764, 750. UV spectrum, λmax, nm
(log ε): 207 (4.44), 222 (4.24), 300 (4.09), 342 (3.63).
1Н NMR spectrum (CDCl3), δ, ppm: 1.49 s (9Н, t-Bu),
2.94 t (2Н, Н1’, J 6.3 Hz), 3.34 s (3Н, ОСН3), 3.63 t (2Н,
Н2’, J 6.6 Hz), 7.43 d (1Н, Н7, J 2.0 Hz), 7.59 d (1Н, Н5,
J 2.0 Hz), 8.85 s (1Н, Н4), 11.32 s (1Н, ОН). 13С NMR
spectrum, δ, ppm: 29.35 [C(CН3)3], 34.61 [С(CH3)3],
35.08 (С1’), 58.29 (ОСН3), 72.19 (С2’), 113.41 (С4a),
118.55 (С3), 127.90 (С5), 130.66 (С7), 136.87 (С6), 138.15
(С8), 151.66 (С8a), 151.84 (С4), 162.25 (С2), 163.41
(СООН). Mass spectrum, m/z (Irel, %): 305 (17), 304
[M]+ (97), 289 (75), 272 (18), 271 (95), 260 (23), 259
(73), 215 (26), 128 (21), 115 (21), 45 (100). C17H20O5.
Calculated M 304.13106.
Reaction of coumarin-3-carboxylic acids with si-
loxydienes XIIa and XIIb. a. To a suspension of 0.66 g
(3.0 mmol) of 5-methoxycoumarin-3-carboxylic acid (IV)
and 0.5 g (3.7 mmol) of ZnCl2 in 20 ml of CH2Cl2 was
added at stirring at room temperature 0.69 g (3.3 mmol)
of 2-(3-trimethylsiloxybuta-1,3-dien-1-yl)furan (XIIa).
The brown reaction mixture was stirred for 8–10 h (TLC
monitoring), then more 0.13 g (0.6 mmol) of the diene
was added, and the stirring was continued for 5 h. The
reaction mixture was diluted with water, the layers were
separated, the reaction products were extracted from the
water layer into dichloromethane. The combined organic
solutions were washed with water and dried with MgSO4.
The drying agent was filtered off, the solution was evapo-
rated, the residue was subjected to chromatography on
silica gel (eluent chloroform–ethanol). Two fractions were
isolated in succession: 0.55 g of a mixture of furfurylide-
neacetone (desilylation product of the unreacted diene)
and dione XV, 8 : 1 (eluent chloroform) and 0.38 g (40%)
of contaminated dione XIII (eluent chloroform–ethanol,
100 : 1 > 10 : 1). A repeated chromatography of the first
fraction provided a sample enriched with compound
XV to 80% (0.063 g). A repeated chromatography of
the second fraction provided 0.29 g (28%) of individual
compound XIII.
6-(3-Acetoxypropyl)-8-(tert-butyl)-2-oxo-2Н-
chromen-3-carboxylic acid (X). Yield 85%, mp
129–132°С. IR spectrum, ν, cm–1: 3436, 2962, 2639,
1766, 1745, 1710, 1688, 1621, 1581, 1493, 1365, 1305,
1294, 1235, 1204, 1049, 894, 795, 748. UV spectrum,
λmax, nm (log ε): 208 (4.58), 223 (4.44), 301 (4.30), 350
(3.84). 1Н NMR spectrum (CDCl3), δ, ppm: 1.48 s (9Н,
t-Bu), 1.97 m (2Н, Н2’), 2.04 s (3Н, СН3СО), 2.76 t (2Н,
Н1’, J 7.8 Hz), 4.08 t (2Н, Н3’, J 6.4 Hz), 7.37 d (1Н, Н5,
J 1.9 Hz), 7.53 d (1Н, Н7, J 1.9 Hz), 8.85 s (1Н, Н4),
11.41 s (1Н, ОН). 13С NMR spectrum (CDCl3), δ, ppm:
20.85 (С2’), 29.66 [C(CН3)3], 29.87 (СН3СО), 31.53
(С1’), 34.98 [С(CH3)3], 63.22 (С3’), 113.73 (С4a), 118.90
(С3), 127.59 (С5), 133.99 (С7), 138.64 (С6), 138.91 (С8),
151.80 (С8a), 152.09 (С4), 162.61 (С2), 163.95 (СООН),
On reacting 0.88 g (5 mmol) of coumarin-3-carboxylic
acid IV and 1.56 g (7 mmol) of 5-methyl-2-(3-trimeth-
ylsiloxybuta-1,3-dien-1-yl)furan (XIIb) followed by
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SYNTHESIS OF 7-(FURAN-2-YL)-7,8,10,10a-TETRAHYDRO-...
1715
7,8,10,10a-tetrahydro-6H-benzo[c]chromen-6,9(6aH)-
dione (XIII). Yield 28% (а), 68% (b), mp 127–130°С
(from ether). IR spectrum, ν, cm–1: 1757, 1683, 1642,
1610, 1576, 1505, 1035, 1103, 964, 850, 800, 755. UV
spectrum, λmax, nm (log ε): 208 (4.08), 250 (3.44), 298
(3.58). 1Н NMR spectrum (CDCl3), δ, ppm: 2.20 d.d (1Н,
Н10, J 14.3, 13.5 Hz), 2.75 m (1Н, Н10), 2.81 m (1Н, Н8),
3.13 d.d (1Н, Н8, J 14.7, 13.6 Hz), 3.44 m (1Н, Н7), 3.59
d.d (1Н, Н6а, J 4.7, 5.2 Hz), 3.77 m (1Н, Н10а), 3.84 s
(3Н, ОСН3), 6.16 d (1Н, Н3’, J 3.3 Hz), 6.32 d.d (1Н, Н4’,
J 3.3, 1.8 Hz), 6.65 d.d (1Н, Н2, J 7.6, 1.1 Hz), 6.70 d.d
(1Н, Н4, J 7.8, 1.1 Hz), 7.07 d.d (1Н, Н3, J 7.8, 7.6 Hz),
7.42 d (1Н, Н5’, J 1.8 Hz). 13С NMR spectrum (CDCl3),
δ, ppm: 29.24 (С10а), 32.18 (С7), 39.86 (С8), 40.91 (С6а),
42.78 (С10), 55.95 (ОСН3), 104.77 (С3’), 105.98 (С2),
108.97 (С4), 110.14 (С4’), 113.36 (С10b), 124.93 (С3),
140.70 (С5’), 151.21 (С4а), 153.74 (С2’), 155.65 (С1),
166.02 (С6), 205.86 (С9). Mass spectrum, m/z (Irel, %):
313 (20), 312 [M]+ (100), 254 (18), 255 (43), 221 (21),
176 (50), 148 (22), 121 (37), 105 (22), 94 (83), 91 (22).
Found, %: C 69.38; H 5.07. C18H16O5. Calculated, %:
C 69.22; H 5.16. M 312.09976.
chromatographic separation of products we obtained
three fractions: I, 0.8 g of pure (E)-4-(5-methylfuran-2-yl)
but-3-en-2-one; II, 0.32 g of a mixture containing 42%
of compound XIV according to 1Н NMR data; III, 0.8 g
of a mixture containing ~60% of compound XVI. The
repeated chromatography of the II and III fractions fur-
nished individual compounds: 0.08 g (5%) of compound
XIV and 0.49 g (30%) of dione XVI.
b. To a suspension of 8.5 mmol of dienophile IV, V
and 0.1 g (0.85 mmol) of L-proline in 25 ml of acetonitrile
was added at stirring 1.93 g (9.3 mmol) of 2-(3-trimeth-
ylsiloxybuta-1,3-dien-1-yl)furan (XIIa). The mixture
was heated at stirring to 60°С over 5 h, then more 0.4 g
(1.9 mmol) of the diene was added, and the stirring at
heating was continued for 7–10 h (TLC monitoring).
The solvent was removed in a vacuum, the residue was
subjected to chromatography on silica gel. Compounds
XIII, XVII were isolated by recrystallization of fractions
from appropriate solvents. Similarly in reaction of diene
XIIb with coumarins IV, V we obtained compounds
XIV, XVIII.
c. To a suspension of 2.5 mmol of dienophile VI, VII,
IX, X and 0.05 g (0.5 mmol) of L-proline in a mixture of
8 ml of acetonitrile and 4 ml of DMF was added at stir-
ring 0.68 g (3.3 mmol) of 2-(3-trimethylsiloxybuta-1,3-
dien-1-yl)furan (XIIa). The solution was stirred at 80°С
over 6–10 h. The reaction mixture was left standing for
free evaporation of the solvent. Compounds XIX–XXII
were isolated by column chromatography followed by
recrystallization. Similarly in reaction of diene XIIb with
coumarin X we obtained compound XXIII.
(6aR,7S,10aR)-7-(5-Methylfuran-2-yl)-1-methoxy-
7,8,10,10a-tetrahydro-6H-benzo[c]chromen-6,9(6aH)-
dione (XIV). Yield 30% (а), 62% (b), mp 148–151°С
(from ether). UV spectrum, λmax, nm (log ε): 207 (4.36).
1
250 (3.74), 298 (3.42). Н NMR spectrum (CDCl3), δ,
ppm: 2.18 s (3Н, СН3), 2.20 m (1Н, Н10), 2.70 m (1Н,
Н10), 2.78 m (1Н, Н8), 3.10 d.d (1Н, Н8, J 15.0, 13.4 Hz),
3.42 m (1Н, Н7), 3.59 d.d (1Н, Н6а, J 5.2, 4.8 Hz), 3.78 m
(1Н, Н10а), 3.87 s (3Н, ОСН3), 5.90 d (1Н, Н3’, J 3.2 Hz),
6.05 d (1Н, Н4’, J 3.2 Hz), 6.65 d.d (1Н, Н2, J 7.5, 1.3 Hz),
6.70 d.d (1Н, Н4, J 7.9, 1.3 Hz), 7.26 d.d (1Н, Н3, J 7.9,
7.5 Hz). 13С NMR spectrum (CDCl3) δ, ppm: 13.13
(С5’СН3), 32.24 (С10а), 36.95 (С7), 40.20 (С8), 41.31
(С6а), 43.14 (С10), 55.66 (ОСН3), 105.75 (С3’), 106.26,
106.30 (С2,4’), 109.31 (С4), 113.87 (С10b), 129.19 (С3),
150.55 (С5’), 151.62 (С4а), 152.20 (С2’), 156.03 (С1),
166.32 (С6), 206.32 (С9). Found, %: C 69.51; H 5.71.
C19H18O5. Calculated, %: C 69.93; H 5.56.
d. To a suspension of 0.56 g (2 mmol) of 5-(2-hydroxy-
3-methoxybenzylidene)-2,2-dimethyl-1,3-dioxane-4,6-
dione (XI) and 0.02 g (0.2 mmol) of L-proline in 20 ml
of acetonitrile was added at stirring 0.68 g (3.3 mmol)
of 2-(3-trimethylsiloxybuta-1,3-dien-1-yl)furan (XIIa).
The mixture was stirred for 10 h, then to the formed
solution was added more 0.23 g of diene XIIa, and the
stirring was continued for 8 h. The reaction progress was
monitored by TLC. The precipitate (0.08 g) was filtered
off and washed with acetonitrile. The mother liquor was
evaporated on a rotary evaporator, and the residue (1.45 g)
was subjected to chromatography on silica gel. The frac-
tions containing the reaction product were combined and
treated with ether. The formed precipitate was filtered
off and repeatedly recrystallized from ethyl acetate. We
obtained 0.55 g of dione XVII.
(6aS,7S)-1-Methoxy-7-(furan-2-yl)-7,8,10,10a-
tetrahydro-6H-benzo[c]chromen-6,9(6aH)-dione
(XV) was isolated in 80% purity. Characteristic signals
in 1Н NMR spectrum (CDCl3), δ, ppm: 2.21 d.d (1Н, Н8,
Jgem 16.1, J7,8 10.6 Hz), 2.71 d.t (1Н, Н8, J 16.1, 4.8),
3.80 s (3Н, ОСН3), 3.90 d.d (1Н, Н6a, J 5.8, 1.2 Hz),
4.12 d.d.d (1Н, Н7, J 10.6, 5.8, 4.8 Hz), 6.08 d (1Н, Н3’,
J 3.5 Hz), 6.28 d.d (1Н, Н4’, J 3.5,1.8 Hz), 6.52 s (1Н,
Н10), 6.70 d.d (1Н, Н2, J 8.0, 1.3 Hz), 6.75 d.d (1Н, Н4,
(6aR,7S,10aR)-1-Methoxy-7-(furan-2-yl)-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 11 2010

SHULTS et al.
1716
1
J 7.8, 1.3 Hz), 7.22 d.d (1Н, Н3, J 8.0, 7.8 Hz), 7.36 d
(1Н, Н5’, J 1.8 Hz).
207 (4.69), 248 (4.08), 296 (3.58). Н NMR spectrum
(CDCl3), δ, ppm: 2.21 s (3Н, С5’СН3), 2.36 m (1Н,
Н10), 2.68 d.d (1Н, Н10, J 15.2, 4.5 Hz), 2.78 d.d (1Н,
Н8, J 15.0, 4.4 Hz), 3.10 d.d (1Н, Н8, J 15.0, 11.5 Hz),
3.34 m (1Н, Н10a), 3.43 m (1Н, Н7), 3.67 d.d (1Н, Н6а,
J 4.0, 5.1 Hz), 3.89 s (3Н, ОСН3), 5.88 d (1Н, Н3’,
J 3.4 Hz), 6.01 d (1Н, Н4’, J 3.4 Hz), 6.72 d.d (1Н, Н3,
J 7.9, 1.8 Hz), 6.88 d.d (1Н, Н1, J 8.3, 1.8 Hz), 7.08 d.d
(1Н, Н2, J 8.3, 7.9 Hz). 13С NMR spectrum (CDCl3), δ,
ppm: 13.27 (С5’СН3), 36.90 (С10а), 38.45 (С7), 40.18 (С8),
41.50 (С6а), 44.79 (С10), 55.97 (ОСН3), 105.91 (С3’),
106.25 (С4’), 111.69 (С3), 118.62 (С1), 124.72 (С2), 126.12
(С10b), 139.91 (С4а), 147.67 (С4), 150.58 (С5’), 151.81 (С2’),
165.64 (С6), 205.89 (С9). Found, %: C 69.51; H 5.71.
C19H18O5. Calculated, %: C 69.93; H 5.56.
(6aS,7S)-7-(5-Methylfuran-2-yl)-1-methoxy-
7,8,10,10a-tetrahydro-6H-benzo[c]chromen-6,9(6aH)-
dione (XVI) was obtained by procedure а. Yield 5%,
mp 160–161°С (from ethyl acetate). UV spectrum, λmax
,
nm (log ε): 208 (4.36), 260 (4.48), 312 (3.76). 1Н NMR
spectrum (CDCl3), δ, ppm: 2.20 d.d (1Н, Н8, Jgem 16.1,
J7,8 13.6 Hz), 2.34 s (3Н, СН3), 2.78 d.t (1Н, Н8, J 16.1,
4.8 Hz), 3.83 s (3Н, ОСН3), 3.96 d.d (1Н, Н6a, J 6.1,
1.2 Hz), 4.08 d.d.d (1Н, Н7, J 13.6, 6.1, 4.8 Hz), 6.10 d
(1Н, Н3’, J 3.5 Hz), 6.55 s (1Н, Н10), 6.65 d (1Н, Н4’,
J 3.5 Hz), 6.70 d.d (1Н, Н2, J 8.0, 1.3 Hz), 6.75 d.d
(1Н, Н4, J 7.8, 1.3 Hz), 7.26 d.d (1Н, Н3, J 8.0, 7.8 Hz).
13С NMR spectrum (CDCl3), δ, ppm: 13.86 (С5’СН3),
31.29 (С7), 40.44 (С8), 41.96 (С6а), 55.68 (ОСН3), 106.54
(С3’), 109.28, 109.59 (С2,4’), 113.03 (С10b), 115.21 (С4),
120.27 (С10), 133.04 (С3), 141.97 (С10а), 149.66 (С2’),
151.63 (С4а), 156.32 (С1), 156.53 (С5’), 166.02 (С6),
195.88 (С9). Found, %: C 70.22; H 5.08. C19H16O5.
Calculated, %: C 70.36; H 4.97.
(6aR,7S,10aR)-7-(Furan-2-yl)-2,4-dichloro-
7,8,10,10a-tetrahydro-6H-benzo[c]chromen-6,9(6aH)-
dione (XIX). Yield 49% (c), mp 167–170°С (from
эфира). UV spectrum, λmax, nm (log ε): 209 (4.32), 256
(3.93), 290 (3.16). 1Н NMR spectrum (CDCl3), δ, ppm:
2.44 d.d (1Н, Н10, J 15.2, 12.5 Hz), 2.72 d.d (1Н, Н10,
J 15.2, 4.8 Hz), 2.81 d.d (1Н, Н8, J 14.3, 4.1 Hz), 3.13 d.d
(1Н, Н8, J 14.3, 11.4 Hz), 3.45 m (1Н, Н7), 3.55 m (1Н,
Н10а), 3.70 d.d (1Н, Н6, J 4.8, 4.2 Hz), 6.18 d (1Н, Н3’,
J 3.3 Hz), 6.36 d.d (1Н, Н4’, J 3.3, 1.8 Hz), 7.12 d (1Н,
Н1, J 2.3 Hz), 7.32 d (1Н, Н5’, J 1.8 Hz), 7.40 d (1Н, Н3,
J 2.3 Hz). 13С (CDCl3), δ, ppm: 32.16 (С10а), 35.43 (С7),
38.36 (С8), 39.61 (С6а), 43.11 (С10), 105.18 (С3’), 110.14
(С4’), 125.96 (С1), 128.13 (С3), 132.07, 132.76 (С2,4),
136.16 (С10b), 141.32 (С5’), 150.38 (С4а), 154.13 (С2’),
166.68 (С6), 205.72 (С9). Found, %: C 58.06; H 3.77;
Cl 20.62. C17H12Cl2O4. Calculated, %: C 58.14; H 3.44;
Cl 20.19.
(6aR,7S,10aR)-4-Methoxy-7-(furan-2-yl)-
7,8,10,10a-tetrahydro-6H-benzo[c]chromen-6,9(6aH)-
dione (XVII). Yield 60% (b), 75% (c), 87% (г), mp
120–122°С (from ethyl acetate). IR spectrum, ν, cm–1:
1757, 1683, 1642, 1610, 1576, 1505, 1103, 1035, 964,
850, 800, 755. UV spectrum, λmax, nm (log ε): 208 (4.08).
1
248 (3.44), 298 (3.58). Н NMR spectrum (CDCl3), δ,
ppm: 2.40 m (1Н, Н10), 2.73 d.d (1Н, Н10, J 15.2, 4.5 Hz),
2.82 d.d (1Н, Н8, J 15.0, 4.4 Hz), 3.13 d.d (1Н, Н8, J 15.0,
9.5 Hz), 3.39 m (1Н, Н10a), 3.47 m (1Н, Н7), 3.69 d.d
(1Н, Н6а, J 3.8, 4.9 Hz), 3.89 s (3Н, ОСН3), 6.18 d
(1Н, Н3’, J 3.1 Hz), 6.32 d.d (1Н, Н4’, J 3.1, 1.8 Hz),
6.74 d.d (1Н, Н3, J 7.7, 1.8 Hz), 6.88 d.d (1Н, Н1, J 8.3,
1.8 Hz), 7.07 d.d (1Н, Н2, J 8.3, 7.7 Hz), 7.27 d (1Н,
Н5’, J 1.8 Hz). 13С NMR spectrum, δ, ppm: 36.80 (С10а),
38.43 (С7), 40.14 (С8), 41.44 (С6а), 44.82 (С10), 55.95
(ОСН3), 105.26 (С3’), 110.47 (С4’), 111.69 (С3), 118.34
(С1), 124.78 (С2), 126.00 (С10b), 139.95 (С4а), 141.01
(С5’), 147.59 (С4), 153.72 (С2’), 165.59 (С6), 205.72
(С9). Mass spectrum, m/z (Irel, %): 313 (20), 312 [M]+
(100), 254 (18), 255 (43), 221 (21), 176 (50), 148 (22),
133 (20), 121 (37), 105 (22), 94 (83), 91 (22). Found,
%: C 69.38; H 5.07. C18H16O5. Calculated, %: C 69.22;
H 5.16. M 312.09976.
(6aR,7S,10aR)-2-Nitro-7-(furan-2-yl)-7,8,10,10a-
tetrahydro-6H-benzo[c]chromen-6,9(6aH)-dione
(XX). Yield 46% (c), mp 164–167°С. IR spectrum, ν,
cm–1: 1753, 1685, 1625, 1591, 1521, 1505, 1484, 1235,
1124, 1090, 1066, 1004, 976, 928, 816, 750, 720. UV
spectrum, λmax, nm (log ε): 205 (4.25), 284 (4.27), 412
1
(3.12). Н NMR spectrum (CDCl3), δ, ppm: 2.42 m
(1Н, Н10, Jgem 14.6 Hz), 2.75 d.d (1Н, Н10, J 14.6,
4.4 Hz), 2.88 d.d (1Н, Н8, J 15.8, 4.8 Hz), 3.10 m (1Н,
Н8, Jgem 15.8 Hz), 3.52 m (1Н, Н7), 3.58 d.d.d (1Н, Н10а,
J 9.6, 5.2, 4.4 Hz), 3.75 d.d (1Н, Н6а, J 5.2, 3.8 Hz), 6.17 d
(1Н, Н3’, J 3.6 Hz), 6.34 d.d (1Н, Н4’, J 3.6, 1.8 Hz),
7.21 d (1Н, Н4, J 8.8 Hz), 7.30 с (1Н, Н5’, J 1.8 Hz), 8.14 d
(1Н, Н1, J 2.8 Hz), 8.21 d.d (1Н, Н3, J 8.8, 2.8 Hz). Mass
spectrum, m/z: 329 (3), 328 (18), 327 [M]+ (100), 270(32),
191 (21), 136 (28), 121 (46), 95 (17), 94 (68), 77 (53),
(6aR,7S,10aR)-7-(5-Methylfuran-2-yl)-4-methoxy-
7,8,10,10a-tetrahydro-6H-benzo[c]-chromen-
6,9(6aH)-dione (XVIII). Yield 56% (c), mp 131–134°С
(from ethyl acetate). UV spectrum, λmax, nm (log ε):
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 11 2010

SYNTHESIS OF 7-(FURAN-2-YL)-7,8,10,10a-TETRAHYDRO-...
1717
66 (23), 65 (56). Found [M]+ 327.07128. C17H13NO6.
Calculated M 327.07420.
6.06 m (1Н, Н4’’, J 2.6 Hz), 6.94 s (1Н, Н1), 7.02 s (1Н,
Н3). 13С NMR spectrum, δ, ppm: 13.38 (С5’СН3), 26.48
(CH2), 28.31 (CH2), 27.97 (СН3СО), 29.65 [C(CН3)3]
,
(6aR,7S,10aR)-4-(tert-Butyl)-2-(2-methoxyethyl)-
7-(furan-2-yl)-7,8,10,10a-tetrahydro-6H-benzo[c]
chromen-6,9(6aH)-dione (XXI). Yield 46% (c), mp
128–130°С (from ethanol). 1Н NMR spectrum (CDCl3),
δ, ppm: 1.49 (9Н, (t-Bu), 2.42 m (1Н, Н10, Jgem 15.2 Hz),
2.69 m (1Н, Н10), 2.78 m (1Н, Н8, Jgem 13.8 Hz), 2.85 t
(2Н, СН2, J 6.2 Hz), 3.16 m (1Н, Н8, Jgem 13.8 Hz),
3.37 s (3Н, ОСН3), 3.49 m (2Н, Н7,10а), 3.58 t (2Н, СН2,
J 7.2 Hz), 3.61 d.d (1Н, Н6а, J 5.0, 4.2 Hz), 6.21 d (1Н,
Н3’, J 3.3 Hz), 6.35 d.d (1Н, Н4’, J 3.3, 1.8 Hz), 6.91 d
(1Н, Н1, J 2.0 Hz), 7.15 d (1Н, Н3, J 2.0 Hz), 7.32 d (1Н,
Н5’, J 1.8 Hz). 13С NMR spectrum (CDCl3), δ, ppm: 29.65
[C(CН3)3], 36.86 [С(CH3)3], 38.09 (С7,10а), 40.99 (СН2),
41.83 (С8), 42.46 (С10), 43.23 (С6а), 51.49 (ОСН3), 70.19
(СН2), 105.52 (С3’), 109.41 (С4’), 122.67 (С1), 124.48
(С3), 134.42 (С2), 135.66 (С10b), 139.28 (С4), 141.88
(С5’), 144.13 (С4а), 156.43 (С2’), 166.75 (С6), 206.09
(С9). Found, %: C 73.12; H 7.01. C24H28O5. Calculated,
%: C 72.70; H 7.12.
38.14 (С7), 38.41 (С10а), 39.88 [С(CH3)3], 41.12 (СН2),
41.68 (С8), 42.13 (С10), 42.38 (С6а), 61.77 (СН2), 105.68
(С3’), 106.22 (С4’), 123.98 (С1), 125.18 (С3), 134.23
(С10b), 139.54 (С2), 139.73 (С4), 145.32 (С4а), 150.28
(С5’), 153.06 (С2’), 166.74 (С6), 176.09 (C=O), 205.78
(С9). Found, %: C 71.36; H 7.28. C27H32O6. Calculated,
%: C 71.66; H 7.13.
XRD investigation of compound XVII. For
the experiment a crystal was selected of dimensions
0.80 × 0.50 × 0.3 mm. Crystals monoclinic: a 9.409(1), b
12.306(2), c 12.984(1) Å, β 98.225(8)°, V 1487.9(3) Å3,
space group P 21/n, Z 4. C18H16O5. dcalc 1.394 g cm–3,
μ 0.102 mm–1. The intensities of 3101 reflections were
measured, among them 2921 independent (Rint 0.034).
The correction for the extinction was performed by the
empirical method using Ψ-curves (transmission 0.54–
0.86). The structure was solved by the direct method
along software SHELXS-97 [23]. The refinement of the
structural parameters was done by least-mean-squares
method in the full-matrix anisotropic approximation for
nonhydrogen atoms and in the isotropic approximation
for the experimentally localized hydrogen atoms with
the use of software SHELXL-97 [23]. The final refine-
ment of the structure was performed for all F2 till wR2
0.1793, S 1.023, 272 parameters were refined (R 0.0604
for 2114 F > 4σ). CIF file containing complete infor-
mation on the investigated structure is deposited to the
Cambridge Crystallographic Database Center under the
number CCDC 755357, and the data are available by the
address: www.ccdc.cam.ac.uk/data_request/cif.
(6aR,7S,10aR)-2-(3-Acetoxypropyl)-4-(tert-butyl)-
7-(furan-2-yl)-7,8,10,10a-tetrahydro-6H-benzo[c]
chromen-6,9(6aH)-dione (XXII). Yield 54% (c), mp
1
138–142°С. Н NMR spectrum (CDCl3), δ, ppm: 1.48
(9Н, t-Bu), 2.10 s (3Н, СН3СО), 2.26 m (2Н, СН2),
2.42 m (1Н, Н8а), 2.60 m (1Н, Н8е), 2.69 m (2Н, СН2),
2.82 m (1Н, Н10е), 3.20 m (1Н, Н10а), 3.55 m (2Н, Н7,10а),
3.92 d.d (1Н, Н6а, J 5.0, 3.6 Hz), 4.12 m (2Н, СН2), 6.16 d
(1Н, Н3’, J 3.0 Hz), 6.28 d.d (1Н, Н4’, J 3.0, 1.5 Hz),
6.91 s (1Н, Н1), 7.08 s (1Н, Н3), 7.32 s (1Н, Н5’, J 1.5 Hz).
13С NMR spectrum, δ, ppm: 25.66 (CH2), 28.22 (CH2),
27.64 (СН3СО), 29.60 [C(CН3)3], 38.22 (С7), 38.48
(С10а), 39.68 [С(CH3)3], 41.88 (С8), 42.21 (С10), 42.54
(С6а), 62.06 (СН2), 105.48 (С3’), 110.37 (С4’), 123.69
(С1), 125.19 (С3), 134.28 (С10b), 139.12 (С2), 139.77
(С4), 142.46 (С5’), 145.25 (С4а), 153.06 (С2’), 166.78 (С6),
176.28 (C=O), 206.09 (С9). Found, %: C 71.12; H 7.12.
C26H30O6. Calculated, %: C 71.21; H 6.90.
ACKNOWLEDGMENTS
The study was carried out under a financial sup-
port from the Russian Foundation for Basic Research
(grant no.08-03-00340).
(6aR,7S,10aR)-2-(3-Acetoxypropyl)-4-(tert-butyl)-
7-(5-methylfuran-2-yl)-7,8,10,10a-tetra-hydro-6H-
benzo[c]chromen-6,9(6aH)-dione (XXIII). Yield 62%
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