Synthesis and reactions of dehydracetic acid difluoroborane complex

Article abstract of DOI:10.1134/S107042800807018X

Dehydracetic acid difluoroborane complex, 3-acetyl-6-methyl-2-oxo-2H-pyran- 4-yl difluoridoborate, was synthesized and characterized. The complex was involved into condensation reactions at the acetyl group with various aromatic and heterocyclic aldehydes

Full text of DOI:10.1134/S107042800807018X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 7, pp. 1054−1060. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © A.V. Manaev, K.V. Tambov, V.F. Traven’, 2008, published in Zhurnal Organicheskoi Khimii, 2008, Vol. 44, No. 7, pp. 1064−
1070.
Synthesis and Reactions of Dehydracetic Acid
Difluoroborane Complex
A. V. Manaev, K. V. Tambov, and V. F. Traven’
Mendeleev Russian University of Chemical Engineering, Moscow, 125047 Russia
e-mail: traven@muctr.edu.ru
Received July 17, 2007
Abstract—Dehydracetic acid difluoroborane complex, 3-acetyl-6-methyl-2-oxo-2H-pyran-4-yl difluoridoborate,
was synthesized and characterized. The complex was involved into condensation reactions at the acetyl group
with various aromatic and heterocyclic aldehydes, and with the 4-dimethylaminobenzaldehyde it reacted also at
the methyl group in the position 6.
DOI: 10.1134/S107042800807018X
Dehydracetic acid (3-acetyl-4-hydroxy-6-methyl-2H-
pyran-2-one) in the presence of bases is capable of
condensation with various aldehydes both at the acetyl
and methyl group in the position 6 [1, 2]. However the
products of these reactions form in low yield and are
difficult to isolate. We investigated a new promising
condensation method of dehydracetic acid with aldehydes
involving an intermediate preparation of its boron
complex.
By a reaction of dehydracetic acid (III) with boron
trifluoride etherate we obtained its boron complex,
3-acetyl-6-methyl-2-oxo-2H-pyran-4-yl difluoridoborate
(IV) (Scheme 1).
In the 1H NMR spectrum of complex IV the proton
signals of the methyl groups are shifted downfield: the
proton signal of the acetyl group is shifted by 0.20 ppm,
and that of the methyl in the position 6, by 0.14 ppm.
This shift reveals the enhanced CH-acidity of both methyl
groups due to the complex formation. The structure of
compound IV was also proved by XRD analysis (see the
figure). According to the XRD data the atoms of the
molecule are located in the same plane. The bond
distances in the six-membered heterocycle involving the
boron atom indicate an efficient electron density
delocalization in the fragment F2BOC=CC=O (see the
table). The observed leveling-off of bond distances in
this moiety is caused by the formation of the donor-
acceptor Β–O bond and by a significant degree of π-de-
It was formerly established that 1,3-diketones and also
the corresponding aromatic and heteroaromatic vic-
hydroxyketones are capable of boron complexes
formation. In particular, boron complexes were obtained
from 2-hydroxyacetophenone (I) [3] and 3-acetyl-4-
hydroxycoumarin (II) [4, 5].
F
F
F
F
B
B
O
O
O
O
CH3
CH3
1
localization. For instance, the bond lengths Β –O1 and
O
O
Scheme 1.
II
I
F
F
The introducing of a boron atom into the molecule
results in a considerable increase in the reactivity of the
methyl group in the acetyl moiety compared to the initial
hydroxy compounds providing a possibility to perform
condensation with carbonyl compounds and their
derivatives, in particular, with acetals and anils [4, 6].
OH
O
O
B
O
O
.
BF3 O(C2H5)2
CH3
CH3
H3C
O
H3C
O
IV
O
III
1054

SYNTHESIS AND REACTIONS OF DEHYDRACETIC ACID
1055
Geometric parameters of boron complex IV from XRD data
aromatic aldehydes possessing electron-withdrawing
substituents, for instance, with 4-nitrobenzaldehyde, and
also with aliphatic aldehydes. From condensation of
compound IV with aromatic aldehydes Va–Vd
difluoridoborates VIa–VId were obtained (Scheme 2).
The structure of the obtained complexes was confirmed
Structure of compound IV from XRD data
°
Β –O2 equal respectrively 1.4829 and 1.5082 A.. The
1
bond lengths C1–O2 and C4–O1 in the formed boron
°
complex also become materially equal: 1.29 and 1.30 A.
respectively. In general the structure of the six-membered
boron ring in complex IV possesses the same bond
distances and angles as in boron complex II [5].
1
by H NMR and mass spectra. In the 1H NMR spectra
alongside the signals of the aromatic protons in the
downfield region (6.10–9.00 ppm) two doublet signals
were observed from methine protons with coupling
constants of ~12–15 Hz. These values of the coupling
constants indicate the mutual trans-location of the
methine protons. The signal of methyl protons of acetyl
group is lacking in these 1H NMR spectra.
Complex IV readily underwent crotonic condensation
with aldehydes in the absence of bases. These reactions
proceed especially cleanly with aromatic and heterocyclic
aldehydes containing electron-donor substituents. We
failed to carry out reactions in the absence of bases with
Scheme 2.
CHO
R1
F
F
F
F
R4
R2
B
B
O
O
R1
O
O
R3
Va_Vd
or AcOH, H SO
R2
R3
CH3
Ac2O
2
4
H3C
OH
O
O
H3C
O
O
R4
VIa_VId
IV
O
O
R1
R2
R3
(1) Na2CO3, EtOH, H2O
(2) HCl
H3C
O
R4
VIIa_VIId
R1 = R2 = R4 = H, R3 = N(CH3)2 (a), OCH3 (b); R1 = H, R2 = R3 = R4 = OCH3 (c); R1 = OCH3, R2 = R3 = H, R4 =Br (d).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

MANAEV et al.
1056
the compounds prepared was confirmed by 1H NMR and
mass spectra. In the 1H NMR spectra of boron complexes
alongside the proton signals of the thiophene ring two
doublets in the downfield region (7.00–8.40 ppm,
coupling constants ~12–15) Hz were observed belonging
to methine protons.
Under the same conditions compound IV reacted also
with the derivatives of cinnamaldehyde, 4-dimethyl-
aminocinnamaldehyde (VIIIa) and 4-methoxy-
cinnamaldehyde (VIIIb) (Scheme 3). Therewith
compounds IXa and IXb formed whose structure was
unambiguously proved by 1H NMR and mass spectra. In
1
the downfeld region of H NMR spectra alongside the
By reaction of boron complex IV with Fischer’s
aldehyde compound XV belonging to trimethine dyes
was successfully synthesized. The structure of the com-
pound was confirmed by 1H NMR spectrum that along-
side the signals of aromatic protons and those of methyl
groups contained the resonances of three methine
protons: a one-proton doublet at 6.10 ppm, a one-
proton triplet at 8.73 ppm, and the doublet of the third
signals of aromatic protons appeared signals from four
methine protons as two triplets and two doublets at 7.10–
8.20 ppm.
3-Acetyl-6-methyl-2-oxo-2H-pyran-4-yl difluorido-
borate (IV) was also brought into condensation with
heterocyclic aldehydes (Scheme 4). In this reaction boron
complexes XII and XV were obtained. The structure of
Scheme 3.
CHO
F
O
F
O
F
O
F
O
B
B
R
a
VIII , VIIIb
CH3
Ac2O or AcOH, H2SO4
H3C
O
O
H3C
O
O
R
a
IX , IXb
IV
OH O
(1) Na2CO3, EtOH, H2O
(2) HCl
H3C
O
O
R
a
X , Xb
R = N(CH3)2 (a), OCH3 (b).
Scheme 4.
F
F
F
F
B
H3C
B
O
O
(1) Na2CO3,
EtOH, H2O
(2) HCl
N
CHO
S
O
O
OH
O
O
H3C
CH3
XI
or AcOH, H SO
Ac2O
2
4
S
S
H3C
O
O
H3C
O
O
H3C
CH3
O
IV
N
N
CH3
H3C
H3C
XIII
XII
H3C
CH3
F
F
CH3
CH3
B
CHO
(1) Na2CO3,
EtOH, H2O
(2) HCl
N
O
O
OH
O
O
H3C
H3C
CH3
XIV
N
N
Ac2O
CH3
CH3
H3C
O
O
H3C
O
XV
XVI
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

SYNTHESIS AND REACTIONS OF DEHYDRACETIC ACID
1057
proton from the trimethine chain superimposed on the
multiplet of aromatic protons at 7.04–7.47 ppm.
by acidification resulted in the formation of the cor-
responding hydroxyketones VIIa–VIId, Xa, Xb, XIII,
1
XVI, XVIIIa, XVIIIb, and XVIIId. In the H NMR
It was formerly reported on the condensation with
benzaldehyde of dihydracetic acid at the position 6 in
the presence of a base N-benzylidenecyclohexylamine
[7]. We found that boron complexes IV, VIa, VIb, and
VId were capable of reacting at the methyl group in the
position 6 even in the absence of a base (Scheme 5).
However due to the longer distance from the acceptor
boron atom the methyl group in the position 6 is less
activated than the methyl from the acetyl moiety (the
shift of these protons on complexing is 0.14 and 0.20 ppm
respectively).Among the other aldehydes only 4-dimethyl-
spectra of these ketones as distinct from the spectra of
the boron complexes appeared the proton signal of the
hydroxy group as a singlet in the downfield region
(17.00–18.00 ppm). Besides the proton signals of the
double bonds are shifted upfield on the average by
0.30 ppm. This shift is due to the elimination of the
acceptor effect of the chelate ring after the hydrolysis of
the boron complexes.
The structure of all compounds obtained was
confirmed by mass spectra and elemental analyses.
Thus by the reaction of the boron complex of
hydracetic acid with various aromatic and heterocyclic
aldehydes boron complexes of the corresponding
chalcones analogs were obtained. The complexes are
deeply colored and exhibit fluorescence. Their hydrolysis
led to the formation of new heterocyclic α,β-unsaturated
ketones also characterized by fluorescence.
1
aminobenzaldehyde readily reacted. In the H NMR
spectrum of compound XVIIa in the downfield region
(6.90–8.52 ppm) four signals of methine protons
appeared as four doublets with coupling constants of
~12–15 Hz. The singlet from methyl group in the position
6 disappeared. We failed to register the 1H NMR spectra
of compounds XVIIb and XVIId because of their poor
solubility.
Compound XVIIa was also synthesized by condensa-
tion of boron complex IV with two equiv of the cor-
responding aldehyde. The reaction proceeded
simultaneously at both reaction sites.
EXPERIMENTAL
1H NMR spectra were registered on a spectrometer
Bruker WP-200-SY, internal reference Me4Si. Mass
spectra were measured on MAT-112 instrument at
ionizing electrons energy 80 eV, ion source temperature
250°C, vaporizer temperature 240°C.
The treatment of boron complexes obtained VIa–VId,
IXa, IXb, XII, XV, XVIIa, XVIIb, and XVIId with
sodium carbonate in aqueous-alcoholic medium followed
Scheme 5.
CHO
F
O
F
O
F
O
F
O
B
B
R1
R4
H3C
R1
R4
N
R2
R3
R2
R3
CH3
Ac2O
H3C
O
O
O
O
H3C
N
CH3
XVIIa, XVIIb, XVIId
VIa, VIb, VId
(1) Na2CO3,
EtOH, H2O
(2) HCl
OH O
R1
R2
R3
O
O
H3C
R4
N
CH3
XVIIIa, XVIIIb, XVIIId
R1 = R2 = R4 = H, R3 = N(CH3)2 (a), OCH3 (b); R1 = OCH3, R2 = R3 = H, R4 = Br (d).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

MANAEV et al.
1058
XRD experiment for compound VI was performed
(1H, CH, J 14.9 Hz), 8.42 d (1H, CH, J 14.9 Hz). Mass
spectrum: m/z 348 [M]+. Found, %: C 58.79; H 4.60; N
4.00. C17H16BF2NO4. Calculated, %: C 58.82; H 4.65;
N 4.04.
on an automatic five-circle diffractometer CAD-4 at
298 K. C8H7BF2O4. Crystals monoclinic, space group
°
P2(1)/c, a 9.486(7), b 5.157(4), c 18.449(14) A,
°
β 104.02(10)°, V 875.54(11) A3, Z 4, dcalc 1.638 mg/m3,
3-{(2E,4E)-5-[4-(Dimethylamino)phenyl]penta-
2,4-dienoyl}-6-methyl-2-oxo-2H-pyran-4-yl
difluoridoborate (IXa). Yield 64%, dark-green crystals,
μ(MoKα) 0.153 mm–1, F(000) 440.0. Intensities of 8800
reflections were measured at 298 K (λMoKα, graphite
monochromator, θ/2θ-scanning, 2θ < 50°), among them
2538 independent reflections with I > 2σ. The structure
was solved by the direct method and by successive
syntheses of the electron density. All hydrogen atoms
localized from the difference synthesis of the electron
density. The refinement by F2hkl was carried out in an
anisotropic approximation for all nonhydrogen atoms and
in isotropic approximation for hydrogen atoms. The final
divergence factors are as follows: R 0.0324 for 2356
independent reflections with I > 2σ(I), Rw 0.0913 for all
measured reflections. All calculations were performed
applying software package SHELXTL 5.10 [8].
1
mp 242–243°C. H NMR spectrum (DMSO-d6), δ, ppm:
2.33 s (3H, CH3), 3.31 s [6H, N(CH3)2], 6.41 s (1H, H5),
6.79 d (2H, Harom, J 8.7 Hz), 7.28 t (1H, CH), 7.57 d (1H,
CH, J 14.3 Hz), 7.65 d (2H, Harom, J 8.7 Hz), 7.68 d (1H,
CH, J 14.3 Hz), 8.17 t (1H, CH). Mass spectrum: m/z
374 [M]+. Found, %: C 61.19; H 4.89; N 3.65.
C19H18BF2NO4. Calculated, %: C 61.16; H 4.86; N 3.75.
3-{(2E)-3-[5-(Dimethylamino)-2-thienyl]prop-2-
enoyl}-6-methyl-2-oxo-2H-pyran-4-yl difluorido-
borate (XII). Yield 88%, dark-blue crystals, mp 223–
224°C. 1H NMR spectrum (DMSO-d6), δ, ppm: 2.26 s
(3H, CH3), 3.38 s [6H, N(CH3)2], 6.22 s (1H, H5), 6.86 d
(1H, HHt, J 5.1 Hz), 7.06 d (1H, CH, J 12.9 Hz), 8.01 d
(1H, HHt, J 5.1 Hz), 8.21 d (1H, CH, J 12.9 Hz). Mass
spectrum: m/z 354 [M]+. Found, %: C 51.04; H 4.09;
N 3.96; S 9.10. C15H14BF2NO4S. Calculated, %: C 51.02;
H 4.00; N 3.97; S 9.08.
Atomic coordinates and complete tables of bond
distances and bond angles were deposited to Cambridge
Structural Database.
3-Acetyl-6-methyl-2-oxo-2H-pyran-4-yl di-
fluoridoborate (IV). To a solution of 10 g (0.06 mol) of
compound III in 17 ml of anhydrous benzene was added
dropwise at boiling 10 g (0.07 mol) of boron trifluoride
etherate. The reaction mixture was heated for 1 h, and
then the separated precipitate was filtered off, washed
with benzene, dried in air, and recrystallized from
benzene. Yield 80%. Yellow needle crystals, mp 135–
136°C. 1H NMR spectrum (CDCl3), δ, ppm: 2.39 s (3H,
6-CH3), 2.86 s (3H, 3-CH3), 6.13 s (1H, H5). Found, %:
C 44.45; H 3.21. C8H7BF2O4. Calculated, %: C 44.50;
H 3.27.
6-Methyl-2-oxo-3-[(2Ε,4Ε)-4-(1,3,3-trimethyl-1,3-
dihydro-2H-indol-2-ylidene)but-2-enoyl]-2H-pyran-
4-yl difluoridoborate (XV). Yield 76%, violet crystals,
1
mp 250–251°C. H NMR spectrum (CDCl3), δ, ppm:
1.68 s [6H, (CH3)2], 2.29 s (3H, CH3), 3.54 s [3H,
N(CH3)], 6.01 s (1H, H5), 6.10 d (1H, CH, J 14 Hz),
7.04–7.47 m (5H, 4Harom), 8.73 t (1H, CH). Mass
spectrum: m/z 400 [M]+. Found, %: C 63.15; H 5.10;
N 3.49 C21H20BF2NO4. Calculated, %: C 63.18; H 5.05;
N 3.51.
Difluoridoborates (VIb–VId, and IXb). General
procedure. To a solution of 0.5 g (0.002 mol) of boron
complex IV in 6 ml of acetic acid at 60°C was added
a solution of 0.002 mol of an appropriate aldehyde in
2 ml of acetic acid and 0.13 ml of concn. sulfuric acid.
The mixture was heated at 90°C for 30 min. On cooling
the settled precipitate was filtered off, washed on the
filter with acetic acid, and recrystallized from acetic acid.
Difluoridoborates VIa, IXa, XII, and XV. General
procedure. To a solution of 0.5 g (0.002 mol) of boron
complex IV in 6 ml of acetic acid at 60°C was added a
solution of 0.002 mol of an appropriate aldehyde in 2 ml
of acetic anhydride. The mixture was heated at 90°C for
30 min. On cooling the settled precipitate was filtered
off, washed on the filter with acetic acid, and
recrystallized from acetic acid.
3-[(2E)-3-(4-Methoxyphenyl)prop-2-enoyl]-6-
methyl-2-oxo-2H-pyran-4-yl difluoridoborate (VIb).
Yield 80%, red crystals, mp 220–221°C. 1H NMR spec-
trum (DMSO-d6), δ, ppm: 2.38 s (3H, CH3), 3.88 s (3H,
OCH3), 6.55 s (1H, H5), 7.11 d (2H, Harom, J 8.8 Hz),
7.90 d (2H, Harom, J 8.8 Hz), 8.13 d (1H, CH, J 15.2 Hz),
8.40 d (1H, CH, J 15.2 Hz). Mass spectrum: m/z 335
3-{(2E)-3-[4-(Dimethylamimino)phenyl]prop-2-
enoyl}-6-methyl-2-oxo-2H-pyran-4-yl difluorido-
borate (VIa). Yield 84%, dark-red crystals, mp 238–
239°C. 1H NMR spectrum (CDCl3), δ, ppm: 2.34 s (3H,
CH3), 3.17 s [6H, N(CH3)2], 6.07 s (1H, H5), 6.70 d (2H,
H
arom, J 8.8 Hz), 7.68 d (2H, Harom, J 8.8 Hz), 8.08 d
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

SYNTHESIS AND REACTIONS OF DEHYDRACETIC ACID
1059
[M]+. Found, %: C 57.56; H 3.98. C16H13BF2O5.
Calculated, %: C 57.72; H 3.92.
red crystals, mp 295–296°C. Mass spectrum: m/z 466
[M]+. Found, %: C 64.50; H 4.73; N 3.01. C25H22BF2NO5.
Calculated, %: C 64.54; H 4.77; N 3.01.
3-[(2Ε)-3-(3,4,5-Trimethoxyphenyl)prop-2-enoyl]-
6-methyl-2-oxo-2H-pyran-4-yl difluoridoborate
(VIc). Yield 65%, red crystals, mp 192–193°C. 1H NMR
spectrum (CDCl3), δ, ppm: 2.39 s (3H, CH3), 3.98 s (9H,
3OCH3), 6.14 s (1H, H5), 6.99 s (2H, Harom), 8.21 d (1H,
CH, J 15.4 Hz), 8.34 d (1H, CH, J 15.4 Hz). Mass
spectrum: m/z 395 [M]+. Found, %: C 54.98; H 4.26.
C18H17BF2O7. Calculated, %: C 54.85; H 4.35.
3-[(2E)-3-(5-Bromo-2-methoxyphenyl)prop-2-
enoyl]-6-{(E)-2-[4-(dimethylamino)phenyl]vinyl-2-
oxo-2H-pyran-4-yl difluoridoborate (XVIId). Yield
38%, dark-red crystals, mp 345–346°C. Mass spectrum:
m/z 546 [M]+. Found, %: C 55.21; H 3.92; N 2.58.
C25H21BBrF2NO5. Calculated, %: C 55.18; H 3.89;
N 2.57.
Hydroxycompounds VIIa–VIId, Xa, Xb, XIII,
XVI, XVIIIa, XVIIIb, and XVIIId. General procedure.
In 10 ml of 60% aqueous ethanol was dissolved 3 mmol
of an appropriate boron complex, and 1.59 g (15 mmol)
of Na2CO3 was added to the solution. The reaction
mixture was heated at reflux for 1–5 h (TLC monitoring,
the reaction was carried out till total disappearance of
the initial boron complex). On cooling the solution
obtained was filtered and acidified with dilute
hydrochloric acid till pH 6.5–7. The separated precipitate
was filtered off, washed with water, and recrystallized
from 2-propanol.
3-[(2E)-3-(5-Bromo-2-methoxyphenyl)prop-2-
enoyl]-6-methyl-2-oxo-2H-pyran-4-yl difluorido-
borate (VId). Yield 80%, orange crystals, mp 198–
199°C. 1H NMR spectrum (CDCl3), δ, ppm: 2.39 s (3H,
CH3), 3.95 s (3H, OCH3), 6.14 s (1H, H5), 6.84 d (1H,
Harom, J 9.2 Hz), 7.54 d (1H, Harom, J 9.2 Hz), 7.83 s (1H,
Harom), 8.39 d (1H, CH, J 15.4 Hz), 8.63 d (1H, CH,
J 15.4 Hz). Mass spectrum: m/z 414 [M]+. Found, %:
C 46.49; H 2.90. C16H12BBrF2O5. Calculated, %: C
46.53; H 2.93.
3-[(2E,4E)-5-(4-Methoxyphenyl)penta-2,4-dieno-
yl]-6-methyl-2-oxo-2H-pyran-4-yl difluoridoborate
(IXb). Yield 74%, dark-blue crystals, mp 198–199°C.
1H NMR spectrum (CDCl3), δ, ppm: 2.36 s (3H, CH3),
3-{(2E)-3-[4-(Dimethylamino)phenyl]prop-2-
enoyl}-4-hydroxy-6-methyl-2H-pyran-2-one (VIIa).
Yield 83%, red crystals, mp 218–219°C (220°C [9]).
1H NMR spectrum (DMSO-d6), δ, ppm: 2.23 s (3H, CH3),
3.87 s (3H, OCH3), 6.11 s (1H, H5), 6.92 d (2H, Harom
,
J 8.7 Hz), 7.02 t (1H, CH), 7.20 d (1H, CH, J 14.3 Hz),
7.53 d (2H, Harom, J 8.7 Hz), 7.80 d (1H, CH, J 14.3 Hz),
8.19 t (1H, CH). Mass spectrum: m/z 361 [M]+. Found,
%: C 60.08; H 4.16. C18H15BF2O5. Calculated, %: C 60.03;
H 4.20.
3.04 s [6H, N(CH3)2], 6.16 s (1H, H5), 6.76 d (2H, Harom
,
J 7.9 Hz), 7.55 d (2H, Harom, J 7.9 Hz), 7.93 s (2H, 2CH,
degenerate, 14.69 s (1H, OH). Mass spectrum: m/z 300
[M]+. Found, %: C 68.19; H 5.68; N 4.61. C17H17NO4.
Calculated, %: C 68.22; H 5.72; N 4.68.
Difluoridoborates XVIIa, XVIIb, and XVIId.
General procedure. To a solution of 0.4 mmol of
an appropriate boron complex in 2 ml of acetic anhydride
at 60°C was added a solution of 0.05 g (0.4 mmol) of
aldehyde Va in 2 ml of acetic anhydride. The mixture
was boiled for 30 min. On cooling the settled precipitate
was filtered off, washed on the filter with acetic acid,
and recrystallized from acetic acid.
3-[(2E)-3-(4-Methoxyphenyl)prop-2-enoyl]-4-
hydroxy-6-methyl-2H-pyran-2-one (VIIb). Yield 80%,
yellow crystals, mp 208–209°C (208°C [9]). H NMR
spectrum (CDCl3), δ, ppm: 2.27 s (3H, CH3), 3.85 s (3H,
OCH3), 5.93 s (1H, H5), 6.90 d (2H, Harom, J 8.7 Hz),
7.63 d (2H, Harom, J 8.7 Hz), 7.91 d (1H, CH, J 15.9 Hz),
8.16 d (1H, CH, J 15.9 Hz), 18.15 s (1H, OH). Mass
spectrum: m/z 287 [M]+. Found, %: C 67.08; H 4.98.
C16H14O5. Calculated, %: C 67.13; H 4.93.
1
3-{(2E)-3-[4-(Dimethylamino)phenyl]prop-2-
enoyl}-6-{(E)-2-[4-(dimethylamino)phenyl]vinyl}-2-
oxo-2H-pyran-4-yl difluoridoborate (XVIIa). Yield
47%, dark-green crystals, mp 330–331°C. Mass
spectrum: m/z 479 [M]+. Found, %: C 65.24; H 5.23; N
5.86. C26H25BF2N2O4. Calculated, %: C 65.29; H 5.27;
N 5.86.
3-[(2Ε)-3-(3,4,5-Trimethoxyphenyl)prop-2-enoyl]-
4-hydroxy-6-methyl-2H-pyran-2-one (VIIc). Yield
78%, yellow crystals, mp 124–125°C. 1H NMR spectrum
(CDCl3), δ, ppm: 2.27 s (3H, CH3), 3.91 s (9H, 3OCH3),
5.95 s (1H, H5), 6.90 s (2H, Harom, degenerate), 7.84 d
(1H, CH, J 15.9 Hz), 8.17 d (1H, CH, J 15.9 Hz),
17.94 C (1H, OH). Mass spectrum: m/z 347 [M]+. Found,
%: C 62.39; H 5.27. C18H18O7. Calculated, %: C 62.42;
H 5.24.
6-{(E)-2-[4-(Dimethylamino)phenyl]vinyl}-3-
[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]-2-oxo-2H-
pyran-4-yl difluoridoborate (XVIIb). Yield 42%, dark-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008

MANAEV et al.
1060
3-{(2E)-3-[4-(Dimethylamino)phenyl]prop-2-
3-[(2E)-3-(5-Bromo-2-methoxyphenyl)prop-2-
enoyl}-6-{(E)-2-[4-(dimethylamino)phenyl]vinyl}-4-
hydroxy-2H-pyran-2-one (XVIIIa). Yield 72%, dark-
enoyl]-4-hydroxy-6-methyl-2H-pyran-2-one (VIId).
Yield 90%, yellow crystals, mp 157–158°C. H NMR
1
1
red crystals, mp 256–257°C. H NMR spectrum (DMSO-
spectrum (CDCl3), δ, ppm: 2.28 s (3H, CH3), 3.90 s (3H,
OCH3), 5.95 s (1H, H5), 6.78 d (1H, Harom, J 8.7Hz),
7.43 d (1H, Harom, J 8.7 Hz), 7.79 s (1H, Harom), 8.15 d
(1H, CH, J 15.9 Hz), 8.28 d (1H, CH, J 15.9 Hz),
17.89 s (1H, OH). Mass spectrum: m/z 366 [M]+. Found,
%: C 52.58; H 3.63. C16H13BrO5. Calculated, %: C 52.63;
H 3.59.
d6 + TFA), δ, ppm: 3.51 s [12H, 2N(CH3)2], 6.52 s (1H,
H5), 6.92 d (1H, CH, J 15.8 Hz), 7.67 d (2H, Harom
,
J 8.8 Hz), 7.71 d (2H, Harom, J 8.7 Hz), 7.75 d (1H, CH,
J 15.8 Hz), 7.87 d (2H, Harom, J 8.8 Hz), 7.99 d (2H,
Harom, J 8.7 Hz), 8.03 d (1H, CH, J 16.2 Hz), 8.44 d (1H,
CH, J 16.2 Hz). Mass spectrum: m/z 431 [M]+. Found,
%: C 72.50; H 6.01; N 6.50. C26H26N2O4. Calculated,
%: C 72.54; H 6.09; N 6.51.
3-{(2E,4E)-5-[4-(Dimethylamino)phenyl]penta-
2,4-dienoyl}-4-hydroxy-6-methyl-2H-pyran-2-one
(Xa). Yield 72%, dark-green crystals, mp 204–205°C.
1H NMR spectrum (DMSO-d6), δ, ppm: 2.23 s (3H, CH3),
6-{(E)-2-[4-(Dimethylamino)phenyl]vinyl}-4-
hydroxy-3-[(2E)-3-(4-methoxyphenyl)prop-2-enoyl]-
2H-pyran-2-one (XVIIIb). Yield 64%, red crystals, mp
240–241°C. Mass spectrum: m/z 418 [M]+. Found, %:
C 71.85; H 5.59; N 3.32. C25H23NO5. Calculated, %:
C 71.93; H 5.55; N 3.36.
2.30 s [6H, N(CH3)2], 6.19 s (1H, H5), 6.72 d (2H, Harom
,
J 8.7 Hz), 7.07–7.71 m (6H, 2Harom, 4CH). Mass
spectrum: m/z 326 [M]+. Found, %: C 70.10; H 5.92;
N 4.31. C19H19NO4. Calculated, %: C 70.14; H 5.89;
N 4.30.
3-[(2E)-3-(5-Bromo-2-methoxyphenyl)prop-2-
enoyl]-6-{(E)-2-[4-(dimethylamino)phenyl]vinyl-4-
hydroxy-2H-pyran-2-one (XVIIId). Yield 65%, dark-
red crystals, mp 263–264°C. Mass spectrum: m/z 497
[M]+. Found, %: C 60.52; H 4.50; N 2.80. C25H22BrNO5.
Calculated, %: C 60.50; H 4.47; N 2.82.
3-[(2E,4E)-5-(4-Methoxyphenyl)penta-2,4-
dienoyl]-4-hydroxy-6-methyl-2H-pyran-2-one (Xb).
Yield 74%, dark-blue crystals, mp 156–157°C. 1H NMR
spectrum (CDCl3), δ, ppm: 2.28 s (3H, CH3), 3.84 s (3H,
OCH3), 5.92 s (1H, H5), 6.88–7.79 m (8H, 4Harom, 4CH),
18.18 C (1H, OH). Mass spectrum: m/z 313 [M]+. Found,
%: C 69.20; H 5.11. C18H16O5. Calculated, %: C 69.22;
H 5.16.
The study was carried out under a financial support
of the Program of Fundamental Research of the Russian
Academy of Sciences (grant no. 8114).
3-{(2E)-3-[5-(Dimethylamino)-2-thienyl]prop-2-
enoyl}-4-hydroxy-6-methyl-2H-pyran-2-one (XIII).
Yield 88%, dark-red crystals, mp 190–191°C. 1H NMR
spectrum (DMSO-d6), δ, ppm: 2.17 s (3H, CH3), 3.16 s
[6H, N(CH3)2], 6.04 s (1H, H5), 6.25 d (1H, HHt,
J 4.1 Hz), 7.26 d (1H, CH, J 14.3 Hz), 7.57 d (1H, HHt,
J 4.1 Hz), 8.04 d (1H, CH, J 14.3 Hz), 14.00 s (1H, OH).
Mass spectrum: m/z 306 [M]+. Found, %: C 59.03;
H 4.98; N 4.63; S 10.56. C15H15NO4S. Calculated, %:
C 59.00; H 4.95; N 4.59; S 10.50.
REFERENCES
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4-Hydroxy-6-methyl-3-[(2Ε,4Ε)-4-(1,3,3-
trimethyl-1,3-dihydro-2H-indol-2-ylidene)but-2-
enoyl]-2H-pyran-2-one (XVI). Yield 76%, red crystals,
1
mp 250–251°C. H NMR spectrum (CDCl3), δ, ppm:
1.66 s [6H, (CH3)2], 2.20 s (3H, CH3), 3.32 s [3H,
N(CH3)], 5.85 s (1H, H5), 6.17 d (1H, CH, J 14 Hz),
6.78–7.48 m (5H, 4Harom), 8.39 t (1H, CH), 18.82 s (1H,
OH). Mass spectrum: m/z 352 [M]+. Found, %: C 71.75;
H 6.08; N 4.02. C21H21NO4. Calculated, %: C 71.78;
H 6.02; N 3.99.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 7 2008