Activated sterically strained C=N bond in N-substituted p-quinone mono- and diimines: XIV. Reaction of some 3,5-dimethyl-1,4-benzoquinone monoimines with alcohols

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 1, pp. 49–59. © Pleiades Publishing, Ltd., 2013.

Original Russian Text © A.P. Avdeenko, S.A. Konovalova, V.M. Vasil’eva, G.V. Palamarchuk, V.N. Baumer, O.V. Shishkin, 2013, published in Zhurnal

Organicheskoi Khimii, 2013, Vol. 49, No. 1, pp. 59–68.

Dedicated to Full Member of the Russian Academy of Sciences

G.A. Tolstikov on his 80th anniversary

Activated Sterically Strained C=N Bond

in N-Substituted p-Quinone Mono- and Diimines:

XIV.* Reaction of Some 3,5-Dimethyl-1,4-benzoquinone

Monoimines with Alcohols

A. P. Avdeenko^a, S. A. Konovalova^a, V. M. Vasil’eva^a, G. V. Palamarchuk^b,

V. N. Baumer^b, and O. V. Shishkin^{b, c}

^aDonbass State Engineering Academy, ul. Shkadinova 72, Kramatorsk, 84313 Ukraine

e-mail: chimist@dgma.donetsk.ua

^bInstitute for Single Crystals, National Academy of Sciences of Ukraine, Kharkiv, Ukraine

^cKarazin Kharkiv National University, Kharkiv, Ukraine

Received July 16, 2012

Abstract—Steric strain in the C=N–C fragment in 3,5-disubstituted N-acyl-1,4-benzoquinone monoimines,

unlike their N-arylsulfonyl analogs, leads to increase of the C=N–C angle above 130° or twisting of the double

C=N bond and loss of planarity of the quinoid ring. This structural transformation enhances the reactivity of the

C=N bond so that 1,2-addition of alcohols becomes possible with formation of sterically unstrained cyclohexa-

dienone structure with sp³-hybridized C⁴carbon atom.

DOI: 10.1134/S1070428013010107

N-Substituted 3,5-dimethyl(chloro)-1,4-benzoqui-

none monoimines are known to readily react with

alcohols [1–4], hydrazines, primary aromatic amines,

dialkyl hydrogen phosphites, and bis(4-dimethyl-

aminophenyl)phosphinite [5] according to the 1,2-ad-

dition pattern (i.e., at the C=N bond). The nature of

substituents on the nitrogen atom [ArSO₂N=C(Me),

ArSO₂, ArSO₂N=C(Ph)] and in positions 3 and 5 of the

quinoid ring (Me, Cl) does not affect the reactivity of

the C=N bond [4, 6], while orientation of the substit-

uent on the nitrogen atom and the size of the entering

AlkO group are crucial [4].

It was presumed that 1,2-addition becomes possible

due to activation of the C=N bond as a result of steric

strain appearing upon increase of the C=N–X bond

angle above 130° [4]. However, according to the X-ray

diffraction data, the C=N–C angle in 3,5-dimethyl-N-

(phenylaminocarbonyl)-1,4-benzoquinone monoimine

Scheme 1.

Me

N

O

Me

O

H

N

+

AlkOH

X

AlkO

Me

Ia–Ig

Me

O

IIa–IIh

IIIa–IIIe, IIIg, IVa–IVd, Va–Vh, VIa–VIe

VIIa–VIIh, VIIIa–VIIIc, IXa, IXb, IXg

I, X = Me (a), PhCH₂(b), 4-MeC₆H₄CH₂(c), PhOCH₂(d), (E)-PhCH=CH (e), Ph (f), 4-MeC₆H₄(g); II–IX, Alk = Me (a), Et (b),

Pr (c), i-Pr (d), Bu (e), i-Bu (f), C₅H₁₁(g), cyclo-C₆H₁₁(h); III, X = Me; IV, X = PhCH₂; V, X = 4-MeC₆H₄CH₂; VI, X = PhOCH₂;

VII, X = (E)-PhCH=CH; VIII, X = Ph; IX, X = 4-MeC₆H₄.

* For communication XIII, see [1].

49

AVDEENKO et al.

50

C^7A

C⁷

C³

C^3A

C^2A

C²

C¹

O^1A

N¹

C⁹

O¹

C⁴

C¹⁰

N^1A

C^4A

C^1A

C^6A

C^10A

C⁶

C^9A

O^2A

O²

C⁵

C⁸

C^5A

C^8A

Fig. 1. Structure of the molecule of N-acetyl-3,5-dimethyl-1,4-benzoquinone imine (Ia) according to the X-ray diffraction data.

is 126.26° [7] which is typical of quinone imines hav-

ing no substituent on C³and C⁵[6], and this compound

did react with alcohols at the C=N bond [8]. No X-ray

diffraction data are available on other 3,5-disubstituted

1,4-benzoquinone monoimines with a carbonyl group

on the nitrogen, though 1,2-additions of alcohols to

N-acetyl-3,5-dimethyl- [3] and N-acetyl-2,3,5,6-tetra-

chloro-1,4-benzoquinone monoimines [4] were

reported.

served for other quinone imine series [4]. The above

alcohol series coincides with the series of their steric

constants E_S⁰calculated with account taken of hyper-

conjugation between C–H and C–C bonds [9]. This

means that the reaction rate is determined by steric

factor, i.e., steric hindrance to attack by alcohol mole-

cule on the C=N bond in quinone imine. tert-Butyl

alcohol characterized by the highest negative value of

E_S⁰(–2.14) failed to react with compounds Ia–Ig.

The goal of the present work was to examine

reactions of alcohols with previously synthesized

N-acyl-3,5-dimethyl-1,4-benzoquinone monoimines

and elucidate structural specificities of the latter.

The structure of quinone imines Ia, Ib, and Id–If

was determined by X-ray analysis (Figs. 1–5). All the

examined molecules were found to suffer a consider-

able steric strain in the C⁴=N–C⁹=O fragment due to

the presence of two methyl groups in positions 3 and 5

of the quinoid ring (Table 1). Unlike 2,6-dimethyl-

substituted analogs [10], quinone imines Ia, Ib, and

Id–If are characterized by increased bond angle

C⁴NC⁹, torsion angle C³C⁴NC⁹, dihedral angle formed

by the N–C⁹bond and C¹–C⁶plane, and deviation of

the C⁹atom from the C¹–C⁶plane; in addition, the

quinoid ring C¹–C⁶becomes less planar. There exists

a correlation between the C⁴NC⁹bond angle and varia-

tions in the quinoid ring and C⁴=N–C⁹=O fragment.

The reactions of N-acyl-3,5-dimethyl-1,4-benzo-

quinone monoimines Ia–Ig with methanol (IIa) and

ethanol (IIb) gave expected 1,2-addition products III–

IX (Scheme 1). In the reactions with propan-1-ol,

propan-2-ol, butan-1-ol, and pentan-1-ol, the corre-

sponding 1,2-addition products were isolated from

quinone imines Ia and Ic–Ie, and with 2-methyl-

propan-1-ol and cyclohexanol, from quinone imines Ic

and Ie. The reaction time increased in parallel with

the size of the alkyl group (Alk) in IIa–IIh (MeOH <

EtOH < PrOH < BuOH < C₅H₁₁OH < i-PrOH <

i-BuOH, cyclo-C₆H₁₁OH). Analogous relation was ob-

Detailed analysis of the geometry variation pattern

showed that steric strain in molecules I relaxes in two

O³

C⁷

C¹⁶

C¹⁰

C²

O¹

C³

C²

O¹

C¹

C⁶

C¹⁵

C¹³

O²

C¹¹

C¹²

C¹⁴

C⁹

C¹

C⁶

C⁴

C⁹

C⁴

C¹¹

O²

C¹³

C¹⁴

N¹

C¹⁰

C⁵

C⁸

C¹⁵

N¹

C⁵

C⁸

C¹⁶

Fig. 2. Structure of the molecule of 3,5-dimethyl-N-phenyl-

acetyl-1,4-benzoquinone imine (Ib) according to the X-ray

diffraction data.

Fig. 3. Structure of the molecule of 3,5-dimethyl-N-phenoxy-

acetyl-1,4-benzoquinone imine (Id) according to the X-ray

diffraction data.

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

ACTIVATED STERICALLY STRAINED C=N BOND ... XIV.

51

O²

C¹⁰

C⁷

O²

C⁷

C³

N¹

C¹⁵

C¹⁴

C²

C¹

C¹⁷

C⁹

C⁴

O¹

C¹⁶

C⁹

C¹²

C²

C¹

C⁴

C¹¹

C¹³

C¹⁰

C¹¹

C⁵

N¹

C⁶

C¹³

C¹⁵

O¹

C¹⁴

C⁸

C⁵

C¹²

C⁶

C⁸

Fig. 4. Structure of the molecule of N-benzylideneacetyl-

3,5-dimethyl-1,4-benzoquinone imine (Ie) according to the

X-ray diffraction data.

Fig. 5. Structure of the molecule of N-benzoyl-3,5-dimethyl-

1,4-benzoquinone imine (If) according to the X-ray diffrac-

tion data.

ways. First of all, the C⁹NC⁴bond angle in Ia, Ib, Ie,

and If is larger by 8–12° than the corresponding angle

in 2,6-dimethyl-1,4-benzoquinone imines [10], which

is typical of quinone imines; this is accompanied by

relatively small twisting of the double C=N bond (by

less than 6°) and small distortion of planarity of the

quinoid ring (Table 1). The C⁹NC⁴bond angle in Ia,

Ib, Ie, and If exceeds 130°, which is consistent with

previous interpretations of high reactivity of the C=N

bond in 1,2-addition reactions.

However, the C⁹NC⁴angle in quinone imine Id, as

well as in N-(phenylaminocarbonyl)-3,5-dimethyl-1,4-

benzoquinone imine [7], is considerably smaller than

130° (Table 1). Nevertheless, compound Id takes up

alcohols at the C=N bond. Detailed analysis of the

geometric parameters of molecule Id revealed another

Table 1. X-Ray diffraction data for 3,5-dimethyl-1,4-benzoquinone imines Ia, Ib, and Id–If^a

H²

H³

H¹

O²

2

O¹

7

1

3

9

6

4

X

N

5

⁸Me

Ia

Parameter

Bond angle C⁹NC⁴, deg

Ib

Id

Ie

If

conformer A conformer B

131.3(2)

(+9.0)

132.0(2)

(+8.2)

132.8(1) 124.1(2) 130.4(2) 132.0(1)

(+9.4) (+4.8) (+12.4) (+8.9)

Bond length C⁴=N, Å

Bond length C⁹–N, Å

Torsion angle C³C⁴NC⁹, deg

1.277(2)

1.389(2)

1.282(2)

1.385(3)

1.276(2) 1.314(3) 1.272(2) 1.283(2)

1.384(2) 1.477(2) 1.399(2) 1.385(2)

+6.4(4) –22.8(5) +7.2(4) +10.8(3)

–4.2(4)

(+3.7)

–5.6(3)

(+6.0)

(+3.6)

(+8.6)

(+3.1)

(+5.9)

Planarity of the quinoid fragment C¹–C⁶

±0.039

±0.032

±0.006

±0.049

±0.016

±0.037

(+0.029)

(+0.026)

(–0.008) (+0.038) (+0.015) (+0.018)

Dihedral angle between the N–C bond and

C¹–C⁶plane, deg

+9.6

(+9.0)

10.0

(+8.1)

+4.8

(+3.5)

14.7

(+7.5)

+9.1

(+3.5)

+13.8

(+11.7)

Deviation of the C⁹atom from the C¹–C⁶

plane, Å

+0.474

(+0.400)

+0.464

(+0.395)

–0.137

+0.594

+0.349

+0.561

(+0.097) (+0.347) (+0.063) (+0.514)

Shortened intramolecular contacts

C⁹···C⁷, Å (3.42 Å)^b

C⁹···H¹, Å (2.87 Å)^b

2.88

2.51

2.92

2.52

2.94

2.60

2.84

2.44

2.89

2.56

2.92

2.66

a

The difference from the corresponding parameter of analogous 2,6-dimethyl-1,4-benzoquinone imine [10] is given in parentheses.

The sum of the van der Waals radii [11].

b

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

AVDEENKO et al.

52

Table 2. Calculated orbital and orbital interaction energies and hybridization of the nitrogen LEP in N-acyl-3,5-dimethyl-1,4-

benzoquinone monoimines Ia, Ib, and Id–If^a

⁷Me

O²

2

O¹

1

3

9

6

4

X

N

5

⁸Me

Parameter

Ia

Ib

Id

Ie

If

Ih

Energy of π(C⁴=N), kJ/mol

–951.8–

(–32.2)

–954.7–

(–31.6)

–968.4–

(–34.0)

–938.5–

(–33.4)

–947.4–

(–33.0)

–1008.0–0

(–88.3)

Energy of π*(C⁴=N), kJ/mol

Energy of n(N) , kJ/mol

0–17.0–

(–12.4)

0–17.3–

(–10.0)

0–37.1–

(–12.3)

0–17.2–

(–27.1)

0–11.9–

(–13.0)

0–63.7–

(–59.0)

–919.2–

(+51.8)

–908.4–

(+62.3)

–938.3–

(+47.8)

–910.2–

(+49.8)

–916.0–

(+50.0)

–961.1–

(+9.8)

Energy of π(C⁴=N)→π*(C⁹=O²)

024.5

029.1

028.8

013.3

021.7

017.3

interaction, kJ/mol

(–17.1)

(–12.7)

(–27.0)

(–30.0)

(–22.4)

(–24.3)

Energy of π*(C⁴=N)→π*(C⁹=O²)

017.4

(–23.5)

017.5

(–14.9)

021.5

(–41.2)

030.4

(–70.1)

036.03

(–56.8)

009.8

(–31.1)

interaction, kJ/mol

Energy of n_N→π*(C⁹=O²) interaction,

060.1

048.8

062.8

086.9

091.2

052.9

kJ/mol

(+18.3)

(+12.4)

(+29.7)

(+40.4)

(+42.3)

(+11.1)

Hybridization of n(N)^b

sp^3.50

sp^3.71

sp^3.61

sp^3.38

sp^3.45

(sp^2.60

)

(sp^2.66

)

(sp^2.66

)

(sp^2.54

)

(sp^2.60

)

(sp^2.60

)

Energy of π(C⁴=N)→π*(C²=C³)

034.7

034.3

033.6

034.1

034.7

interaction, kJ/mol

Energy of π(C²=C³)→π*(C⁴=N)

0(–0.8)

0(–1.1)

0(–0.4)

0(–1.3)

0(–0.8)

0(–0.1)

072.7

073.6

074.8

072.2

073.0

063.8

interaction, kJ/mol

Energy of π(C⁴=N)→π*(C⁵=C⁶)

0(–8.5)

0(–8.2)

0(–9.4)

0(–8.6)

(–17.8)

039.2

038.7

038.0

038.9

038.8

039.3

interaction, kJ/mol

Energy of π(C⁵=C⁶)→π*(C⁴=N)

0(–1.3)

0(–1.6)

0(–1.2)

0(–2.0)

0(–1.4)

0(–1.0)

067.2

067.5

069.0

066.4

067.2

059.4

interaction, kJ/mol

0(–7.5)

0(–7.6)

0(–8.1)

0(–7.6)

(–15.5)

a

Increase (+) or decrease (–) of the corresponding parameter relative to that of 2,6-dimethyl-1,4-benzoquinone monoimine [10] is given

in parentheses.

Hybridization of the nitrogen LEP in 2,6-dimethyl derivative [10] is given in parentheses.

b

way of structural relaxation with retention of an appre-

ciable steric strain (see shortened intramolecular con-

tacts in Table 1). Instead of increase of the C⁹NC⁴bond

angle we observed considerable twisting of the C=N

bond [the torsion angle C³C⁴NC⁹is –22.8(5)°] and

some distortion of the quinoid ring from planar struc-

ture (Table 1). In addition, the C⁹–N¹bond is extended

to 1.477(2) Å against 1.384(2)–1.399(2) Å in other

compounds of the same series, and the C⁴=N bond is

extended to 1.314(3) Å against 1.272(2)–1.283(2) Å.

According to quantum-chemical calculations, steric

strain in the C⁴=N–C⁹=O fragment of 3,5-dimethyl-

1,4-benzoquinone imines Ia, Ib, and Id–If leads to

reduction of the energy of the π(C⁴=N) and π*(C⁴=N)

orbitals and energy of the orbital donor–acceptor inter-

actions π(C⁴=N¹)→π*(C⁹=O²) and π*(C⁴=N¹)→

π*(C⁹=O²), increase of the energy of the lone electron

pair (LEP) on the nitrogen atom n(N), and the energy

of the donor–acceptor interaction n_N→π*(C⁹=O²)

(Table 2) as compared to 2,6-dimethyl-substituted

analogs [10]. As a result, the LEP on the nitrogen atom

acquires a higher p-character, and the nitrogen atom

becomes more nucleophilic and capable of abstracting

hydrogen from an alcohol molecule. This is confirmed

by the mass spectra of N-substituted 1,4-benzoquinone

monoimines [12]. Only 3,5-disubstituted 1,4-benzo-

Thus, analysis of the X-ray diffraction data shows

that the C=N–X angle cannot be regarded as the only

parameter indicating that the C=N bond in the C=N–C

fragment of quinone imines is sterically strained and

activated. Steric strain is also reflected in considerable

twisting (by more than 20°) of the double C=N bond.

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

ACTIVATED STERICALLY STRAINED C=N BOND ... XIV.

53

Scheme 2.

R¹

R⁷

Me

N

O

R⁴

O

Me

O

R⁴

R⁷

H

N

MeO

R²

+

MeOH

R²

R³

MeO

R³

R⁵

R⁶

MeO

O

R⁵

XIa–XIc

R⁶

Xa–Xc

R¹= R³= R⁷= Cl, R²= Me, R⁴= R⁵= R⁶= H (a); R¹= R²= R³= R⁴= R⁵= Cl, R⁶= R⁷= MeO (b); R¹= R⁵= H,

R²= R³= R⁴= Br, R⁶= R⁷= MeO (c).

quinone monoimines displayed in the mass spectra

strong peaks of [M + 1]⁺ions formed via addition of

one hydrogen atom.

(NBO) theory [22] (NBO 5.0 [23]). The X-ray diffrac-

tion data were used as starting geometric parameters

for optimization, and the optimized parameters of Ia,

Ib, and Id–If were consistent with the experimental

values.

Furthermore, unlike 2,6-dimethyl analogs, 3,5-di-

methyl derivatives Ia, Ib, and Id–If are characterized

by considerably lower energies of the following orbital

donor–acceptor interactions: π(C⁴=N)→π*(C²=C³),

π(C²=C³)→π*(C⁴=N), π(C⁴=N)→π*(C⁵=C⁶), and

π(C⁵=C⁶)→π*(C⁴=N), indicating weakened conjuga-

tion along the N=C–C=C bond sequence.

X-Ray analysis of compounds Ia (C₁₀H₁₁NO₂,

M 177.20), Ib (C₁₆H₁₅NO₂, M 253.29), Ie (C₁₇H₁₅NO₂,

M 265.30), and If (C₁₅H₁₃NO₂, M 239.26) was per-

formed at 293 K on an Xcalibur 3 four-circle auto-

matic diffractometer with a CCD detector (MoK_α

irradiation, graphite monochromator, ω-scanning). The

structures were solved by the direct method using

SHELXTL software package [24]. The positions of

non-hydrogen atoms were refined in anisotropic ap-

proximation. The positions of hydrogen atoms were

determined by difference synthesis of electron density

and were refined according to the riding model with

We can conclude that steric strain in the C=N–C

fragment of N-acyl-3,5-dimethyl-1,4-benzoquinone

imines increases the energy of the nitrogen LEP,

reduces the energy of the π-C=N bond, and weakens

conjugation of the latter with the quinoid C=C bonds

and carbonyl bond. As a result, the C=N bond becomes

more reactive toward 1,2-addition of nucleophiles.

U_iso= nU_equivfor non-hydrogen atom linked to a given

Quantum-chemical calculations for model N-acetyl-

3,5-dichloro-1,4-benzoquinone imine (Ih) showed that

its energy parameters differ from those of 2,6-disubsti-

tuded analog in a way similar to compounds Ia, Ib,

and Id–If (Table 2). Presumably, such compounds

should also react with alcohols according to the 1,2-ad-

dition pattern. Insofar as N-acyl-3,5-dichloro-1,4-ben-

zoquinone monoimines are very unstable, the above

assumption was verified using N-aroyl derivatives

Xa–Xc. As expected, compounds Xa–Xc fairly readily

reacted with methanol to give the corresponding

1,2-addition products XIa–XIc (Scheme 2).

hydrogen atom (n = 1.5 for methyl groups and n = 1.2

for other hydrogen atoms) with fixed thermal vibration

parameters.

The X-ray powder diffraction pattern for a sample

of Id (C₁₆H₁₅NO₃, M 269.29) was obtained on

a Siemens D500 diffractometer (Cu irradiation, graph-

ite monochromator for the reflected beam, θ–2θ scan-

ning, Bregg–Brentano geometry). The full-profile dif-

fraction patterns were measured in the 2θ range from 2

to 84° with a step of 0.02°; measurement time 60 s;

LaB₆was used as calibration standard. The X-ray

powder diffraction pattern was processed with the aid

of PowderX [25], ITO [26], and DICVOL [27]; the

structure was resolved using Fox program [28] and

was refined by the Rietveld method using FullProf

[29]. The positions of hydrogen atoms were set on the

basis of geometry considerations and were refined

according to the riding model. The principal crystal-

lographic parameters are given in Table 3. The com-

plete sets of crystallographic data for compounds Ia,

EXPERIMENTAL

Quantum-chemical calculations were performed in

terms of the density functional theory using B3LYP

functional [13–18] and standard 6-31+G(d) basis set

[19, 20] with the aid of Gaussian 03 software package

[21]. Conjugative and hyperconjugative interactions

were simulated in terms of the natural bond orbitals

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

AVDEENKO et al.

54

Table 3. Principal crystallographic parameters of N-acyl-3,5-dimethyl-1,4-benzoquinone monoimines Ia, Ib, and Id–If

Parameter

Ia

Ib

Id

Ie

If

a, Å

05.0575(3)

12.5593(7)

14.3550(9)

85.974(5)

86.198(5)

82.919(5)

901.10(9)

Triclinic

P-1

07.9649(2)

11.4653(5)

14.6182(5)

90

13.7055(7)

09.4015(5)

05.2867(3)

90

12.999(5)

07.311(3)

14.918(6)

90

8.1584(2)

32.5732(14)

90

b, Å

c, Å

α, deg

β, deg

γ, deg

V, Å³

92.940(3)

90

98.567(5)

90

103.66(4)

90

120

1333.18(8)

Monoclinic

P21/n

673.61(6)

Monoclinic

P21

1377.7(10)

Monoclinic

P21/n

4

1877.59(10)

Hexagonal

P61

Crystal system

Space group

Z

4

2

6

F(000)

376

536

284

560

756

D

_calc, g/cm³

1.306

1.262

1.328

1.279

1.270

μ(MoK_α), mm^–1

0.092

0.083

0.092

0.084

0.085

2θ_max, deg

60

84

50

60

Total number of reflections

Number of independent reflections

R_int

9662

21146

3866

6886

8003

17145

3601

5172

3580

2412

0.1492

2202

0.1011

2503

0.0551

0.0754

1257

0.0675

2233

Number of reflections with F > 4σ(F)

Number of variables

wR₂

0239

0174

49

0183

0166

0.0531

0.0542

0.8160

874659

0.1522

0.0577

1.0470

874661

0.076

0.0923

0.0445

0.8460

874660

0.1003

0.0478

0.9060

874662

R₁[F > 4σ(F)]

Goodness of fit

Entry no. in CCDC

874663

Ig were consistent with published data [30]. Quinone

imines Xa–Xc were obtained by halogenation of

N-aroyl-1,4-benzoquinone imines as reported in [31].

Ib, and Id–If were deposited to the Cambridge Crys-

tallographic Data Centre (12 Union Road, Cambridge,

CB2 1EZ, UK; fax: +44 1223 336033; e-mail:

deposit@ccdc.cam.ac.uk).

Reaction of N-acyl-3,5-dimethyl-1,4-benzo-

quinone monoimines Ia–Ig and Xa–Xc with alco-

hols (general procedures). a. A solution of 1.1 mmol

of quinone imine Ib–Ig in 5 ml of anhydrous alcohol

IIa–IId was heated for 1–3 h under reflux with protec-

tion from atmospheric moisture. When the reaction

was complete (TLC), the mixture was cooled, and the

white crystalline solid was filtered off and recrystal-

lized from petroleum ether (40–65°C). We thus isolat-

ed compounds IVa–IVd, Va–Vd, VIa–VId, VIIa–

VIId, VIIIa–VIIIc, IXa, IXb, and IXg.

The H and ¹³C NMR spectra were measured on

1

a Varian VXR-300 instrument at 300 and 75.4 MHz,

rspectively, using CDCl₃as solvent and tetramethyl-

silane as internal reference. The progress of reactions

and the purity of products were monitored by TLC on

Silufol UV-254 plates; spots were applied from solu-

tions in chloroform, plates were eluted with hexane–

benzene (1 :10), and spots were visualized under

UV light.

Initial quinone imine (Ia) was synthesized by

oxidation of N-(4-hydroxy-2,6-dimethylphenyl)acet-

amide with silver(I) oxide in chloroform according to

the procedure described in [2]. Quinone imines Ib–Ig

were prepared by oxidation of the corresponding

4-aminophenols with lead tetraacetate in acetic acid

according to [10]. The properties of compounds If and

b. Anhydrous alcohol IIa, IIc, and IIe–IIh, 3 ml,

was added to a solution of 1.1 mmol of quinone imine

Ia in 5 ml of anhydrous diethyl ether, and the reaction

vessel was tightly capped, shaken, and left to stand at

room temperature until the reaction was complete (1–

14 days; the mixture turned colorless). The precipitate

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

ACTIVATED STERICALLY STRAINED C=N BOND ... XIV.

55

was filtered off and recrystallized from petroleum

ether (40–65°C). We thus isolated compounds IIIa–

IIIe, IIIg, Ve–Vh, VIe–VIh, and VIIe–VIIh.

CH₂), 5.87 br.s (1H, NH), 6.27 s (2H, 3-H, 5-H), 7.26–

7.41 m (5H, Ph). Found, %: N 5.14, 5.23. C₁₇H₁₉NO₃.

Calculated, %: N 4.91.

N-(1-Ethoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-2-phenylacetamide (IVb). Yield 51%,

mp 204–205°C. H NMR spectrum, δ, ppm: 1.09 t

(3H, CH₂CH₃), 1.78 s (6H, 2-Me, 6-Me), 3.08 q (2H,

OCH₂, J = 7.2 Hz), 3.53 s (2H, CH₂), 5.84 br.s (1H,

NH), 6.23 s (2H, 2-H, 6-H), 7.29–7.41 m (5H, Ph).

Found, %: N 4.52, 4.86. C₁₈H₂₁NO₃. Calculated, %:

N 4.68.

c. A solution of 1.1 mmol of quinone imine Xa–Xc

in 3 ml of anhydrous methanol was heated for 3.5 h

under reflux. When the solution turned colorless, it

was cooled to 0°C, and the precipitate was filtered off

and recrystallized from benzene to isolate compounds

XIa–XIc.

1

N-(1-Methoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)acetamid (IIIa). Yield 99%, mp 179–180°C.

¹H NMR spectrum, δ, ppm: 1.89 s (6H, Me), 1.97 s

(3H, MeCO), 2.99 s (3H, OMe), 6.07 br.s (1H, NH),

6.26 s (2H, 3-H, 5-H). Found, %: N 6.47, 6.40.

C₁₁H₁₅NO₃. Calculated, %: N 6.69.

N-(2,6-Dimethyl-4-oxo-1-propoxycyclohexa-2,5-

dien-1-yl)-2-phenylacetamide (IVc). Yield 48%,

1

mp 179–180°C. H NMR spectrum, δ, ppm: 0.84 t

(3H, CH₂CH₃), 1.47 d.d (2H, CH₂CH₃, J = 21.0,

6.6 Hz), 1.77 s (6H, 2-Me, 6-Me), 2.97 t (2H, OCH₂),

3.54 s (2H, CH₂), 5.84 br.s (1H, NH), 6.24 s (2H, 3-H,

5-H), 7.29–7.41 m (5H, Ph). Found, %: N 4.41, 4.29.

C₁₉H₂₃NO₃. Calculated, %: N 4.47.

The properties of compound IIIb were in agree-

ment with published data [2].

N-(2,6-Dimethyl-4-oxo-1-propoxycyclohexa-

2,5-dien-1-yl)acetamide (IIIc). Yield 70%, mp 176–

N-(1-Isopropoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-2-phenylacetamide (IVd). Yield 52%,

1

177°C. H NMR spectrum, δ, ppm: 0.90 t (3H,

CH₂CH₃), 1.53 d.d (2H, CH₂CH₃, J = 12.3, 6.9 Hz),

1.90 s (6H, 2-Me, 6-Me), 2.00 s (3H, MeCO), 3.03 t

(2H, OCH₂), 6.06 s (1H, NH), 6.27 s (2H, 3-H, 5-H).

Found, %: N 5.68, 6.15. C₁₃H₁₉NO₃. Calculated, %:

N 5.90.

1

mp 191–192°C. H NMR spectrum, δ, ppm: 1.01 d

(6H, CHMe₂, J = 6.6 Hz), 1.81 s (6H, 2-Me, 6-Me),

3.53 s (2H, CH₂), 3.49–3.57 m (1H, OCH), 5.80 s

(1H, NH), 6.22 s (2H, 3-H, 5-H), 7.29–7.41 m (5H,

Ph). Found, %: N 4.73, 4.55. C₁₉H₂₃NO₃. Calculated,

%: N 4.47.

N-(1-Isopropoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)acetamide (IIId). Yield 65%, mp 176–

N-(1-Methoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-2-(4-methylphenyl)acetamide (Va). Yield

1

177°C. H NMR spectrum, δ, ppm: 1.06 d (6H,

CHMe₂, J = 6.0 Hz), 1.94 s (6H, 2-Me, 6-Me), 2.00 s

(3H, MeCO), 3.56–3.65 m (1H, OCH), 6.05 s (1H,

NH), 6.25 s (2H, 3-H, 5-H). Found, %: N 5.74, 5.81.

C₁₃H₁₉NO₃. Calculated, %: N 5.90.

1

89%, mp 214–215°C. H NMR spectrum, δ, ppm:

1.77 s (6H, 2-Me, 6-Me), 2.36 s (3H, 4′-Me), 2.93 s

(3H, OMe), 3.50 s (2H, CH₂), 5.80 br.s (1H, NH),

6.27 s (2H, 3-H, 5-H), 7.14 d (2H, 2′-H, 6′-H, J =

7.8 Hz), 7.27 d (2H, 3′-H, 5′-H, J = 8.1 Hz). ¹³C NMR

spectrum, δ_C, ppm: 16.81 (2-Me, 6-Me), 21.09

(4′-Me), 43.33 (CH₂), 49.63 (MeO), 83.31 (C¹), 129

(C³, C⁵), 129.9 (C^2′, C^6′), 130.74 (C^3′, C^5′), 137.36 (C^4′),

153.04 (C², C⁶), 168.64 (NC=O), 184.97 (C⁴). Found,

%: N 4.34, 4.42. C₁₈H₂₁NO₃. Calculated, %: N 4.68.

N-(1-Butoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)acetamide (IIIe). Yield 82%, mp 170–

1

171°C. H NMR spectrum, δ, ppm: 0.89 t (3H,

CH₂CH₃), 1.29–1.49 m (4H, CH₂CH₂Me), 1.89 s (6H,

2-Me, 6-Me), 1.99 s (3H, MeCO), 3.06 t (2H, OCH₂),

6.07 s (1H, NH), 6.26 s (2H, 3-H, 5-H). Found, %:

N 5.33, 5.95. C₁₄H₂₁NO₃. Calculated, %: N 5.57.

N-(1-Ethoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-2-(4-methylphenyl)acetamide (Vb). Yield

N-(2,6-Dimethyl-4-oxo-1-pentyloxycyclohexa-

2,5-dien-1-yl)acetamide (IIIg). Yield 65%, mp 121–

122°C. ¹H NMR spectrum, δ, ppm: 0.87–3.07 m (11H,

C₅H₁₁O), 1.89 s (6H, 2-Me, 6-Me), 2.00 s (3H, MeCO),

6.00 s (1H, NH), 6.26 s (2H, 3-H, 5-H). Found, %:

N 5.02, 5.17. C₁₅H₂₃NO₃. Calculated, %: N 5.28.

1

71%, mp 223–224°C. H NMR spectrum, δ, ppm:

1.09 t (3H, OCH₂Me), 1.78 s (6H, 2-Me, 6-Me), 2.36 s

(3H, 4′-Me), 3.07 q (2H, OCH₂, J = 6.9 Hz), 3.48 s

(2H, CH₂), 5.84 br.s (1H, NH), 6.23 s (2H, 3-H, 5-H),

7.15 d (2H, 2′-H, 6′-H, J = 8.4 Hz), 7.19 d (2H, 3′-H,

5′-H, J = 8.4 Hz). Found, %: N 4.29, 4.66. C₁₉H₂₃NO₃.

Calculated, %: N 4.47.

N-(1-Methoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-2-phenylacetamide (IVa). Yield 59%,

1

mp 183–184°C. H NMR spectrum, δ, ppm: 1.77 s

N-(2,6-Dimethyl-4-oxo-1-propoxycyclohexa-2,5-

dien-1-yl)-2-(4-methylphenyl)acetamide (Vc). Yield

(6H, 2-Me, 6-Me), 2.93 s (3H, OMe), 3.54 s (2H,

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

AVDEENKO et al.

56

1

62%, mp 185–186°C. H NMR spectrum, δ, ppm:

0.85 t (3H, CH₂CH₃), 1.47 d.d (2H, CH₂CH₃, J = 21.3,

6.9 Hz) , 1.78 s (6H, 2-Me, 6-Me), 2.35 s (3H, 4′-Me),

2.97 t (2H, OCH₂), 3.49 s (2H, CH₂), 5.90 br.s (1H,

NH), 6.23 s (2H, 3-H, 5-H), 7.14 d (2H, 2′-H, 6′-H, J =

9.3 Hz), 7.18 d (2H, 3′-H, 5′-H, J = 7.8 Hz). Found, %:

N 4.53, 4.37. C₂₀H₂₅NO₃. Calculated, %: N 4.28.

5-H), 7.16 d (2H, 2′-H, 6′-H, J = 8 Hz), 7.18 d (2H,

3′-H, 5′-H, J = 8 Hz). Found, %: N 3.65, 4.08.

C₂₃H₂₉NO₃. Calculated, %: N 3.81.

N-(1-Methoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-2-phenoxyacetamide (VIa). Yield 68%,

1

mp 114–115°C. H NMR spectrum, δ, ppm: 1.86 s

(6H, 2-Me, 6-Me), 3.03 s (3H, OMe), 4.46 s (2H,

OCH₂), 6.32 s (2H, 3-H, 5-H), 6.95 br.s (1H, NH),

6.94–7.37 m (5H, Ph). Found, %: N 4.54, 4.41.

C₁₇H₁₉NO₄. Calculated, %: N 4.65.

N-(1-Isopropoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-2-(4-methylphenyl)acetamide (Vd).

Yield 75%, mp 229–230°C. H NMR spectrum, δ,

1

ppm: 1.01 d (6H, CHMe₂, J = 6 Hz), 1.82 s (6H, 2-Me,

6-Me), 2.36 s (3H, 4′-Me), 3.48 s (2H, CH₂), 3.51–

3.59 m (1H, OCH), 5.86 s (1H, NH), 6.22 s (2H, 3-H,

5-H), 7.15 d (2H, 2′-H, 6′-H, J = 8.1 Hz), 7.18 d (2H,

3′-H, 5′-H, J = 8.4 Hz). Found, %: N 4.04, 4.46.

C₂₀H₂₅NO₃. Calculated, %: N 4.28.

N-(1-Ethoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-2-phenoxyacetamide (VIb). Yield 70%,

mp 155–156°C. H NMR spectrum, δ, ppm: 1.19 t

(3H, CH₂Me), 1.87 s (6H, 2-Me, 6-Me), 3.16 q (2H,

OCH₂, J = 6.6 Hz), 4.56 s (2H, PhOCH₂), 6.29 s (2H,

3-H, 5-H), 6.96–7.38 m (5H, Ph). Found, %: N 4.68,

4.75. C₁₈H₂₁NO₄. Calculated, %: N 4.44.

1

N-(1-Butoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-2-(4-methylphenyl)acetamide (Ve). Yield

N-(2,6-Dimethyl-4-oxo-1-propoxycyclohexa-2,5-

dien-1-yl)-2-phenoxyacetamide (VIc). Yield 60%,

1

80%, mp 192–193°C. H NMR spectrum, δ, ppm:

1.06 t (3H, CH₂CH₃), 1.23–1.43 m (2H, CH₂Me),

1.43–1.47 m (2H, OCH₂CH₂), 1.82 s (6H, 2-Me,

6-Me), 2.36 s (3H, 4′-Me), 3.19 t (2H, OCH₂), 3.48 s

(2H, CH₂), 5.87 s (1H, NH), 6.21 br.s (2H, 3-H, 5-H),

7.16 d (2H, 2′-H, 6′-H, J = 8 Hz), 7.18 d (2H, 3′-H,

5′-H, J = 8 Hz). Found, %: N 3.82, 4.38. C₂₁H₂₇NO₃.

Calculated, %: N 4.10.

1

mp 130–131°C. H NMR spectrum, δ, ppm: 0.92 t

(3H, CH₂CH₃), 1.57 d.d (2H, CH₂CH₃, J = 21.2,

7.2 Hz), 1.87 s (6H, 2-Me, 6-Me), 3.05 t (2H, OCH₂),

4.64 s (2H, PhOCH₂), 6.29 s (2H, 3-H, 5-H), 6.97 br.s

(1H, NH), 7.00–7.38 m (5H, Ph). Found, %: N 4.13,

3.95. C₁₉H₂₃NO₄. Calculated, %: N 4.25.

N-(1-Isopropoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-2-phenoxyacetamide (VId). Yield

75%, mp 156–157°C. H NMR spectrum, δ, ppm:

N-(1-Isobutoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-2-(4-methylphenyl)acetamide (Vf).

1

Yield 47%, mp 187–188°C. H NMR spectrum, δ,

1.07 d (6H, CHMe₂, J = 5.7 Hz), 1.89 s (6H, 2-Me,

6-Me), 3.59–3.63 m (1H, OCH), 4.43 s (2H, PhOCH₂),

6.25 s (2H, 3-H, 5-H), 6.89 s (1H, NH), 6.94–7.36 m

(5H, Ph). Found, %: N 4.06, 4.42. C₁₉H₂₃NO₄. Calcu-

lated, %: N 4.25.

ppm: 0.84 d (6H, CHMe₂, J = 6.8 Hz), 1.65–1.75 m

(1H, CHMe₂), 1.77 s (6H, 2-Me, 6-Me), 2.36 s (3H,

4′-Me), 2.78 d (2H, OCH₂), J = 6.4 Hz), 5.91 br.s (1H,

NH), 6.23 s (2H, 3-H, 5-H), 7.16 d (2H, 2′-H, 6′-H, J =

8 Hz), 7.18 d (2H, 3′-H, 5′-H, J = 8 Hz). Found, %:

N 4.33, 4.41. C₂₁H₂₇NO₃. Calculated, %: N 4.10.

N-(1-Butoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-2-phenoxyacetamide (VIe). Yield 47%,

N-(2,6-Dimethyl-4-oxo-1-pentyloxycyclohexa-

1

mp 129–130°C. H NMR spectrum, δ, ppm: 0.91 t

2,5-dien-1-yl)-2-(4-methylphenyl)acetamide (Vg).

1

(3H, CH₂CH₃), 1.29–1.41 m (2H, CH₂Me), 1.48–

1.57 m (2H, OCH₂CH₂), 1.86 s (6H, 2-Me, 6-Me),

3.08 t (2H, OCH₂), 4.45 s (2H, PhOCH₂), 6.29 s (2H,

3-H, 5-H), 6.99 s (1H, NH), 6.96–7.38 m (5H, Ph).

Found, %: N 5.60, 5.55. C₁₄H₂₁NO₃. Found, %:

N 4.25, 4.10. C₂₀H₂₅NO₄. Calculated, %: N 4.08.

Yield 18%, mp 174–175°C. H NMR spectrum, δ,

ppm: 0.88–1.67 m (10H, C₅H₁₁O), 1.78 s (6H, 2-Me,

6-Me), 2.36 s (3H, 4′-Me), 3.01 t (1H, OCH₂), 3.49 s

(1H, CH₂), 5.88 br.s (1H, NH), 6.23 s (2H, 3-H, 5-H),

7.16 d (2H, 2′-H, 6′-H, J = 8 Hz), 7.18 d (2H, 3′-H,

5′-H, J = 8 Hz). Found, %: N 3.74, 3.82. C₂₂H₂₉NO₃.

Calculated, %: N 3.94.

N-(1-Isobutoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-2-phenoxyacetamide (VIf). Yield 38%,

N-(1-Cyclohexyloxy-2,6-dimethyl-4-oxocyclo-

1

hexa-2,5-dien-1-yl)-2-(4-methylphenyl)acetamide

mp 159–160°C. H NMR spectrum, δ, ppm: 0.9 d

1

(Vh). Yield 35%, mp 210–211°C. H NMR spectrum,

(6H, CHMe₂, J = 6.4 Hz), 1.78–1.84 m (1H, CHMe₂),

1.85 s (6H, 2-Me, 6-Me), 2.85 d (2H, OCH₂, J =

6.8 Hz), 4.47 s (2H, PhOCH₂), 6.28 br.s (2H, 3-H,

5-H), 6.93 br.s (1H, NH), 6.97–7.38 m (5H, Ph).

δ, ppm: 1.20–1.61 m (10H, C₆H₁₁O), 1.82 s (6H, 2-Me,

6-Me), 2.36 s (3H, 4′-Me), 3.17–3.22 m (1H, OCH),

3.48 s (2H, CH₂), 5.87 s (1H, NH), 6.21 br.s (2H, 3-H,

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

ACTIVATED STERICALLY STRAINED C=N BOND ... XIV.

57

Found, %: N 3.79, 3.95. C₂₀H₂₅NO₄. Calculated, %:

N 4.08.

NH), 6.30 s (2H, 3-H, 5-H), 6.43 d (1H, 3′-H, J =

15.6 Hz), 7.38–7.50 m (5H, Ph), 7.60 d (1H, 2′-H, J =

15.9 Hz). Found, %: N 4.14, 4.05. C₂₀H₂₃NO₃. Calcu-

lated, %: N 4.30.

N-(2,6-Dimethyl-4-oxo-1-pentyloxycyclohexa-

2,5-dien-1-yl)-2-phenoxyacetamide (VIg). Yield

1

34%, mp 121–122°C. H NMR spectrum, δ, ppm:

(E)-N-(1-Butoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-3-phenylprop-2-enamide (VIIe). Yield

0.90–1.55 m (9H, C₅H₁₁O), 1.86 s (6H, 2-Me, 6-Me),

3.06–3.09 t (2H, OCH₂), 4.46 s (2H, PhOCH₂),

6.28 br.s (2H, 3-H, 5-H), 6.94 br.s (1H, NH), 6.97–

7.37 m (5H, Ph). Found, %: N 4.28, 4.15. C₂₁H₂₇NO₄.

Calculated, %: N 3.92.

1

39%, mp 197–198°C. H NMR spectrum, δ, ppm:

0.91 t (3H, (CH₂CH₃), 1.29–1.41 m (2H, CH₂CH₃),

1.48–1.57 m (2H, OCH₂CH₂), 1.97 s (6H, 2-Me,

6-Me), 3.08 t (2H, OCH₂), 6.11 br.s (1H, NH), 6.30 s

(2H, 3-H, 5-H), 6.43 d (1H, 3′-H, J = 15.6 Hz),

7.38–7.50 m (5H, Ph), 7.60 d (1H, 2′-H, J = 15.9 Hz).

Found, %: N 4.38, 4.25. C₂₁H₂₅NO₃. Calculated, %:

N 4.13.

N-(1-Cyclohexyloxy-2,6-dimethyl-4-oxocyclo-

hexa-2,5-dien-1-yl)-2-phenoxyacetamide (VIh).

1

Yield 28%, mp 186–187°C. H NMR spectrum, δ,

ppm: 1.22–1.68 m (10H, C₆H₁₁O), 1.91 s (6H, 2-Me,

6-Me), 3.24–3.30 m (1H, OCH), 4.46 s (2H, PhOCH₂),

6.26 br.s (2H, 3-H, 5-H), 6.93 br.s (1H, NH), 6.97–

7.38 m (5H, Ph). Found, %: N 4.63, 4.52. C₂₂H₂₇NO₄.

Calculated, %: N 3.79.

(E)-N-(1-Isobutoxy-2,6-dimethyl-4-oxocyclo-

hexa-2,5-dien-1-yl)-3-phenylprop-2-enamide (VIIf).

1

Yield 26%, mp 216–217°C. H NMR spectrum, δ,

ppm: 0.92 d (6H, CHMe₂, J = 6.9 Hz), 1.77–1.85 m

(1H, CHMe₂), 1.92 s (6H, 2-Me, 6-Me), 2.88 d (2H,

OCH₂, J = 6.0 Hz), 6.15 br.s (1H, NH), 6.32 s (2H,

3-H, 5-H), 6.45 d (1H, 3′-H, J = 15.3 Hz), 7.38–7.50 m

(5H, Ph), 7.63 d (1H, 2′-H, J = 15.9 Hz). Found, %:

N 3.85, 4.10. C₂₁H₂₅NO₃. Calculated, %: N 4.13.

(E)-N-(1-Methoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-3-phenylprop-2-enamide (VIIa). Yield

1

74%, mp 195–196°C. H NMR spectrum, δ, ppm:

1.93 s (6H, 2-Me, 6-Me), 3.05 s (3H, OMe), 6.32 br.s

(1H, NH), 6.35 s (2H, 3-H, 5-H), 6.45 d (1H, 3′-H, J =

15.6 Hz), 7.36–7.50 m (5H, Ph), 7.61 d (1H, 2′-H, J =

15.3 Hz). Found, %: N 5.05, 4.89. C₁₈H₁₉NO₃. Cal-

culated, %: N 4.71.

(E)-N-(2,6-Dimethyl-4-oxo-1-pentyloxycyclo-

hexa-2,5-dien-1-yl)-3-phenylprop-2-enamide (VIIg).

1

Yield 36%, mp 175–176°C. H NMR spectrum, δ,

ppm: 0.88–3.13 m (11H, C₅H₁₁O), 1.93 s (6H, 2-Me,

6-Me), 6.16 br.s (1H, NH), 6.32 s (2H, 3-H, 5-H),

6.43 d (1H, 3′-H, J = 15.6 Hz), 7.37–7.51 m (5H, Ph),

7.63 d (1H, 2′-H, J = 15.9 Hz). Found, %: N 3.75,

4.23. C₂₂H₂₇NO₃. Calculated, %: N 3.96.

(E)-N-(1-Ethoxy-2,6-dimethyl-4-oxocyclohexa-

2,5-dien-1-yl)-3-phenylprop-2-enamide (VIIb).

1

Yield 80%, mp 199–200°C. H NMR spectrum, δ,

ppm: 1.19 t (3H, CH₂Me), 1.93 s (6H, 2-Me, 6-Me),

3.18 q (2H, OCH₂, J = 6.9 Hz), 6.21 s (1H, NH), 6.32 s

(2H, 3-H, 5-H), 6.42 d (1H, 3′-H, J = 15.9 Hz), 7.38–

7.49 m (5H, Ph), 7.61 d (1H, 2′-H, J = 15.9 Hz).

Found, %: N 4.23, 4.67. C₁₉H₂₁NO₃. Calculated, %:

N 4.50.

(E)-N-(1-Cyclohexyloxy-2,6-dimethyl-4-oxo-

cyclohexa-2,5-dien-1-yl)-3-phenylprop-2-enamide

1

(VIIh). Yield 42%, mp 213–214°C. H NMR spec-

trum, δ, ppm: 1.15–1.69 m (10H, C₆H₁₁O), 1.97 s (6H,

2-Me, 6-Me), 3.28–3.34 m (1H, OCH), 6.13 br.s (1H,

NH), 6.29 br.s (2H, 3-H, 5-H), 6.43 d (1H, 3′-H, J =

15.6 Hz), 7.37–7.50 m (5H, Ph), 7.63 d (1H, 2′-H, J =

15.9 Hz). Found, %: N 3.64, 3.57. C₂₃H₂₇NO₃. Calcu-

lated, %: N 3.83.

(E)-N-(2,6-Dimethyl-4-oxo-1-propoxycyclohexa-

2,5-dien-1-yl)-3-phenylprop-2-enamide (VIIc). Yield

1

98%, mp 209–210°C. H NMR spectrum, δ, ppm:

0.93 t (3H, CH₂CH₃), 1.58 d.d (2H, CH₂CH₃, J = 20.7,

7.2 Hz), 1.93 s (6H, 2-Me, 6-Me), 3.08 t (OCH₂),

6.19 br.s (1H, NH), 6.32 s (2H, 3-H, 5-H), 6.43 d (1H,

3′-H, J = 15.6 Hz), 7.38–7.50 m (5H, Ph), 7.63 d

(1H, 2′-H, J = 15.6 Hz). Found, %: N 4.55, 4.48.

C₂₀H₂₃NO₃. Calculated, %: N 4.30.

N-(1-Methoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)benzamide (VIIIa). Yield 70%, mp 150–

1

151°C. H NMR spectrum, δ, ppm: 1.94 s (6H, 2-Me,

6-Me), 3.08 s (3H, OMe), 6.36 s (2H, 3-H, 5-H),

6.65 br.s (1H, NH), 7.44–7.81 m (5H, Ph). Found, %:

N 4.93, 5.25. C₁₆H₁₇NO₃. Calculated, %: N 5.16.

(E)-N-(1-Isopropoxy-2,6-dimethyl-4-oxocyclo-

hexa-2,5-dien-1-yl)-3-phenylprop-2-enamide (VIId).

1

Yield 41%, mp 219–220°C. H NMR spectrum, δ,

N-(1-Ethoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)benzamide (VIIIb). Yield 56%, mp 189–

ppm: 1.09 d (6H, CHMe₂, J = 6.3 Hz), 1.97 s (6H,

2-Me, 6-Me), 3.60–3.73 m (1H, OCH), 6.11 br.s (1H,

1

190°C. H NMR spectrum, δ, ppm: 1.21 t (3H,

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

AVDEENKO et al.

58

CH₂Me), 1.95 s (6H, 2-Me, 6-Me), 3.21 q (2H, OCH₂,

J = 7.2 Hz), 6.34 s (2H, 3-H, 5-H), 6.62 s (1H, NH),

7.44–7.83 m (5H, Ph). Found, %: N 5.06, 5.39.

C₁₆H₁₉NO₃. Calculated, %: N 5.12.

benzamide (XIb). Yield 74%, mp 242–243°C.

¹H NMR spectrum, δ, ppm: 2.28 s (3H, 6-Me), 3.13 s

(3H, 1-MeO), 3.90 s (6H, 3′-Me, 5′-MeO), 3.95 s (3H,

4′-MeO), 6.36 br.s (1H, NH). Found, %: Cl 34.28,

34.36; N 2.55, 2.64. C₁₈H₁₆Cl₅NO₆. Calculated, %:

Cl 34.12; N 2.70.

N-(2,6-Dimethyl-4-oxo-1-propoxycyclohexa-2,5-

dien-1-yl)benzamide (VIIIc). Yield 32%, mp 177–

1

178°C. H NMR spectrum, δ, ppm: 0.94 t (3H,

N-2-Bromo-(2,3-dibromo-1-methoxy-6-methyl-

4-oxocyclohexa-2,5-dien-1-yl)-3,4,5-trimethoxy-

benzamide (XIc). Yield 69%, mp 178–180°C.

¹H NMR spectrum, δ, ppm: 2.19 s (3H, 6-Me), 3.22 s

(3H, 1-MeO), 3.88 s (3H, 3′-MeO), 3.89 s (3H,

4′-MeO), 3.92 s (3H, 5′-MeO), 7.06 br.s (1H, NH),

7.15 s (1H, 6′-H). Found, %: Br 31.42, 31.53; N 2.86,

2.91. C₁₈H₁₉Br₂NO₆. Calculated, %: Br 31.64; N 2.77.

CH₂Me), 1.58 d.d (2H, CH₂Me, J = 21, 6.9 Hz), 1.94 s

(6H, 2-Me, 6-Me), 3.11 t (2H, OCH₂), 6.33 s (2H, 3-H,

5-H), 6.64 br.s (1H, NH), 7.44–7.83 m (5H, Ph).

Found, %: N 4.57, 4.72. C₁₇H₂₁NO₃. Calculated, %:

N 4.87.

N-(1-Methoxy-2,6-dimethyl-4-oxocyclohexa-2,5-

dien-1-yl)-4-methylbenzamide (IXa).** Yield 91%,

1

mp 143–144°C. H NMR spectrum, δ, ppm: 1.93 s

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(6H, 2-Me, 6-Me), 2.41 s (3H, 4′-Me), 3.07 s (3H,

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7.25 d (2H, 2′-H, 6′-H, J = 8.1 Hz), 7.71 d (2H, 3′-H,

5′-H, J = 8.1 Hz). Found, %: N 5.20, 5.16. C₁₇H₁₉NO₃.

Calculated, %: N 4.91.

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7.69 d.d (1H, 6′-H, J = 8.4, J = 2.4 Hz), 7.79 d (1H,

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** Compounds IXa and IXb were synthesized by I.L. Marchenko.

RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

ACTIVATED STERICALLY STRAINED C=N BOND ... XIV.

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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 1 2013

Article Doi

Activated sterically strained C=N bond in N-substituted p-quinone mono- and diimines: XIV. Reaction of some 3,5-dimethyl-1,4-benzoquinone monoimines with alcohols

DOI: 10.1134/S1070428013010107

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