A facile route to phenyl, phenylsulfanyl and phenylselanyl substituted pyrano[3,2-c]chromenes

Article abstract of DOI:10.1016/j.tet.2009.11.057

The synthesis of phenyl, phenylsulfanyl and phenylselanyl substituted pyrano[3,2-c]chromenes 4 is accomplished via cyclocondensation of 4-oxo-4H-chromen-3-carbaldehydes 1 with appropriately substituted acetic acids 2 under mild conditions. Further treatment of 4 with alcohol or water led to 5-alkoxy- and 5-hydroxy-2H,5H-pyrano[3,2-c]chromen-2-ones 5 and 6, respectively. Acid and thermal catalysed rearrangement of 4-6 gave 5-hydroxypyrano[2,3-b]chromen-2(10aH)-ones 7 and their subsequent substitution led to 5-alkoxyderivatives 8. Reaction of 4 with amides led to 5-acylamino or 5-phenylsulfonamino substituted 2H,5H-pyrano[3,2-c]chromen-2-ones 9. Reactions were performed under heating or microwave irradiation.

Full text of DOI:10.1016/j.tet.2009.11.057

Tetrahedron 66 (2010) 1410–1419
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
A facile route to phenyl, phenylsulfanyl and phenylselanyl substituted
pyrano[3,2-c]chromenes
a
,
b
,
c
´
´
ˇ
´
ˇ a
´ ˇ a
*
*
Margita Lacova , Renata Gasparova , Pavol Kois , Andrej Bohac , Hafez M. El-Shaaer
a
´
Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University, Mlynska dolina CH-2, SK-842 15 Bratislava, Slovak Republic
b Department of Chemistry, Faculty of Natural Sciences, University of Ss. Cyril and Methodius, SK-917 01 Trnava, Slovak Republic
c Department of Chemistry, Faculty of Education, Ain Shams University, Cairo-Roxy-Egypt
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 26 March 2009
Received in revised form 27 October 2009
Accepted 12 November 2009
Available online 15 November 2009
The synthesis of phenyl, phenylsulfanyl and phenylselanyl substituted pyrano[3,2-c]chromenes 4 is
accomplished via cyclocondensation of 4-oxo-4H-chromen-3-carbaldehydes with appropriately
1
substituted acetic acids 2 under mild conditions. Further treatment of 4 with alcohol or water led to 5-
alkoxy- and 5-hydroxy-2H,5H-pyrano[3,2-c]chromen-2-ones 5 and 6, respectively. Acid and thermal
catalysed rearrangement of 4–6 gave 5-hydroxypyrano[2,3-b]chromen-2(10aH)-ones 7 and their sub-
sequent substitution led to 5-alkoxyderivatives 8. Reaction of 4 with amides led to 5-acylamino or 5-
phenylsulfonamino substituted 2H,5H-pyrano[3,2-c]chromen-2-ones 9. Reactions were performed under
heating or microwave irradiation.
Keywords:
Chromenes
Condensation
Rearrangement
Acetic acids
Ó 2009 Published by Elsevier Ltd.
Microwave
Antineoplastic activity
1. Introduction
properties of chromene derivatives, we decided to investigate their
reactions with phenyl-, phenylsulfanyl- and phenylselanylacetic
4-Oxo-4H-chromen-3-carbaldehyde
1
has been extensively
acids under mild conditions. Particularly, thermolabile phenyl-
selanylacetic acids are not convenient components for condensa-
tion reactions at higher temperature.15 There are known aldol
reactions of phenylselanylacetic acid only with substituted benz-
aldehydes16 and heptanal. 17
studied since its convenient synthesis by Vilsmeier–Haack for-
mylation.1 Synthetic application of 1 and its derivatives results from
their reactivity towards nucleophiles. The presence of three strong
electrophilic centres in the molecule of 1 and the ability to open or
retain the pyrone ring can give access to wide variety of hetero-
cycles.2 Many of chromene derivatives exhibit significant biological
activity, such as antialergic,3 antitumour,4 antimycobacterial5 or
antiviral.6
Phenyl- and phenylhetero-substituted acetic acids as active
methylene compounds are versatile synthons for synthesis of
heterocycles.7 In recent years, interest in the chemistry of orga-
noselenium compounds has increased remarkably due to their
chemical properties8 and biological activities.9 Ammonium salts of
some phenylselanylacetic acids have interesting pharmacological
properties as inhibitors of thrombocyte aggregation, hypo-
coagulative activity and moderate antihemolytic activity.10
In connection with this, and as an extension of our studies on
the synthesis,11 kinetics,12 photochemical13 and theoretical14
In our recent work,18 we have described the atypical reaction
course of aldehydes 1 with coumarin-4-acetic acids under Perkin
conditions to afford the pyrano[3,2-c]chromene skeleton. The aim
of this study was to examine this mechanism on the reactions of 1
with the different acids.
2. Results and discussion
The reaction of 4-oxo-4H-chromen-3-carbaldehyde 1 with
phenylacetic acid 2a was already described by Silva and co-
workers19 to give styrylchromones by heating a pyridine solu-
tion of equimolar quantities of both reagents at reflux for 6 h in
the presence of potassium tert-butoxide. Condensation of 1
with phenylsulfonylacetic acid by heating in acetic acid led to
3-[(2-phenylsulfonyl)ethenyl]-4H-chromen-4-one.20 According
to our knowledge the condensations of 1 with phenylsulfanyl-
acetic acid 2b or phenylselanylacetic acid 2c have not been
described.
* Corresponding authors. Tel.: þ421 2 60296 338/33 59 21 411.
E-mail addresses: lacova@fns.uniba.sk (M. La´cova´), renata.gasparova@ucm.sk
ˇ
´
(R. Gasparova).
0040-4020/$ – see front matter Ó 2009 Published by Elsevier Ltd.
doi:10.1016/j.tet.2009.11.057

´
´
M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1411
The unexpected 3-R-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl
acetates 4 were the result of atypical reaction course of equimolar
quantities of aldehydes 1 and acids 2 in acetic anhydride in the
presence of potassium acetate (Scheme 1). The heating of the re-
action mixture at 60–80 ꢀC for 2–3 h proved to be advantageous for
condensation with the thermolabile selene components. If the re-
action was realized at room temperature, the reaction time had to
be prolonged to 12 h. The isolation of acetates 4 from reaction
mixtures was simple because they are formed as the first pre-
cipitates. The acetates 4 were isolated as only products in high
yields (73–83%). The mechanism, assumed for the formation of 4
has been described in.18 Acetates 4 were isolated when the same
reaction was accomplished in microwave oven. The yields of
products 4 were slightly higher (86–88%), but the duration under
microwave irradiation was considerably shorter (10–20 min) and
the purity of 4 increased.
The acetyloxy group at C-5 of pyrano[3,2-c]chromen-5-yl ace-
tates 4 easily undergoes nucleophilic substitution under acidic
catalysis. Heating and stirring of 4 in alcohol or water in the
presence of catalytic amount of p-toluenesulfonic acid for 0.5–3 h
at 60–70 ꢀC yielded alkyloxy derivatives 5 (68–82%) and alcohols 6
(57–73%), respectively (Scheme 1). 3-Phenyl-5-propyloxy-2H,5H-
pyrano[3,2-c]chromen-2-one 5h was synthesized in 76% yield
under microwave irradiation. The reaction was fast (10 min) and
the product was obtained in high purity.
Alternatively, alcohols
6 were prepared by the direct
reaction of 1 with 2 in toluene in the presence of catalytic
amount of potassium acetate at 60 ꢀC. Reaction time had to be
prolonged to 8 h, but products 6 were obtained in higher yields
(74–80%).
The rearrangement of compounds 4–6 in acidic conditions
at elevated temperature furnished 5-hydroxy-3-R-pyrano[2,3-
O
R4
Se
Se
R
Δ
Ac2O
+
R4
R1
CHO
COOH
3
O
4
2
1
R
= H, Br
toluene, AcOK
Ac2O
AcOK
O
O
OR3
O
OH
O
OAc
R
H2O
H
R3OH
H
R1
R1
R1
O
O
R
R
O
O
O
4
5
6
3
1
R
= CH3, C2H5, C3H7, C5H11
R
= H, CH3, Cl, Br, NO2
H2O, H
R2
Z
R2
R =
,
2
Z = S, Se, R = H, CH3, Br, NO2
Scheme 1.
On the other hand, when 1 and 2c were treated either under
reflux or using Perkin conditions without acetic anhydride and the
reaction mixture heated at 180 ꢀC, only decomposition and poly-
meric products were obtained, from which diphenyldiselenides 3
were isolated.
b]chromen-2(10aH)-ones 7 (Scheme 2). The reaction time was
only 1 h and the enones
(74–86%).
7 were obtained in good yields
The 2-oxo-2H,5H-pyrane ring of 4–6 is acid-sensitive (struc-
ture A) and ring opening easily takes place (structure B). The next
O
OR5
OR5
OR5
O
O
O
AcOH
R1
R1
R1
O
OH
R
R
R
4-6
R5 = Ac, H, R3
O
O
H
O
B
A
3
R
= CH3, C2H5, C3H7, C5H11
O
OR5
O
O
O
O
R
O
O
O
R
R6OH
H
R1
1,6-ring
closure
R1
R1
R
OR6
8
OH
OH
7
C
6
R
= CH3, C2H5
Scheme 2.

´ ´
M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1412
step of the rearrangement involves the rotation of a part of mol-
ecule around the single bond (structure C) followed by 1,6-ring
closure to result 5-hydroxy-3-R-pyrano[2,3-b]chromen-2(10aH)-
ones 7.
4. Experimental section
4.1. General
5-Hydroxy-3-phenylpyrano[2,3-b]chromen-2(10aH)-one (7a)
was synthesized by heating at 60 ꢀC for 1 h as well as by micro-
wave-assisted reaction. Conventional heating gave 77% of 7a, and
the further method led to the increase of yield to 84% within
10 min.
Melting points were determined on a Kofler hot plate appa-
ratus and are uncorrected. 1H NMR/13
C NMR spectra were
obtained on a 300 MHz/75 MHz VARIAN GEMINI 2000 spec-
trometer in CDCl3 or DMSO-d6 with tetramethylsilane as an
internal standard. Elemental analyses were performed on CARLO
ERBA STRUMENTAZIONE 1106 apparatus. IR spectra were recor-
ded on FTIR NICOLET 6700 spectrometer in KBr. All microwave-
assisted reactions were performed in an Initiator BIOTAGE
microwave synthesizer. All solvents were distilled and dried ap-
propriately prior to use. The course of reactions was monitored
by TLC in ethyl acetate–isohexane. The protocol in1 was followed
for the synthesis of 6-R1-chromone-3-carbaldehydes. Phenyl-
selanylacetic acids 2 were prepared according to.15a The other
chemicals were purchased from the suppliers as the highest
purity grade.
Further reaction of 7 with methanol or ethanol, respectively in
the presence of p-toluenesulfonic acid led to 5-alkoxy-3-R-pyr-
ano[2,3-b]chromen-2(10aH)-ones
8 in high yields (87, 90%)
(Scheme 2).
Treatment of acetates 4 with amides (acetamide, benzamide or
4-methylphenylsulfonamide) in the presence of p-toluenesulfonic
acid led to 5-R7-aminosubstituted 3-R-pyrano[2,3-b]chromen-
2(10aH)-ones 9 in 80–90% yields (Scheme 3). Nearly quantitative
yields of 9 (92, 95%) were obtained under microwave irradiation for
15 min.
H
O
O
O
O
O
O
O
N
O
O
R7NH2
H
R7
R
H
O
OH
O
R
R
R
O
O
D
O
O
9
4
E
R7 = COPh, SO2Ph
Scheme 3.
The mechanism, assumed for the formation of 9 can be
explained by the protonation of acetyloxy group of 4 (structure
D) and cleavage of acetic acid led to the 2-oxo-2H-pyrano[3,2-
c]chromen-6-ium (structure E), which is converted to prod-
uct 9 by the addition of amino-group from amides R7NH2
(Scheme 3).
Compounds 4a, 4d, 4m, 4p, 5k, 6a, 6c and 9b were screened on
antineoplastic activity in NCI USA.21 Compounds 4a, 4p, 5m and 9b
were not active enough to be selected for the next screening.
Compounds 4d, 5k, 6a and 6c have progressed to the 5-dose screen
performed on 60 human cancer cell lines panel assay at 5 con-
centrations (from 10ꢁ4 M to 10ꢁ8 M). From them compounds 4d
and 6a were identified as low micromolar anti-proliferative sub-
4.2. Diphenyldiselenides (3a, 3b)
A mixture of chromone-3-carbaldehyde 1a (20 mmol) and
phenylselanylacetic acid 2c (20 mmol) in acetic anhydride (15 mL)
was heated to reflux at 120 ꢀC (or heated at 180 ꢀC without acetic
anhydride) for 3 h. Decomposition polymeric products, obtained
after evaporation of acetic anhydride, were washed with water
(2ꢂ30 mL) and then with ethanol (2ꢂ30 mL). The ethanolic solu-
tion thus obtained was heated to reflux with activated carbon. After
filtration and evaporation of the ethanol, diphenyldiselenides 3
were acquired.
4.2.1. Diphenyl diselenide (3a)23. Work-up as described above gave
45% of 3a as pale yellow solid: mp 62–63 ꢀC (dioxane). [Found: C,
46.30; H, 3.24. C12H10Se2 (312.1) requires: C, 46.18; H, 3.23%]; dH
(300 MHz, CDCl3): 7.21–7.29 (6H, m, H-3, 4, 5, 30, 40, 50), 7.57–7.62
(4H, m, H-2, 20, 6, 60).
stances with average GI50¼5.37 or 7.41
mM, and max GI50¼1.20 or
1.62
m
M, respectively.22
3. Conclusions
4.2.2. (4,40-Dibromodiphenyl) diselenide (3b). Work-up as de-
scribed above gave 48% of 3b as pale yellow solid: mp 111–113 ꢀC
(dioxane). [Found: C, 30.79; H, 1.75; Br, 34.22. C12H8Br2Se2 (469.9)
requires: C, 30.67; H, 1.72; Br, 34.01%]; dH (300 MHz, CDCl3): 7.39
(4H, dd, J 8.6, 2.0 Hz, H- 3, 5, 30, 50), 7.43(4H, m, H-2, 20, 6, 60).
3-Substituted 2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl ace-
tates 5 were synthesized by the Perkin reaction of 4-oxo-4H-
chromen-3-carbaldehydes
1 with phenyl, phenylsulfanyl or
phenylselanylacetic acids in acetic anhydride. Reaction of 4 with
alcohols or water gave corresponding 5-alkoxy- and 5-hydroxy-
2H,5H-pyrano[3,2-c]chromen-2-ones 5 and 6, respectively. De-
rivatives 4–6 rearrange to 5-hydroxypyrano[2,3-b]chromen-
2(10aH)-ones 7 under acid catalysis and elevated temperature.
Further reaction of 7 with alcohols yielded 5-alkoxy-3-R-pyr-
ano[2,3-b]chromen-2(10aH)-ones 8. Reaction of 4 with amides
gave 5-acylamino or 5-phenylsulfonamino substituted 2H,5H-
pyrano[3,2-c]chromen-2-ones 9. Synthesis of some derivatives 4,
5, 7 and 9 were accelerated under microwave irradiation and
completed within 10–20 min.
4.3. 3-R-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl acetates
(4a–4s)
Method A: A mixture of 6-R1-chromone-3-carbaldehyde 1
(20 mmol) and substituted acetic acid 2 (20 mmol) in freshly dis-
tilled acetic anhydride (10 mL) in the presence of freshly fused
potassium acetate (45 mg, 1.14 mmol) was stirred for 2 h at 60–
70ꢀC. After cooling the solid product 4 was filtered off, washed with

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M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1413
cold diethyl ether and crystallized either from toluene, ethyl acetate
or dioxane.
1231, 1166, 1123, 1042, 921, 877, 784, 698, 525 cmꢁ1
;
dH (300 MHz,
DMSO-d6): 2.02 (3H, s, CH3), 7.29 (1H, d, J 8.2 Hz, H-7), 7.45 (1H, s,
H-5), 7.63–7.69 (3H, m, H-30, 40, 50), 7.70 (1H, d, J 1.9 Hz, H-10), 7.75
(2H, dd, J 7.3, 1.5 Hz, H-20, 60), 7.81 (1H, dd, J 8.2, 1.9 Hz, H-8), 7.99
(1H, s, H-4); dC (75 MHz, DMSO-d6): 15.6, 63.7, 96.3, 108.1, 114.6,
117.5, 122.2, 122.5, 124.7, 127.9, 128.2, 128.2, 128.4, 128.4, 132.5,
134.3, 139.4, 150.3, 152.1, 159.5.
Method B: A mixture of 6-R1-chromone-3-carbaldehyde
1
(20 mmol) and substituted acetic acid 2 (20 mmol) in freshly
distilled acetic anhydride (10 mL) in the presence of potassium
carbonate (10 mg, 0.72 mmol) was irradiated in microwave oven at
110 ꢀC and 16–19 W for 10–20 min. The products 4 were isolated
and purified in the same manner as in Method A.
4.3.6. 9-Bromo-3-phenyl-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl
acetate (4f). Method B, work-up as described above gave 87% of 4f
as yellow powder: mp 266–268 ꢀC (toluene). [Found: C, 58.24; H,
3.19; Br, 19.06. C20H13BrO5 (413.2) requires: C, 58.13; H, 3.17; Br,
4.3.1. 3-Phenyl-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl
(4a). Method A, work-up as described above gave 81% of 4a as
yellow powder: mp 230–232 ꢀC (ethyl acetate). [Found: C, 71.67; H,
acetate
4.24. C20H14O5 (334.3) requires: C, 71.85; H, 4.22%];
3059,1717,1651, 1638, 1565, 1550,1490, 1460, 1376,1222,1198, 1116,
1043, 1001, 949, 893, 783, 760, 694, 531 cmꢁ1
dH (300 MHz, CDCl3):
2.05 (3H, s, CH3), 7.13 (1H, d, J 8.2, 0.8 Hz, H-7), 7.21 (1H, ddd, J 7.7,
0.8 Hz, H-9), 7.39 (1H, s, H-5), 7.41–7.45 (3H, m, H-30, 40, 50), 7.48
(1H, ddd, J 7.7, 1.4 Hz, H-8), 7.51 (1H, s, H-4), 7.68–7.71 (2H, m, H-20,
60), 7.92 (1H, dd, J 7.7, 1.4 Hz, H-10); dC (75 MHz, DMSO-d6): 21.1,
91.3, 109.8, 114.5, 117.6, 122.1, 122.2, 124.7, 128.1, 128.1, 128.4, 128.4,
128.5, 132.5, 134.5, 139.9, 150.1, 152.7, 159.8, 172.1.
n
(KBr): 3391,
19.34%];
1265, 1223, 1195, 1176, 1053, 1002, 961, 915, 884, 780, 682,
595 cmꢁ1
dH (300 MHz, DMSO-d6): 2.02 (3H, s, CH3), 7.19 (1H, d, J
8.7 Hz, H-7), 7.42–7.47 (3H, m, H-30, 40, 50), 7.49 (1H, s, H-5), 7.69
(1H, dd, J 8.7, 2.3 Hz, H-8), 7.74 (2H, dd, J 8.5, 2.3 Hz, H-20, 60),7.86
(1H, d, J 2.3 Hz, H-10), 8.00 (1H, s, H-4); dC (75 MHz, DMSO-d6):
20.6, 106.6, 110.2, 113.3, 114.8, 116.3, 124.2, 124.4, 125.5, 125.7, 127.9,
128.2, 128.5, 128.6, 134.1, 134.5, 148.3, 151.6, 159.3, 168.9.
n(KBr): 3412, 3039, 1731, 1706, 1639, 1540, 1480, 1354,
;
;
4.3.7. 9-Bromo-3-(4-nitrophenyl)-2-oxo-2H,5H-pyrano[3,2-c]chro-
men-5-yl acetate (4g). Method A, work-up as described above gave
79% of 4g as yellow powder: mp 278–279 ꢀC (toluene). [Found: C,
52.11; H, 2.65; Br, 17.66; N, 3.20. C20H12BrNO7 (458.2) requires: C,
4.3.2. 9-Methyl-3-Phenyl-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl
acetate (4b). Method A, work-up as described above gave 79% of 4b
as yellow powder: mp 264–266 ꢀC (ethyl acetate). [Found: C, 72.17;
H, 4.60. C21H16O5 (348.4) requires: C, 72.41; H, 4.63%];
3058, 1733, 1714, 1645, 1556, 1496, 1359, 1272, 1189, 1128, 1041,
1008, 934, 882, 784, 694, 576 cmꢁ1
dH (300 MHz, DMSO-d6): 1.91
n
(KBr): 3453,
52.42; H, 2.64; Br, 17.44; N, 3.06%];
1601, 1550, 1514, 1479, 1345, 1216, 1194, 1109, 1047, 1007, 946, 863,
851, 776, 695, 542 cmꢁ1
dH (300 MHz, DMSO-d6): 2.02 (3H, s, CH3),
n(KBr): 3444, 1761, 1735, 1644,
;
;
(3H, s, CH3), 2.34 (3H, s, CH3), 6.86 (1H, s, H-5), 7.19 (1H, d, J 8.2 Hz,
H-7), 7.33 (1H, dd, J 8.2, 1.6 Hz, H-8), 7.41–7.48 (3H, m, H-30, 40, 50),
7.53 (1H, d, J 1.6 Hz, H-10), 7.55 (1H, s, H-4), 7.56–7.58 (2H, m, H-20,
60); dC (75 MHz, DMSO-d6): 20.1, 20.2, 91.1, 109.7, 114.1, 117.4, 121.9,
124.4, 127.9, 128.0, 128.0, 128.3, 128.3, 128.4, 131.1, 134.5, 139.9,
150.2, 150.6, 152.7, 159.8.
7.21 (1H, d, J 8.8 Hz, H-7), 7.48 (1H, s, H-5), 7.71 (1H, dd, J 8.8, 2.5 Hz,
H-8), 7.89 (1H, d, J 2.5 Hz, H-10), 8.04 (2H, d, J 7.7, 2.7 Hz, H-20, 60),
8.23 (1H, s, H-4), 8.33 (d, 2H, J¼7.6, 1.9 Hz, H-30, 50); dC (75 MHz,
DMSO-d6): 20.6, 88.9, 106.6, 114.9, 115.7, 119.8, 123.4, 123.5, 124.7,
124.7, 129.1, 129.1, 135.7, 140.5, 141.0, 147.0, 150.6, 150.9, 158.5, 168.9.
4.3.8. 9-Fluoro-3-phenyl-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl
acetate (4h). Method A, work-up as described above gave 83% of 4h
as yellow powder: mp 263–265 ꢀC (toluene). [Found: C, 68.31; H,
4.3.3. 8,9-Dimethyl-3-phenyl-2-oxo-2H,5H-pyrano[3,2-c]chromen-
5-yl acetate (4c). Method A, work-up as described above gave 74%
of 4c as yellow powder: mp 205–207 ꢀC (ethyl acetate). [Found: C,
73.09; H, 4.97. C22H18O5 (362.4) requires: C, 72.92; H, 5.01%];
3.75. C20H13FO5 (352.3) requires: C, 68.18; H, 3.72%];
3030, 1740, 1720, 1701, 1643, 1559, 1489, 1356, 1304, 1220, 1188,
1172, 1109, 1039, 985, 926, 878, 819, 783, 696, 538 cmꢁ1
dH
n(KBr): 3430,
n
(KBr): 3541, 3034, 2917, 1725, 1714, 1646, 1551, 1502, 1357, 1227,
;
1187, 1136, 1024, 1001, 935, 912, 887, 783, 699, 521 cmꢁ1
;
dH
(300 MHz, DMSO-d6): 2.01 (3H, s, CH3), 7.26 (1H, dd, J 8.9, 1.4 Hz, H-
7), 7.38 (1H, dd, J 8.9, 2.0 Hz, H-8), 7.42–7.45 (3H, m, H-30, 40, 50),
7.46 (1H, s, H-5), 7.57 (1H, dd, J 8.8, 4.2 Hz, H-10), 7.75 (2H, dd, J 8.2,
1.9 Hz, H-20, 60).8.01 (1H, s, H-4); dC (75 MHz, DMSO-d6): 20.6, 91.2,
107.8, 108.1, 110.3, 115.1, 118.8, 119.2, 119.3, 125.4, 127.9, 127.9, 128.2,
128.2, 128.5, 134.2, 139.3, 148.7, 155.2, 159.4.
(300 MHz, DMSO-d6): 1.97 (3H, s, CH3), 2.27 (6H, s, 2 CH3), 7.01 (1H,
s, H-7), 7.39 (1H, s, H-5), 7.40–7.48 (3H, m, H-30, 40, 50), 7.54 (1H, s,
H-4), 7.70–7.74 (2H, m, H-20, 60), 7.92 (1H, s, H-10); dC (75 MHz,
DMSO-d6): 18.6, 19.8, 20.7, 89.5, 105.3, 109.0, 111.5, 118.1, 122.5,
123.9, 127.9, 128.0, 128.3, 128.5, 131.8, 134.4, 139.6, 142.8, 149.9,
151.5, 159.4, 169.1.
4.3.9. 9-Acetyloxy-3-phenyl-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-
yl acetate (4i). Method A, work-up as described above gave 77% of
4i as yellow powder: mp 179–181 ꢀC (toluene). [Found: C, 67.51; H,
4.3.4. 8,9-Dimethyl-3-(4-fluorophenyl)-2-oxo-2H,5H-pyrano[3,2-c]-
chromen-5-yl acetate (4d). Method A, work-up as described above
gave 73% of 4d as yellow powder: mp 246–248 ꢀC (ethyl acetate).
[Found: C, 69.29; H, 4.47. C22H17FO5 (380.4) requires: C, 69.47; H,
4.11. C22H16O7 (392.4) requires: C, 67.35; H, 4.11%]; n(KBr): 3430,
3059, 1764, 1745, 1731, 1645, 1579, 1552, 1495, 1398, 1363, 1222,
1185, 1165, 1119, 1070, 1040, 1006, 939, 909, 847, 785, 701, 628,
4.50%];
1377, 1357, 1303, 1233, 1163, 1105, 1051, 1030, 965, 893, 837, 774,
663, 527 cmꢁ1
dH (300 MHz, DMSO-d6): 2.00 (3H, s, CH3), 2.25 (3H,
n(KBr): 3443, 2926, 2857, 1728, 1686, 1638, 1547, 1510, 1459,
573 cmꢁ1
; dH (300 MHz, DMSO-d6): 2.03 (3H, s, CH3), 2.29 (3H, s,
;
CH3), 7.24 (1H, d, J 8.6 Hz, H-7), 7.29 (1H, dd, J 8.6, 2.5 Hz, H-8), 7.40–
7.46 (3H, m, H-30, 40, 50), 7.47 (1H, s, H-5), 7.59 (1H, d, J 2.5 Hz, H-10),
7.75 (1H, dd, J 8.4, 2.0 Hz, H-20, 60), 8.01 (1H, s, H-4); dC (75 MHz,
DMSO-d6): 20.6, 20.7, 89.2, 106.4, 114.4, 115.6, 118.4, 125.4, 125.4,
126.2,127.9,128.3,128.3,128.6,134.1,139.0,145.7,148.8,150.1,159.1,
168.9, 169.3.
s, CH3), 2.48 (3H, s, CH3), 7.01 (1H, s, H-5), 7.29 (2H, ddd, J 8.9, 2.1 Hz,
H-20, 60), 7.37 (1H, s, H-7), 7.54 (1H, s, H-10), 7.77 (2H, ddd, J 8.9,
2.0 Hz, H-30, 50), 7.95 (1H, s, H-4); dC (75 MHz, DMSO-d6): 18.6, 19.8,
20.8, 91.2, 109.0, 111.9, 115.1, 115.3, 118.3, 122.3, 127.4, 130.1, 130.2,
131.9, 133.6, 134.9, 140.0, 142.0, 150.7, 150.9, 159.9, 161.6.
4.3.5. 9-Chloro-3-phenyl-2-oxo-2H,5H-pyrano[3,2-c]chromen-5-yl
acetate (4e). Method A, work-up as described above gave 82% of 4e
as yellow powder: mp 280–283 ꢀC (ethyl acetate). [Found: C, 64.99;
H, 3.57; Cl, 9.58. C20H13ClO5 (368.8) requires: C, 65.14; H, 3.55; Cl,
4.3.10. 3-(4-Methylphenylsulfanyl)-2-oxo-2H,5H-pyrano[3,2-c]chro-
men-5-yl acetate (4j). Method A, work-up as described above gave
75% of 4j as yellow powder: mp 239–241 ꢀC (toluene). [Found: C,
69.97; H, 4.45; S, 9.04. C21H16O5S (380.4) requires: C, 69.21; H, 4.43;
9.61%];
n
(KBr): 3369, 3064, 1736, 1700, 1637, 1540, 1484, 1358, 1298,
S, 8.80%]; n(KBr): 3066, 2902, 1732, 1710, 1644, 1554, 1492, 1357,

´ ´
M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1414
1200, 1188, 1127, 1039, 1008, 926, 916, 811, 781, 688, 561, 545,
529 cmꢁ1
dH (300 MHz, DMSO-d6): 1.95 (3H, s, CH3), 2.35 (3H, s,
3066, 2919, 1761, 1718, 1693, 1632, 1481, 1362, 1346, 1205, 1182,
1053, 1005, 923, 880, 806, 755, 501 cmꢁ1
dH (300 MHz, DMSO-d6):
;
;
CH3), 7.15 (1H, d, J 8.2 Hz, H-7), 7.24 (1H, s, H-5), 7.25 (1H, ddd, J 7.7,
0.7 Hz, H-9), 7.31 (1H, s, H-4), 7.28–7.33 (2H, m, H-30, 50), 7.38–7.44
(2H, m, H-20, 60), 7.50 (1H, ddd, J 7.4, 1.6 Hz, H-8), 7.74 (1H, dd, J 7.7,
1.5 Hz, H-10). The 13C NMR spectrum was unmeasurable because of
the low solubility of 4j.
1.95 (3H, s, CH3), 2.36 (3H, s, CH3), 7.13 (1H, d, J 8.7 Hz, H-7), 7.17
(1H, s, H-5), m7.32 (1H, s, H-4), 7.33 (2H, dd, J 8.0 Hz, H-30, 50,), 7.44
(2H, dd, J 8.0, 1.6 Hz, H-20, 60), 7.64 (1H, dd, J 8.8, 2.2 Hz, H-8), 7.81
(1H, dd, J 2.5 Hz, H-10). The 13C NMR spectrum was unmeasurable
because of the low solubility of 4o.
4.3.11. 3-(4-Chlorophenylsulfanyl)-2-oxo-2H,5H-pyrano[3,2-c]chro-
men-5-yl acetate (4k). Method B, work-up as described above gave
88% of 4k as yellow powder: mp 179–181 ꢀC (toluene). [Found: C,
60.08; H, 3.27; Cl, 8.76; S, 7.91. C20H13ClO5S (400.8) requires: C,
4.3.16. 9-Nitro-3-(4-chlorophenylsulfanyl)-2-oxo-2H,5H-pyrano[3,2-
c]chromen-5-yl acetate (4p). Method A, work-up as described
above gave 75% of 4p as yellow powder: mp 255–258 ꢀC (ethyl
acetate). [Found: C, 54.11; H, 2.73; N, 3.19; Cl, 8.26; S, 7.39.
C20H12ClNO7S (445.8) requires: C, 53.88; H, 2.71; N, 3.14; Cl, 7.95; S,
59.93; H, 3.27; Cl, 8.84; S, 8.00%];
1632,1573,1531,1476,1459,1391,1364,1312,1244,1201,1154,1094,
1051, 1013, 932, 881, 762, 693, 505 cmꢁ1
dH (300 MHz, DMSO-d6):
n(KBr): 3425, 2927, 1713, 1690,
7.19%];
n
(KBr): 3079, 3010, 1758, 1727, 1644, 1574, 1478, 1339, 1327,
dH
;
1257, 1208, 1193, 1096, 999, 933, 908, 832, 735, 503 cmꢁ1
;
1.97 (3H, s, CH3), 7.19 (1H, d, J 8.2 Hz, H-7), 7.26 (1H, ddd, J 8.2,
1.5 Hz, H-8), 7.34 (1H, s, H-5), 7.49–7.55 (5H, m, H-9, 20, 30, 50, 60),
7.56 (1H, s, H-4), 7.76 (1H, dd, J 7.8, 1.5 Hz, H-10); dC (75 MHz,
DMSO-d6): 20.7, 90.8, 106.9, 109.4, 114.2, 117.5, 121.9, 122.0, 122.3,
129.7, 129.8, 132.4, 132.9, 133.5, 133.6, 149.4, 151.3, 152.4, 158.1,
168.8.
(300 MHz, DMSO-d6): 1.99 (3H, s, CH3), 7.41 (1H, d, J 9.0 Hz, H-7),
7.45 (2H, dd, H-20, 60), 7.56 (4H, m, H-4, 5, 30, 50), 8.33 (1H, dd, J 8.9,
2.8 Hz, H-8), 8.44 (1H, d, J 2.6 Hz, H-10); dC (75 MHz, DMSO-d6):
20.6, 89.4, 106.9, 114.4, 117.8, 118.6, 126.2, 127.4, 128.7, 129.9, 129.9,
133.9, 134.4, 134.4, 137.2, 142.7, 147.6, 155.4, 157.2, 168.6.
4.3.17. 9-Chloro-3-(phenylselanyl)-2-oxo-2H,5H-pyrano[3,2-c]chro-
men-5-yl acetate (4r). Method A, work-up as described above gave
73% of 4r as yellow powder: mp 266–268 ꢀC (ethyl acetate). [Found:
C, 53.81; H, 3.01; Cl, 8.15. C20H13ClO5Se (447.7) requires: C, 53.65; H,
4.3.12. 9-Methyl-3-(4-methylphenylsulfanyl)-2-oxo-2H,5H-pyr-
ano[3,2-c]chromen-5-yl acetate (4l). Method A, work-up as de-
scribed above gave 75% of 4l as yellow powder: mp 179–182 ꢀC
(toluene). [Found: C, 67.13; H, 4.58; S, 8.26. C22H18O5S (394.4) re-
2.93; Cl, 7.92%];
1357, 1298, 1201, 1186, 1095, 1039, 931, 906, 890, 782, 690, 555, 518,
486 cmꢁ1
dH (300 MHz, CDCl3): 1.97 (3H, s, CH3), 6.73 (1H, s, H-5),
n(KBr): 3060, 3034, 1736, 1717, 1646, 1553, 1481,
quires: C, 66.99; H, 4.60; S, 8.13%];
1655, 1554, 1498, 1360, 1231, 1186, 1147, 1058, 1011, 944, 827, 786,
687, 572, 528 cmꢁ1
dH (300 MHz, DMSO-d6): 1.94 (3H, s, CH3), 2.34
n(KBr): 3364, 3002, 1730, 1715,
;
;
6.99 (1H, d, J 8.5 Hz, H-7), 7.06 (1H, s, H-4), 7.32 (1H, dd, J 8.6, 2.8 Hz,
H-8), 7.43–7.53 (3H, m, H-30, 40, 50), 7.65–7.70 (2H, m, H-20, 60), 7.82
(1H, d, J 2.8 Hz, H-10); dC (75 MHz, CDCl3): 21.7, 89.8, 106.8, 115.9,
118.9, 122.4, 123.1, 124.2, 125.4, 125.8, 127.2, 128.9, 130.2, 130.5,
132.9, 132.9, 136.8, 150.2, 158.1, 169.5.
(3H, s, CH3), 2.36 (3H, s, CH3), 7.05 (1H, d, J 8.4 Hz, H-7), 7.23 (1H, s,
H-5), 7.27 (1H, s, H-4), 7.28–7.33 (2H, m, H-8, 30, 50), 7.43 (2H, dd, J
8.2, 1.9 Hz, H-20, 60), 7.55 (1H, d, J 1.3 Hz, H-10). The 13C NMR
spectrum was unmeasurable because of the low solubility of 4l.
4.3.13. 8, 9-Dimethyl-3-(4-methylphenylsulfanyl)-2-oxo-2H,5H-pyr-
ano[3,2-c]chromen-5-yl acetate (4m). Method A, work-up as de-
scribed above gave 78% of 4m as yellow powder: mp 230–232 ꢀC
(toluene). [Found: C, 67.49; H, 4.97; S, 7.78. C23H20O5S (408.5) re-
4.3.18. 9-Chloro-3-(4-bromophenylselanyl)-2-oxo-2H,5H-pyr-
ano[3,2-c]chromen-5-yl acetate (4s). Method A, work-up as de-
scribed above gave 76% of 4s as yellow powder: mp 284–287 ꢀC
(dioxane). [C20H12BrClO5Se (526.6) requires: C 45.61, H 2.30, Br
quires: C, 67.63; H, 4.94; S, 7.85%];
1638, 1531, 1493, 1459, 1351, 1272, 1208, 1181, 1110, 1020, 997, 931,
913, 809, 758, 577 cmꢁ1
dH (300 MHz, DMSO-d6): 1.93 (3H, s, CH3),
n
(KBr): 3461, 2923, 1725, 1707,
15.17, Cl 6.73; Found: C 45.83, H 2.34, Br 15.39, Cl 6.88%];
3455, 2927, 1729, 1713, 1697, 1660, 1606, 1560, 1465, 1446, 1350,
1329, 1307, 1223, 1178, 1121, 1073, 996, 835, 773, 663, 547 cmꢁ1
dH
n(KBr):
;
;
2.25 (6H, s, 2 CH3), 2.35 (3H, s, CH3), 6.98 (1H, s, H-5), 7.26 (1H, s, H-
7), 7.27 (1H, s, H-4), 7.29 (2H, dd, J 7.9, 1.3 Hz, H-30, 50), 7.41 (2H, dd, J
8.0, 1.6 Hz, H-20, 60), 7.50 (1H, s, H-10). The 13C NMR spectrum was
unmeasurable because of the low solubility of 4m.
(300 MHz, DMSO-d6): 2.13(3H, s, CH3), 6.32 (1H, s, H-5), 7.33–7.56
(4H, m, H-20, 30, 50 60), 7.78 (1H, d, J 9.0 Hz, H-7), 7.89 (1H, dd, J 9.0,
2.8 Hz, H-8), 8.00 (d, 1H, J 2.8 Hz, H-10), 8.69 (1H, s, H-4); dC
(75 MHz, CDCl3): 20.6, 83.6, 106.9, 110.4, 115.6, 118.9, 120.9, 122.1,
123.8, 125.8, 127.3,130.5,132.7,133.0, 134.7,134.7,137.2,150.9,158.1,
168.2.
4.3.14. 9-Chloro-3-(4-methylphenylsulfanyl)-2-oxo-2H,5H-pyr-
ano[3,2-c]chromen-5-yl acetate (4n). Method B, work-up as de-
scribed above gave 86% of 4n as yellow powder: mp 211–213 ꢀC
(dioxane). [Found: C, 60.67; H, 3.65; Cl, 8.61; S, 7.64. C21H15ClO5S
4.4. 5-Alkoxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-2-ones
(5a–5l)
(414.9) requires: C, 60.80; H, 3.64; Cl, 8.55; S, 7.73%];
2913, 1721, 1695, 1634, 1586, 1524, 1483, 1399, 1348, 1293, 1243,
1200, 1092, 1054, 986, 945, 901, 880, 804, 753, 560, 504, 486 cmꢁ1
dH (300 MHz, DMSO-d6): 1.94 (3H, s, CH3), 2.35 (3H, s, CH3), 7.17
(1H, s, H-5), 7.19 (1H, d, J 8.8 Hz, H-7), 7.32 (1H, s, H-4), 7.33 (2H, dd,
J 7.9, 2.4 Hz, H-30, 50,), 7.44 (2H, dd, J 8.2, 1.9 Hz, H-20, 60), 7.53 (1H,
dd, J 8.8, 2.5 Hz, H-8), 7.68 (1H, d, J 2.5 Hz, H-10); dC (75 MHz,
DMSO-d6): 20.6, 20.8, 89.2, 106.6, 115.6, 119.2, 121.3, 125.2, 127.2,
127.3, 128.1, 128.7, 130.6, 131.9, 133.6, 134.9, 139.2, 147.3, 149.6, 157.4,
168.7.
n(KBr): 3440,
Method A: A solution of 3-R-2-oxo-2H,5H-pyrano[3,2-c]chro-
men-5-yl acetate 4 (10 mmol) and p-toluenesulfonic acid (8 mg,
0.04 mmol) in the appropriate alcohol (methanol, ethanol or pen-
tan-1-ol) (10 mL) was stirred and heated at 60 ꢀC for 3 h. After
cooling the solid was filtered off, washed with diethyl ether and
crystallized from above used alcohol.
Method B: A solution of 3-phenyl-2-oxo-2H,5H-pyrano[3,2-
c]chromen-5-yl acetate 4a (10 mmol) and p-toluenesulfonic acid
(8 mg, 0.04 mmol) in propan-1-ol (10 mL) was irradiated in mi-
crowave oven at 60 ꢀC and 48 W for 10 min. After cooling the solid
was filtered off, washed with diethyl ether and crystallized from
ethanol.
;
4.3.15. 9-Bromo-3-(4-methylphenylsulfanyl)-2-oxo-2H,5H-pyr-
ano[3,2-c]chromen-5-yl acetate (4o). Method A, work-up as de-
scribed above gave 78% of 4o as yellow powder: mp 205–207 ꢀC
(dioxane). [Found: C, 55.19; H, 3.31; Br, 17.64; S, 7.24. C21H15BrO5S
4.4.1. 9-Chloro-5-methoxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-
(459.3) requires: C, 54.91; H, 3.29; Br, 17.40; S, 6.98%];
n
(KBr): 3440,
2-one (5a). Method A, work-up as described above gave 72% of 5a

´
´
M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1415
as yellow powder: mp 188–190 ꢀC (methanol). [Found: C, 67.28; H,
3.87; Cl, 10.62. C19H13ClO4 (340.8) requires: C, 66.97; H, 3.85; Cl,
885, 786, 688, 575 cmꢁ1
;
dH (300 MHz, DMSO-d6): 1.14 (3H, t, CH3),
2.29 (3H, t, CH3), 3.85 (2H, q, CH2), 6.32 (1H, s, H-5), 7.21–7.27 (2H,
m, H-7,8), 7.41–7.50 (3H, m, H-30, 40, 50), 7.52 (1H, dd, J 2.4 Hz, H-10),
7.73 (2H, dd, J 8.4, 1.7 Hz, H-20, 60), 7.93 (1H, s, H-4). The 13C NMR
spectrum was unmeasurable because of the low solubility of 5f.
10.40%];
1372, 1271, 1230,1185, 1118,1073, 1037, 1021, 977, 915, 897, 786, 765,
697, 584 cmꢁ1
dH (300 MHz, DMSO-d6): 3.51 (3H, s, CH3), 6.24 (1H,
n(KBr): 3425, 2985, 1722, 1646, 1609, 1558, 1487, 1461,
;
s, H-5), 7.26 (1H, d, J 8.8 Hz, H-7), 7.42–7.51 (3H, m, H-30, 40, 50), 7.55
(1H, dd, J 8.8, 2.5 Hz, H-8), 7.70 (1H, d, J 2.5 Hz, H-10), 7.73 (2H, d, J
8.0 Hz, H-20, 60), 7.94 (1H, s, H-4); dC (75 MHz, DMSO-d6): 55.5, 97.6,
108.6, 116.0, 119.5, 121.4, 125.7, 126.4, 127.9, 127.9, 128.2, 128.2,
128.6, 131.9, 134.1, 139.0, 148.9, 150.6, 159.2.
4.4.7. 9-Bromo-5-ethoxy-3-(4-nitrophenyl)-2H,5H-pyrano[3,2-
c]chromen-2-one (5g). Method A, work-up as described above gave
77% of 5g as yellow powder: mp 278–280 ꢀC (ethanol). [Found: C,
54.29; H, 3.18; Br, 18.26; N, 3,34; C20H14BrNO6 (444.2) requires: C,
54.07; H, 3.18; Br, 17.99; N, 3,15%];
1600,1545,1517,1480,1340,1295,1267,1239,1181,1112,1083,1069,
1034, 969, 911, 851, 820, 775, 691, 556 cmꢁ1
dH (300 MHz, DMSO-
d6): 6.35 (1H, s, H-5), 7.20 (1H, d, J 8.6 Hz, H-7), 7.69 (1H, dd, J 8.5,
2.2 Hz, H-8), 7.84 (1H, d, J 2.2, H-10), 8.04 (2H, d, J 8.2 Hz, H-20, 60),
8.15 (1H, s, H-4), 8.31 (2H, d, J 8.2 Hz, H-30, 50); dC (75 MHz, DMSO-
d6): 15.5, 64.6, 97.0, 109.3, 114.6, 116.9, 120.6, 123.9, 123.9, 124.0,
125.1, 129.7, 129.7, 135.9, 141.3, 141.6, 147.5, 150.7, 152.1, 159.3.
n(KBr): 3444, 2926, 1728, 1649,
4.4.2. 5-Ethoxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-2-one
(5b). Method A, work-up as described above gave 69% of 5b as
yellow powder: mp 153–155 ꢀC (ethanol). [Found: C, 74.81; H, 5.01.
;
C20H16O4 (320.3) requires: C, 74.99; H, 5.03%];
1716, 1645, 1608, 1555, 1486, 1460, 1371, 1294, 1230, 1184, 1155,
1070, 1035, 1020, 999, 915, 895, 764, 696, 583 cmꢁ1
dH (300 MHz,
n(KBr): 3419, 2984,
;
DMSO-d6): 1.12 (3H, t, CH3), 3.71 (2H, q, CH2), 6.29 (1H, s, H-5), 7.16–
7.23 (2H, m, H-7,8), 7.38–7.52 (4H, m, H-9, 30, 40, 50), 7.69–7.76 (3H,
m, H-10, 20, 60), 7.91 (1H, s, H-4); dC (75 MHz, DMSO-d6): 15.0, 63.8,
96.4, 108.2, 114.7, 117.6, 122.3, 122.6, 124.9, 128.0, 128.0, 128.3, 128.3,
128.5, 132.6, 134.4, 139.5, 150.4, 152.2, 159.6.
4.4.8. 3-Phenyl-5-propyloxy-2H,5H-pyrano[3,2-c]chromen-2-one
(5h). Method B, work-up as described above gave 76% of 5h as
yellow powder: mp 184–186 ꢀC (propanol). [Found: C, 75.59; H,
5.41. C21H18O4 (334.4) requires: C, 75.43; H, 5.43%];
2962, 1722, 1706, 1643, 1556, 1488, 1460, 1376, 1294, 1208, 1197,
1129, 1040, 1013, 978, 899, 785, 686, 569, 511 cmꢁ1
dH (300 MHz,
DMSO-d6): 0.87 (3H, t, CH3), 1.51–1.62 (2H, m, CH2), 3.66 (2H, q,
CH2), 6.07 (1H, s, H-5), 7.07 (1H, d, J 8.2 Hz, H-7), 7.14 (1H, ddd, J 7.6,
1.2 Hz, H-9), 7.37–7.47 (5H, m, H-4, 8, 30, 40, 50), 7.70 (2H, d, J 7.7 Hz,
H-20, 60), 7.89 (1H, dd, J 7.7, 1.4 Hz, H-10); dC (75 MHz, DMSO-d6):
10.4, 22.4, 69.9, 96.5, 108.3, 114.6, 117.6, 122.3, 122.6, 124.9, 125.5,
128.0, 128.3, 128.5, 132.6, 134.4, 137.5, 139.5, 150.4, 152.3, 159.7.
n(KBr): 3408,
4.4.3. 9-Chloro-5-ethoxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-2-
one (5c). Method A, work-up as described above gave 82% of 5c as
yellow powder: mp 204–206 ꢀC (ethanol). [Found: C, 67.93; H, 4.28;
Cl, 10.21. C20H15ClO4 (354.8) requires: C, 67.71; H, 4.26; Cl, 9.99%];
;
n
(KBr): 3416, 2975, 1719, 1645, 1564, 1485, 1472, 1378, 1294, 1184,
1155, 1091, 1076, 1034, 989, 925, 895, 774, 696, 583, 526 cmꢁ1
;
dH
(300 MHz, CDCl3): 1.23 (3H, t, CH3), 3.72 (2H, q, CH2), 6.08 (1H, s, H-
5), 7.03 (1H, d, J 8.7 Hz, H-7), 7.35 (1H, dd, J 8.6, 2.5 Hz, H-8), 7.38–
7.48 (3H, m, H-30, 40, 50), 7.42 (1H, s, H-4), 7.67–7.72 (2H, m, H-20, 60),
7.87 (1H, d, J 2.5 Hz, H-10); dC (75 MHz, DMSO-d6): 14.9, 63.7, 96.3,
108.2, 114.6, 117.5, 122.2, 122.5, 124.8, 127.9, 127.9, 128.2, 128.2,
128.4, 132.5, 134.3, 139.5, 150.3, 152.2, 159.5.
4.4.9. 5-Pentyloxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-2-one
(5i). Method A, work-up as described above gave 68% of 5i as
yellow powder: mp 130–132 ꢀC (chloroform). [Found: C, 76.39; H,
6.17; C23H22O4 (362.4) requires: C, 76.22; H, 6.12%];
2932, 1715, 1642, 1550, 1486, 1459, 1374, 1269, 1229, 1184, 1072,
1040, 958, 900, 785, 757, 696, 583 cmꢁ1
dH (300 MHz, CDCl3):
0.85–0.86 (3H, m, CH3), 1.23–1.33 (4H, m, (CH2)2), 1.53–1.61 (2H, m,
CH2), 3.69 (1H, q CH–Ha), 3.94 (1H, q CH–Hb), 6.07 (1H, s, H-5), 7.07
(1H, dd, J 8.2, 0.7 Hz, H-7), 7.14 (1H, ddd, J 7.9. 0.8 Hz, H-9), 7.37–7.41
(4H, m, H-8, 30, 40, 50), 7.42 (1H, s, H-4), 7.71 (2H, dd, J 7.9, 1.7 Hz, H-
20, 60), 7.89 (1H, dd, J 7.9, 1.5 Hz, H-10); dC (75 MHz, DMSO-d6): 13.8,
21.6, 27.5, 28.6, 31.0, 68.1, 96.5, 108.2, 114.6, 117.5, 122.2, 122.5, 124.8,
124.9, 127.9, 128.2, 128.4, 132.5, 134.3, 139.4, 150.3, 152.2, 159.5.
n(KBr): 3428,
4.4.4. 9-Fluoro-5-ethoxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-2-
one (5d). Method A, work-up as described above gave 74% of 5d as
yellow powder: mp 199–202 ꢀC (ethanol). [Found: C, 70.87; H, 4.45.
;
C20H15FO4 (338.3) requires: C, 71.00; H, 4.47%];
1719, 1646, 1556, 1486, 1446, 1304, 1259, 1169, 1069, 1030, 976, 928,
816, 785, 696, 573 cmꢁ1
dH (300 MHz, DMSO-d6): 1.14 (3H, t, CH3),
n(KBr): 3427, 2975,
;
3.84 (2H, q, CH2), 6.31 (1H, s, H-5), 7.24 (1H, dd, J 8.9, 3.1 Hz, H-8),
7.38–7.49 (3H, m, H-30, 40, 50), 7.51 (1H, dd, J 8.5, 3.1 Hz, H-10), 7.73
(2H, dd, J 8.2, 1.5 Hz, H-20, 60), 7.93 (1H, s, H-4); dC (75 MHz, DMSO-
d6): 15.0, 63.9, 96.5, 108.1, 108.5, 109.0, 115.5, 115.7, 119.1, 119.3,
119.4, 125.7, 128.1, 128.3, 128.6, 134.3, 139.2, 148.3, 158.7, 159.4.
4.4.10. 5-Ethoxy-3-(phenylsulfanyl)-2H,5H-pyrano[3,2-c]chromen-
2-one (5j). Method A, work-up as described above gave 76% of 5j as
yellow powder: mp 145–147 ꢀC (ethanol). [Found: C, 67.89; H, 4.55;
S, 9.33. C20H16O4S (352.4) requires: C, 68.16; H, 4.58; S, 9.10%];
4.4.5. 8,9-Dimethyl-5-ethoxy-3-phenyl-2H,5H-pyrano[3,2-c]chro-
men-2-one (5e). Method A, work-up as described above gave 71% of
5e as yellow powder: mp 205–207 ꢀC (ethanol). [Found: C, 76.01; H,
n
(KBr): 3016, 2993, 1723, 1693, 1635, 1526, 1481, 1458, 1341, 1245,
5.80. C22H20O4 (348.4) requires: C, 75.84; H, 5.79%];
2972,1711,1641,1543,1499,1448,1356,1303,1293,1174,1065,1012,
967, 905, 881, 781, 688, 573 cmꢁ1
dH (300 MHz, DMSO-d6): 1.12
n
(KBr): 3417,
1179, 1065, 1039, 981, 943, 758, 733, 687, 572 cmꢁ1
;
dH (300 MHz,
CDCl3): 1.15 (3H, t, CH3), 3.66 (2H, q, CH2), 5.84 (1H, s, H-5), 6.73 (1H,
s, H-4), 7.02 (1H, d, J 8.2 Hz, H-7), 7.11 (1H, ddd, J 8.2,1.7 Hz, H-8), 7.37
(1H, ddd, J 7.7, 1.3 Hz, H-9), 7.42–7.47 (3H, m, H-30, 40, 50), 7.53–7.58
(2H, m, H-20, 60), 7.80 (1H, dd, J 7.7,1.7 Hz, H-10); dC (75 MHz, DMSO-
d6): 14.9, 54.9, 96.8, 107.8, 114.6, 117.5, 122.0, 122.6, 123.9, 128.8,
128.9, 129.9, 130.3, 132.0, 132.3, 132.4, 138.5, 149.3, 151.8, 158.1.
;
(3H, t, CH3), 2.26 (3H, s, CH3), 2.27 (3H, s, CH3), 3.70 (2H, q, CH2),
6.24 (1H, s, H-5), 6.99 (1H, s, H-7), 7.36–7.49 (4H, m, H-10, 30, 40, 50),
7.69–7.74 (2H, m, H-20, 60), 7.88 (1H, s, H-4); dC (75 MHz, DMSO-d6):
15.0, 18.6, 19.8, 63.6, 96.4, 107.6, 112.1, 118.3, 122.4, 122.4, 123.9,
127.9, 128.3, 128.3, 130.8, 134.5, 134.8, 140.0, 142.2, 150.6, 150.9,
159.7.
4.4.11. 5-Ethoxy-3-(4-methylphenylsulfanyl)-2-oxo-2H,5H-pyr-
ano[3,2-c]chromen (5k). Method A, work-up as described above
gave 79% of 5k as yellow powder: mp 168–170 ꢀC (ethanol).
[Found: C, 68.61; H, 4.92; S, 9.00. C21H18O4S (366.4) requires: C,
4.4.6. 9-Acetyloxy-5-ethoxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-
2-one (5f). Method A, work-up as described above gave 74% of 5f as
yellow powder: mp 182–184 ꢀC (ethanol). [Found: C, 70.03; H, 4.76.
68.83; H, 4.95; S, 8.75%];
1532, 1490, 1458, 1359, 1341, 1285, 1245, 1180, 1072, 1057, 1025, 981,
931, 903, 813, 763, 617, 578, 512 cmꢁ1
dH (300 MHz, DMSO-d6):
n(KBr): 3444, 2982, 1711, 1640, 1607, 1574,
C22H18O6 (378.4) requires: C, 69.83; H, 4.79%];
n(KBr): 3422, 2963,
1714, 1649, 1545, 1492, 1455, 1356, 1290, 1174, 1067, 1032, 976, 915,
;

´ ´
M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1416
1.04 (3H, t, CH3), 2.36 (3H, s, CH3), 3.70 (2H, q, CH2), 6.19 (1H, s, H-5),
7.09 (1H, s, H-4), 7.14 (1H, d, J 8.2 Hz, H-7), 7.18 (1H, ddd, J 8.2,
1.4 Hz, H-8), 7.32 (2H, dd, J 8.2, 2.5 Hz, H-30, 50), 7.43 (2H, d, J 7.7 Hz,
H-20, 60), 7.46 (1H, ddd, J 7.4, 1.6 Hz, H-9), 7.69 (1H, dd, J 7.7, 1.4 Hz,
H-10); dC (75 MHz, DMSO-d6): 15.0, 20.8, 63.5, 96.1, 108.1, 114.7,
117.5, 121.9, 122.5, 122.5, 125.3, 126.2, 130.7, 132.3, 133.2, 136.9,
136.9, 139.0, 148.7, 158.7, 159.1.
11.07. C18H11ClO4 (326.7) requires: C, 66.17; H, 3.39; Cl, 10.85%];
(KBr): 3401, 2938, 1709, 1645, 1550, 1480, 1354, 1295, 1184, 1063,
1037, 956, 935, 878, 821, 783, 697, 549 cmꢁ1
dH (300 MHz, DMSO-
d6): 6.46 (1H, d, J 6.6 Hz, H-5), 7.17 (1H, d, J 8.7 Hz, H-7), 7.39–7.48
(3H, m, H-30, 40, 50), 7.51 (1H, dd, J 8.8, 2.5 Hz, H-8), 7.68 (1H, d, J
2.5 Hz, H-10), 7.74 (2H, dd, J 7.9, 1.7 Hz, H-20, 60), 7.86 (1H, d, J 6.3 Hz,
OH), 7.88 (1H, s, H-4). The 13C NMR spectrum was unmeasurable
because of the low solubility of 6b.
n
;
4.4.12. 9-Bromo-5-ethoxy-3-(4-methylphenylsulfanyl)-2-oxo-
2H,5H-pyrano[3,2-c]chromen (5l). Method A, work-up as described
above gave 82% of 5l as yellow powder: mp 189–193 ꢀC (ethanol).
[Found: C, 56.47; H, 3.86; Br 18.21; S 7.42. C21H17BrO4S (445.3) re-
4.5.3. 5-Hydroxy-3-(4-methylphenylsulfanyl)-2H,5H-pyrano[3,2-
c]chromen-2-one (6c). Method A, work-up as described above gave
75% of 6c, method B, work-up as described above gave 57% of 6c as
yellow powder: mp 250–254 ꢀC (dioxane). [Found: C, 67.68; H, 4.18;
S, 9.72. C19H14O4S (338.1) requires: C, 67.44; H, 4.17; S, 9.48%];
quires: C, 56.64; H, 3.85; Br, 17.94; S, 7.20%];
1714, 1637, 1565, 1480, 1341, 1242, 1178, 1069, 1048, 934, 922, 866,
757, 615, 505 cmꢁ1
dH (300 MHz, DMSO-d6): 1.03 (3H, t, CH3), 2.37
n(KBr): 3076, 2865,
;
n
(KBr): 3350, 2924, 1738, 1693, 1641, 1582, 1532, 1493, 1475, 1355,
1301,1255,1209,1189,1092,1054,1014, 952, 916, 885, 827, 814, 760,
628, 508 cmꢁ1
dH (300 MHz, DMSO-d6): 2.36 (3H, s, CH3), 6.27 (1H,
(3H, s, CH3), 3.61–3.72 (2H, m, CH2), 6.22 (1H, s, H-5), 7.01 (1H, s, H-
4), 7.12 (1H, d, J 8.5 Hz, H-7), 7.33 (2H, d, J 8.2, 2.2 Hz, H-30, 50), 7.46
(2H, d, J 7.9,1.9 Hz, H-20, 60), 7.61 (1H, dd, J 8.2, 2.5 Hz, H-8), 7.75 (1H,
d, J 2.5 Hz, H-10); dC (75 MHz, DMSO-d6): 14.9, 20.7, 63.6, 96.1,
108.6, 113.8, 116.6, 119.7, 123.9, 125.5, 127.1, 130.7, 130.7, 133.6, 134.4,
135.1, 135.1, 139.3, 146.7, 150.7, 157.6.
;
d, J 6.3 Hz, H-5), 6.95 (1H, s, H-4), 7.06 (1H, d, J 8.2 Hz, H-7), 7.14
(1H, ddd, J 8.2, 0.9 Hz, H-9), 7.33 (2H, dd, J 7.9, 1.8 Hz, H-30, 50), 7.42
(1H, ddd, J 8.2, 1.6 Hz, H-8), 7.45 (2H, dd, J 8.2, 1.9 Hz, H-20, 60), 7.60
(1H, d, J 6.9 Hz, OH), 7.67 (1H, dd, J 7.7, 1.6 Hz, H-10); dC (75 MHz,
DMSO-d6): 20.8, 90.9, 109.5, 114.4, 117.4, 121.8, 122.0, 122.0, 125.4,
125.9, 130.8, 132.1, 133.6, 136.5, 139.3, 148.1, 152.2, 158.2, 161.3.
4.4.13. 9-Chloro-5-ethoxy-3-(phenylselanyl)-2H,5H-Pyrano[3,2-c]-
chromen-2-one (5m). Method A, work-up as described above gave
80% of 5m as yellow powder: mp 133–135 ꢀC (ethanol). [Found: C,
55.59; H, 3.51; Cl, 8.34. C20H15ClO4Se (433.7) requires: C, 55.38; H,
4.5.4. 9-Bromo-5-hydroxy-3-(4-methylphenylsulfanyl)-2H,5H-pyr-
ano[3,2-c]chromen-2-one (6d). Method A, work-up as described
above gave 80% of 6d, method B, work-up as described above gave
73% of 6d as yellow powder: mp 266–268 ꢀC (dioxane). [Found: C,
54.80; H, 3.17; Br, 19.24; S, 7.71. C19H13BrO4S (417.3) requires: C,
3.49; Cl, 8.17%];
1342, 1297, 1245, 1180, 1118, 1072, 1051, 976, 936, 810, 759, 617, 571,
507 cmꢁ1
dH (300 MHz, CDCl3): 1.12 (3H, t, CH3), 3.63 (1H, q, CH2),
n(KBr): 3440, 2983, 1717, 1640, 1567, 1525, 1481,
;
5.79 (1H, s, H-5), 6.69 (1H, s, H-4),6.93 (1H, d, J 8.6 Hz, H-7), 7.28
(1H, dd, J 8.6, 2.6 Hz, H-8), 7.42–7.51 (3H, m, H-30, 40, 50), 7.67–7,70
(2H, m, H-20, 60), 7.79 (1H, d, J 2.6 Hz, H-10); dC (75 MHz, DMSO-d6):
14.9, 20.7, 63.6, 96.1, 108.6, 110.1, 115.8, 119.3, 120.8, 125.3, 125.7,
127.1, 130.8, 131.3, 133.6, 135.0, 139.5, 146.2, 150.7, 157.7.
54.69; H, 3.14; Br, 19.15; S, 7.68%];
1636, 1565, 1528, 1482, 1348, 1293, 1243, 1201, 1180, 1166, 1064,
1056, 986, 944, 881, 828, 807, 754, 572, 508 cmꢁ1
dH (300 MHz,
DMSO-d6): 2.37 (3H, s, CH3), 6.31 (1H, d, J 6.3 Hz, H-5), 6.87 (1H, s,
H-4), 7.05 (1H, d, J 8.7 Hz, H-7), 7.34 (2H, dd, J 7.9, 2.1 Hz, H-30, 50),
7.46 (2H, dd, J 7.9, 1.9 Hz, H-20, 60), 7.57 (1H, dd, J 8.7, 2.4 Hz, H-8),
7.70 (1H, d, J 6.8 Hz, OH), 7.73 (1H, d, J 2.4 Hz, H-10); dC (75 MHz,
DMSO-d6): 20.7, 91.1, 110.0, 113.2, 116.2, 119.6, 123.3, 125.3, 127.1,
130.8, 130.8, 133.9, 133.9, 134.1, 135.0, 139.4, 146.1, 151.1, 157.7.
n(KBr): 3452, 2925, 1748, 1694,
;
4.5. 5-Hydroxy-3-R-2H,5H-pyrano[3,2-c]chromen-2-ones
(6a–6e)
Method A: A mixture of 6-R1-chromone-3-carbaldehyde 1
(10 mmol) and substituted acetic acid 2 (10 mmol) in toluene
(15 mL) in the presence of freshly fused potassium acetate (25 mg)
was stirred for 8 h at 60 ꢀC. After cooling the solid product was
filtered off, washed with cold diethyl ether and crystallized from
dioxane.
Method B: Compound 4 (or 5) (200 mg) and p-toluenesulfonic
acid (15 mg, 0.09 mmol) was heated in 50 mL of dioxane–water
(3:1) at 70 ꢀC for 30 min. The solid product was cooled, separated
and crystallized from dioxane.
4.5.5. 5-Hydroxy-9-methyl-3-(phenylselanyl)- 2H,5H-pyrano[3,2-c]-
chromen-2-one (6e). Method A, work-up as described above gave
74% of 6e, method B, work-up as described above gave 60% of 6e as
yellow powder: mp 257–259 ꢀC (dioxane). [Found: C, 59.01; H,
3.69. C19H14O4Se (385.3) requires: C, 59.23; H, 3.66%];
2964, 1728, 1694, 1621, 1555, 1530, 1492, 1348, 1295, 1248, 1172,
1158, 1082, 1056, 992, 954, 878, 759, 568, 505 cmꢁ1
dH (300 MHz,
n(KBr): 3386,
;
CDCl3): 2.39 (3H, s, CH3), 6.25 (1H, s, H-5), 6.45 (1H, s, H-4), 6.57
(1H, d, J 8.4 Hz, H-7), 7.15 (1H, dd, J 8.2, 1.6 Hz, H-8), 7.36 (2H, dd, J
7.5, 1.6 Hz, H-30, 50), 7.48 (1H, ddd, J 7.3, 1.3 Hz, H-40), 7.55 (2H, dd, J
6.3, 1.3 Hz, H-20, 60), 7.51 (1H, d, J 1.5 Hz, H-10), 7.65 (1H, d, J 6.4 Hz,
OH); dC (75 MHz, CDCl3): 25.8, 96.5, 115.2, 119.7, 123.0, 127.5, 127.7,
135.5, 135.5, 135.8, 136.8, 138.8, 139.1, 139.3, 139.3, 146.4, 155.4,
156.2, 163.9.
4.5.1. 5-Hydroxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-2-one
(6a). Method A, work-up as described above gave 74% of 6a as
yellow powder: mp 150–151 ꢀC (dioxane). [Found: C, 74.19; H, 4.13.
C18H12O4 (292.3) requires: C, 73.97; H, 4.14%];
1760, 1705,1639,1610,1546,1464, 1371,1352, 1220, 1191, 1175, 1042,
1018, 973, 933, 899, 758, 696, 608, 505 cmꢁ1
dH (300 MHz, CDCl3):
n(KBr): 3381, 3030,
;
3.51 (1H, d, J 6.4 Hz, OH), 6.43 (1H, d, J 6.6 Hz, H-5), 7.07 (1H, d, J 8.1,
1.0 Hz, H-7), 7.13 (1H, ddd, J 8.1, 1.0 Hz, H-8), 7.39–7.44 (4H, m, H-9,
30, 40, 50), 7.49 (1H, s, H-4), 7.66–7.71 (2H, m, H-20, 60), 7.87 (1H, dd, J
7.8, 1.7 Hz, H-10); dC (75 MHz, DMSO-d6): 91.1, 109.6, 114.4, 117.5,
121.9, 122.0, 124.5, 124.8, 125.2, 127.9, 128.2, 132.3, 134.4, 134.8,
139.7, 152.6, 159.7, 168.3.
4.6. 5-Hydroxy-3-phenylpyrano[2,3-b]chromen-2(10aH)-ones
(7a–7g)
Method A: Compound 4 (or 5, 6) (10 mmol) was dissolved in
acetic acid (10 mL) and the solution was stirred at 60 ꢀC for 1 h.
After cooling the yellow precipitate was filtered off, washed with
diethyl ether and crystallized from toluene or acetic acid.
4.5.2. 9-Chloro-5-hydroxy-3-phenyl-2H,5H-pyrano[3,2-c]chromen-
2-one (6b). Method A, work-up as described above gave 78% of 6b,
method B, work-up as described above gave 59% of 6b as yellow
powder: mp 260–262 ꢀC (dioxane). [Found: C, 66.39; H, 3.41; Cl,
Method B: Compound 4a (10 mmol) was dissolved in acetic acid
(10 mL) and the solution was irradiated in microwave oven at 80 ꢀC
and 76–79 W for 10 min. After cooling the yellow solid was filtered
off, washed with diethyl ether and crystallized from acetic acid.

´
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M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1417
4.6.1. 5-Hydroxy-3-phenylpyrano[2,3-b]chromen-2(10aH)-one
(7a). Method A, work-up as described above gave 77% of 7a,
method B, work-up as described above gave 84% of 7a as yellow
powder: mp 256–258 ꢀC (acetic acid). [Found: C, 74.18; H, 4.16.
76% of 7f as yellow powder: mp 254–256 ꢀC (acetic acid). [Found: C,
67.31; H, 4.16; S, 9.45. C20H14O6 (338.4) requires: C, 67.44; H, 4.17; S,
9.48%];
1459, 1397, 1362, 1325, 1244, 1199, 1181, 1107, 1048, 1020, 940, 808,
750, 692, 585, 506 cmꢁ1
dH (300 MHz, DMSO-d6): 2.46 (3H, s, CH3),
n(KBr): 3450, 3063, 2920, 1727, 1717, 1644, 1575, 1537, 1490,
C18H12O4 (292.3) requires: C, 73.97; H, 4.14%];
n
(KBr): 3450, 3060,
;
1731, 1715, 1645, 1610, 1557, 1489, 1460, 1371, 1355, 1316, 1296, 1271,
1233, 1204, 1180, 1113, 1037, 1019, 951, 912, 785, 759, 737, 697, 623,
6.62 (1H, s, H-10a), 6.66 (1H, d, J 7.9 Hz, H-9), 7.23 (1H, ddd, J 7.9,
0.6 Hz, H-8), 7.36–7.38 (5H, m, H-4, 20, 30, 50, 60), 7.50 (1H, ddd, J 7.9,
1.0 Hz, H-7), 7.63 (1H, dd, J 7.4,1.3 Hz, H-6), OH notseen. The 13C NMR
spectrum was unmeasurable because of the low solubility of 7f.
589 cmꢁ1
; dH (300 MHz, DMSO-d6): 6.73 (1H, s, H-10a), 7.15 (1H, s,
H-4), 7.17 (1H, dd, J 8.2, 1.0 Hz, H-9), 7.21 (1H, ddd, J 7.6, 1.0 Hz, H-7),
7.35–7.41 (3H, m, H-30, 40, 50), 7.42 (1H, ddd, J 8.2, 1.5 Hz, H-8), 7.47–
7.51 (2H, m, H-20, 60), 7.89 (1H, dd, J 7.7,1.5 Hz, H-6), 8.12 (1H, s, OH);
dC (75 MHz, DMSO-d6): 30.7, 96.9, 107.5, 114.3, 117.7, 122.1, 122.6,
122.8, 125.0, 128.0, 128.3, 128.6, 132.5, 134.4, 139.4, 150.3, 151.8,
159.4.
4.6.7. 7-Bromo-5-hydroxy-3-(4-methylphenylsulfanyl)-pyrano[2,3-
b]chromen-2(10aH)-one (7g). Method A, work-up as described
above gave 80% of 7g as yellow powder: mp 280–282 ꢀC (acetic
acid). [Found: C, 54.41; H, 3.16; Br, 19.27; S, 7.49. C19H13BrO4S
(417.3) requires: C, 54.69; H, 3.14; Br, 19.15; S, 7.68%];
3022, 2919, 1716, 1695, 1646, 1564, 1531, 1490, 1419, 1346, 1245,
1198, 1181, 1049, 932, 879, 806, 755, 616, 554, 507 cmꢁ1
dH
(300 MHz, DMSO-d6): 2.34 (3H, s, CH3), 6.96 (1H, s, H-10a), 7.02
(1H, d, J 8.6 Hz, H-9), 7.31 (2H, dd, J 7.9, 1.9 Hz, H-30, 50), 7.32 (1H, dd,
J 8.5, 1.6 Hz, H-8), 7.43 (2H, dd, J 7.9, 2.0 Hz, H-20, 60), 7.54 (1H, s, H-
4), 7.72 (1H, d, J 1.6 Hz, H-6), OH not seen. The 13C NMR spectrum
was unmeasurable because of the low solubility of 7g.
n(KBr): 3452,
4.6.2. 7-Fluoro-5-hydroxy-3-phenylpyrano[2,3-b]chromen-2(10aH)-
one (7b). Method A, work-up as described above gave 74% of 7b as
yellow powder: mp 267–268 ꢀC (acetic acid). [Found: C, 69.52; H,
;
3.56. C18H11FO4 (310.3) requires: C, 69.68; H, 3.57%];
3061, 1731, 1709, 1644, 1607, 1566, 1552, 1483, 1326, 1266, 1232,
1186, 1120, 1048, 945, 750, 697, 550 cmꢁ1
dH (300 MHz, DMSO-d6):
n(KBr): 3536,
;
6.44 (1H, s, H-10a), 7.17 (1H, dd, J 8.9, 4.5 Hz, H-9), 7.34 (1H, dd, J 8.8,
2.9 Hz, H-8), 7.41–7.51 (4H, m, H-6, 30, 40, 50), 7.73 (2H, dd, J 8.0,
1.3 Hz, H-20, 60), 7.79 (1H, s, H-6), 7.89 (1H, s, OH). The 13C NMR
spectrum was unmeasurable because of the low solubility of 7b.
4.7. 5-Alkoxy-3-R-pyrano[2,3-b]chromen-2(10aH)-ones
(8a, 8b)
4.6.3. 7-Chloro-5-hydroxy-3-phenylpyrano[2,3-b]chromen-2(10aH)-
one (7c). Method A, work-up as described above gave 82% of 7c as
yellow powder: mp 294–296 ꢀC (acetic acid). [Found: C, 66.36; H,
3.40; Cl, 11.04. C18H11ClO4 (326.7) requires: C, 66.17; H, 3.39; Cl,
Compound 7 (10 mmol) was dissolved in methanol or ethanol
(5 mL). p-Toluenesulfonic acid (8 mg, 0.04 mmol) was added and
the mixture was heated to reflux for 2 h. After cooling the yellow
precipitate was filtered off, washed with diethyl ether and crys-
tallized from above given alcohol.
10.85%];
n(KBr): 3063, 3034, 1736, 1716, 1646, 1552, 1481, 1357, 1298,
1201, 1187, 1096, 1038, 1008, 929, 906, 889, 815, 782, 688, 555 cmꢁ1
;
dH (300 MHz, DMSO-d6): 6.73 (1H, s, H-10a), 7.17 (1H, d, J 8.7, H-9),
7.32 (1H, dd, J 8.8, 1.5 Hz, H-8), 7.40–7.51 (4H, m, H-4, 30, 40, 50), 7.67–
7.77 (2H, m, H-20, 60), 7.88 (1H, s, H-6), 8.12 (1H, s, OH). The 13C NMR
spectrum was unmeasurable because of the low solubility of 7c.
4.7.1. 5-Methoxy-3-phenylpyrano[2,3-b]chromen-2(10aH)-one
(8a). Work-up as described above gave 87% of 8a as yellow powder:
mp 192–194 ꢀC (methanol). [Found: C, 74.77; H, 4.64. C19H14O4
(306.3) requires: C, 74.50; H, 4.61%];
1644,1610,1557,1485, 1465,1377,1298,1259, 1191,1148,1061,1038,
977, 912, 895, 771, 689, 568, 508 cmꢁ1
dH (300 MHz, DMSO-d6): 3.49
n(KBr): 3416, 3046, 2965, 1718,
4.6.4. 7-Bromo-5-hydroxy-3-(4-nitrophenyl)-pyrano[2,3-b]chro-
men-2(10aH)-one (7d). Method A, work-up as described above
gave 86% of 7d as yellow powder: mp 285–286 ꢀC (acetic acid).
[Found: C, 52.10; H, 2.44; Br, 19.34; N, 3.45. C18H10BrNO6 (416.2)
;
(3H, s, CH3), 6.27 (1H, s, H-10a), 7.19 (1H, dd, J 8.2, 1.0 Hz, H-9), 7.23
(1H, ddd, J 7.6,1.0 Hz, H-7), 7.40–7.52 (5H, m, Ph), 7.72 (1H, ddd, J 8.0,
1.1 Hz, H-8), 7.78 (1H, dd, J 7.7, 1.5 Hz, H-6), 7.93 (1H, s, H-4); dC
(75 MHz, DMSO-d6): 55.3, 97.4,108.0,114.6,117.5,122.2,122.6,124.7,
124.7,127.9,128.2,128.2,128.4,132.5,134.3,139.4,150.3,152.1,159.5.
requires: C, 51.95; H, 2.42; Br, 19.20; N, 3.37%];
2929, 1736, 1728, 1644, 1600, 1573, 1552, 1515, 1479, 1345, 1298,
1235, 1202, 1183, 1111, 1040, 938, 853, 823, 777, 737, 695 cmꢁ1
dH
n(KBr): 3400, 3079,
;
4.7.2. 5-Ethoxy-3-(phenylsulfanyl)-pyrano[2,3-b]chromen-2(10aH)-
one (8b). Work-up as described above gave 90% of 8b as yellow
powder: mp 135–137 ꢀC (ethanol). [Found: C, 67.49; H, 4.55; S, 9.32.
(300 MHz, DMSO-d6): 7.72 (1H, d, J 8.7 Hz, H-9), 7.74 (1H, s, H-10a),
7.81 (1H, d, J 2.4 Hz, H-6), 7.87 (1H, dd, J 7.1, 2.4 Hz, H-8), 8.02–8.06
(2H, m, H-20, 60), 8.25–8.29 (3H, m, H-4, 30, 50), 8.54 (1H, br s, OH).
The 13C NMR spectrum was unmeasurable because of the low sol-
ubility of 7d.
C20H16O4S (352.4) requires: C, 68.16; H, 4.58; S, 9.10%];
3026, 2984, 1715, 1644, 1608, 1554, 1485, 1460, 1371, 1294, 1270,
1184, 1155, 1070, 1035, 1020, 974, 914, 895, 763, 695, 582, 506 cmꢁ1
n(KBr): 3419,
;
dH (300 MHz, DMSO-d6): 1.14 (3H, t, CH3), 3.66 (2H, q, CH2), 6.21
(1H, s, H-10a), 7.15 (1H, dd, J 8.2, 1.0 Hz, H-9), 7.20 (1H, ddd, J 7.4,
0.9 Hz, H-8), 7.28 (1H, s, H-4), 7.44–7.54 (6H, m, H-7, Ph), 7.72 (1H,
dd, J 7.7, 1.6 Hz, H-6); dC (75 MHz, DMSO-d6): 15.0, 63.7, 96.3, 108.2,
114.6, 117.5, 122.2, 122.5, 124.8, 124.9, 127.9, 128.2, 128.3, 128.4,
132.5, 134.3, 139.4, 150.3, 152.2, 159.5.
4.6.5. 7-Acetyloxy-5-hydroxy-3-phenylpyrano[2,3-b]chromen-
2(10aH)-one (7e). Method A, work-up as described above gave 76%
of 7e as yellow powder: mp 202–204 ꢀC (acetic acid). [Found: C,
68.32; H, 4.04. C20H14O6 (350.3) requires: C, 68.57; H, 4.03%];
n
(KBr): 3326, 3061, 1759, 1731, 1706, 1642, 1552, 1493, 1450, 1369,
1308, 1290, 1211, 1201, 1183, 1164, 1058, 1014, 967, 957, 920, 883,
869, 785, 744, 698, 539 cmꢁ1
dH (300 MHz, DMSO-d6): 2.29 (3H, s,
;
CH3), 6.44 (1H, s, H-10a), 7.15 (1H, d, J 8.8 Hz, H-9), 7.23 (1H, dd, J
8.8, 2.1 Hz, H-8), 7.38–7.48 (3H, m, H-4, 30, 50), 7.51 (1H, d, J 2.6 Hz,
H-6), 7.74 (2H, dd, J 8.3, 1.1 Hz, H-20, 60), 7.81 (1H, br s, OH), 7.88 (1H,
s, H-4); dC (75 MHz, DMSO-d6): 20.7, 91.3, 110.0, 114.7, 115.1, 118.4,
125.1, 125.6, 125.6, 127.9, 127.9, 128.2, 128.4, 134.3, 139.5, 144.7,
149.2, 149.9, 159.5, 169.4.
4.8. 5-(R1-amino)-3-R-pyrano[2,3-b]chromen-2(10aH)-ones
(9a–9i)
Method A: The solution of amide (10 mmol) in nitromethane
(7 mL) was added to the solution of acetate 4 (10 mmol) in nitro-
methane (7 mL) in the presence of p-toluenesulfonic acid (15 mg).
The mixture was heated at 60–70 ꢀC for 1 h. After cooling the solid
product was filtered off, washed with cold diethyl ether and crys-
tallized from nitromethane.
4.6.6. 5-Hydroxy-3-(4-methylphenylsulfanyl)-pyrano[2,3-b]chro-
men-2(10aH)-one (7f). Method A, work-up as described above gave

´ ´
M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1418
Method B: The solution of amide (10 mmol) in toluene (7 mL)
described above gave 90% of 9e as yellow powder: mp 225–
was added to the solution of acetate 4 (10 mmol) in toluene (2 mL)
in the presence of p-toluenesulfonic acid (15 mg). The mixture was
irradiated in microwave oven at 80 ꢀC and 80 W for 15 min. After
cooling the solid product was filtered off, washed with cold diethyl
ether and crystallized from ethanol.
227 ꢀC. [Found: C, 67. 74; H, 4.62; N, 3.11; S, 7.17. C26H21NO5S
(459.5) requires: C, 67.96; H, 4.61; N, 3.05; S, 6.98%]; n(KBr): 3462,
3216, 2921, 1710, 1699, 1631, 1579, 1523, 1492, 1446, 1334, 1304,
1246, 1209, 1185, 1166, 1094, 1043, 997, 953, 920, 868, 815, 757,
675, 567, 536, 507 cmꢁ1
; dH (300 MHz, DMSO-d6): 2.28 (3H, s,
CH3), 2.41 (3H, s, CH3), 6.29 (1H, d, J 8.4 Hz, H-7), 6.58 (1H, d, J
8.9 Hz, H-5), 7.12 (1H, dd, J 8.3, 2.0 Hz, H-8), 7.38 (2H, d, J 8.4 Hz,
300, 500), 7.42–7.49 (4H, m, H-10, 20,40, 60), 7.51 (1H, s, H-4), 7.62–
7.67 (2H, m, H-30, 50), 7.72 (2H, d, J 8.3 Hz, H-200, 600), 9.36 (1H, d, J
8.8 Hz, NH); dC (75 MHz, DMSO-d6): 20.0, 20.9, 78.9, 106.6, 114.4,
116.9, 121.9, 122.4, 124.2, 126.5, 126.6, 127.8, 128.3, 128.4, 128.6,
129.4, 131.6, 132.9, 134.0, 138.9, 139.0, 142.9, 149.2, 150.6, 159.4,
170.1.
4.8.1. 5-(N-Acetylamino)- 3-phenyl-2H,5H-pyrano[3,2-c]chromen-2-
one (9a). Method B, work-up as described above gave 92% of 9a as
yellow powder: mp 218–220 ꢀC. [Found: C, 71.93; H, 4.52; N, 4.16.
C20H15NO4 (333.1) requires: C, 72.06; H, 4.54; N, 4.20%]; n(KBr): 3318,
3262, 3028, 1729, 1704, 1687, 1667, 1638, 1551, 1518, 1487, 1458, 1367,
1292, 1226, 1198, 1154, 1083, 995, 969, 877, 784, 767, 695, 595,
526 cmꢁ1
; dH (300 MHz, DMSO-d6): 1.83 (3H, s, CH3), 6.86 (1H, d, J
8.6 Hz, H-5), 7.04 (1H, d, J 8.2, Hz, H-7), 7.18 (1H, ddd, J 7.6, 1.5 Hz, H-
9), 7.36–7.50 (4H, m, H-8, 30, 40, 50), 7.69–7.78 (3H, m, H-10, 20, 60),
7.82 (1H, s, H-4), 9.24 (1H, d, J 8.6 Hz, NH); dC (75 MHz, DMSO-d6):
22.7, 74.5, 107.6, 114.9, 117.6, 117.6, 122.3, 122.4, 122.5, 124.5, 128.0,
128.3, 128.5, 132.7, 134.3, 139.6, 150.5, 152.8, 159.7, 159.5.
4.8.6. 9-Fluoro-5-[N-(4-methylphenyl)sulfonamino]-3-phenyl-
2H,5H-pyrano[3,2-c]chromen-2-one (9f). Method B, work-up as
described above gave 95% of 9f as yellow powder: mp 210–212 ꢀC.
[Found: C, 64. 96; H, 3.92; N, 3.16; S, 7.18. C25H18FNO5S (463.5)
requires: C, 64.79; H, 3.91; N, 3.02; S, 6.92%];
2881, 1707, 1639, 1546, 1487, 1450, 1342, 1260, 1185, 1164, 1059,
1042, 972, 914, 868, 784, 697, 574, 554, 534 cmꢁ1
dH (300 MHz,
n(KBr): 3195, 3064,
4.8.2. 5-(N-Acetylamino)-9-methyl-3-phenyl-2H,5H-pyrano[3,2-
c]chromen-2-one (9b). Method A, work-up as described above
gave 88% of 9b as yellow powder: mp 270–271 ꢀC. [Found: C,
72.79; H, 4.92; N, 4.11. C21H17NO4 (347.4) requires: C, 72.61; H,
;
DMSO-d6): 2.39 (3H, s, CH3), 6.38 (1H, d, J 8.8 Hz, H-7), 6.62 (1H,
d, J 8.9 Hz, H-5), 7.14–7.24 (1H, m, H-8,), 7.37–7.50 (2H, m, H-300,
500), 7.42–7.50 (4H, m, H-10, 30, 40, 50), 7.55 (1H, s, H-4), 7.65 (2H,
dd, J 7.9, 1.3 Hz, H-20, 60), 7.72 (2H, d, J 8.3 Hz, H-200, 600), 9.41 (1H,
d, J 8.9 Hz, NH); dC (75 MHz, DMSO-d6): 20.8, 78.9, 107.2, 107.8,
108.2, 115.6, 115.7, 119.0, 125.1, 125.2, 126.4, 127.8, 128.0, 128.2,
128.6, 128.7, 129.4, 133.8, 138.5, 138.7, 142.9, 147.2, 149.4, 155.4,
159.0.
4.93; N, 4.03%];
1513, 1492, 1425, 1371, 1302, 1251, 1229, 1209, 1183, 1131, 1085,
1045, 993, 979, 924, 879, 828, 786, 702, 594, 534 cmꢁ1
dH
n(KBr): 3305, 2930, 1725, 1662, 1645, 1577, 1554,
;
(300 MHz, DMSO-d6): 1.83 (3H, s, CH3), 2.33 (3H, s, CH3), 6.82 (1H,
d, J 8.5 Hz, H-5), 6.94 (1H, d, J 8.5, Hz, H-7), 7.25 7.55 (1H, dd, J 8.5,
2.1 Hz, H-8), 7.36–7.49 (3H, m, H-30, 40, 50), 7.54 (1H, d, J 1.8 Hz, H-
5), 7.73–7.77 (2H, m, H-20, 60), 7.81 (1H, s, H-4), 9.19 (1H, d, J
8.5 Hz, NH); dC (75 MHz, DMSO-d6): 19.9, 20.7, 84.8, 111.3, 118.0,
122.6, 125.0, 127.9, 132.7, 134.7, 138.4, 138.7, 138.9, 140.0, 141.8,
143.7, 144.8, 150.1, 161.1, 161.2, 179.9.
4.8.7. 5-(N-Benzoylamino)-9-bromo-3-(4-methylphenylsulfanyl)-
2H,5H-pyrano[3,2-c]chromen-2-one (9g). Method A, work-up as
described above gave 87% of 9g as yellow powder: mp 208–211 ꢀC.
[Found: C, 60.23; H, 3.51; Br, 15.47; N, 2.74; S, 6.29. C26H18BrNO4S
(520.4) requires: C, 60.01; H, 3.49; Br, 15.35; N, 2.69; S, 6.16%];
4.8.3. 5-(N-Benzoylamino)-3-phenyl-2H,5H-pyrano[3,2-c]chromen-
2-one (9c). Method A, work-up as described above gave 87% of 9c as
yellow powder: mp 228–230 ꢀC. [Found: C, 76.11; H, 4.32; N, 3.47.
n
(KBr): 3373, 3060, 2919, 1817, 1708, 1676, 1633, 1580, 1516, 1489,
1352, 1331, 1299, 1244, 1210, 1183, 1134, 1118, 1076, 1054, 987, 952,
814, 763, 715, 695, 575, 507 cmꢁ1
dH (300 MHz, DMSO-d6): 2.30
C25H17NO4 (395.4) requires: C, 75.94; H, 4.33; N, 3.54%];
3284, 3025, 2639, 1711, 1667, 1640, 1552, 1510, 1485, 1458, 1365, 1295,
1265, 1234, 1200, 1136, 1111, 1060, 967, 842, 753, 697, 579, 524 cmꢁ1
n(KBr):
;
(3H, s, CH3), 6.99 (1H, d, J 8.6 Hz, H-5), 7.01 (1H, d, J 8.3 Hz, H-7),
7.06 (1H, s, H-4), 7.26 (2H, dd, J 7.9, 1.1 Hz, H-300, 500), 7.39–7.41 (2H,
m, H-30, 50), 7.47 (2H, dd, J 7.6, 2.0 Hz, H-20, 6’), 7.52–7.60 (2H, m, H-
8,400), 7.74–7.78 (3H, m, H-9, 200, 600), 9.52 (1H, d, J 8.3 Hz, NH). The
13C NMR spectrum was unmeasurable because of the low solubility
of 9g.
;
dH (300 MHz, CDCl3): 7.06 (1H, d, J 8.2 Hz, H-5), 7.14 (1H, d, J 8.2 Hz,
H-7), 7.19 (1H, ddd, J 7.6, 1.4 Hz, H-9), 7.36–7.47 (6H, m, H-30, 40, 50,
300,400, 500), 7.55 (1H, ddd, J 7.6, 1.4 Hz, H-8), 7.73–7.79 (3H, m, H-10,
2’,60), 7.86 (2H, d, J 7.1 Hz, H-200, 600), 7.92 (1H, s, H-4), 9.69 (1H, d, J
8.2 Hz, NH); dC (75 MHz, DMSO-d6): 75.3, 107.3, 115.1, 115.2, 117.5,
122.2, 122.3, 122.3, 124.4, 127.8, 127.8, 128.0, 128.0, 128.3, 128.3, 128.4,
132.0, 132.5, 133.0, 134.4, 139.8, 151.0, 152.8, 159.8, 166.2.
4.8.8. 5-(N-Benzoylamino)-9-methyl-3-(4-methylphenylsulfanyl)-
2H,5H-pyrano[3,2-c]chromen-2-one (9h). Method A, work-up as
described above gave 87% of 9h as yellow powder: mp 238–240 ꢀC.
[Found: C, 70.98; H, 4.64; N, 2.98; S, 7.19. C27H21NO4S (455.5) re-
4.8.4. 5-[N-(4-methylphenyl)sulfonamino]-3-phenyl-2H,5H-pyr-
ano[3,2-c]chromen-2-one (9d). Method A, work-up as described
above gave 80% of 9d as yellow powder: mp 242–244 ꢀC. [Found: C,
67. 63; H, 4.34; N, 3.19; S, 7.38. C25H19NO5S (445.4) requires: C, 67.40;
quires: C, 71.19; H, 4.65; N, 3.07; S, 7.04%];
1710, 1648, 1545, 1488, 1461, 1347, 1275, 1185, 1135, 1068, 1054, 988,
916, 869, 769, 697, 567, 553, 531, 502 cmꢁ1
dH (300 MHz, DMSO-
n(KBr): 3245, 3068, 2952,
;
H, 4.30; N, 3.14; S, 7.20%];
1485, 1451, 1335,1285,1165, 1154, 1092,1042, 981, 915, 856, 785, 701,
675, 567, 539 cmꢁ1
dH (300 MHz, DMSO-d6): 2.39 (3H, s, CH3), 6.42
(1H, d, J 8.2 Hz, H-7). 6.62 (1H, d, J 8.5 Hz, H-5), 7.13 (1H, ddd, J 8.2,
1.6 Hz, H-8), 7.32 (1H, ddd, J 8.2, 1.5 Hz, H-9), 7.39 (2H, d, J 7.9 Hz, 300,
500), 7.42–7.49 (3H, m, H-20,40, 60), 7.50 (1H, s, H-4), 7.61–7.68 (3H, m,
H-10, 30, 50), 7.72 (2H, d, J 7.9 Hz, H-200, 600), 9.40 (1H, d, J 8.5 Hz, NH);
dC (75 MHz, DMSO-d6): 20.9, 79.4, 106.7, 114.8, 117.2, 122.2, 122.6,
124.6, 124.6, 126.6, 126.6, 127.3, 127.9, 128.4, 128.4, 128.6, 129.4, 129.5,
132.4, 134.1, 138.9, 150.6, 151.4, 159.5, 170.3.
n
(KBr): 3164, 3052, 2879, 1706, 1637, 1548,
d6): 2.29 (3H, s, CH3), 2.32 (3H, s, CH3), 6.90 (1H, d, J 8.3 Hz, H-5),
6.94 (1H, d, J 8.9 Hz, H-7), 7.19 (1H, s, H-4), 7.20 (1H, dd, J 8.3, 1.5 Hz,
H-8), 7.25 (2H, d, J 8.2 Hz, H-30, 50), 7.39–7.42 (2H, m, H-300, 500), 7.46
(2H, d, J 8.2 Hz, H-20, 60), 7.49 (1H, d, J 1.5 Hz, H-9), 7.53–7.59 (1H, m,
H-40), 7.77 (2H, dd, J 8.5, 1.9 Hz, H-200, 600), 9.49 (1H, d, J 8.2 Hz, NH);
dC (75 MHz, DMSO-d6): 20.1, 20.7, 75.2, 107.2, 114.7, 117.2, 121.9,
124.3,126.4, 127.6, 128.3, 130.5,130.5, 130.6, 131.4, 131.4, 132.1,132.1,
132.9, 133.0, 137.7, 137.7, 138.8, 149.5, 150.4, 158.3, 166.1.
;
4.8.9. 9-Methyl-3-(4-methylphenylsulfanyl)-5-[N-(4-methyl-
phenyl)sulfonamino]-2H,5H-pyrano[3,2-c]chromen-2-one (9i). Method
A, work-up as described above gave 87% of 9i as yellow powder: mp
235–237 ꢀC. [Found: C, 64.34; H, 4.56; N, 2.74; S, 12.58. C27H23NO5S2
4.8.5. 9-Methyl-5-[N-(4-methylphenyl)sulfonamino]-3-phenyl-
2H,5H-pyrano[3,2-c]chromen-2-one (9e). Method A, work-up as

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M. Lacova et al. / Tetrahedron 66 (2010) 1410–1419
1419
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Selenium Reagents and Intermediates in Organic Synthesis; Pergamon: Oxford,
1986.
9. (a) Burger, K.; Gold, M.; Neuhauser, H.; Rudolph, M.; Hoess, E. Synthesis 1992,
1145–1150; (b) Burling, F. T.; Goldenstein, B. M. J. Am. Chem. Soc. 1992, 114,
2313–2320; (c) Selenium in Biology and Human Health; Burk, R. F., Ed.; Springer:
New York, NY, 1994.
10. Nefedova, T. V.; Kubatiev, A. A.; Martynov, A. V.; Guseva, S. A.; Kazimir-
ovskya, V. B.; Mirskova, A. N.; Novikova, N. V.; Lobanova, E. G.; Nepsha, V.
D.; Moskvitina, L. T.; Voronkov, M. G. Khim. Pharm. Zh. 1987, 21, 1081–
1084.
(505.6) requires: C, 64.14; H, 4.59; N, 2.77; S, 12.68%];
3059, 2866, 1711, 1696, 1629, 1577, 1521, 1490, 1445, 1331, 1245, 1164,
1093, 1041, 995, 918, 867, 814, 756, 674, 560, 535, 506 cmꢁ1
dH
(300 MHz, DMSO-d6): 2.27 (3H, s, CH3), 2.39 (3H, s, CH3), 2.41 (3H, s,
CH3), 6.14 (1H, d, J 8.3 Hz, H-5), 6.46 (1H, d, J 8.9 Hz, H-7), 6.86 (1H, s,
H-4), 7.06 (1H, dd, J 8.3, 2.1 Hz, H-8), 7.30–7.44 (7H, m, H-9, 30, 50, 200,
300, 500, 600), 7.61 (2H, dd, J 8.2, 2.3 Hz, H-20, 60), 9.22 (1H, d, J 8.9 Hz, NH);
dC (75 MHz, DMSO-d6): 20.0, 20.7, 20.9, 78.6, 106.3,114.4,116.7, 121.6,
124.8, 125.7, 126.4, 129.3, 130.6, 131.5, 131.5, 132.6, 132.6, 133.2, 136.2,
136.2, 138.7, 138.8, 139.1, 142.8, 148.8, 148.9, 157.8.
n(KBr): 3206,
;
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11. (a) La´cova´, M.; Gasparova, R.; Loos, D.; Liptay, T.; Pronayova, N. Molecules 2000,
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5, 167–178; (b) Gasparova, R.; Lacova, M.; Krutosıkova, A. Collect. Czech. Chem.
Acknowledgements
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Commun. 2005, 70, 2101–2111; (c) Stankovicova, H.; Gasparova, R.; Lacova, M.;
Chovancova´, J. Collect. Czech. Chem. Commun. 1997, 62, 781–790; (d) Stankovi-
This work was supported by the Slovak Research Agency under
the contracts No. VEGA 1/1005/09, VEGA 1/4467/07, LPP 0153-06
APVV20-031904 and APVV-51-046505.
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cova, H.; Gaplovsky, A.; Lacova, M.; Chovancova, J.; Puchala, A. J. Heterocycl.
Chem. 2006, 43, 843–848.
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12. Stankovicova, H.; Lacova, M.; Gaplovsky, A.; Chovancova, J.; Pronayova, N.
Tetrahedron 2001, 57, 3455–3464.
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13. Ga´ plovsky´, A.; Donovalova´ , J.; Lacova´ , M.; Mracnova, R.; El-Shaaer, H. M.
J. Photochem. Photobiol., A 2000, 136, 61–65.
14. (a) El-Shaaer, H. M.; Perjessy, A.; Zahradnı´k, P.; La´cova´, M.; Sustekova´, Z.
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