Reaction of 2-(2,4-dimethylbenzoyl)cyclohexanone with o-phenylenediamine

Full text of DOI:10.1134/S1070428011120256

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 12, pp. 1906–1907. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.G. Mikhailovskii, Z.G. Aliev, A.A. Pantyukhin, N.N. Pershina, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47,
No. 12, pp. 1868–1869.
SHORT
COMMUNICATIONS
Reaction of 2-(2,4-Dimethylbenzoyl)cyclohexanone
with o-Phenylenediamine
A. G. Mikhailovskiia, Z. G. Alievb, A. A. Pantyukhina, and N. N. Pershinaa
a Perm State Pharmaceutical Academy, ul. Polevaya 2, Perm, 614990 Russia
e-mail: neorghim@pfa.ru
b Institute of Chemical Physics Problems, Russian Academy of Sciences,
Chernogolovka, Moscow oblast, Russia
Received February 10, 2011
DOI: 10.1134/S1070428011120256
1,3-Diketones are widely used as reagents in the
synthesis of various heterocyclic compounds [1]. We
previously studied reactions of 2-aroylcyclohexanones
with hydrazine and hydroxylamine and obtained the
corresponding 1,2-azoles [2]. o-Phenylenediamine as
difunctional nucleophile is capable of reacting with
1,3-diketones along several pathways: condensation
with formation of the corresponding Schiff base,
closure of seven-membered 1,4-diazepine ring, and
formation of spirobenzimidazole. It is almost impos-
sible to distinguish products of these reactions by
NMR spectroscopy.
benzoyl chloride [3]. Compound II failed to react with
o-phenylenediamine in boiling alcohol (no new com-
pounds were detected by TLC). However, the reaction
of II with o-phenylenediamine in boiling glacial acetic
acid gave compound III as the only isolated product.
Presumably, this reaction pathway is favored by ther-
modynamic stability of the resulting structure. Acyla-
tion at the nitrogen atom makes the molecule more
symmetric, which is likely to enhance its stability.
The structure of compound III was unambiguously
determined by X-ray analysis of a single crystal ob-
tained by slow crystallization from a solution in alco-
hol. Molecule III is nearly planar (see figure). The
2,4-dimethylphenyl rings are slightly turned with
respect to the central tricyclic fragment due to steric
effect of methyl groups in the ortho positions. All bond
lengths and bond angles in molecule III conform to the
The present communication reports on the reaction
of 2-(2,4-dimethylbenzoyl)cyclohexan-1-one (II) with
o-phenylenediamine and structure of the obtained
product. Initial diketone II was synthesized by acyla-
tion of 1-piperidinocyclohexene (I) with 2,4-dimethyl-
Me
O
O
Me
N
(1) 2,4-Me2C6H3COCl
(2) H+/H2O
o-C6H4(NH2)2
AcOH
Me
NH
N
Me
I
II
Me
Me
N
II
Me
N
Me
O
III
1906

REACTION OF 2-(2,4-DIMETHYLBENZOYL)CYCLOHEXANONE
C19
1907
C18
C20
O1
C17
C5
N1
C6
C15
C4
C3
C22
C21
C16
C11
C14
C30
C1
C10
C23
C24
C26
C2
C12
C29
C13
N2
C28
C27
C9
C25
C8
C7
Structure of the molecule of 2,4-dimethylphenyl[11-(2,4-dimethylphenyl)-2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepin-5-yl]-
methanone (III) according to the X-ray diffraction data.
corresponding standard values. No shortened intra- or
intermolecular contacts were found in crystal.
(ω/2Θ scanning, monochromatized MoKα irradiation,
2Θ ≤ 25.1%). Total of 4036 independent reflections
were measured. No correction for absorption was
introduced (μ = 0.073 mm–1). The structure was solved
by the direct method using SIR92 program [4] with
subsequent series of calculation of electron density
maps. Hydrogen atoms in methyl groups and aromatic
rings were placed into positions calculated on the basis
of geometry considerations, and the other hydrogen
atoms were visualized by difference synthesis of elec-
tron density. Full-matrix anisotropic (for non-hydrogen
atoms) refinement by the least-squares procedure
(SHELXL-97 [5]) was complete at R1 = 0.1045, wR2 =
0.2103 [4215 reflections with I ≥ 2σ(I)] and R1 =
0.3386, wR2 = 0.3160 (all reflections); GOF 0.917.
1
The H NMR spectrum of III contained signals
from aromatic protons, a broadened singlet corre-
sponding to 12 methyl protons, and multiplet signals
from methylene protons.
2,4-Dimethylphenyl[11-(2,4-dimethylphenyl)-
2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepin-5-
yl]methanone (III). A solution of 4.58 g (20 mmol) of
2-(2,4-dimethylbenzoyl)cyclohexanone (II) and 2.16 g
(20 mmol) of o-phenylenediamine in 20 ml of glacial
acetic acid was heated for 30 min under reflux. The
mixture was cooled to 20°C and diluted with 100 ml of
water, and the precipitate was filtered off, dried, and
recrystallized. Yield 38%, mp 190–191°C. IR spec-
trum: ν 1640 cm–1 (C=O). 1H NMR spectrum (CDCl3),
δ, ppm: 1.34–1.80 m (4H, 2-H, 3-H, 2J = 13 Hz), 2.12–
REFERENCES
2
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2.40 m (4H, 1-H, 4-H, J = 15 Hz), 2.30 br.s (12H,
CH3), 6.43–7.36 m (10H, Harom). Found, %: C 82.77;
H 6.83; N 6.55. C30H30N2O. Calculated, %: C 82.92;
H 6.96; N 6.45.
The IR spectrum of III (in mineral oil) was re-
corded on a Specord M-80 spectrometer. The 1H NMR
spectrum was obtained on a Bruker DRX-300 instru-
ment (300 MHz) relative to hexamethyldisiloxane.
X-Ray diffraction data for compound III. Unit cell
parameters: a = 8.634(3), b = 19.872(4), c =
14.461(3) Å; β = 104.97(3)°; V = 2396.9(8) Å3;
M 434.56; dcalc = 1.204 g/cm3. The set of experimental
reflection intensities was acquired on a KM-4 auto-
matic four-circle diffractometer with χ-geometry
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Gualardi, A., J. Appl. Crystallogr., 1993, vol. 26, p. 343.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 12 2011