Quinonimines and aminoquinones, the reaction products of 3,6-di(tert-butyl)-o-benzoquinone with primary and secondary amines

Article abstract of DOI:10.1007/s11172-006-0398-5

Reactions of 3,6-di(tert-butyl)-o-benzoquinone with primary amines occur by the nucleophilic 1,4-addition mechanism and lead to the corresponding 2-hydroxy-p-quinonimines, which exist in solutions in equilibrium with tautomeric 4-amino-o-quinones. The the

Full text of DOI:10.1007/s11172-006-0398-5

Russian Chemical Bulletin, International Edition, Vol. 55, No. 7, pp. 1195—1199, July, 2006
1195
Quinonimines and aminoquinones, the reaction products
of 3,6ꢀdi(tertꢀbutyl)ꢀoꢀbenzoquinone with primary and secondary amines
G. A. Abakumov, V. K. Cherkasov, T. N. Kocherova,ꢀ N. O. Druzhkov, Yu. A. Kurskii, and L. G. Abakumova
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49 ul. Tropinina, 603950 Nizhnii Novgorod, Russian Federation.
Fax: +7 (831 2) 62 7497. Eꢀmail: tanya@iomc.ras.ru
Reactions of 3,6ꢀdi(tertꢀbutyl)ꢀoꢀbenzoquinone with primary amines occur by the nucleoꢀ
philic 1,4ꢀaddition mechanism and lead to the corresponding 2ꢀhydroxyꢀpꢀquinonimines,
which exist in solutions in equilibrium with tautomeric 4ꢀaminoꢀoꢀquinones. The thermoꢀ
dynamic parameters of this prototropic isomerism were determined by NMR spectroscopy. In
the case of a secondary amine (piperidine), a derivative of 4ꢀaminoꢀoꢀquinone was obtained;
the corresponding oꢀsemiquinone complexes were studied in solution by ESR spectroscopy.
Key words: oꢀquinones, amines, pꢀquinonimines, nucleophilic addition, oꢀsemiquinone
complexes, ESR spectra.
Scheme 1
A new and promising application of the chemistry of
oꢀsemiquinone metal complexes is the synthesis of coorꢀ
dination compounds with bifunctional ligands.
For sterically hindered 3,6ꢀdi(tertꢀbutyl)ꢀoꢀbenzoꢀ
quinone (1), 1,4ꢀaddition of nucleophilic reagents to the
conjugated quinone system with participation of one carꢀ
bonyl group is typical. It affords new 4ꢀsubstituted
oꢀquinones. Earlier, the anions of CH acids (dimedone1
and malononitrile2) and ammonia3 have been used as
nucleophilic reagents.
Here we studied reactions of quinone 1 with amines
with the aim of obtaining new aminoꢀ3,6ꢀdi(tertꢀbutyl)ꢀ
oꢀbenzoquinones.
Reactions of quinone 1 with a series of primary anilines
(aniline, oꢀtoluidine, 2,6ꢀdimethylaniline, and 2,6ꢀdiisoꢀ
propylaniline) in methanol in the presence of a catalytic
amount of formic acid led to Nꢀarylꢀ3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀ
hydroxyꢀpꢀquinonimines 2a—d but not to substituted
oꢀbenzoquinones (Scheme 1). This suggests the nucleoꢀ
philic 1,4ꢀaddition of amines onto the oꢀquinone fragꢀ
ment (see Scheme 1).
In all cases, the reaction mixture contained 3,6ꢀdi(tertꢀ
butyl)pyrocatechol in the amount that corresponds to apꢀ
proximately half that of quinone 1 used in the reaction.
This is explained by the fact that rearrangement of a priꢀ
mary adduct gives 4ꢀarylaminoꢀ3,6ꢀdi(tertꢀbutyl)pyroꢀ
catechol, which is easily oxidized by the starting quinone
and partly by atmospheric oxygen. Because of this, the
yields of pꢀquinonimines 2 were slightly above 50% with
respect to the starting oꢀquinone.
2: Ar = Ph (a), 2ꢀMeC6H4 (b), 2,6ꢀMe2C6H3 (c), 2,6ꢀPriC6H3 (d)
and, on the other hand, by intramolecular hydrogen bondꢀ
ing between the carbonyl O atom and the OH proton.
Their IR spectra show absorption bands characteristic of
the C=O (1650 and 1630 cm–1) and O—H stretching
vibrations (3350 cm–1). The shapes of the ν(OH) bands
Compounds 2 exist in the pꢀquinonimine rather than
oꢀquinone form. The former is stabilized by conjugation
of the aryl substituent with the πꢀsystem of pꢀquinonimine
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1151—1155, July, 2006.
1066ꢀ5285/06/5507ꢀ1195 © 2006 Springer Science+Business Media, Inc.

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Russ.Chem.Bull., Int.Ed., Vol. 55, No. 7, July, 2006
Abakumov et al.
Scheme 3
and their frequencies suggest the presence of strong inꢀ
tramolecular hydrogen bonding. It should be noted
that these bands become narrower when moving from
pꢀquinonimine 2a to sterically more hindered comꢀ
pound 2d. Apparently, this is because the shielding of the
N atom in pꢀquinonimines with methyl (in 2b,c) and
especially isopropyl substituents (2d) hinders intermoꢀ
lecular hydrogen bonding.
In the series of the aromatic amines used, the reaction
time increases and the yield of pꢀquinonimine decreases
when moving from unsubstituted aniline to 2,6ꢀdiisoꢀ
propylaniline. This can be associated with a substantial
role of the steric factor in the reactions of quinone 1 with
sterically hindered anilines.
The reaction of compound 1 with benzidine was carꢀ
ried out under the aforementioned conditions; the ratio
of the quinone to the diamine was 2 : 1. The course of the
reaction was monitored by TLC. As expected, this reacꢀ
tion yielded 1,4ꢀadducts in two steps involving one
(monoadduct 3) and both amino groups of benzidine
(bisadduct 4) (Scheme 2).
Quinone 1 reacted with cyclohexylamine more rapꢀ
idly than with anilines, giving Nꢀcyclohexyl derivative 6
(Scheme 4).
Scheme 4
Scheme 2
It is worth noting that quinonimine 6, unlike aryl anaꢀ
logs 2—5, exhibit a number of specific features. Its soluꢀ
tions in saturated and aromatic hydrocarbons are colored
yellow, while those in chloroform and dichloromethane
turn intensely violet. Its IR spectra substantially vary with
solvents: in hexane, characteristic bands appear at 3340
(narrow, OH) and 1640 and 1625 cm–1 (C=O); in
CH2Cl2, a new narrow peak appears at 3470 cm–1 (NH);
in the carbonyl range, the band at 1680 cm–1 is characterꢀ
istic of oꢀquinones. The existence of compound 6 as two
tautomers, viz., pꢀquinonimine (6) and oꢀquinone (6´),
was unambiguously confirmed by NMR data (Scheme 4).
The 1H NMR spectrum of compound 6 in C6D6 shows
signals for the protons of two nonequivalent tertꢀbutyl
groups, multiplets for the protons of the cyclohexyl subꢀ
stituent, and narrow signals for the H(5) proton at δ 6.91
The IR spectrum of compound 3 contains bands charꢀ
acteristic of the O—H and N—H (3450, 3370, and
3220 cm–1) and C=O stretching vibrations (1640 and
1625 cm–1). The structures of pꢀquinonimines 3 and 4
were also confirmed by NMR data.
In a reaction of quinone 1 with pꢀphenylenediamine,
both monoꢀ and bisadducts formed together already at
the initial step. Apparently, in contrast to the reaction
with benzidine, here the rates of the first and second steps
are comparable; because of this, only bis(pꢀquinonimine)
5 was isolated in the individual state (Scheme 3).
1
and for the OH proton at δ 7.66. The H NMR spectrum
of compound 6 in CDCl3 shows strongly broadened sigꢀ
nals for the H(5) and OH protons at δ 7.10 and 7.47,
respectively. In addition, new signals observed at δ 6.85

New quinonimines and aminoquinones
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 7, July, 2006
1197
Scheme 5
and 5.68 are due to the H(5) proton of the quinone ring
and to the NH proton, respectively. According to the
intensities of these signals, the ratio of pꢀquinonimine 6
to oꢀquinone 6´ in CDCl3 at 20 °C is 2 : 1.
A study of the temperature dependence of the 1H NMR
spectrum of compound 6 in CDCl3 from –50 to 50 °C
confirmed the above assumption. With a decrease in
the temperature, the signals for the H(5) (δ 7.08) and
OH protons (δ 7.53) become narrower and less intense.
This is accompanied by the appearance and growth of two
new signals for the NH (δ 6.00, br.s) and H(5) protons in
the oꢀquinone form (δ 6.87). At –50 °C, the presence of
the two forms is also indicated by the signals for the
tertꢀbutyl groups: along with the signals of the But protons
in the pꢀquinonimine form 6 (δ 1.26 and 1.44), more
intense peaks of 4ꢀaminoꢀoꢀquinone (6´) become proꢀ
nounced (δ 1.24 and 1.40). With an increase in the temꢀ
perature, the 1H NMR pattern returns to its original state,
which suggests reversible tautomerism.
i. Mn2(CO)10, toluene, hν.
The temperature dependence of the 1H NMR spectra
was used to determine the thermodynamic parameters of
The isotropic ESR spectrum of potassium semiꢀ
quinonolate shows a doublet due to the HFC between the
unpaired electron and the H(5) proton in the quinone
ring (a = 0.35 mT, gi = 2.0061). The ESR spectrum of
manganese derivative 8 in toluene (gi = 2.0033) (Fig. 1)
reflects the HFC between the unpaired electron and the
magnetic isotopes of one Mn atom (55Mn, I = 5/2, 100%
(see Ref. 5), ai (1Mn) = 0.67 mT), the amino N atom
(14N, I = 1, ai (1N) = 0.05 mT), and one H(5) proton in
the quinone ring (ai(1H) = 0.34 mT). In addition, this
spectrum shows a weak coupling with two equivalent proꢀ
tons of the αꢀmethylene groups of the piperidine fragꢀ
ment (ai (2H) = 0.06 mT). The absence of such an addiꢀ
tional splitting in the ESR spectrum of potassium semiꢀ
quinonolate can be due to the fact that its HFC constants
of the unpaired electron with the N atom and the protons
of the piperidine fragment are comparable with the line
width.
the equilibrium 6
6´. Because the signals correspondꢀ
ing to the HO and HN protons are broadened, we emꢀ
ployed the signals for the H(5) proton of the quinone
ring for both the forms (δ 7.08 and 6.87, respectively).
The equilibrium constants for this temperature range
were calculated from the integral intensity ratio of the
signals (Table 1). The enthalpy and entropy of this proꢀ
cess were determined from a plot of lnk vs. the reciproꢀ
cal temperature: ∆H = –11.2 1 kJ mol–1 and ∆S =
–42.8 4 J mol–1 K–1
.
Earlier,4 a similar isomerism has been reported for
4ꢀNꢀphenylꢀ1,2ꢀnaphthoquinone; however, in that case,
the oꢀquinone form is stable in the solid state, while the
quinonimine form exists in a solution in F3CCO2H.
In the case of secondary aliphatic amines, the formaꢀ
tion of an oꢀquinone product should be expected. Inꢀ
deed, a reaction of quinone 1 with piperidine gave new
4ꢀpiperidinoꢀoꢀbenzoquinone derivative 7 (Scheme 5).
The structure of oꢀquinone 7 was confirmed by the
ESR spectra of oꢀsemiquinone derivatives (potassium
oꢀsemiquinonolate and tetracarbonylmanganese oꢀsemiꢀ
quinonolate 8) obtained by its reduction.
Thus, 3,6ꢀdi(tertꢀbutyl)ꢀoꢀbenzoquinone (1) is prone
to add various amines at position 4. The resulting prodꢀ
ucts can exist in the 2ꢀhydroxyꢀpꢀquinonimine and/or
4ꢀaminoꢀoꢀquinone forms, depending on the structure of
the amine.
Table 1. Temperature dependence of the equiꢀ
librium constant for the transition 6
6´
T/K
K
223
243
263
283
303
323
2.56
1.27
0.90
0.60
0.58
0.33
0.5 mT
H
Fig. 1. Isotropic ESR spectrum of tetracarbonylmanganese
oꢀsemiquinonolate 8 in toluene at 290 K.

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Abakumov et al.
H(4´)); 7.08 (d, 2 H, H(3´) + H(5´), J = 7.4 Hz); 7.66 (s, 1 H,
OH). 13C DEPT NMR (CDCl3, 50 MHz), δ: 18.5 (CHMe2);
28.7, 29.2 (CMe3 (But)); 34.4, 36.5 (CMe3); 123.5 (pꢀCHarom);
124.7 (oꢀCarom); 126.2 (C(5)H); 126.6 (C—N); 127.8
(mꢀCHarom); 146.0, 148.5, 148.7 (C(2), C(3), C(6)); 159.0
(C=N); 183.0 (C=O).
Experimental
NMR spectra were recorded on Tesla BSꢀ567A (100 MHz
(1H)) and Bruker Avance DPXꢀ200 spectrometers (200 (1H)
and 50 MHz (13C)) with HMDS as the internal standard. ESR
spectra were recorded on a Bruker ER 200 DꢀSRC spectrometer
fitted with a ER 4105 DR double resonator (9.5 GHz). Spectra
were simulated with the WinEPR SimFonia v1.25 program
(Bruker). g Factor was determined with diphenylpicrylhydrazyl
as a standard. IR spectra were recorded on a Specord M80
spectrometer.
Solvents were purified and dehydrated according to stanꢀ
dard procedures.6 3,6ꢀDi(tertꢀbutyl)ꢀoꢀbenzoquinone (1) was
prepared according to a known procedure.7 Commercial aniline,
oꢀtoluidine, benzidine, pꢀphenylenediamine, piperidine
(Reakhim), 2,6ꢀdimethylaniline, cyclohexylamine (Fluka), and
2,6ꢀdiisopropylaniline (Aldrich) were used. Column chromaꢀ
tography was carried out on Silokhrom Sꢀ120 (Reakhim) with
hexane—ethyl acetate (100 : 1) as an eluent.
Nꢀ(2,6ꢀDiisopropylphenyl)ꢀ3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀhydroxyꢀ
pꢀbenzoquinone 4ꢀmonoimine (2d). 2,6ꢀDiisopropylaniline (5 mL,
26.5 mmol) and HCOOH (2—3 drops) were added to a solution
of quinone 1 (3 g, 13.6 mmol) in MeOH (50 mL). The reaction
mixture was refluxed for ~72 h and concentrated. The residue
was dissolved in hexane and chromatographed to collect a dark
cherry fraction. The yield of compound 2d was 1.7 g (31%), dark
cherry crystals, m.p. 120—121 °C. Found (%): C, 78.70; H, 9.38.
C26H37NO2. Calculated (%): C, 78.94; H, 9.43. IR (Nujol),
ν/cm–1: 3350 (OH); 1650, 1635 (C=O). 1H NMR (CDCl3,
100 MHz), δ: 1.04 (d, 6 H, CH3CHCH3, J = 6.6 Hz); 1.07 (s,
9 H, ButC(6)); 1.13 (d, 6 H, CH3CHCH3, J = 6.6 Hz); 1.58 (s,
9 H, ButC(3)); 2.58 (sept, 2 H, CHMe2, J = 6.6 Hz); 6.48
(s, 1 H, H(5)); 7.17 (m, 3 H, H(3´), H(4´), H(5´)); 7.68
(s, 1 H, OH).
Nꢀ[4ꢀ(4ꢀAminophenyl)phenyl]ꢀ3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀhydroxyꢀ
pꢀbenzoquinone 4ꢀmonoimine (3). Quinone 1 (3 g, 13.6 mmol)
and benzidine (2.5 g, 13.6 mmol) were dissolved in MeOH
(30 mL) and HCOOH (2 drops) were added. The reaction mixꢀ
ture was stirred with a magnetic stirring bar at room temperature
for 6 h. The precipitate that formed was recrystallized from
toluene. The yield of compound 3 was 2.96 g (54%), dark lilac
needleꢀlike crystals, m.p. 197—199 °C. Found (%): C, 77.84;
H, 7.31. C26H30N2O2. Calculated (%): C, 77.58; H, 7.51.
IR (Nujol), ν/cm–1: 3450, 3370, 3220 (OH, NH); 1640, 1625
(C=O). 1H NMR (CDCl3, 100 MHz), δ: 1.17 (s, 9 H, ButC(6));
1.55 (s, 9 H, ButC(3)); 3.60 (br.s, 2 H, NH2); 6.86 (s, 1 H,
H(5)); 6.70—7.60 (m, 8 H, C6H4—C6H4); 7.7 (br.s, 1 H, OH).
4,4´ꢀBis[2,5ꢀdi(tertꢀbutyl)ꢀ3ꢀhydroxyꢀ4ꢀoxocyclohexaꢀ
2,5ꢀdienꢀ1ꢀylideneamino]ꢀ1,1´ꢀbiphenyl (4). Quinone 1 (1 g,
4.55 mmol) and compound 3 (1.5 g, 3.74 mmol) were dissolved
in MeOH (30 mL). The reaction mixture was stirred with a
magnetic stirring bar at room temperature for 8 h. The precipiꢀ
tate that formed was recrystallized from heptane—diethyl ether
(3 : 1). The yield of compound 4 was 1.13 g (49%), lilac crystals,
m.p. 243—244 °C. Found (%): C, 77.60; H, 8.03. C40H48N2O4.
Calculated (%): C, 77.39; H, 7.79. IR (Nujol), ν/cm–1: 3350
(OH); 1650, 1630 (C=O). 1H NMR (CDCl3, 100 MHz), δ: 1.19
(s, 18 H, ButC(6)); 1.56 (s, 18 H, ButC(3)); 6.87 (s, 2 H, H(5));
6.85 (m, 4 H, oꢀCHarom); 7.62 (m, 4 H, mꢀCHarom); 7.66
(s, 2 H, OH).
NꢀPhenylꢀ3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀhydroxyꢀpꢀbenzoquinone
4ꢀmonoimine (2a). Aniline (2 mL, 21.9 mmol) and HCOOH
(2—3 drops) were added to a solution of quinone 1 (3 g,
13.6 mmol) in MeOH (50 mL). The reaction mixture was reꢀ
fluxed for 2 h and concentrated. The residue was dissolved in
hexane and chromatographed to collect a red fraction. The yield
of compound 2a was 2.3 g (54%), red crystals, m.p. 79—80 °C.
Found (%): C, 77.02; H, 8.31. C20H25NO2. Calculated (%):
C, 77.14; H, 8.09. IR (Nujol), ν/cm–1: 3360, 3340 (OH); 1655
1
and 1640 (C=O, C=N). H NMR (CDCl3, 200 MHz), δ: 1.16,
1.55 (s, 9 H, But); 6.74 (m, 2 H, H(2´), H(6´)); 6.77 (s, 1 H,
3
H(5)); 7.13 (tt, 1 H, H(4´), J = 7.4 Hz, 4J = 1.2 Hz); 7.36 (m,
2 H, H(3´), H(5´)); 7.66 (s, 1 H, OH). 13C DEPT NMR (CDCl3,
50 MHz), δ: 28.7, 31.6 (CMe3); 34.7, 36.4 (CMe3); 119.9
(oꢀCHPh); 128.7 (mꢀCHPh); 124.4 (CH, pꢀCHPh); 126.8
(CH(5)); 127.1 (C(3)); 145.8, 148.5, 149.9 (C(2), C(6), C(Ph));
157.7 (C=N); 183.3 (C=O).
Nꢀ(2ꢀMethylphenyl)ꢀ3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀhydroxyꢀpꢀbenzoꢀ
quinone 4ꢀmonoimine (2b). oꢀToluidine (1.6 mL, 15 mmol) and
HCOOH (2—3 drops) were added to a solution of quinone 1
(3 g, 13.6 mmol) in MeOH (50 mL). The reaction mixture was
refluxed for 3 h and concentrated. The residue was dissolved in
hexane and chromatographed to collect a dark red fraction. The
yield of compound 2b was 2.2 g (50%), cherryꢀcolored crystals,
m.p. 59—60 °C. Found (%): C, 77.31; H, 8.52. C21H27NO2.
Calculated (%): C, 77.50; H, 8.36. IR (Nujol), ν/cm–1: 3350
(OH); 1645, 1630 (C=O). 1H NMR (CDCl3, 100 MHz), δ: 1.13
(s, 9 H, ButC(6)); 1.56 (s, 9 H, ButC(3)); 2.12 (s, 3 H, Me); 6.44
(m, 1 H, H(6´)); 6.67 (s, 1 H, H(5)); 7.00—7.30 (m, 3 H, H(3´),
H(4´), H(5´)); 7.68 (s, 1 H, OH).
Nꢀ(2,6ꢀDimethylphenyl)ꢀ3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀhydroxyꢀpꢀbenꢀ
zoquinone 4ꢀmonoimine (2c). 2,6ꢀDimethylaniline (2 mL,
16.2 mmol) and HCOOH (2—3 drops) were added to a solution
of quinone 1 (3 g, 13.6 mmol) in MeOH (50 mL). The reaction
mixture was refluxed for 8 h and concentrated. The residue was
dissolved in hexane and chromatographed to collect a cherryꢀ
colored fraction. The yield of compound 2c was 2.1 g (47%),
cherryꢀcolored crystals, m.p. 94—95 °C. Found (%): C, 77.52;
H, 8.78. C22H29NO2. Calculated (%): C, 77.83; H, 8.61.
IR (Nujol), ν/cm–1: 3350 (OH); 1645, 1625 (C=O, C=N).
1H NMR (CDCl3, 200 MHz), δ: 1.10, 1.60 (both s, 9 H each,
But); 1.96 (s, 6 H, CH3); 6.46 (s, 1 H, H(5)); 6.96 (m, 1 H,
4,4´ꢀ(1,4ꢀPhenylenedinitrilo)bis[3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀhydrꢀ
oxycyclohexaꢀ2,5ꢀdienꢀ1ꢀone] (5). Quinone 1 (5.5 g, 25 mmol)
and pꢀphenylenediamine (1.5 g, 13.9 mmol) were dissolved in
MeOH (30 mL). The reaction mixture was stirred with a magꢀ
netic stirring bar at room temperature for 12 h. The precipitate
that formed was recrystallized from heptane—ether (3 : 1). The
yield of compound 5 was 5.12 g (67%), dark lilac crystals, m.p.
229—231 °C. Found (%): C, 75.21; H, 8.17. C34H44N2O4. Calꢀ
culated (%): C, 74.97; H, 8.14. IR (Nujol), ν/cm–1: 3340 (OH);
1645, 1630 (C=O). 1H NMR (CDCl3, 100 MHz), δ: 1.19 (s,
18 H, ButC(6)); 1.56 (s, 18 H, ButC(3)); 6.80 (s, 4 H, C6H4);
6.85 (s, 2 H, H(5)); 7.86 (s, 2 H, OH).
NꢀCyclohexylꢀ3,6ꢀdi(tertꢀbutyl)ꢀ2ꢀhydroxyꢀpꢀbenzoquinone
4ꢀmonoimine (6). Cyclohexylamine (1.65 mL, 16.6 mmol) and

New quinonimines and aminoquinones
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 7, July, 2006
1199
HCOOH (2—3 drops) were added to a solution of quinone 1
(3 g, 13.6 mmol) in THF (50 mL). The reaction mixture was
refluxed for ~48 h. The product was extracted with ether, the
extract was concentrated, and the residue was dissolved in hexꢀ
ane and chromatographed to collect a yellow fraction. The yield
of compound 6 was 1.8 g (42%), yellow crystals, m.p. 88—89 °C.
Found (%): C, 75.73; H, 9.76. C20H31NO2. Calculated (%):
C, 75.67; H, 9.84. IR (Nujol), ν/cm–1: 3360 (OH); 1645, 1635
(C=O). IR (hexane), ν/cm–1: 3340 nar. (OH); 1640; 1625
(C=O). IR (CH2Cl2), ν/cm–1: 3470; 3340 br (OH), (NH); 1680;
1640; 1625; 1550 (C=O). 1H NMR (C6D6, 200 MHz), δ: 1.11
(s, 9 H, ButC(6)); 1.77 (s, 9 H, ButC(3)); 1.34—1.73 (m, 10 H,
(CH2)5); 3.78 (m, 1 H, CHN); 6.98 (s, 1 H, H(5)); 7.72 (s, 1 H,
OH). 13C DEPT NMR (C6D6, 50 MHz), δ: 24.4, 26.0 (C(3´)H2,
C(4´)H2, C(5´)H2); 28.9, 32.4 (CMe3); 34.8, 37.0 (CMe3,
C(2´)H2, C(6´)H2); 34.9 (C(2´)H, C(6´)H); 60.2 (C(1´)H);
122.0 (C(5)H); 128.4, 145.1 and 148.2 (C(2), C(3) and C(6));
156.6 (C=N); 183.6 (C=O).
Form 6. 1H NMR (CDCl3, 200 MHz), δ: 1.27, 1.46 (both s,
9 H each, But(3)); 1.48—1.69 (m, 10 H, (CH2)5); 3.92 (sept,
1 H, CHN, J = 4.3 Hz); 7.09 (br.s, 1 H, H(5)); 7.47 (br.s,
1 H, OH). 13C DEPT NMR (CDCl3, 50 MHz), δ: 24.2, 25.7
(C(3´)H2, C(4´)H2, C(5´)H2); 28.9, 31.9 (Me3C); 34.6 (C(2´)H,
C(6´)H2); 34.7, 36.6 (CMe3); 60.0 (C(1´)H); 121.8 (C(5)H);
128.5, 144.8, 147.4 (C(2), C(3), C(6)); 155.9 (C=N);
183.5 (C=O).
Form 6´. 1H NMR (CDCl3, 200 MHz), δ: 1.24, 1.40 (both s,
9 H each, ButC(3)); 1.48—1.69 (m, (CH2)5); 3.51—3.66 (m,
1 H, CHN); 5.68 (d, 1 H, NH, J = 7.0 Hz); 6.85 (br.s, 1 H,
H(5)). 13C DEPT NMR (CDCl3, 50 MHz), δ: 24.4, 25.2
(C(3´)H2, C(4´)H2, C(5´)H2); 29.0, 30.9 (Me3C); 34.2, 35.0
(CMe3); 34.8 (C(2´)H, C(6´)H); 52.5 (C(1´)H); 115.9, 150.2,
151.6 (C(2), C(3), C(6)); 128.8 (C(5)H); 177.2, 183.1 (C=O).
3,6ꢀDi(tertꢀbutyl)ꢀ4ꢀpiperidinoꢀ1,2ꢀbenzoquinone (7). Piperiꢀ
dine (0.8 mL, 8.1 mmol) and HCOOH (2—3 drops) were added
to a solution of quinone 1 (1 g, 4.55 mmol) in MeCN (30 mL).
The reaction mixture was stirred at ~20 °C until quinone 1 was
completely consumed (TLC monitoring) and then concentrated.
The brown crystals that formed were filtered off. The yield of
compound 7 was 1.15 g (83%), m.p. 109—110 °C. Found (%):
C, 75.55; H, 9.40. C19H29NO2. Calculated (%): C, 75.19;
H, 9.63. IR (Nujol), ν/cm–1: 1675, 1665 (C=O). 1H NMR
(CDCl3, 200 MHz), δ: 1.23 (s, 9 H, But); 1.31 (s, 9 H, But); 1.66
(br.m, 6 H, mꢀ, pꢀCH2); 3.14 (br.m, 4 H, N(CH2)2); 6.90 (s,
1 H, H(5)). 13C NMR (CDCI3, 50 MHz), δ: 24.0 (pꢀCH2); 26.7
(mꢀCH2); 29.1, 30.3 (Me3C)); 34.8, 35.7 (CMe3); 53.5 (oꢀCH2);
132.2 (N—C(4)); 133.5 (C(5)H); 146.6, 157.8 (C(3), C(6));
182.0, 182.3 (C=O).
Potassium and tetracarbonylmanganese oꢀquinone 7 semiꢀ
quinolates were obtained according to known procedures.8,9
This work was financially supported by the Russian
Foundation for Basic Research (Project Nos. 04ꢀ03ꢀ32409
and 04ꢀ03ꢀ32413) and the Council on Grants of the Presiꢀ
dent of the Russian Federation (Program for State Support
of Leading Scientific Schools, Grant NShꢀ4947.2006.3).
References
1. G. A. Abakumov, V. I. Nevodchikov, N. V. Zaitova, N. O.
Druzhkov, L. G. Abakumova, Yu. A. Kurskii, and V. K.
Cherkasov, Izv. Akad. Nauk, Ser. Khim., 1997, 2206 [Russ.
Chem. Bull., 1997, 46, 2093 (Engl. Transl.)].
2. G. A. Abakumov, V. I. Nevodchikov, N. V. Zaitova, N. O.
Druzhkov, L. G. Abakumova, Yu. A. Kurskii, and V. K.
Cherkasov, Izv. Akad. Nauk, Ser. Khim., 1997, 351 [Russ.
Chem. Bull., 1997, 46, 337 (Engl. Transl.)].
3. V. B. Vol´eva, T. I. Prokof´eva, A. I. Prokof´ev, I. S.
Belostotskaya, N. L. Komissarov, and V. V. Ershov, Izv. Akad.
Nauk, Ser. Khim., 1995, 1789 [Russ. Chem. Bull., 1995, 44,
1720 (Engl. Transl.)].
4. I. D. Biggs and J. M. Tedder, Tetrahedron, 1978, 34, 1377.
5. B. A. Goodman and J. B. Raynor, Adv. Inorg. Chem.
Radiochem., 1970, 13, p. 584.
6. A. Gordon and R. Ford, Chemist´s Companion, Wiley
Interscience, New York, 1972.
7. E. G. Rozantsev and V. D. Sholle, Organicheskaya khimiya
svobodnykh radikalov [Organic Chemistry of Free Radicals],
Khimiya, Moscow, 1973, 344 pp. (in Russian).
8. E. Müller, F. Günter, K. Scheffler, and A. Reiker, Liebigs
Ann. Chem., 1965, 688, 134.
9. B. L. Tumanskii, K. A. Sarbasov, S. P. Solodovnikov, N. N.
Bubnov, A. I. Prokof´ev, and M. I. Kabachnik, Dokl. Akad.
Nauk SSSR, 1981 [Dokl. Chem., 1981 (Engl. Transl.)].
Received January 10, 2006;
in revised form June 6, 2006