Five-membered 2,3-dioxo heterocycles: LXXVIII.* acylation of Fischer's base with aroylketenes. Crystalline and molecular structure of (1E, 3Z)-4-(4-chlorophenyl)-4-hydroxy-1-(1,3,3-trimethyl-2,3-dihydro-1H-indol-2- ylidene)but-3-en-2-one

Article abstract of DOI:10.1134/S1070428011070153

Aroylketenes generated by thermolysis of 6-aryl-2,2-dimethyl-4H-1,3-dioxin- 4-ones reacted with 1,3,3-trimethyl-2-methylidene-1,3-dihydro-2H-indole (Fischer's base) to produce (1E,3Z)-4-aryl-4-hydroxy-1-(1,3,3-trimethyl-1,3- dihydro-2H-indol-2-ylidene)but-3-en-2-ones. The crystalline and molecular structures of (1E,3Z)-4-(4-chlorophenyl)-4-hydroxy-1-(1,3,3-trimethyl-2,3- dihydro-1H-indol-2-ylidene)but-3-en-2-one were determined by X-ray analysis.

Full text of DOI:10.1134/S1070428011070153

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 7, pp. 1062–1065. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.V. Konovalova, Yu.V. Shklyaev, P.A. Slepukhin, A.N. Maslivets, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47,
No. 7, pp. 1045–1048.
Five-Membered 2,3-Dioxo Heterocycles:
LXXVIII.* Acylation of Fischer’s Base with Aroylketenes.
Crystalline and Molecular Structure of (1E, 3Z)-4-(4-Chloro-
phenyl)-4-hydroxy-1-(1,3,3-trimethyl-2,3-dihydro-1H-indol-
2-ylidene)but-3-en-2-one
V. V. Konovalovaa, Yu. V. Shklyaeva, P. A. Slepukhinb, and A. N. Maslivetsc
a Institute of Technical Chemistry, Ural Division, Russian Academy of Sciences, Perm, Russia
b Postovskii Institute of Organic Synthesis, Ural Division, Russian Academy of Sciences,
ul. S. Kovalevskoi 20, Yekaterinburg, 620219 Russia
c Perm State University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received October 16, 2010
Abstract— Aroylketenes generated by thermolysis of 6-aryl-2,2-dimethyl-4H-1,3-dioxin-4-ones reacted with
1,3,3-trimethyl-2-methylidene-1,3-dihydro-2H-indole (Fischer’s base) to produce (1E,3Z)-4-aryl-4-hydroxy-1-
(1,3,3-trimethyl-1,3-dihydro-2H-indol-2-ylidene)but-3-en-2-ones. The crystalline and molecular structures of
(1E,3Z)-4-(4-chlorophenyl)-4-hydroxy-1-(1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene)but-3-en-2-one were
determined by X-ray analysis.
DOI: 10.1134/S1070428011070153
5-Arylfuran-2,3-diones are known to undergo ther-
mal decarbonylation with formation of aroylketenes
that are capable of reacting with active dienophiles
according to the cycloaddition pattern [2, 3] and
acylating weak nucleophiles yielding aroylacetyl
derivatives [2, 4]. On the other hand, furandiones
themselves can acylate nucleophiles at a temperature
below that necessary for generation of aroylketenes,
leading to aroylpyruvoyl derivatives [2, 5]. We previ-
ously reported on the reaction of 5-arylfuran-2,3-di-
ones with 1-methyl-3,4-dihydroisoquinolines, which
gave β-CH-acylation products of their enamino tauto-
mers, (2Z,5Z)-1-aryl-3-hydroxy-5-[3,3-dialkyl-3,4-di-
hydroisoquinolin-1(2H)-ylidene]pent-2-ene-1,4-
diones; the product structure was confirmed by X-ray
analysis [6]. It is known that 6-aryl-2,2-dimethyl-4H-
1,3-dioxin-4-ones [7], [4+2]-cycloaddition products of
aroylketenes at the C=O bond of acetone, undergo
thermal retro-Diels–Alder reaction thus acting as
a source of aroylketenes [8].
In continuation of our studies on reactions of dioxo
heterocycles and heterocumulenes based thereon with
enamines of the isoquinoline series, in the present
work we examined reactions of 6-aryl-2,2-dimethyl-
4H-1,3-dioxin-4-ones with another heterocyclic
enamine, 1,3,3-trimethyl-2-methylidene-2,3-dihydro-
1H-indole (II, Fischer’s base).
6-Aryl-2,2-dimethyl-4H-1,3-dioxin-4-ones Ia–Id
reacted with compound II at a ratio of 1:1 on heating
in boiling anhydrous toluene over a period of 10–
30 min (TLC) to produce in good yield the correspond-
ing (1E,3Z)-4-aryl-4-hydroxy-1-(1,3,3-trimethyl-2,3-
dihydro-2H-indol-2-ylidene)but-3-en-2-ones IIIa–IIId
(Scheme 1). Presumably, thermally induced elimina-
tion of acetone molecule from 6-aryl-2,2-di-
methyl-4H-1,3-dioxin-4-one Ia–Id generates aroyl-
ketene IVa–IVd which acylates the exocyclic meth-
ylene carbon atom in Fischer’s base II, as was reported
previously for the reaction of dioxinones I with
1-methyl-3,4-dihydroisoquinolines [9]. The structure
of compound IIIc was proved by X-ray analysis (see
figure).
* For communication LXXVII, see [1].
1062

FIVE-MEMBERED 2,3-DIOXO HETEROCYCLES: LXXVIII.
1063
Scheme 1.
O
O
·
Δ
O
–Me2CO
Me
Me
Ar
O
Ar
O
Ia–Id
IVa–IVd
H
O
O
·
·
·
Me
N
Me
N
Me
N
O
Ar
O
Ar
Me
CH2
Me
Me
IVa–IVd
Me
Me
Me
II
A
IIIa–IIId
B
Ar = Ph (a), 4-MeC6H4 (b), 4-ClC6H4 (c), 4-EtOC6H4 (d).
Compounds IIIa–IIId were isolated as orange
crystalline substances, which were readily soluble in
dimethyl sulfoxide and dimethylformamide, poorly
soluble in other common organic solvents, and in-
soluble in water and saturated hydrocarbons; they
showed a positive color test (cherry color) for enolic
hydroxy group with an alcoholic solution of iron(III)
chloride.
Compounds IIIa–IIId displayed in the IR spectra
absorption bands due to stretching vibrations of the
enolic hydroxy group involved in intramolecular
hydrogen bond (broad band at 3060–3085 cm–1) and
H-bonded carbonyl group in the side chain (broad band
at 1605–1610 cm–1). The 1H NMR spectra of IIIa–IIId
contained signals from protons in the aromatic rings
and substituents therein, a six-proton singlet from
methyl groups in position 3 of the indole ring (δ 1.72–
1.76 ppm), a singlet from the N-methyl group (δ 3.29–
3.32 ppm), a singlet from 1-H (δ 5.40–5.42 ppm),
a singlet from 3-H (δ 6.39–6.45 ppm), and a broadened
singlet from the enol OH proton (δ 17.39–17.45 ppm);
these signals correspond to enol tautomer A. In addi-
tion, minor signals assignable to diketone tautomer B
were present, δ, ppm: 1.56–1.57 (6H, 3-CH3), 3.13–
3.32 (3H, 1-CH3), 4.09–4.16 (C3H2), 5.27–5.30 (1-H).
These findings indicate that compounds IIIa–IIId in
DMSO-d6 exist as mixtures of enol (A) and diketone
(B) tautomers at a ratio of ~5:1.
1.51(2), O1 ···O2 2.449(2) Å, ∠O1H1O2 155(1)°. The
bond lengths in the side chain (see table) indicate their
strong conjugation. Despite obvious lack of conjuga-
tion in the indole system, the benzene ring therein
turned out to be conjugated with the keto enol frag-
ment through the enamino moiety. This is reflected,
e.g., in leveling of the C–N bond lengths in the indole
fragment and redistribution of bond lengths in the
ylidene fragment. The C8–C9 bond is somewhat longer
than standard isolated double C=C bond (1.34 Å),
whereas the C9–C10 bond is considerably shorter than
standard single C–C bond (1.54 Å). Molecules III in
crystal extend along the 0a axis and are packed in
layers parallel to the Miller plane (100) so that chlorine
atoms in molecules located in neighboring layers
appear maximally close to each other. No shortened
intermolecular contacts were found in the crystalline
structure of compound III, except for several contacts
with methyl hydrogen atoms, which are likely to be
related to general geometric requirements for packing
of molecular layers.
Cl1
C17
C21
N1
C16
C18
C13
C2
C4
C9
C11
C1
C6
C5
C8
C3
C15
C10
C12
C14
O2
C7
C20
According to the X-ray diffraction data, compound
IIIc crystallizes in space group P21/c belonging to
monoclinic crystal system. Molecules III in crystal
exist in the keto enol rather than diketone form, where
the carbonyl group in the p-chlorobenzoyl fragment is
enolized. The hydroxy proton is involved in intramo-
lecular hydrogen bond: O1–H1 1.00(2), H1 · · · O2
O1
C19
Structure of the molecule of (1E,3Z)-4-(4-chlorophenyl)-4-
hydroxy-1-(1,3,3-trimethyl-2,3-dihydro-1H-indol-2-ylidene)-
but-3-en-2-one (IIIc) according to the X-ray diffraction data;
non-hydrogen atoms are shown as thermal vibration ellip-
soids with a probability of 50%.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 7 2011

KONOVALOVA et al.
1064
Selected bond lengths in the molecule of (1E,3Z)-4-(4-
chlorophenyl)-4-hydroxy-1-(1,3,3-trimethyl-2,3-dihydro-
1H-indol-2-ylidene)but-3-en-2-one (IIIc)
5.27 s (1H, 1-H), 6.96–7.90 m (8H, Harom). Found, %:
C 79.19; H 6.95; N 4.03. C22H23NO2. Calculated, %:
C 79.25; H 6.95; N 4.20.
(1E,3Z)-4-(4-Chlorophenyl)-4-hydroxy-1-(1,3,3-
trimethyl-2,3-dihydro-1H-indol-2-ylidene)but-3-en-
2-one (IIIc). Yield 90%, mp 172–173°C (decomp.,
from CCl4). IR spectrum, ν cm–1: 3060 br (OH),
Bond
d, Å
Bond
d, Å
Cl1–C16
O1–C12
O2–C10
N1–C8
N1–C1
N1–C21
C6–C7
1.7327(17)
1.3280(15)
1.2832(14)
1.3669(15)
1.3945(17)
1.4506(15)
1.5086(19)
C7–C8
C8–C9
C9–C10
C10–C11
C11–C12
C12–C13
1.5303(17)
1.3662(18)
1.4252(17)
1.4373(18)
1.3598(18)
1.4740(19)
1
1610 br (C=O). H NMR spectrum, δ, ppm: A: 1.73 s
(6H, Me), 3.31 s (3H, NMe), 5.42 s (1H, 1-H), 6.45 s
(1H, 3-H), 7.00–7.88 m (8H, Harom), 17.45 s (1H, OH);
B: 1.57 s (6H, Me), 3.22 s (3H, NMe), 4.15 s (2H,
3-H), 5.29 s (1H, 1-H), 6.96–8.00 m (8H, Harom).
13C NMR spectrum, δC, ppm: 23.18 (3′-CH3), 47.66
(CH3N), 93.04 (C3′), 98.68 (C3), 108.54 (C1), 121.65–
142.94 (Carom), 171.00 (C2′), 172.60 (C4), 187.28 (C2).
Found, %: C 71.17; H 5.75; N 3.82. C21H20ClNO2.
Calculated, %: C 71.28; H 5.70; N 3.96.
EXPERIMENTAL
The IR spectra were recorded on an FSM-1201
spectrometer from samples dispersed in mineral oil.
1
The H and 13C NMR spectra were measured on
X-Ray analysis of compound IIIc. The X-ray dif-
fraction data were acquired from a 0.25×0.22×0.19-
mm fragment of a red prismatic crystal of III at
150(2) K on an Xcalibur-3 automatic diffractometer
with a CCD detector (Oxford Diffraction) according to
standard procedure [ω-scanning, scan step 1°, λ =
0.71073 Å (MoKα)]; CrysAlis program [10]. Mono-
clinic crystal system, space group P21/c; unit cell
parameters: a = 17.0539(14), b = 10.1234(6), c =
10.8388(4) Å; β = 104.258(6)°; V = 1813.6(2) Å3;
C21H20ClNO2; Z = 4; d = 1.296 g/cm3. Total of
11 442 reflection intensities were measured in the
range –23 < h < 24, –7 < k < 14, –15 < l < 6; 5408 re-
flections were independent (Rint = 0.0220), and
3003 reflections were characterized by I > 2σ(I);
completeness 97.5% for 2.79 < Θ < 30.51. The struc-
ture was solved by the direct method using SHELXS-
97 program and was refined with respect to F2 in
anisotropic approximation for non-hydrogen atoms
(SHELXL-97 [11]); hydrogen atoms were included in
the refinement procedure according to the riding model
in isotropic approximation with dependent thermal
parameters. The enol OH hydrogen atom was refined
independently in isotropic approximation. No correc-
tion for absorption was introduced because of its
smallness (μ = 0.224 mm–1). The final divergence
factors were R1 = 0.0408, wR2 = 0.1075 [for reflections
with I > 2σ(I)] and R1 = 0.0817, wR2 = 0.1150 (all
reflections); S = 1.012. The maximal and minimal
residual electron density peaks were 0.368 and
–0.354 ē/Å3, respectively.
1
a Bruker AM-400 instrument (400 MHz for H) from
solutions in DMSO-d6 using tetramethylsilane as
internal reference. The purity of the isolated com-
pounds was checked by TLC on Silufol plates using
ethyl acetate–benzene (1:5) or ethyl acetate as eluent;
spots were visualized by treatment with iodine vapor.
(1E,3Z)-4-Hydroxy-4-phenyl-1-(1,3,3-trimethyl-
2,3-dihydro-1H-indol-2-ylidene)but-3-en-2-one
(IIIa). A solution of 1.5 mmol of compound Ia and
1.5 mmol of Fischer’s base (II) in 20 ml of anhydrous
toluene was heated for 30 min under reflux. The mix-
ture was cooled, and the precipitate was filtered off.
Yield 92%, mp 184–186°C (decomp., from ethanol).
IR spectrum, ν, cm–1: 3080 br (OH), 1610 br (C=O).
1H NMR spectrum, δ, ppm: tautomer A: 1.73 s (6H,
Me), 3.30 s (3H, NMe), 5.42 s (1H, 1-H), 6.43 s (1H,
3-H), 7.00–7.87 m (9H, Harom), 17.39 s (1H, OH);
tautomer B: 1.57 s (6H, Me), 3.21 s (3H, NMe), 4.14 s
(2H, 3-H), 5.30 s (1H, 1-H), 6.97–8.00 m (9H, Harom).
Found, %: C 78.82; H 6.75; N 4.20. C21H21NO2. Cal-
culated, %: C 78.97; H 6.63; N 4.39.
Compounds IIIb–IIId were synthesized in a simi-
lar way.
(1E,3Z)-4-Hydroxy-4-(4-methylphenyl)-1-(1,3,3-
trimethyl-2,3-dihydro-1H-indol-2-ylidene)but-3-en-
2-one (IIIb). Yield 89%, mp 180–182°C (decomp.,
from ethanol). IR spectrum, ν, cm–1: 3085 br (OH),
1605 br (C=O). H NMR spectrum, δ, ppm: A: 1.72 s
(6H, Me), 2.37 s (3H, MeC6H4), 3.29 s (3H, NMe),
1
5.40 s (1H, 1-H), 6.39 s (1H, 3-H), 6.99–7.77 m (8H,
H
arom), 17.42 s (1H, OH); B: 1.56 s (6H, Me), 2.21 s
(1E,3Z)-4-(4-Ethoxyphenyl)-4-hydroxy-1-(1,3,3-
trimethyl-2,3-dihydro-1H-indol-2-ylidene)but-3-en-
(3H, MeC6H4), 3.13 s (3H, NMe), 4.09 s (2H, 3-H),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 7 2011

FIVE-MEMBERED 2,3-DIOXO HETEROCYCLES: LXXVIII.
1065
2. Andreichikov, Yu.S., Gein, V.L., Zalesov, V.V., Koz-
lov, A.P., Kollents, G., Maslivets, A.N., Pimenova, E.V.,
and Shurov, S.N., Khimiya pyatichlennykh 2,3-diokso-
geterotsiklov (Chemistry of Five-Membered 2,3-Dioxo
Heterocycles), Perm: Perm. Gos. Univ., 1994, p. 5.
3. Nekrasov, D.D. and Shurov, S.N., Khim. Geterotsikl.
Soedin., 2005, p. 1245.
4. Novikov, A.A., Vostrov, E.S., and Maslivets, A.N., Russ.
J. Org. Chem., 2005, vol. 41, p. 1234.
5. Andreichikov, Yu.S., Voronova, L.A., and Milyu-
tin, A.V., Zh. Org. Khim., 1979, vol. 15, p. 847.
6. Khalturina, V.V., Shklyaev, Yu.V., Aliev, Z.G., and Mas-
livets, A.N., Russ. J. Org. Chem., 2009, vol. 45, p. 728.
7. Andreichikov, Yu.S., Gein, L.F., and Plakhina, G.D.,
Zh. Org. Khim., 1980, vol. 16, p. 2336.
8. Vostrov, E.S., Novikov, A.A., Maslivets, A.N., and
Aliev, Z.G., Russ. J. Org. Chem., 2007, vol. 43, p. 224.
9. Khalturina, V.V., Shklyaev, Yu.V., Aliev, Z.G., and Mas-
livets, A.N., Russ. J. Org. Chem., 2009, vol. 45, p. 1515.
10. CrysAlis CCD, Version 1.171.29.9 (release 23-03-2006
CrysAlis171.NET), Oxford Diffraction.
2-one (IIId). Yield 88%, mp 142–144°C (decomp.,
from CCl4). IR spectrum, ν, cm–1: 3080 br (OH),
1610 br (C=O). H NMR spectrum, δ, ppm: A: 1.39 t
1
(3H, CH2CH3), 1.76 s (6H, Me), 3.32 s (3H, NMe),
4.11–4.18 m (2H, OCH2), 5.42 s (1H, 1-H), 6.39 s (1H,
3-H), 7.04–7.87 m (8H, Harom), 17.40 s (1H, OH);
B: 1.26 t (3H, CH2CH3), 1.57 s (6H, Me), 3.20 s (3H,
NMe), 4.05–4.08 m (2H, OCH2), 4.16 s (2H, 3-H),
5.29 s (1H, 1-H), 6.95–7.96 m (8H, Harom). Found, %:
C 76.00; H 7.13; N 3.67. C23H25NO3. Calculated, %:
C 76.01; H 6.93; N 3.85.
This study was performed under financial support
by the Presidium of the Russian Academy of Sciences
(program no. 18), by the Russian Foundation for Basic
Research (project no. 08-03-01 032), and by the
President of the Russian Federation (project no. MK-
2998.2011.13).
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1. Stepanova, E.E., Babenysheva, A.V., and Maslivets, A.N.,
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 7 2011