Reactions of amines with zwitterionic quinoneimines: synthesis of new anionic and zwitterionic quinonoids

Article abstract of DOI:10.1002/ejoc.200900154

Following the discovery of an unprecedented transamination reaction between primary alkylamines and a quinonoid molecule of the type [C₆H ₂(-NHCH₂R)₂(-O)₂] (1), obtained from commercially available di

Full text of DOI:10.1002/ejoc.200900154

FULL PAPER
DOI: 10.1002/ejoc.200900154
Reactions of Amines with Zwitterionic Quinoneimines: Synthesis of New
Anionic and Zwitterionic Quinonoids
Farba B. Tamboura,[a] Catherine S. J. Cazin,[a][‡] Roberto Pattacini,[a] and
Pierre Braunstein*[a]
Keywords: C–N activation / Hydrogen bonds / Quinones / Amination / Zwitterions
Following the discovery of an unprecedented transamination
reaction between primary alkylamines and a quinonoid
amine. Whereas for the transamination reaction basic amines
react under mild conditions, slightly harsher conditions are
needed for less basic amines such as piperidine, diisopropyl-
amine, or diethylamine. Transamination reactions were also
performed with bis(methylamino) quinoneimine 4c, which is
more soluble in organic solvents than 3. This led to the first
examples of quinonoidal zwitterions functionalized with dif-
molecule of the type [C6H2(–NHCH2R)2(–O)2] (1), obtained
ត
ត
from commercially available diaminoresorcinol·2HCl, we
have extended this method to the use of primary arylamines,
and found that, in contrast, secondary amines led to a dif-
ferent outcome. Whereas functionalized molecules of type 1,
which are best described as 6π + 6π zwitterions, were ob- ferent alkyl groups on the nitrogen atoms. A number of com-
tained with aniline or 4-methoxyaniline, no transmination
was observed with tBuNH2 in ethanol. In water, however, a
reaction took place, but it afforded instead salt 6a, which re-
sulted from hydrolysis of the imine group and deprotonation.
Under similar conditions, secondary amines led to compar-
able results. The cations associated with the anionic quino-
noid are readily exchanged in the presence of a primary
pounds were characterized by X-ray diffraction, which al-
lowed a better understanding of their electronic situation,
and in many cases, the presence of multiple hydrogen-bond
donors and acceptors results in crystal packings dominated
by these interactions.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
which after reduction by LiAlH4 followed by aerobic work
up yielded quinonoid molecule 1. Interestingly, 1 is a rare
example of a zwitterion being more stable than its canonical
forms, and its structure is best described as involving two
chemically connected but electronically not conjugated 6π-
electron subunits.[38] A more efficient synthesis was sub-
sequently developed, which involved acylation of diami-
noresorcinol followed by reduction with LiAlH4 and aero-
bic work up.[20,38] However, only –NCH2R substituted de-
rivatives could be obtained by using this procedure. This
prompted us to develop a more versatile synthetic pathway
for this new class of molecules. It consisted of an unprece-
dented, one-pot transamination reaction on a quinonoid
fragment obtained after neutralization of commercially
available diaminoresorcinol·2HCl, followed by air oxidation
(Scheme 1).[40,46] Although this method allowed the synthe-
sis of a range of new functionalized zwitterions, it was
found to be efficient only for the transamination of nonste-
rically hindered primary alkylamines.
Introduction
Organic compounds containing a quinonoid fragment
are of great interest because of their intrinsic properties and
their numerous applications in chemistry, physical chemis-
try, and biology.[1–33] In particular, benzoquinonemonoim-
ines have been found to display unique properties in various
areas such as color,[34] organic,[35,36] supramolecular,[37] co-
ordination, and organometallic chemistry[37–44] and homo-
geneous catalysis.[39,43,45]
The first member of a new family of 12π-electron qui-
none-based zwitterions (1, R = tBu) was reported in
2002.[36] Its original preparation involved the reaction of
1,2,4,5-tetraaminobenzene with tBuC(O)Cl in wet acetoni-
trile, which led to an aromatic diamidodiester derivative,
Considering the diverse areas in which benzoqui-
nonemonoimines are involved, and the unique electronic
structure of molecules such as 1 and 3, which has aroused
considerable theoretical interest,[38,47] it appeared important
to explore the possibility of introducing various substitu-
ents R on the nitrogen atoms, which could influence the
physical properties of these molecules, such as solubility in
[a] Laboratoire de Chimie de Coordination, Institut de Chimie
(UMR 7177 CNRS),
Université de Strasbourg,
4 rue Blaise Pascal, 67070 Strasbourg, France
E-mail: braunstein@chimie.u-strasbg.fr
[‡] Present address: School of Chemistry, University of St And-
rews,
North Haugh, St Andrews, KY16 9ST, UK
3340
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Synthesis of New Anionic and Zwitterionic Quinonoids from Amines
Following these positive results with primary arylamines,
we re-examined the initially unsuccessful reactions of steri-
cally hindered alkyl congeners under these more forcing
conditions. Gratifyingly, iPrNH2 reacted in refluxing etha-
nol, within 1 h, to afford the corresponding functionalized
1
zwitterion of type 4 (4a, R = iPr, 91% yield). Its H and
13C{1H} NMR spectroscopic data are consistent with the
anticipated structure, which was unambiguously confirmed
by single-crystal X-ray diffraction (Figure 1). All crystal
structures determined in the course of this work are dis-
cussed in a separate paragraph (see below).
Scheme 1. Amination reactions on the parent quinonemonoimine
zwitterion 3.[40,46]
water and/or in organic solvents, and their electronic prop-
erties, as a result of a change in the nature of the R substitu-
ent. We thus investigated the behavior of a range of amines
toward parent zwitterion 3. Herein, we report that the scope
of this transamination reaction can be extended to primary
arylamines, and that, in contrast, secondary amines lead to
a totally different outcome. In particular, ammonium salts
of 2-amino-5-hydroxide-1,4-benzoquinone were obtained
and structurally characterized for the first time, and these
compounds are related to biologically active substituted
aminobenzoquinones.[10,11,48]
Figure 1. Molecular structure of 4a. Ellipsoids include 50% of the
electron density.
Results and Discussion
Surprisingly, when parent zwitterion 3 was treated with
tBuNH2, no transamination product was observed. In
water, however, a reaction took place that afforded salt 6a
(Scheme 3). Hydrolysis of the imine group and deproton-
ation by the base account for the formation of this salt. The
1H NMR spectrum of 6a contains two singlets correspond-
ing to the CH protons of the ring, upfield shifted with re-
spect to the CH signals of N-functionalized zwitterions. The
13C{1H} NMR spectroscopic data show two signals for the
CH groups, and the one corresponding to N–C=CH is
shifted to 94.6 ppm, downfield with respect to that of the
The first primary arylamine selected for the synthesis of
functionalized zwitterions was 4-methoxyaniline because of
the electron-donor properties of the methoxy group, which
should favor the transamination reaction. When the reac-
tion was conducted under the conditions reported for the
alkyl analogues,[46] it proved totally inefficient, but more
forcing conditions resulted in the formation of desired
product 5a. When the same conditions (reflux in ethanol
for 3 d) were applied to aniline and with the use of a much
larger excess of the amine (50 equiv.), 5b was isolated in
95% yield (Scheme 2). The 1H NMR spectra of these prod-
ucts contain singlets at 5.15 and 5.77 ppm for 5a and at
5.20 and 5.81 ppm for 5b, which are characteristic of the
zwitterions. The O–C–CH resonance was found at
ត ត
99.8 ppm. The quaternary carbon atoms give rise to four
singlets, two of them corresponding to the two O–C carbon
ត
CH groups of the quinonoid fragment (N–C–CH and O–
ត ត
atoms with very close chemical shifts.
C–CH, respectively). The 13C{1H} NMR spectroscopic
ត
ត
data are also consistent with the structures illustrated in
Scheme 2, with characteristic signals at 84.6, 98.0, 154.9,
and 172.0 ppm for 5a and at 85.2, 98.1, 155.5, and
171.8 ppm for 5b, corresponding to the N–C–C, O–C–C
ត ត ត ត
and N–C, O–C carbon atoms, respectively.
ត
ត
Scheme 2. Synthesis of aryl-functionalized zwitterions.
Scheme 3.
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FULL PAPER
The use of secondary amines under comparable experi-
mental conditions led to a similar outcome, and salts 6b–f
were obtained in good yields. Note that the ammonium cat-
ion of 6a can be exchanged by an incoming amine, as exem-
plified by the synthesis of 6c in 90% yield from the reaction
of 6a with iPr2NH (Scheme 3). 1H and 13C{1H} NMR spec-
troscopic data for compounds 6b–f are very similar to those
obtained for 6a (see Experimental Section). X-ray diffrac-
tion studies were performed on 6b, 6c, and 6d·H2O (Fig-
ures 2, 3, and 4).
Figure 4. ORTEP plot of the molecular structure of 6d·H2O, illus-
trating the H-bonding interactions between O1 and O3 of the anion
and a NH proton of the diethylammonium cation. In addition, O3
interacts with a proton of a water molecule. Ellipsoids include 50%
of the electron density.
Figure 2. ORTEP plot of the molecular structure of 6b, illustrating
the H-bonding interactions between O1 and O3 of the anion and
a NH proton of the piperidinium cation. Ellipsoids include 50% of
the electron density.
Scheme 4.
An alternative route for the synthesis of N-substituted
zwitterions consists of performing a transamination reac-
tion on the quinonoid ring of NMe derivative 4c rather
than on that of 3, a compound that is less soluble in organic
solvents (Scheme 5).[46] Such a pathway appears of great
interest for two main reasons: (1) partial transamination
could lead to N,NЈ-asymmetrically substituted zwitterions,
and (2) it could provide a route to zwitterions bearing sec-
ondary amines, which would represent an interesting exten-
sion, as the synthetic strategy applied above had proven in-
efficient so far.
Figure 3. ORTEP plot of the molecular structure of 6c, illustrating
the H-bonding interactions between O1 and O3 of the anion and a
NH proton of the diisopropylammonium cation. Ellipsoids include
50% of the electron density.
Interestingly, the more basic amines react under milder
conditions, whereas slightly harsher conditions are needed
for the less basic amines. Indeed, for piperidine, diisopro-
pylamine, or diethylamine, the reaction was complete at
room temperature within 8 h, whereas for dimethylamine
the reaction time had to be increased to 23 h. For the much
less basic morpholine, the reaction mixture had to be heated
at reflux for 7 h to obtain 6f.
Scheme 5.
The first amine selected for this transamination reaction
of 4c was iPrNH2, as we showed above that anticipated
When salts of type 6 were treated with two equivalents product 4a could be obtained by reaction of zwitterion 3
of the primary alkylamine NH2CH2CH2OH, known func- with this amine. As shown in Scheme 6, reaction of 4c with
tionalized zwitterionic product 4b was obtained an excess amount of iPrNH2 led to the formation of dis-
(Scheme 4).[46] The quinone function was thus transformed symmetric zwitterion 4e, together with the symmetric prod-
back into an imine group, which carries an additional do- uct of double transamination, 4a (Figure 1). Repeating the
nor function able to coordinate, for example, to ZnII experiment with secBuNH2 led to the isolation of dissym-
ions.[46]
metric zwitterion 4f in 64% yield (Scheme 6).
3342
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Eur. J. Org. Chem. 2009, 3340–3350

Synthesis of New Anionic and Zwitterionic Quinonoids from Amines
Scheme 6.
These are, to the best of our knowledge, the first exam-
ples of quinonoid zwitterions bearing different alkyl groups
on the nitrogen atoms. The structure of 4e was also unam-
biguously determined by single-crystal X-ray diffraction
(Figure 5).
Figure 6. ORTEP plot of the molecular structure of 4c·1/2C6H7N
showing the intermolecular O···H–N interactions between two
molecules of zwitterions 4c and a molecule of 4c and aniline. The
plotted hydrogen bonds (dashed lines) correspond to those ob-
served between the asymmetric unit molecules. Ellipsoids include
50% of the electron density.
a second product, 7b, whose anionic part was the same as
that in 7a. When pure 7b was treated with an excess amount
of tBuNH2 at room temperature in dichloromethane, ex-
change of the ammonium countercation occurred, leading
to the quantitative formation of 7a (Scheme 8). This cation
exchange reaction is consistent with the stronger basicity of
tBuNH2 relative to that of MeNH2. This methodology was
thus applied to the reaction mixture of 7a and 7b to obtain
pure 7a in good yield. Single-crystal X-ray diffraction con-
Figure 5. ORTEP plot of the molecular structure of 4e. Ellipsoids firmed the structure of 7a (Figure 7). Salts 7a and 7b clearly
include 50% of the electron density.
result from partial hydrolysis of 4c, which transforms the
ត ត ត ត
tral fragment [MeNH–C=CH–C=O].
cationic moiety [MeNH–C–CH–C–NHMe]+ into the neu-
We then attempted to use primary arylamines to synthe-
size unsymmetrically substituted zwitterions having an alkyl
or an aryl group on the nitrogen atoms. Surprisingly, the
reaction of 4c with aniline did not lead to transamination
products, even under thermal conditions for many hours,
but instead it afforded a dark brown product that was
shown by X-ray diffraction to be an adduct between 4c and
aniline of the formula 4c·1/2C6H7N (Scheme 7, Figure 6).
The formation of the latter compound certainly does not
require such harsh conditions but these emphasize the re-
luctance of aniline to undergo transamination with 4c, in
contrast to 3 (Scheme 2).
Scheme 8.
As in the case of parent zwitterions 3 (Scheme 3), sec-
ondary amines behaved similarly to tBuNH2 when treated
with 4c. In this instance, products 7c–e were formed,
Scheme 7.
whereas 7b results again from partial hydrolysis of 4c. Mix-
We also investigated whether or not the transamination tures of salts were obtained, and in the case of the piperidi-
reaction was possible on 4c with the bulky, primary alk- nium salt, the yield of 7e was increased by further addition
ylamine tBuNH2. Unsurprisingly, methyl-functionalized of piperidine to the reaction mixture (Scheme 9).
zwitterion 4c reacted similarly to its parent zwitterion 3
Finally, when salts of type 7 were treated with an excess
when treated with tBuNH2 (Scheme 3), as formation of salt amount of 2-aminoethanol, functionalized zwitterion 4b
7a occurred (Scheme 8). However, in this case, the 1H NMR was again formed (Scheme 10), similarly to the reaction
spectrum of the reaction mixture indicated the presence of starting from non N-substituted analogues 6 (Scheme 4).
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3343

F. B. Tamboura, C. S. J. Cazin, R. Pattacini, P. Braunstein
FULL PAPER
Table 1. Selected distances [Å] and angles for the crystal structures
determined by X-ray diffraction. For 4c·1/2C6H7N, only one crys-
tallographically independent molecule is reported. The second dis-
plays similar metrical data.
Figure 7. ORTEP plot of the molecular structure of 7a·H2O, illus-
trating the H-bonding interactions between O1 and O3 of the anion
and a NH proton of the cation. In addition, the N1–H proton
interacts with the oxygen atom of a water molecule. The plotted
hydrogen bonds (dashed lines) correspond to those observed be-
tween the asymmetric unit molecules. Ellipsoids include 50% of the
electron density.
4a
4c·1/2C6H7N
4e
6b
6c
6d·H2O 7a·H2O
C1–C2 1.391(4)
C2–C3 1.526(5)
C3–C4 1.391(4)
C4–C5 1.387(4)
C5–C6 1.529(4)
C6–C1 1.390(4)
O1–C2 1.252(4)
O2–C6 1.253(4)
N–C5 1.316(4)
C3–E 1.316(4)
1.400(2)
1.523(2)
1.388(2)
1.394(2)
1.525(2)
1.390(2)
1.254(1)
1.256(1)
1.316(2)
1.313(1)
1.393(4) 1.389(2) 1.378(3) 1.393(3) 1.391(3)
1.524(4) 1.537(2) 1.532(3) 1.534(3) 1.537(3)
1.396(3) 1.413(2) 1.401(3) 1.395(3) 1.412(2)
1.384(4) 1.362(2) 1.364(3) 1.376(3) 1.371(2)
1.516(4) 1.525(2) 1.515(3) 1.523(3) 1.521(2)
1.383(3) 1.397(2) 1.404(3) 1.384(3) 1.392(2)
1.249(3) 1.262(2) 1.274(3) 1.257(2) 1.261(2)
1.264(3) 1.256(2) 1.243(3) 1.264(3) 1.260(2)
1.318(3) 1.335(2) 1.323(3) 1.325(3) 1.331(2)
1.320(3) 1.241(2) 1.254(3) 1.255(3) 1.248(2)
The structural parameters of 4a, 4c·1/2C6H7N, and 4e
are as expected, and similar to those reported elsewhere for
other members of this family of zwitterions containing a
fully delocalized π system within each of the O–C–C–C–O
ត ត ត ត
Scheme 9.
and N–C–C–C–N moieties.[38] The lengths of the carbon–
ត ត ត ត
carbon bonds connecting these two π systems correspond
clearly to single bonds and indicate a lack of conjugation
between the two “6π halves” of the ligand, which is thus
best described as a zwitterionic 6π + 6π-electron molecule.
In anionic 6b, 6c, 6d·H2O, and 7a·H2O, where one of the
NHR moieties is replaced with an oxygen atom in the 3-
position, the C3–C4 bonds are, as expected, longer than
those in 4a, 4c·1/2C6H7N, and 4e. This variation is, how-
ever, not significant (within the 3σ criterion) [mean C3–C4
distance for 4a, 4e, and 4c·1/2C6H7N: 1.391(3) Å vs.
1.405(3) Å for 6b, 6c, 6d·H2O, and 7a·H2O], and the struc-
tural data indicate that a delocalization, similar to that ob-
served in the zwitterionic species, exists. Consistently, the
C4–C5 bond length is similar to that observed for the zwit-
terions and deviates significantly from that expected for a
C=C bond [mean for 6b, 6c, 6d·H2O, and 7a·H2O:
1.378(3) Å]. These data indicate an extended delocalization
within the anionic O–C–CH–C–O system, as reported in
Scheme 11. The C2–C3 and C5–C6 bond lengths remain
typical for C–C bonds.
Scheme 10.
This product results from two consecutive reactions: a
nucleophilic attack at the C=O group and a transamination
at HNMe. Our efforts to isolate an intermediate resulting
from one of these two steps and thus gain more insight into
the reaction sequence involved were unsuccessful.
To the best of our knowledge, no crystal structure on this
class of anions has been previously reported, and only one
crystal structure of a neutral, protonated derivative has
been determined thus far, featuring R = CH2–tBu and an
Discussion of the Crystal Structures
Selected bond lengths and angles for the crystal struc- OH group in the 2-position.[20]
tures determined by X-ray diffraction are given in Table 1,
The presence of multiple hydrogen-bond donors and ac-
which contains a unified labeling scheme to facilitate com- ceptors results in crystal packings dominated by these inter-
parisons.
3344
actions. In zwitterions 4a, 4c·1/2C6H7N, and 4e but also
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Synthesis of New Anionic and Zwitterionic Quinonoids from Amines
Pair A (Figure 9) displays the stacking of two zwitter-
ionic molecules that are disposed in a mutual staggered ar-
rangement. The distance between the centroids of the six-
membered rings is 3.318(1) Å. The central pair (B, Figure 9)
features a different arrangement, and the stacking involves
the N–C–CH–C–N, formally cationic, moieties. Pairs of
ត ត ត ត
Scheme 11.
atoms lie almost on the same line perpendicular to the
mean C6 planes, namely, N3–C13 and C9–C14, together
with their centrosymmetric counterparts. The distance be-
tween the atoms forming these couples is 3.519(2) Å. A
stacking similar to that shown in Figure 9B involves centro-
symmetric pairs of anions in 6d (Figure 10).
in monoanionic 6c and 6d·H2O, couples of molecules are
connected as shown, for example, in Figure 6, through
double NH···O hydrogen bonds. These interactions result in
infinite chains in the case of 4a and 4e (see Figure 8 for 4e).
Other classical hydrogen bonds (e.g., NH···O and OH···O)
are present, for example, in salts 6b, 6c, 6d·H2O, and
7a·H2O, where the cation interacts with the anion through
bifurcated hydrogen bonds of the type shown in Figures 2–
4 and 7. Other hydrogen bonds involve, when present, the
cocrystallized molecules, such as aniline in 4c·1/2C6H7N
and water in 6d·H2O and 7a·H2O, contributing to the for-
mation of extended 1D, 2D, and 3D networks.
Figure 10. Partial view of the molecular stacking in crystals of
6d·H2O. In A the view is perpendicular to the mean plane defined
by the atoms forming the six-membered cycles of the molecule clos-
est to the observer. In B, the view is tilted by 20°.
It is worthy to note that the stacking observed in 6d·H2O
involves two anions. Moreover, it involves the formally an-
ionic group of the anion, which may be counterintuitive, in
view of the expected electrostatic repulsion between the two
moieties. Similarly, the stacking of 4c·1/2C6H7N (Fig-
Figure 8. View of the crystal packing of 4e displaying a section ure 9B) is observed between the cationic “halves” of the
of the infinite net of molecules connected through double NH···O
hydrogen bonds.
molecules.
In addition to the hydrogen bonds mentioned above, col-
Conclusions
umns formed by the stacking of four zwitterionic molecules
are present in 4c·1/2C6H7N, as shown in Figure 9.
We have shown that the scope of the reactions leading to
the functionalization of zwitterionic quinoneimines can be
extended to aryl groups. Furthermore, by performing a
transamination reaction on zwitterions already bearing sub-
stituents on the nitrogen atoms, the first examples of dis-
symmetric quinonoid zwitterions were obtained. Further
extension of the scope of these reactions to secondary
amines proved impossible, as the zwitterions undergo par-
tial hydrolysis, leading to a new series of salts. Finally, we
showed that these salts react with primary alkylamines to
regenerate a zwitterionic structure. A number of crystal
structures were determined, which provide a firm basis for
the description of the electronic situation in these mole-
cules. In particular, ammonium salts of 2-amino-5-hydrox-
ide-1,4-benzoquinone were obtained and structurally char-
acterized for the first time, which has allowed a better un-
derstanding of the electronic situation in these molecules.
Furthermore, it is interesting to recall that these com-
pounds are related to neutral, biologically active, substi-
tuted 2-amino-5-hydroxy-1,4-benzoquinones, such as the
Figure 9. Partial view of the molecular stacking in crystals of 4c·
1/2C6H7N, in which columns formed by four molecules of the zwit-
terion are present. In A and B the view is perpendicular to the
mean plane defined by the atoms forming the six-membered cycles
of the molecule closest to the observer.
marine quinone sesquiterpenes nakijiquinone
A
and
smenospongidine or embelin derivatives.[10,11,48]
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for 3 d. The solvent was removed in vacuo, and the crude solid was
purified by preparative thin-layer chromatography (SiO2; CH2Cl2/
MeOH, 80:20). The product was obtained as a red solid (0.080 g,
Experimental Section
General: 1H NMR spectra were recorded at 300 MHz and 13C{1H}
NMR spectra at 75.5 MHz with an FT Bruker Avance 300 instru-
ment. Mass spectra were recorded with a Bruker Daltonics micro-
TOF (ESI; positive mode; capillary voltage: 4.8 kV; nebulizer pres-
sure: 0.2 bar; desolvation temperature: 180 °C; desolvation gas flow
rate: 4.5 Lmin–1).
1
3
64%). H NMR (300 MHz, CDCl3): δ = 0.97 (t, JH,H = 7.4 Hz, 3
3
H, CH2CH3), 1.31 (d, JH,H = 6.5 Hz, 3 H, CHCH3), 1.69 (m, 2
H, CH2CH3), 3.10 (s, 3 H, NCH3), 3.66 (m, 1 H, CHCH3), 5.13 (s,
1 H, N–C–CH), 5.43 (s, 1 H, O–C–CH), 8.22 (br. s, 1 H, NH), 8.45
ត ត
ត ត
(br. s, 1 H, NH) ppm. 13C{1H} NMR (75.5 MHz, CDCl3): δ = 10.6
(s, CH2CH3), 19.6 (s, CHCH3), 29.2 (s, CH2), 29.9 (s, NCH3), 51.2
Compound 4a: Isopropylamine (0.372 g, 6.28 mmol) was added to
an ethanol (10 mL) suspension of parent zwitterion 3 (0.062 g,
0.45 mmol). The reaction mixture was heated to reflux for 1 h. The
solvent was removed in vacuo, and the crude solid was washed with
diethyl ether (2ϫ10 mL). The product was obtained as a violet
solid (0.090 g, 0.40 mmol, 88%). Single crystals suitable for X-ray
diffraction were obtained by slow evaporation of an ethanol solu-
tion of the product. 1H NMR (300 MHz, [D6]DMSO): δ = 1.24 (d,
3JH,H = 6.4 Hz, 12 H, CH3), 4.06 (m, 2 H, CHCH3), 4.98 (s, 1 H,
(s, NCH), 80.5 (s, N–C–CH), 99.0 (s, O–C–CH), 156.0 (s, C–N),
ត ត ត ត
ត
157.7 (s, C–N), 172.4 (s, C–O), 172.7 (s, C–O) ppm. MS (ESI+):
ត
ត
ត
m/z (%) = 215 (80) [M + Li]+.
Compound 5a: p-Methoxyaniline (0.750 g, 6.09 mmol) was added
to an ethanol (20 mL) suspension of parent zwitterion 3 (0.120 g,
0.87 mmol). The reaction mixture was heated to reflux for 3 d. The
crude solid was washed with diethyl ether (2ϫ40 mL) and dichlo-
romethane (20 mL). The product was obtained as a black solid
(0.180 g, 59%). 1H NMR (300 MHz, [D6]DMSO): δ = 3.75 (s, 6 H,
N–C–C-H), 5.56 (s, 1 H, O–C–C-H), 8.64 (br. s, 2 H, NH) ppm.
ត ត ត ត
13C{1H} NMR (75.5 MHz, [D6]DMSO): δ = 21.1 (s, CHCH3), 44.6
OCH3), 5.15 (s, 1 H, N–C–CH), 5.77 (s, 1 H, O–C–CH), 7.00 (d,
ត ត
ត ត
3
(s, CHCH ), 81.2 (s, N–C–CH), 97.6 (s, O–C–CH), 154.7 (s, C–N),
ត ត
ត ត
ត
3JH,H = 7.2 Hz, 4 H, CH aromatic), 7.35 (d, JH,H = 7.2 Hz, 4 H,
3
172.0 (s, C–O) ppm. MS (ESI+): m/z (%) = 223 (87) [M + H]+, 245
ត
CH aromatic), 10.78 (br. s, 2 H, NH) ppm. 13C{1H} NMR
(11) [M + Na]+, 229 (2) [M + Li]+. C12H18N2O2·1/3H2O: calcd. C
(75.5 MHz, [D6]DMSO): δ = 55.4 (s, OCH3), 84.6 (s, N–C–CH),
ត ត
63.13, H 8.24, N 12.27; found C 63.47, H 7.99, N 12.64.
98.0 (s, O–C–CH), 114.4 (s, CH aromatic), 126.0 (s, CH aromatic),
ត ត
129.0 (s, C aromatic), 154.9 (s, C-N), 158.2 (s, 1 C), 172.0 (s, C–O)
ត
Compound 4c·1/2C6H7N: To a solution of zwitterion 4c (0.100 g,
0.60 mmol) dissolved in EtOH (10 mL) was added aniline (0.392 g,
4.21 mmol). The reaction mixture was heated to reflux for 18 h and
cooled to room temperature, and after slow evaporation, dark
brown crystals were obtained. These were washed with pentane
(3ϫ10 mL) and dried, and the compound was obtained as a brown
solid (0.090 g, 70%). Crystals suitable for X-ray diffraction were
ppm. MS (ESI+): m/z (%) = 351 (38) [M + H]+. C20H18N2O4·2/
3H2O: calcd. C 66.29, H 5.38, N 7.73; found C 66.43, H 5.58, N
7.26.
Compound 5b: Aniline (3.370 g, 36 mmol) was added to an ethanol
(20 mL) suspension of parent zwitterion 3 (0.100 g, 0.72 mmol).
The reaction mixture was heated to reflux for 4 d. The mixture was
cooled down to room temperature, and the crude solid was washed
with diethyl ether (3ϫ40 mL). The product was obtained as a
obtained by slow evaporation of an ethanol solution of the com-
3
pound. 1H NMR (300 MHz, [D6]DMSO): δ = 2.99 (d, JH,H
=
1
5.4 Hz, 12 H, CH3), 4.93 (s, 2 H, N–C–C-H), 5.32 (s, 2 H, O–C–
ត ត
black solid (0.200 g, 95%). H NMR (300 MHz, [D6]DMSO): δ =
ត
C-H), 6.47 (m, 1 H, CH aromatic), 6.54 (m, 2 H, CH aromatic),
5.20 (s, 1 H, N–C–CH), 5.81 (s, 1 H, O–C–CH), 7.26–7.33 (m, 2
ត
ត ត
ត ត
6.99 (m, 2 H, CH aromatic), 9.12 (br. s, 4 H, NH) ppm. 13C{1H}
H, CH aromatic), 7.36–7.47 (m, 8 H, CH aromatic), 10.97 (br. s, 2
H, NH) ppm. 13C{1H} NMR (75.5 MHz, [D6]DMSO): δ = 85.2 (s,
N–C–CH), 98.1 (s, O–C–CH), 124.8 (s, CH aromatic), 127.4 (s, CH
NMR (75.5 MHz, [D6]DMSO): δ = 29.6 (s, CH3), 81.3 (s, N–C–
ត
CH), 97.5 (s, O–C–CH), 113.8 (s, CH aromatic), 115.6 (s, CH aro-
ត ត
ត
ត ត
ត ត
matic), 128.8 (s, CH aromatic), 148.6 (s, C aromatic), 156.9 (s, C–
aromatic), 129.2 (s, CH aromatic), 136.5 (s, C aromatic), 155.5 (s,
N), 172.2 (s, C–O) ppm. MS (ESI+): m/z (%) = 355 (33)
C–N), 171.8 (s, C–O) ppm. MS (ESI+): m/z (%) = 291 (80) [M +
ត
ត
ត
ត
[C16H20N4NaO4]+,
333 (13)
[C16H21N4O4]+, 205
(11)
H]+. C18H14N2O2·1/6H2O: calcd. C 73.71, H 4.93, N 9.55; found
[C8H10KN2O2]+, 189 (16) [C8H10N2NaO2]+, 167 (27) [C8H11N2O2]
+. C22H27N5O4 (425.49): calcd. C 62.10, H 6.40, N 16.46; found C
61.86, H 6.32, N 16.28.
C 73.72, H 5.23, N 9.77.
Compound 6a: tert-Butylamine (0.115 g, 1.57 mmol) was added to
a water (10 mL) suspension of zwitterion 3 (0.031 g, 0.22 mmol).
The reaction mixture was stirred at room temperature for 18 h and
then washed with dichloromethane (3ϫ10 mL). Removal of the
solvent led to compound 6a as a red solid (0.035 g, 75%). 1H NMR
(300 MHz, [D6]DMSO): δ = 1.23 (s, 9 H, tBu), 4.85 (s, 1 H,
Compound 4e: Isopropylamine (0.490 g, 8.28 mmol) was added to
an ethanol (20 mL) suspension of zwitterion 4c (0.100 g,
0.60 mmol). The reaction mixture was stirred at room temperature
overnight. The solvent was removed in vacuo, and the crude solid
was purified by preparative thin-layer chromatography (SiO2;
CH2Cl2/MeOH, 80:20). The product was obtained as a red solid
(0.050 g, 43%). Single crystals suitable for X-ray diffraction were
obtained after 2 d from an acetonitrile solution of the product in
NC=CH), 5.13 (s, 1 H, O–C–CH), 6.49 (br. s, 1 H, NH), 7.20 (br.
ត ត
s, 1 H, NH), 7.75 (br. s, 3 H, NH3) ppm. 13C{1H} NMR
(75.5 MHz, [D6]DMSO): δ = 28.1 (s, CH3), 50.5 [s, C(CH3)3], 94.6
(s, NC=CH), 99.8 (s, O–C–CH), 155.7 (s, NC), 175.8 (s, C–O),
ត ត
ត
1
an NMR tube. H NMR (300 MHz, [D3]acetonitrile): δ = 1.30 (d,
176.8 (s, C–O), 183.4 (s, C=O) ppm. MS (ESI+): m/z (%) = 213
ត
3JH,H = 6.5 Hz, 1 H, CHCH3), 3.05 (s, 3 H, NCH3), 3.99 (m, 1 H,
CHCH ), 5.06 (s, 1 H, N–C–CH), 5.37 (s, 1 H, O–C–CH), 7.84 (br.
(97) [M + H]+. C10H16N2O3·2H2O: calcd. C 48.38, H 8.12, N 11.28;
found C 48.3, H 7.2, N 11.8.
ត ត
ត ត
3
s, 1 H, NH), 8.11 (br. s, 1 H, NH) ppm. 13C{1H} NMR (75.5 MHz,
Compound 6b: Piperidine (0.133 g, 1.56 mmol) was added to a
water (10 mL) suspension of zwitterion 3 (0.031 g, 0.22 mmol). The
reaction mixture was stirred at room temperature for 8 h and then
washed with dichloromethane (3ϫ20 mL). The aqueous phase was
filtered, and the solvent was removed in vacuo. The crude solid was
washed with pentane (2ϫ10 mL) and dichloromethane
(1ϫ10 mL), then dissolved in methanol (1ϫ10 mL), and filtered.
Removal of the solvents afforded compound 6b as a red solid
[D3]acetonitrile): δ = 21.7 (s, CHCH3), 30.2 (s, NCH3), 46.2 (s,
CHCH ), 82.2 (s, N–C–CH), 98.1 (s, O–C–CH), 158.5 (s, C–N),
ត ត ត ត
ត
3
173.2 (s, C–O), 173.4 (s, C–O) ppm. MS (ESI+): m/z (%) = 195
ត
ត
(20) [M + H]+, 217 (80) [M + Na]+.
Compound 4f: sec-Butylamine (0.620 g, 8.48 mmol) was added to
an ethanol (20 mL) suspension of zwitterion 4c (0.100 g,
0.60 mmol). The reaction mixture was stirred at room temperature
3346
www.eurjoc.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3340–3350

Synthesis of New Anionic and Zwitterionic Quinonoids from Amines
(0.024 g, 48%). Crystals suitable for X-ray diffraction were ob-
tained by slow diffusion of pentane into an ethanol solution of the
compound. H NMR (300 MHz, [D6]DMSO): δ = 1.48–1.69 (m, 6
[C8H13N2O3]+, 184 (27) [C8H12N2O3]. C8H12N2O3·1/2H2O: calcd.
C 49.7, H 6.8, N 14.5; found C 49.2, H 6.6, N 13.4.
1
Compound 6f: Morpholine (0.821 g, 9.42 mmol) was added to a
water (30 mL) suspension of zwitterion 3 (0.186 g, 1.35 mmol). The
reaction mixture was stirred at reflux for 8 h, cooled to room tem-
perature, and washed with dichloromethane (4ϫ10 mL). Removal
of the solvent led to compound 6f as a brown solid (0.248 g, 81%).
1H NMR (300 MHz, [D6]DMSO): δ = 3.02 (br. s, 4 H, N-CH2-),
3.71 (br. s, 4 H, OCH2), 4.96 (s, 1 H, NC=CH), 5.18 (s, 1 H,
H, CH2CH2CH2), 2.98 (br. m, 4 H, CH2NCH2), 4.85 (s, 1 H,
NC=CH), 5.13 (s, 1 H, O–C–CH), 6.40 (br. s, 1 H, NH), 7.22 (br.
ត ត
s, 1 H, NH), 8.45 (br. s, 2 H, NH) ppm. 13C{1H} NMR (75.5 MHz,
[D6]DMSO): δ = 22.0 (s, CH2CH2CH2), 22.6 (s, CH2CH2CH2),
43.9 (s, CH2NCH2), 94.6 (s, NC=CH), 99.7 (s, O–C–CH), 155.7 (s,
ត ត
NC), 175.6 (s, C–O), 177.0 (s, C–O), 183.5 (s, C=O) ppm. MS
ត
ត
(MADI-TOF+): m/z (%) = 225 (24) [M + H]+. C11H16N2O3·
1/2 H2O: calcd. C 56.64, H 7.35, N 12.01; found C 56.79, H 7.23,
N 11.73.
O–C–CH), 6.63 (br. s, 1 H, NH), 7.36 (br. s, 1 H, NH), 8.93 (br. s,
ត ត
2 H, NH) ppm. 13C{1H} NMR (75.5 MHz, [D6]DMSO): δ = 43.2
(s, NCH2), 63.8 (s, OCH2), 94.5 (s, NC=CH), 99.9 (s, O–C–CH),
ត ត
155.7 (s, NC), 176.4 (s, C–O), 176.6 (s, C–O), 183.5 (s, C=O) ppm.
MS (ESI+): m/z (%) = 179 (100). C10H14N2O4·1/2 H2O: calcd. C
51.06, H 6.43, N 11.91; found C 51.39, H 6.61, N 11.30.
ត
ត
Compound 6c: Diisopropylamine (0.158 g, 1.56 mmol) was added
to a water (10 mL) suspension of zwitterion 3 (0.031 g, 0.22 mmol).
The reaction mixture was stirred at room temperature for 8 h and
then washed with dichloromethane (3ϫ20 mL). The water was re-
moved in vacuo. The crude product was dissolved in methanol
(10 mL), and the solution was filtered. Removal of the solvent in
General Procedure for the Synthesis of 4b from Compounds of the
Type 6 or 7: 2-Aminoethanol (1.0 or 3.5 mmol) was added to an
ethanol (15 mL) solution of 6 or 7 (0.50 mmol). The reaction mix-
ture was stirred at room temperature for 17 h. The solvent was
removed in vacuo, and the crude product was washed with pentane
(1ϫ10 mL). The product was obtained as a red solid. NMR spec-
troscopic data were comparable to those published.[46]
1
vacuo led to the product as a red solid (0.036 g, 68%). H NMR
(300 MHz, CD3OD): δ = 1.28 (d, 3JH,H = 6.5 Hz, 12 H, CH3), 3.42
(br. m, 2 H, CHCH3), 5.30 (s, 1 H, NC=CH), 5.38 (s, 1 H, O–C–
ត
1
3
CH) ppm. H NMR (300 MHz, [D6]DMSO): δ = 1.20 (d, JH,H
6.5 Hz, 12 H, CH3), 3.35 (m, JH,H = 6.5 Hz, 2 H, CHCH3), 5.04
=
ត
3
Compound 7a, Starting from 4c: tert-Butylamine (0.308 g,
4.21 mmol) was added to a water (15 mL) solution of function-
alized zwitterion 4c (0.100 g, 0.60 mmol). The reaction mixture was
stirred at room temperature for 17 h. The aqueous solution was
washed with dichloromethane (3ϫ20 mL) and water was removed
in vacuo. The solid was washed with pentane (1ϫ10 mL), and then
dichloromethane (15 mL) and tert-butylamine (0.18 mL,
1.67 mmol) were added. The reaction mixture was stirred at room
temperature overnight, and the solvent was removed in vacuo. The
crude solid was washed with pentane (1ϫ10 mL), and the product
was obtained as a red solid (0.070 g, 52%). 1H NMR (300 MHz,
(s, 1 H, NC=CH), 5.20 (s, 1 H, O–C–CH), 6.62 (br. s, NH), 7.31
ត ត
(br. s, NH), 7.88 (br. s, NH) ppm. 13C{1H} NMR (75.5 MHz, [D6]-
DMSO): δ = 18.8 (s, CH3), 46.1 [s, CH(CH3)2], 94.8 (s, NC=CH),
99.9 (s, O–C–CH), 155.3 (s, NC), 175.4 (s, C–O), 176.4 (s,
ត ត
ត
C–O), 183.1 (s, C=O) ppm. MS (ESI–): m/z (%) = 138 (100)
ត
[C6H4NO3]–. MS (ESI+): m/z (%) = 241 (35) [M + H]+, 102 (30)
[C6H16N]+. C12H20N2O3·1/2H2O: calcd. C 57.81, H 8.49, N 11.24;
found C 57.95, H 8.35, N 11.48. It was observed that an alternative
to the direct synthesis of 6c reported above is the cation exchange
reaction starting from 6a.
3
[D6]DMSO): δ = 1.25 [s, 9 H, C(CH3)3], 2.70 (d, JH,H = 5.0 Hz, 3
Compound 6d: Diethylamine (0.115 g, 1.57 mmol) was added to a
water (10 mL) suspension of zwitterion 3 (0.031 g, 0.22 mmol). The
reaction mixture was stirred at room temperature for 8 h and then
washed with dichloromethane (3ϫ20 mL). The aqueous phase was
filtered, and the solvent was removed in vacuo. The crude solid
was washed with dichloromethane (2ϫ10 mL), then dissolved in
methanol and filtered. Removal of the solvent led to compound 6d
as a red solid (0.027 g, 56%). Crystals suitable for X-ray diffraction
were obtained by slow diffusion of pentane into an ethanol solution
of the compound. 1H NMR (300 MHz, [D6]DMSO): δ = 1.13 (t,
H, NCH ), 4.90 (s, 1 H, NC=CH), 4.91 (s, 1 H, O–C–CH), 7.26
3
ត ត
(br. s, 1 H, NH), 8.01 (br. s, 3 H, NH3) ppm. 13C{1H} NMR
(75.5 MHz, [D6]DMSO): δ = 27.1 [s, C(CH3)], 28.6 (s, HNCH3),
50.5 [C(CH )], 92.0 (s, NC=CH), 99.7 (s, O–C–CH), 154.4 (s, NC),
ត ត
3
175.1 (s, C–O), 177.0 (s, C–O), 182.7 (s, C=O) ppm. C H N O ·
ត
ត
11 18
2
3
4/3H2O: calcd. C 52.8, H 8.3, N 11.2; found C 52.7, H 7.7, N 10.9.
MS (ESI–): m/z (%) = 152 (88) [C7H6NO3]–.
Compound 7a, Starting from 7b (Ammonium Exchange): tert-Bu-
tylamine (0.280 g, 3.80 mmol) was added to a dichloromethane
(10 mL) suspension of salt 7b (0.100 g, 0.54 mmol). The reaction
mixture was stirred at room temperature for 17 h. The solvent was
removed in vacuo, and the crude product was washed with pentane
(1ϫ10 mL) and dried in vacuo. Compound 7a was obtained as
a red solid (0.095 g, 78%). Crystals of 7a·H2O suitable for X-ray
diffraction were obtained by slow diffusion of pentane into an etha-
nol solution of the compound.
3
3JH,H = 7.2 Hz, 6 H, CH3CH2), 2.90 (q, JH,H = 7.2 Hz, 4 H,
CH3CH2), 4.86 (s, 1 H, NC=CH), 5.14 (s, 1 H, O–C–CH), 6.53 (br.
ត ត
s, 1 H, NH), 7.20 (br. s, 1 H, NH), 8.40 (br. s, 2 H, NH2) ppm.
13C{1H} NMR (75.5 MHz, [D6]DMSO): δ = 11.0 (s, CH3), 41.3 (s,
CH2), 94.6 (s, N-C=CH), 99.8 (s, O–C–CH), 155.5 (s, N-C), 175.8
ត ត
(s, C–O), 176.5 (s, C–O), 183.3 (s, C=O) ppm. MS (ESI+): m/z (%)
ត
ត
= 231 (24) [M + H2O + H]+. C10H16N2O3·1/2 H2O: calcd. C 54.3,
H 7.7, N 12.7; found C 53.9, H 7.0, N 12.7.
Compound 7c: Diethylamine (0.154 g, 2.11 mmol) was added to a
water (5 mL) solution of functionalized zwitterion 4c (0.050 g,
0.30 mmol). The reaction mixture was stirred at room temperature
for 17 h and then washed with dichloromethane (3ϫ20 mL). The
aqueous phase was evaporated, and the crude product was washed
with dichloromethane (1ϫ20 mL) and dried in vacuo. The product
was obtained as a pale-red solid (0.033 g, 48%). 1H NMR
Compound 6e: Dimethylamine (0.105 g, 2.33 mmol) was added to
a water (10 mL) suspension of zwitterion 3 (0.046 g, 0.33 mmol).
The reaction mixture was stirred at room temperature for 23 h and
then washed with dichloromethane (3ϫ20 mL). The solvent was
removed in vacuo, and the product was obtained as a red solid
(0.036 g, 59%). 1H NMR (300 MHz, [D6]DMSO): δ = 2.48 (s, 6 H,
3
Me), 4.93 (s, 1 H, NC=CH), 5.19 (s, 1 H, O–C–CH), 6.66 (br. s, 1
ត ត
(300 MHz, [D6]DMSO): δ = 1.15 (t, JH,H = 7.3 Hz, 6 H, CH3),
3
3
H, NH), 7.44 (br. s, 1 H, NH), 9.08 (br. s, 2 H, NH2) ppm. 13C{1H} 2.69 (d, JH,H = 5.0 Hz, 3 H, CH3), 2.92 (d, JH,H = 7.3 Hz, 4 H,
NMR (75.5 MHz, [D6]DMSO): δ = 34. 3 (s, CH3), 94.4 (s,
CH2), 4.95 (s, 1 H, NC=CH), 5.00 (s, 1 H, O–C–CH), 7.30 (br. s,
ត ត
NC=CH), 99.7 (s, O–C–CH), 155.6 (s, NC), 176.0 (s, C–O), 176.7 (s, 1 H, NH), 8.63 (br. s, 2 H, NH2) ppm. 13C{1H} NMR (75.5 MHz,
ត ត
ត
C–O), 183.4 (s, C=O) ppm. MS (ESI+): m/z (%) = 185 (73) [D6]DMSO): δ = 11.0 (CH2CH3), 28.6 (HNCH3), 41.3 (CH2), 91.9
ត
Eur. J. Org. Chem. 2009, 3340–3350
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
3347

F. B. Tamboura, C. S. J. Cazin, R. Pattacini, P. Braunstein
FULL PAPER
(s, NC=CH), 99.7 (s, O–C–CH), 154.4 (s, NC), 175.4 (s, C–O),
ត ត
C=O) ppm. C9H14N2O3·H2O: calcd. C 49.99, H 7.46, N 12.96;
found C 49.71, H 6.89, N 11.89. MS (ESI+): m/z (%) = 199 (100)
[M + H]+.
ត
176.8 (s, C–O), 182.8 (s, C=O) ppm. C11H18N2O3·H2O: calcd. C
ត
54.08, H 8.25, N 11.47; found C 54.21, H 8.27, N 10.55. MS
(ESI+): m/z (%) = 227 (100) [M + H]+.
Compounds 7e and 7b: Piperidine (0.301 g, 3.53 mmol) was added
to a water (5 mL) solution of functionalized zwitterion 4c (0.084 g,
0.50 mmol). The reaction mixture was stirred at room temperature
for 17 h and then washed with dichloromethane (3ϫ20 mL). The
aqueous solution was evaporated to dryness, and the solid residue
was suspended in dichloromethane (20 mL). Compound 7b was
collected by filtration, washed with dichloromethane (1ϫ20 mL),
and obtained as a red solid (0.035 g, 38%). The dichloromethane
Compound 7d: Dimethylamine (0.074 g, 1.64 mmol) was added to
an aqueous solution (5 mL) of functionalized zwitterion 4c
(0.039 g, 0.23 mmol). The reaction mixture was stirred at room
temperature for 17 h and then washed with dichloromethane
(3ϫ20 mL). The solvent was removed in vacuo, and the solid was
washed with dichloromethane (1ϫ20 mL). The product was ob-
tained as a red solid (0.032 g, 69%). 1H NMR (300 MHz, [D6]-
DMSO): δ = 2.54 (s, 6 H, CH3), 2.69 (d, 3JH,H = 4.6 Hz, 3 H, CH3), solutions were combined and the solvent evaporated to dryness,
4.92 (s, 1 H, NC=CH), 4.93 (s, 1 H, O–C–CH), 7.28 (br. s, 1 H,
leading to compound 7e as a red solid (0.062 g, 52%). Data for 7e:
1H NMR (300 MHz, [D6]DMSO): δ = 1.55 (br. m, 2 H, -CH2-CH2-
CH2-),1.65 (br. m, 4 H, -CH2-CH2-CH2-), 2.72 (d, 3JH,H = 5.22 Hz,
3 H, CH3), 2.98 (br. m, 4 H, CH2NCH2), 5.24 (s, 1 H, NC=CH),
ត ត
NH), 8.47 (br. s, 2 H, NH2) ppm. 1H (300 MHz, D2O): δ = 2.70 (s,
6 H, 2CH3), 2.91 (d, 3 H, CH3), 5.30 (s, 1 H, CH) ppm. [Note: the
anionic part of this salt reacts with D2O, which exchanges the H
atom of the (O–C–CH) moiety for deuterium; this explains the ap-
5.73 (s, 1 H, O–C–CH), 7.80 (br. s, 1 H, NH), 8.78 (br. s, 2 H,
ត ត
ត ត
pearanceofthesignalatδ=5.30 ppm].13C{1H}NMR(75.5 MHz,[D6]-
NH2) ppm. 13C{1H} NMR (75.5 MHz, [D6]DMSO): δ = 21.7 (s,
DMSO): δ = 28.8 (CH3), 34.4 (CH3), 92.4 (s, NC=CH), 101.5 (s, CH2CH2CH2), 22.1 (s, CH2CH2CH2), 29.0 (s, CH3), 43.5 (s,
O–C–CH), 152.4 (s, N-C), 169.6 (s, C–O), 178.9 (s, C–O), 180.6 (s, NCH2), 92.8 (s, NC=CH), 103.4 (s, O–C–CH), 150.2 (s, N-C),
ត ត
ត
ត
ត ត
Table 2. Data collection and refinement parameters for all compounds.
4a
4c·1/2C6H7N
4e
6b
Formula
Mr
C12H18N2O2
222.28
2(C8H10N2O2)·C6H7N
425.49
C10H14N2O2
194.23
C5H12N·C6H4NO3
224.26
Cell setting
Space group
a [Å]
b [Å]
c [Å]
orthorhombic
P212121
5.6951(5)
15.3531(11)
14.0639(9)
90.00
1229.71(16)
4
1.201
monoclinic
P21/c
11.5189(4)
16.0820(7)
11.6051(5)
92.498(2)
2147.77(15)
4
1.316
monoclinic
P21/c
12.744(1)
7.399(1)
10.838(1)
90.754(7)
1021.9(2)
4
monoclinic
P21/c
8.4333(3)
12.6529(5)
11.0569(5)
108.824(2)
1116.73(8)
4
β [°]
V [Å3]
Z
Dx [Mgm–3]
1.263
0.09
1.334
0.10
µ [mm–1]
0.08
0.09
Crystal size [mm]
Measured, independent,
observed reflections
Rint
0.22ϫ0.20ϫ0.10
12445, 1658, 1210
0.10ϫ0.10ϫ0.06
12483, 7437, 4371
0.18ϫ0.14ϫ0.12
3169, 1887, 838
0.22ϫ0.20ϫ0.18
4143, 2547, 1693
0.117
27.5
0.076, 0.116, 1.14
157
0.20, –0.19
0.035
32.0
0.054, 0.142, 1.01
388
0.31, –0.26
0.072
25.5
0.056, 0.121, 0.99
138
0.24, –0.28
0.027
27.5
0.043, 0.122, 1.05
161
0.21, –0.26
θmax [°]
R[F2 Ͼ 2σ(F2)], wR(F2), S
No. parameters
∆ρmax, ∆ρmin [eÅ–3]
6c
6d·H2O
7a·H2O
Formula
Mr
C6H4NO3·C6H16N
240.30
C4H12N·C6H4NO3·H2O
230.26
C22H38N4O7
470.56
Cell setting,
Space group
a [Å]
b [Å]
c [Å]
monoclinic
P21/c
orthorhombic
Pbca
13.9133(6),
12.6639(6),
14.9583(8)
90.00
2635.6(2)
8
1.161
0.09
monoclinic
C2/c
7.5733(8),
14.247(1),
12.3760(8)
95.566(6)
1329.0(2)
4
13.6464(10),
11.8438(10),
17.2223(9)
112.091(4)
2579.2(3)
4
β [°]
V [Å3]
Z
Dx [Mgm–3]
1.201
0.09
1.212
0.09
µ [mm–1]
Crystal size [mm]
Measured, independent,
observed reflections
Rint
0.20ϫ0.10ϫ0.10
4528, 2607, 1305
0.25ϫ0.22ϫ0.08
5398, 2948, 1158
0.25ϫ0.25ϫ0.14
7780, 2950, 1735
0.054
26.0
0.058, 0.134, 1.07
174
0.23, –0.24
0.104
27.5
0.052, 0.108, 0.96
169
0.17, –0.19
0.057
27.5
0.058, 0.123, 1.01
174
0.17, –0.23
θmax [°]
R[F2 Ͼ 2σ(F2)], wR(F2), S
No. parameters
∆ρmax, ∆ρmin [eÅ–3]
3348
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2009, 3340–3350

Synthesis of New Anionic and Zwitterionic Quinonoids from Amines
[13] O. Siri, P. Braunstein, M.-M. Rohmer, M. Bénard, R. Welter,
J. Am. Chem. Soc. 2003, 125, 13793.
162.0 (s, C–O), 178.3 (s, C–O), 182.5 (s, C=O) ppm. MS (ESI+):
ត
ត
m/z (%) = 239 (100) [M + H]+. C12H18N2O3·H2O: calcd. C 56.23,
1
[14] M. Oh, G. B. Carpenter, D. A. Sweigart, Organometallics 2003,
H 7.87, N 10.93; found C 55.71, H 7.83, N 11.32. Data for 7b: H
22, 2364.
NMR (300 MHz, [D6]DMSO): δ = 2.37 (s, 3 H, CH3), 2.70 (br. s
[15] K. S. Min, T. Weyhermüller, K. Wieghardt, Dalton Trans. 2003,
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3 H, CH3), 4.88 (s, 1 H, NC=CH), 4.90 (s, 1 H, O–C–CH), 7.22
ត ត
(br. s, 1 H, NH), 7.79 (br. s, 3 H, NH3) ppm. 13C{1H} NMR
(75 MHz, [D6]DMSO): δ = 24.6 (s, CH3), 28.6 (s, CH3), 91.9 (s,
NC=CH), 99.6 (s, O–C–CH), 154.5 (s, N-C), 175.2 (s, C–O), 177.1
ត ត
ត
[17] R. S. Coliman, F. X. Felpin, W. Chen, J. Org. Chem. 2004, 69,
(s, C–O), 182.8 (s, C=O) ppm. MS (ESI–): m/z (%) = 152 (100)
7309.
ត
[M – H3NMe]–. MS (ESI+): m/z (%) = 154 (47) [M – H3NMe +
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Braunstein, Chem. Eur. J. 2004, 10, 134.
2H]+.
X-ray Data Collection, Structure Solution, and Refinement for All
Compounds: Suitable crystals for X-ray analysis were obtained as
described above. The intensity data was collected at 173(2) K with
a Kappa CCD diffractometer[49] (graphite monochromated Mo-Kα
radiation, λ = 0.71073 Å). Crystallographic and experimental de-
tails for the structures are summarized in Table 2. The structures
were solved by direct methods (SHELXS-97) and refined by full-
matrix least-squares procedures (based on F2, SHELXL-97)[50] with
anisotropic thermal parameters for all the non-hydrogen atoms.
The hydrogen atoms were introduced into the geometrically calcu-
lated positions (SHELXS-97 procedures) and refined riding on the
corresponding parent atoms, except those on the nitrogen or oxy-
gen atoms, which were found in the ∆F2 maps and refined iso-
tropically. CCDC-720164 (for 4a), -720165 (for 4c·1/2C6H7N), -
720166 (for 4e), -720167 (for 6b), -720168 (for 6c), -720169 (for
6d·H2O), and -720170 (for 7a·H2O) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
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Acknowledgments
We thank the Centre National de la Recherche Scientifique
(CNRS), the Ministère de la Recherche (Paris), the Agence Nation-
ale de la Recherche (ANR) (07-BLAN-0274-04), and the Agence
de la Francophonie for financial support and the Département de
Chimie, Faculté des Sciences et Techniques, Université Cheikh
Anta Diop, Dakar, for allowing F.B.T. to prepare his PhD Thesis
in Strasbourg.
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www.eurjoc.org
3349

F. B. Tamboura, C. S. J. Cazin, R. Pattacini, P. Braunstein
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Received: February 13, 2009
Published Online: June 3, 2009
3350
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Eur. J. Org. Chem. 2009, 3340–3350