Direct phenylamination of 6-aminonaphthacenequinones promoted by metal salts

Article abstract of DOI:10.1023/A:1015354708978

6-Amino-5,12- and -5,11-naphthacenequinones react with aniline in the presence of cobalt, copper, and manganese salts, resulting in replacement of hydrogen in the peri-position with respect to the carbonyl group by phenylamino group and formation of 11- and 12-phenylamino-6-amino(phenylamino)-5,12- and -5,11-naphthacenequinones.

Full text of DOI:10.1023/A:1015354708978

Russian Journal of Organic Chemistry, Vol. 38, No. 1, 2002, pp. 70 75. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 1, 2002,
pp. 79 84.
Original Russian Text Copyright
2002 by Sokolyuk, Pisulina, V’yugin.
Direct Phenylamination of 6-Aminonaphthacenequinones
Promoted by Metal Salts
1
2
2
N. T. Sokolyuk , L. P. Pisulina , and A. I. V’yugin
1
Research Institute of Fine Organic Synthesis, TOS Joint-Stock Company,
Dolgoprudnyi, Moscow oblast, 141700 Russia
2
Institute of Solution Chemistry, Russian Academy of Sciences,
ul. Akademicheskaya 1, Ivanovo, 153045 Russia
Received April 11, 2000
Abstract 6-Amino-5,12- and -5,11-naphthacenequinones react with aniline in the presence of cobalt, copper,
and manganese salts, resulting in replacement of hydrogen in the peri-position with respect to the carbonyl
group by phenylamino group and formation of 11- and 12-phenylamino-6-amino(phenylamino)-5,12- and
-5,11-naphthacenequinones.
Phenylamino group can be introduced into the peri-
position with respect to the carbonyl group of 5,12-
(para) and 5,11-(ana)naphthacenequinones via nucleo-
philic replacement of halogen [1, 2] or phenoxy group
[3, 4] by aniline residue. Substitution of the hydroxy
group in 6-hydroxy- and 6,11-dihydroxy-5,12-naph-
thacenequinones by aniline in the presence of boric
acid is accompanied by reorganization of the para-
quinoid structure into ana-quinoid with formation
of 6-phenylamino- and 6,12-bis(phenylamino)-5,11-
naphthacenequinones, respectively [2, 5, 6]. Highly
reactive unsubstituted ana-naphthacenequinone reacts
[2] with aniline directly to form product of hydrogen
replacement by phenylamino group [7], 6-phenyl-
amino-5,11-naphthacenequinone. We have found that
an analogous reaction can be effected with less reac-
tive p-naphthacenequinone: Its 6-hydroxy derivative
reacts with aniline in the presence of copper acetate,
yielding 6-hydroxy-11-phenylamino-5,12-naphtha-
cenequinone [8].
The present communication reports on the results of
our study on the possibility of direct phenylamination
Scheme 1.
III, R = NHBu; IV, R = morpholino; V, R = NHAc.
1070-4280/02/3801-0070$27.00 2002 MAIK Nauka/Interperiodica

DIRECT PHENYLAMINATION OF 6-AMINONAPHTHACENEQUINONES
71
Table 1. Melting points and spectral parameters of 6-aminonaphthacenequinone derivatives III, IV, VI, VII, X, and XI
1
Electron absorption
spectrum (toluene),
max, nm (log )
IR spectrum (KBr), , cm
Comp.
no.
mp,
C
C O
1656
C Carom
C C C Cquinoid
1288
C H
III
IV
159 160a
242 243b
382 sh (3.58)
395 (3.62)
504 (4.07)
391 (3.67)
447 (3.55)
1620
1580
2960,
2928
2868
1672
1656
1610
1596
1580
1272
2968
2956
2888
2852
3404 (NH)
VI
VII
X
252 253b
442 (3.80)
544 (4.16)
571 sh (4.11)
463 (3.98)
566 (4.13)
595 sh (4.08)
547 (4.29)
586 (4.43)
546 (4.33)
585 (4.48)c
542 (4.28)
580 (4.41)d
571 (4.36)
611 (4.48)
571 (4.44)
611 (4.57)c
562 (4.01)
601 (4.13)d
1652
1620
1600
1584
1272
1256
255 256,a
244 246
(AcOH) [5]
235.5 236.5b
1652
1620
1576
1266
1336
1652
1636
1616
1592
3408 (NH)
XI
314 315,b
314 315 [8]
1652
1590
1576
1328
a
b
c
From benzene hexane.
From chloroform hexane.
In CCl4.
d
In MeOH.
of 6-amino derivatives of para- and ana-naphtha-
cenequinones. We found that heating of 6-amino-
5,12-naphthacenequinones I V in aniline in the
presence of metal salts results in replacement of
hydrogen in the peri-position with respect to the
carbonyl group by phenylamino group with formation
of the corresponding 11-phenylamino derivatives VI
and VII (Scheme 1). The structure of products VI
and VII was proved by independent synthesis and
spectral data. The melting points and IR and electron
spectral parameters of VI and VII, as well as of
previously unknown naphthacenequinones III and IV,
are given in Table 1.
in introduction of phenylamino group into the naph-
thacene core, and initial compounds I and II were
quantitatively recovered from the reaction mixture.
Among the examined salts, manganese acetate showed
the highest activity in the direct phenylamination of
naphthacenequinones I and II (Table 2). Metal salts
promote not only phenylamination of p-aminonaph-
thacenequinone (I) but also its transamination, as
follows from the presence in the reaction mixture of
6-phenylamino-5,12-naphthacenequinone (II). In addi-
tion, the transformation of 6-amino-5,12-naphthacene-
quinone (I) into phenylamino derivative VI is accom-
panied by formation of 6,11-bis(phenylamino)naph-
thacenequinone VII whose yield attains 13% in the
presence of cobalt nitrate. The yield of VII decreases
to 1.5% when the reaction is carried out in the
Preliminarily, we have found that prolonged
heating of p-aminonaphthacenequinones I and II in
aniline in the absence of metal salt does not result
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 1 2002

72
SOKOLYUK et al.
Table 2. Direct phenylamination of 6-aminonaphthacenequinone derivatives I V, VIII, and IX
Initial
compound
no.
Reaction conditions
Yield, %
metal salt
reaction time, h
I
II
III
V
VI
VII
I
6.0
2.5
7.0
7.0
6.5
6.5
4.5a
6.5
6.5b
6.5
7.0
1.5
1.5
7.0
7.0
97
CO(NO3)2 6H2O
3
15
12
16
15
36
63
Cu(OAc)2 H2O
Mn(OAc)2 4H2O
51
22
1
II
98
31
57
29
51
9
Co(NO3)2 6H2O
Mn(OAc)2 4H2O
27
29
54
3
III
IV
V
3
36
4
Mn(OAc)2 4H2O
Mn(OAc)2 4H2O
Mn(OAc)2 4H2O
35
9
34
95
84
94
32
0.9
10
VIII
IX
X
XI
VIII
IX
0.5
5.5
0.5
1.5
1.5
1.5b
1.5
1.5c
44
4
35
Traces
4
21
59
1
60
6
Mn(OAc)2 4H2O
Mn(OAc)2 4H2O
83
4
32
2
8
88
54
73
10
Cu(OAc)2 H2O
Zn(OAc)2 2H2O
51
a
b
c
With bubbling of air over a period of 2 h.
Metal salt-to-substrate ratio 0.1:1 (mol/mol).
6-Hydroxy-5,12-naphthacenequinone, 13%, was also isolated.
presence of manganese acetate, and it is not formed were 6-amino-11-phenylamino-5,12-naphthacene-
at all in the reaction with copper acetate. Presumably,
bis(phenylamino) derivative VII arises from trans-
amination of 6-amino-11-phenylamino-5,12-naphtha-
cenequinone (VI), which is likely to be favored by
the presence of cobalt nitrate in the reaction medium.
By special experiments we showed that cobalt nitrate
promotes the transformation of compound VI into bis-
(phenylamino)naphthacenequinone VII in 18% yield.
Probably, naphthacenequinone II (which is present
in the reaction mixture) is also converted into bis-
(phenylamino) derivative VII.
quinone (VI) and 6,11-bis(phenylamino)-5,12-naph-
thacenequinone (VII) at a ratio of 1:1. The formation
of compound VI may be explained by dealkylation of
the butylamino group in III and subsequent amination
of 6-aminonaphthacene I. The dealkylation process is
favored by the presence of manganese acetate. This
follows from the fact that 6-aminonaphthacenequinone
I is formed in 5% yield by heating 6-butylaminonaph-
thacenequinone III in boiling aniline in the absence of
manganese acetate. An alternative way of formation of
naphthacenequinone VI should be noted. It involves
addition of phenylamino group at C11 of 6-butyl-
aminonaphthacenequinone III, followed by dealkyla-
Treatment of 6-butylamino-5,12-naphthacene-
quinone (III) with aniline in the presence of manga-
nese acetate gave only traces of the direct phenyl- tion. The second product, 6,11-bis(phenylamino)-5,12-
amination product (TLC), whereas the major products naphthacenequinone (VII) could appear as a result of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 1 2002

DIRECT PHENYLAMINATION OF 6-AMINONAPHTHACENEQUINONES
73
Scheme 2.
Xa, R = NH2; XIa, R = NHPh.
transamination of 6-butylaminonaphthacenequinone
III and subsequent replacement of hydrogen by
phenylamino group in 6-phenylamino-5,12-naphtha-
cenequinone (II). The ability of 6-butylaminonaphtha-
cenequinone III to undergo transamination is likely
to be responsible for its transformation into II, which
occurs in 50% yield by the action of aniline even in
the absence of manganese acetate.
6-Morpholino-5,12-naphthacenequinone (IV) failed
to react with aniline to give hydrogen replacement
product. Heating of IV in boiling aniline for a short
time both in the presence and in the absence of
manganese acetate resulted in transamination and
formation of 6-phenylaminonaphthacenequinone II in
high yield.
in complete conversion of IX into 6,12-bis(phenyl-
amino)-5,11-naphthacenequinone (XI). Direct phenyl-
amination products X and XI were formed in high
yield and at a higher rate (as compared to the corre-
sponding para analogs I and II) when ana-amino-
naphthacenequinones VIII and IX were treated with
aniline in the presence of manganese acetate. Like-
wise, ana-phenylaminonaphthacenequinone IX readily
reacts with aniline in the presence of copper acetate,
but the yield of the product is smaller. Zinc acetate
turned out to be ineffective in the phenylamination of
IX. The yield of target product XI was poor, and the
process was accompanied by formation of 6-hydroxy-
naphthacenequinone via hydrolysis of ana-phenyl-
aminonaphthacenequinone IX.
Reduction of the amount of manganese acetate
from 2 mol to 0.1 mol leads to insignificant decrease
of the yield of product XI in the phenylamination
of ana-phenylaminonaphthacenequinone IX, while
in the reaction with para-phenylamino derivative II
increase in the yield of product VII is observed. These
data suggest some difference in the mechanisms of
direct phenylamination of para- and ana-phenyl-
aminonaphthacenequinones II and IX.
The reaction of 6-acetylaminonaphthacenequinone
V with aniline and manganese acetate gave 10% of
6-amino-11-phenylaminonaphthacenequinone VI as
a result of direct phenylamination and hydrolysis of
the acetylamino group. In the absence of manganese
acetate less than 1% of VI was obtained, and un-
changed initial compound V was recovered from the
mixture in high yield.
Unlike para isomers I and II, ana-aminonaphtha-
cenequinones VIII and IX react with aniline in the
absence of metal salts to afford 5 9% of 6-amino-12-
phenylamino-5,12-naphthacenequinone (X) and
6,12-bis(phenylamino)-5,12-naphthacenequinone (XI)
(Scheme 2). However, the predominant process is
transamination of VIII, which leads to formation of
6-phenylamino-5,11-naphthacenequinone (IX) in 40%
yield. Further heating of the reaction mixture results
Scheme 3.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 1 2002

74
SOKOLYUK et al.
6-Phenylamino-5,11-naphthacenequinone (IX) [9]
chloric acid, and the precipitate was filtered off,
washed with water, dried, and subjected to column
chromatography on aluminum oxide (Brockman
activity grade II) using chloroform as eluent. The
major fraction (crimson) was evaporated, and the
residue was recrystallized from benzene hexane.
Yield 0.195 g (85%), dark red crystals.
6-Morpholino-5,12-naphthacenequinone (IV)
was synthesized in a similar way, but the reaction
time was 10 min. Recrystallization from chloroform
hexane gave compound IV in 89% yield; brownish
yellow crystals.
6-Acetylamino-5,12-naphthacenequinone (V)
was synthesized by acylation of 6-amino-5,12-naph-
thacenequinone (I) with acetic anhydride, following
the procedure described in [4] for preparation of
6-acetylamino-11-phenoxy-5,12-naphthacenequinone.
mp 250 251 C (from benzene); published data [13]:
mp 249 and 254 C (from benzene).
6-Amino-11-phenylamino-5,12-naphthacene-
quinone (VI) (independent synthesis). A mixture of
0.044 g of 6-amino-11-phenoxy-5,12-naphthacene-
quinone [4] and 5 ml of aniline was refluxed for 0.5 h.
It was then cooled and poured into 10% hydrochloric
acid, and the precipitate was filtered off, washed with
water, dried, and subjected to chromatography on
porous quartz (50 150 m) using chloroform as
eluent. The major fraction (violet) was evaporated,
and the residue was recrystallized from chloroform
hexane. Yield 0.042 g (95%), dark violet needles with
a greenish tinge. The electron absorption and IR
and 4-amino-9-phenylamino-1,10-anthraquinone (XII)
[10] are capable of undergoing tautomeric transforma-
tions via proton migration between the phenylamino
group and carbonyl oxygen atom in the peri position
(Scheme 3). By contrast, ana-aminonaphthacene-
quinones X and XI are incapable of prototropic trans-
formations, as follows from their spectral data: The
spectral curves of compounds X and XI do not change
their shape on variation of the solvent polarity. In
going from a less polar solvent to more polar, com-
pound X and, to a greater extent, ana-diphenylamino-
naphthacenequinone XI exhibit a negative solvato-
chromism, i.e., the long-wave absorption maxima of
X and XI shift to shorter wavelengths, and their
intensity decreases (Table 1). This means [11] that the
ground state of molecules X and XI is more polar
than the excited state; therefore, it is described better
by dipolar structures Xa and XIa (Scheme 2). The
predominant contribution of dipolar structures is
likely to result from the lower energy of the para-
quinonimine structure relative to ana-quinoid.
Thus, direct phenylamination promoted by metal
salts can be effected with 6-amino- and 6-phenyl-
aminonaphthacenequinones having both para- and
ana-quinoid structure. This reaction can be used as
a method for introduction of phenylamino group into
the peri-position with respect to the carbonyl group
of 6-amino- and 6-phenylaminonaphthacenequinone
derivatives.
EXPERIMENTAL
value coincided with
those found for compound VI obtained by direct
phenylamination of naphthacenequinone (I).
spectra, melting point, and Rf
The electron absorption spectra were measured on
a Specord M-40 spectrophotometer. The IR spectra
were obtained on a Specord M-80 spectrometer in
KBr. The melting points were determined with the aid
of a PTP device (TU 25-11-1144-76).
6-Amino-5,12-naphthacenequinone (I), 6-phenyl-
amino-5,12-naphthacenequinone (II) [1], 6-amino-
5,11-naphthacenequinone (VIII) [12], 6-phenylamino-
5,11-naphthacenequinone (IX) [3], and 6,11-bis-
(phenylamino)-5,12- and 6,12-bis(phenylamino)-5,11-
naphthacenequinones VII and XI [5] were synthesized
and purified by known methods. Their properties
were consistent with published data. Cobalt, manga-
nese, copper, and zinc salts (crystal hydrates) of
pure or analytical grade were used without additional
purification.
6-Amino-12-phenylamino-5,11-naphthacene-
quinone (X) (independent synthesis). Compound X
was synthesized from 6-amino-12-(4-ethylphenoxy)-
5,11-naphthacenequinone which was obtained by acid-
catalyzed isomerization of the corresponfing para
isomer prepared by the procedure reported in [14].
A mixture of 0.3 g of 6-amino-12-(4-ethylphenoxy)-
5,11-naphthacenequinone, 50 ml of aniline, and
250 ml of ethanol was refluxed for 2 h. The solvent
was distilled off under reduced pressure, and the
residue was subjected to chromatography on silica gel
(40 100 m) using chloroform as eluent. The major
fraction (dark violet) was evaporated, and the residue
was recrystallized first from benzene and then from
ethanol. Yield 0.25 g (90%). Found, %: C 79.57;
H 4.54; N 7.60. C24H16N2O2. Calculated, %: C 79.10;
H 4.43; N 7.69. The electron absorption and IR spe-
ctra, melting point, and Rf value coincided with those
6-Butylamino-5,12-naphthacenequinone (III).
A mixture of 0.207 g of 6-chloro-5,12-naphthacene-
quinone and 7 ml of butylamine was refluxed for
1.5 h. It was then cooled and poured into 10% hydro-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 1 2002

DIRECT PHENYLAMINATION OF 6-AMINONAPHTHACENEQUINONES
75
found for compound X obtained by direct phenyl-
amination of aminonaphthacenequinone (VIII).
2. Marschalk, Ch., Bull. Soc. Chim. Fr., 1952, vol. 19,
pp. 155 162.
Direct phenylamination of 6-aminonaphthacene-
3. Gerasimenko, Yu.E. and Poteleshchenko, N.T.,
Zh. Org. Khim., 1971, vol. 7, no. 11, pp. 2413 2415.
quinone derivatives I V, VIII, and IX (general
4
procedure). A mixture of 10 mol of compound I V,
4. Gerasimenko, Yu.E., Poteleshchenko, N.T., and
Romanov, V.V., Zh. Org. Khim., 1980, vol. 16,
no. 9, pp. 1938 1945.
4
VIII, or IX, 2 10 mol of appropriate metal salt
hydrate, and aniline was refluxed under continuous
stirring. It was then cooled and poured into 10%
hydrochloric acid, and the precipitate was filtered off,
washed with water, dried, and subjected to chromatog-
raphy on porous quartz (50 150 m) using chloroform
as eluent. Fractions containing the phenylamination
products were collected and evaporated. Each product
was additionally purified by chromatography on silica
gel (40 100 m) using benzene as eluent. The solvent
was distilled off from the eluate, the residue was
dissolved in chloroform, the solution was filtered
from mechanical impurities through a folded filter,
the filtrate was transferred to a porcelain evaporating
dish and was evaporated on a water bath, and the
residue was dried at 90 95 C and weighed. The yield
of each reaction product was calculated from the
results of 2 3 parallel runs (Table 2).
5. Postovskii, I.Ya. and Goldyrev, L.N., Zh. Obshch.
Khim., 1941, vol. 11, nos. 5 6, pp. 429 445.
6. Postovskii, I.Ya. and Beiles, R.G., Zh. Obshch.
Khim., 1950, vol. 20, no. 3, pp. 522 530.
7. Gorelik, M.V. and Efros, L.S., Khimiya i tekhnolo-
giya promezhutochnykh produktov (Chemistry and
Technology of Intermediate Products), Leningrad:
Khimiya, 1979, p. 265.
8. Sokolyuk, N.T., Pisulina, L.P., and V’yugin, A.I.,
Russ. J. Org. Chem., 1996, vol. 32, no. 1, pp. 121
122.
9. Nurmukhametov, R.N., Rodionova, G.N., Roma-
nov, V.V., Poteleshchenko, N.T., and Gerasimen-
ko, Yu.E., Zh. Prikl. Spektrosk., 1979, vol. 30, no. 5,
pp. 856 859.
Reaction of 6-amino-11-phenylamino-5,12-naph-
thacenequinone (VI) with aniline in the presence of
cobalt nitrate. The reaction was carried out following
the above procedure. The mixture was refluxed for
6 h. By chromatographic treatment we isolated 18% of
6,11-bis(phenylamino)-5,12-naphthacenequinone (VII)
and 44% of unreacted initial compound VI.
10. Romanov, V.V., Cand. Sci. (Chem.) Dissertation,
Moscow, 1981.
11. Terenin, A.N., Fotonika molekul krasitelei (Photonics
of Dye Molecules), Moscow: Nauka, 1967, p. 159.
12. Sokolyuk, N.T. and Pisulina, L.P., Zh. Org. Khim.,
1994, vol. 30, no. 5, p. 795.
13. Beilsteins Handbuch der organischen Chemie, EIV,
vol. 14, part 1, p. 510.
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na, L.P., Zh. Org. Khim., 1990, vol. 26, no. 5,
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1. Waldmann, H. and Polak, G., J. Prakt. Chem., Neue
Folge, 1938, vol. 150, nos. 1 3, pp. 113 120.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 1 2002