Reversible capture and release of aromatic amines by vicinal tricarbonyl compound

Article abstract of DOI:10.1016/j.tet.2016.03.093

In this paper, we report reversible capture and release of aromatic amines by diphenylpropanetrione (DPPT). Addition of aromatic amines to the central carbonyl group occurred readily at ambient temperature to provide the aromatic amine adducts of DPPT (DPPT-aromatic amines), which has a hemiaminal structure. On the other hand, washing a solution of DPPT-aromatic amine with diluted hydrochloric acid (HCl) enabled successful recovery of DPPT to demonstrate the reversible nature of this system.

Full text of DOI:10.1016/j.tet.2016.03.093

Tetrahedron 72 (2016) 2868e2873
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Reversible capture and release of aromatic amines by vicinal
tricarbonyl compound
,
Tatsuya Yuki a b, Morio Yonekawa c, Yoshio Furusho d, Yoshihisa Sei e, Ikuyoshi Tomita b,
,
Takeshi Endo a
*
a Molecular Engineering Institute, Kinki University, 11-6 Kayanomori, Iizuka, Fukuoka 820-8555, Japan
b Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259-G1-9
Nagatsuta, Midori-ku, Yokohama 226-8502, Japan
c Osaka Municipal Technical Research Institute, 1-6-50, Morinomiya, Joto-ku, Osaka 536-8553, Japan
d Department of Chemistry, Shiga University of Medical Science, Seta, Otsu, Shiga 520-2192, Japan
e Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
In this paper, we report reversible capture and release of aromatic amines by diphenylpropanetrione
(DPPT). Addition of aromatic amines to the central carbonyl group occurred readily at ambient tem-
perature to provide the aromatic amine adducts of DPPT (DPPTearomatic amines), which has a hemi-
aminal structure. On the other hand, washing a solution of DPPTearomatic amine with diluted
hydrochloric acid (HCl) enabled successful recovery of DPPT to demonstrate the reversible nature of this
system.
Received 10 December 2015
Received in revised form 28 March 2016
Accepted 29 March 2016
Available online 8 April 2016
Keywords:
Ó 2016 Elsevier Ltd. All rights reserved.
Vicinal tricarbonyl
Hemiaminal
Reversibility
1. Introduction
synthesized polystyrene derivatives containing vicinal tricarbonyl
moieties in its side chain, and confirmed that water and alcohols
Vicinal tricarbonyl compounds, such as alloxan, 1,2,3-
indanetrione (dehydrate form of ninhydrin), and dehydroascorbic
acid (oxidative form of Vitamin C), are defined as compounds
containing three consecutive carbonyl groups, and show highly
electrophilic reactivity due to the electron-poor central carbonyl
group.1,2 One of the intriguing properties of vicinal tricarbonyl
compounds is high reactivity to various nucleophiles. For instance,
addition of vicinal tricarbonyl compounds and water, alcohol, or
amine afford gem-diol, hemiketal, or hemiaminal, respectively
(Scheme 1). Because these reactions proceed without any catalysts,
vicinal tricarbonyl compounds are usually obtained as their hy-
drated form. These hydrates can be dehydrated by heating under
vacuum,3,4 sublimation,4,5 distillation,6e8 crystallization,7 azeo-
tropic removal of water,8 and utilization of dehydrating agents5,8,9
to afford the free vicinal tricarbonyls.
added to the vicinal tricarbonyl polymer in a reversible manner.10
Based on the reaction, we have designed and synthesized a re-
versible network formation and dissociation system using the
vicinal tricarbonyl polymer and 1,6-hexanediol11 or poly(ethylene
glycol).12 Moreover, we have also reported the synthesis of a bi-
functional vicinal tricarbonyl compound (bistriketone) and
To date, we have investigated the reactivity of tricarbonyl
compounds to water or alcohols in detail, and exploited the re-
actions to develop functional network materials. We have
* Corresponding author. Tel.: þ81 948 22 7210; fax: þ81 948 21 9132; e-mail
Scheme 1. Reversible addition of water, alcohol, or amine to vicinal tricarbonyl
compounds.
address: tendo@moleng.fuk.kindai.ac.jp (T. Endo).
http://dx.doi.org/10.1016/j.tet.2016.03.093
0040-4020/Ó 2016 Elsevier Ltd. All rights reserved.

T. Yuki et al. / Tetrahedron 72 (2016) 2868e2873
2869
reversible crosslinking and decrosslinking systems of commercially
available alcoholic polymers, namely, poly(2-hydroxyethyl meth-
acrylate) and poly(vinyl alcohol), using bistriketone as a cross-
linker.13 Thus, exploiting a new crosslinking unit plays an important
role in developing functional networked materials.
each) reached 90% and 75%, respectively, both of which are much
higher than those at ambient temperature (Figs. S1 and S2). By the
reversible nature of the reaction, the conversion of DPPT of the
0.1 M solution changed to 40% soon after it was warmed to ambient
temperature. These results indicated that the addition reaction of
DPPT and p-toluidine was reversible and much faster than the ad-
dition reaction of benzyl alcohol to DPPT, which took 19.5 h or more
than 120 h to reach equilibrium at a concentration of 4 M or 0.1 M,
respectively.11a It should be noted here that the equilibrium of the
amine addition was shifted to the left side at ambient temperature
when compared to that of the benzyl alcohol addition, of which the
content ratio of the alcohol adduct was 79% and ca. 50% at a con-
centration of 4 M or 0.1 M, respectively.
As mentioned above, vicinal tricarbonyl groups can also un-
dergo the addition of amines to the central carbonyl group. Pre-
viously reported methods for preparing hemiaminals of vicinal
tricarbonyl compounds include the addition of amines,14,15 imine,16
or amide17,18 to vicinal tricarbonyl compounds. However, there was
no report on reversibility of neither their hemiaminal formation
nor their regeneration of vicinal tricarbonyl compounds, to the best
of our knowledge, since most of the works focused on developing
synthetic methods for natural products. These facts prompted us to
construct novel, reversible capture and release system of amines by
vicinal tricarbonyl compounds (Scheme 1). Herein, we describe our
investigation on reversible capture and release behavior of aro-
matic amines by vicinal tricarbonyl compounds.
45
40
35
30
25
20
15
10
5
2. Results and discussion
First, we investigated capture and release behavior of amines by
diphenylpropanetrione (DPPT) by 1H NMR (Fig. 1). The 1H NMR
spectrum of a chloroform-d (CDCl3) solution of an equimolar
mixture of DPPT and p-toluidine (0.1 M each) 10 min after mixing
showed characteristic peaks at 8.01, 7.46, and 7.32 ppm as well as
2.18 ppm due to the protons of p-toluidine-adduct of DPPT
(DPPTLp-toluidine). Fig. 2 shows the time dependence of con-
version of DPPT in the addition of p-toluidine determined by 1H
NMR analysis. The conversion reached about 40% in 10 min and
virtually no change was observed after 43 h, and besides. Upon five-
fold dilution, the peaks due to DPPTep-toluidine almost dis-
appeared within 10 min (0.02 M, Fig. 1d). In an attempt to evaluate
the kinetics of the reaction in more detail, 1H NMR analysis was
carried out at lower temperature. We found that the addition re-
action was so fast even at ꢀ40 ꢁC that it reached equilibrium within
5 min. It is worth mentioning here that the equilibrium is highly
dependent on temperature; the conversion of DPPT in the solution
of an equimolar mixture of DPPT and p-toluidine (0.1 and 0.02 M
0
0
20
40
60
2560
2580
2600
Reaction Time /min
Fig. 2. Time-dependence of conversion of DPPT in the addition of p-toluidine at
ambient temperature.
To elucidate the capture of p-toluidine to DPPT, we attempted
the isolation of DPPTLp-toluidine. The reaction of DPPT with p-
toluidine was carried out in anhydrous CH2Cl2 at ambient tem-
perature for 1 h. As a result, DPPTLp-toluidine was obtained as
a yellow crystal in 73% yield as n-hexane-insoluble part. The
structure of DPPTep-toluidine was confirmed by IR and elemental
analysis (Fig. 3). While DPPT shows the IR absorption due to the
central carbonyl group of DPPT at 1720 cmꢀ110a
this absorption
,
disappeared completely and new peaks due to OeH and NeH of
hemiaminal structure appeared at 3415 and 3333 cmꢀ1, re-
spectively, in the IR spectrum of DPPTLp-toluidine. As mentioned
above, since DPPTLp-toluidine exists in fast equilibrium with
DPPT and p-toluidine in solution, the 1H NMR spectrum of a CDCl3
solution of DPPTLp-toluidine gave three sets of signals assignable
to DPPT, p-toluidine, and DPPTLp-toluidine. These spectroscopic
results indicate that the capture of p-toluidine by DPPT proceeded
smoothly to provide DPPTLp-toluidine.
Generally, hemiaminal compounds can not be isolated normally
because they are so instable that they are easily split into the
starting amine and carbonyl compounds or they are converted to
the imine through dehydration reaction.20 In order to disclose the
unusual stability of the hemiaminals, we carried out X-ray crys-
tallographic study for the hemiaminals. p-Nitroaniline-adduct of
DPPT (DPPTep-nitroaniline) could be isolated in the same way to
synthesize DPPTep-toluidine. Single crystals of DPPTep-nitro-
aniline suitable for X-ray analysis were grown from a solution in
diethyl ether. The X-ray analysis revealed that the p-nitroaniline
was added to the central carbonyl group, and the central carbon
atom adopted the tetrahedral configuration (Fig. 4)19 as in the case
of benzyl alcoholeadduct of DPPT (DPPTeBnOH).11b Additionally,
there were intramolecular hydrogen bonds between the hydroxyl
Fig. 1. 1H NMR (300 MHz, CDCl3, 298 K) spectra of (a) DPPT, (b) p-toluidine, (c) an
equimolar mixture of DPPT and p-toluidine (0.1 M) 10 min after mixing, (d) an equi-
molar mixture of DPPT and p-toluidine (0.02 M) 10 min after mixing.

2870
T. Yuki et al. / Tetrahedron 72 (2016) 2868e2873
spectrum was taken (Fig. S3e7). The content ratios of DPPT, the
amine, and the adduct were calculated based on the integral values
of the 1H NMR signals, being estimated to be 42, 32, 32, and 30% for
DPPTep-anisidine, eaniline, ep-chloroaniline, and ep-nitro-
aniline, respectively (entry 1e4). The ratio increased as the
electron-donating nature of the substituent on the amine became
higher. The ratio of hemiaminal in the solution containing DPPT and
4,4’-methylenedianiline (42%) was very close to that of DPPTep-
toluidine (40%) which has a very similar structure (entry 5). The
ratio of DPPTeo-toluidine was less than that of DPPTep-toluidine
probably because of the steric hindrance of methyl group (entry 6).
The ratio of DPPTe3,5-xylidine was the highest among the sub-
strates we examined here. This is probably attributed to the
electron-donating nature of the two methyl groups (entry 7). The
1H NMR spectra of the solution containing DPPT and 2,4,6-
trimethylaniline, or diphenylamine did not show any signals at-
tributed to the adducts, indicating that the addition reaction of
DPPT with these amines could not occur owing to their steric
hindrance (entry 8, 9).
The DPPTeamine adducts were isolated by precipitation with
hexane. The amine was added to the CH2Cl2 solution of DPPT, and
the solution was stirred at room temperature for 1 h. Subsequently,
large amount of hexane was added to the reaction mixture, and the
resulting precipitation was collected by filtration. While DPPTep-
anisidine, eaniline, ep-chloroaniline, ep-nitroaniline, and
Fig. 3. IR spectra of DPPT (a), p-toluidine (b), and DPPTep-toluidine (c) (ATR).
Table 1
group and the neighboring carbonyl group (O1/O2) and between
the amino group and the other carbonyl group (N1/O3) with
atomic distances of 2.573 and 2.561 A, respectively. These hydrogen
Synthesis of DPPT-aromatic amine adducts
ꢀ
bonds unambiguously stabilize the hemiaminal. Fig. 4 shows the
bond lengths and bond angles around the central carbons in
DPPTep-nitroaniline and DPPTeBnOH, which are very close to
each other.
Next we examined the capture of various amines by DPPT (Table
1). An equimolar solution of DPPT and the amine in CDCl3 was
allowed to stand at ambient temperature for 1 h, and the 1H NMR
Entry
R1
R2
H
H
H
H
H
Ratio of hemiaminal/%a Yield/%b
1
2
3
4
5
42
32
32
30
42
91
74
87
87
88
O2
C2
C2
C1
C3
C3
C1
O1
O1
O3
N1
6
7
H
H
15
48
0
0
DPPT–p-nitroaniline
1.559 Å
DPPT–BnOH
1.538 Å
C1–C2
8
H
0
0
0
0
C1–C3
C1–O1
1.570 Å
1.563 Å
1.408 Å
1.394 Å
9
C2–C1–C3
111.45°
110.12°
a
Fig. 4. Single crystal X-ray structures of DPPTep-nitroaniline and DPPTeBnOH.
Thermal ellipsoids are drawn at 50% probability.
Estimated by 1H NMR (CDCl3, 0.1 M, rt, ca. 10 min after mixing).
Isolated yield (by precipitation with hexane).
b

T. Yuki et al. / Tetrahedron 72 (2016) 2868e2873
2871
e4,40-methylenedianiline were obtained in good yield (entry
1e5), DPPTeo-toluidine and e3,5-xylidine could not be isolated
because of their higher solubility (entry 6, 7). The absorption peak
due to the central C]O bond at 1720 cmꢀ1 disappeared completely
in the IR spectra of these isolated amineeadducts (Fig. S8). Simi-
larly, the equimolar mixtures of DPPT and o-toluidine or DPPT and
3,5-xylidine, which were obtained by concentrating the CH2Cl2
alcohol-adduct of DPPT simply by heating in vacuo as reported in
our previous work,11a amines could not be removed from amine-
adduct of DPPT by heating for the above reason.
Finally, recovery of DPPT from the amine-adducts of DPPT was
investigated (Table 2). A solution of DPPT-p-toluidine in CH2Cl2
was washed with diluted hydrochloric acid to remove the amines,
since their hydrochlorides are soluble in the aqueous layer. Con-
centrating the organic layer gave the mixture of DPPT and its hy-
drate as a yellow solid, which was purified by sublimation to obtain
DPPT (93%). DPPT was also recovered from the other amine-adducts
in the same way in good yields.
solutions, showed a significant change of the peak at 1720 cmꢀ1
,
which suggests that a certain amount of the adducts were formed
(Fig. S9a,b). In contrast, virtually no change was observed in the
case of 2,4,6-trimethylaniline and diphenylamine, unambiguously
indicating that DPPT could not react with 2,4,6-trimethylaniline
and diphenylamine (Fig. S9c,d).
Table 2
The thermal stability of DPPTep-toluidine was estimated by
using TG analysis. In the TGA measurements, DPPTep-toluidine
was heated from 30 ꢁC up to 600 ꢁC under nitrogen flow (Fig. 5). A
clear weight loss of the DPPTep-toluidine was observed at around
120 ꢁC. This significant weight loss is attributed not only to the
release of p-toluidine from DPPTep-toluidine but also to the de-
composition of hemiaminal, such as the generation of the corre-
sponding imine by dehydration (wwater¼5%; wwaterþp-toluidine¼36%).
Heating DPPTep-toluidine at 100 ꢁC for 3 h without any solvent
afforded the corresponding imine compound 2 (Scheme 2). The
structure of 2 was confirmed by NMR, IR spectra (Fig. S10e12). The
1H NMR spectrum showed characteristic peaks at 8.3e7.3 ppm due
to the aromatic protons of phenyl groups of 2. These peaks became
a little more complicated than that of DPPTep-toluidine because
the structure of the molecule lacked symmetry. 13C NMR showed
a characteristic peak at 162.5 ppm attributed to the imino carbon.
Additionally, the IR absorption due to C]N bond at 1652 cmꢀ1 was
observed. Although benzyl alcohol could be released from benzyl
Recovery of DPPT from DPPTeamine adducts
Entry
R
Yield of DPPT/%
1
2
3
4
5
6
84
93
98
96
96
90
7
8
92
91
Fig. 5. TG profiles of DPPT (red), p-toluidine (blue), and DPPTep-toluidine (green).
3. Conclusion
The reversible capture and release behavior of the aromatic
amines by diphenylpropanetrione was investigated in detail. The
capture of the amines by DPPT proceeded smoothly to provide the
aromatic amine adducts of DPPT (DPPTꢀamine adducts). Since
addition reactions of DPPT and the aromatic amines were re-
versible, DPPTꢀamine adducts exist in fast equilibrium with DPPT
and the amines in solution. Furthermore, we succeeded in the re-
covery of DPPT from DPPTꢀamine adducts by washing a solution of
DPPTꢀamine adducts with diluted hydrochloric acid. We believe
that the insights obtained in this study may give access to smart
polymeric materials responding to external stimuli such as
chemical-recyclable network or self-healing materials.
DPPT–p-toluidine
2
Scheme 2. Dehydration of DPPTep-toluidine.

2872
T. Yuki et al. / Tetrahedron 72 (2016) 2868e2873
4. Experimental section
vacuum, which would lead to the elemental analysis values of
which the carbon content is larger than expected.
4.1. General information
4.4. 1,3-Diphenyl-2-(p-tolylimino)propane-1,3-dione (2)
Chloroform and chloroform-d (CDCl3) were distilled over mo-
lecular sieves 4A (MS 4A). Dichloromethane and aniline were dis-
tilled over CaH2. n-Hexane and diethyl ether were dried over MS
4A. Tetrahydrofuran (THF) was distilled over sodium benzophe-
none ketyl. p-Toluidine, p-chloroaniline, p-nitroaniline, 4,40-meth-
ylenedianiline, acetic acid (Wako), p-anisidine, o-toluidine, 3,5-
xylidine, 2,4,6-trimethylaniline, diphenylamine (TCI) were pur-
DPPTep-toluidine (238 mg) was heated at 100 ꢁC for 3 h. The
resulting dark brown solid was dissolved in CH2Cl2 (6.9 mL), and
the solution was washed with 1 M HCl (6.9 mLꢂ3). The organic
layer was concentrated in vacuo, and the resulting solid was heated
at 80 ꢁC for 12 h under reduced pressure. The crude material was
purified
(EtOAc:hexane¼1:30) to obtain 2 (91.5 mg, 41%) as an orange solid:
1H NMR (300 MHz, 298 K, CDCl3):
by
column
chromatography
on
silica
gel
chased
and
used
without
further
purification. 1,3-
Diphenylpropanetrione (DPPT) was synthesized in the same way
d
8.28 (d, J¼7.6 Hz, 2H), 7.77 (d,
for the literature method.10
J¼7.6 Hz, 2H), 7.64 (t, J¼7.6 Hz, 1H), 7.52 (dd, J¼7.6, 7.6 Hz, 2H), 7.50
(t, J¼7.6 Hz, 1H), 7.37 (dd, J¼7.6, 7.6 Hz, 2H), 7.00 (d, J¼8.3 Hz, 2H),
6.92 (d, J¼8.3 Hz, 2H), 2.21 (s, 3H) ppm; 13C NMR (100 MHz, 298 K,
1H spectra were taken on a JEOL JNM-AL300 operating at
300 MHz or on a JEOL JNM-ECS400 at 400 MHz with tetrame-
thylsilane as an internal standard. 13C NMR spectrum was taken on
a JEOL JNM-ECS400 operating at 100 MHz with tetramethylsilane
as an internal standard. IR spectra were recorded on a Thermo
Scientific Nicolet iS10 spectrometer. Thermogravimetric analysis
(TGA) was performed with a Seiko Instrument Inc. TG-DTA 6200
with an aluminum pan under a 200 mL/min N2 flow at a heating
rate of 10 ꢁC/min.
CDCl3):
d 196.7, 191.2, 162.5, 144.2, 137.0, 134.8, 134.3, 134.2, 133.9,
130.9, 129.6, 129.2, 128.8, 128.4, 120.9, 21.0 ppm; IR (ATR): 3059,
3026, 2920, 1652 cmꢀ1; EIMS [M]þ m/z calcd for C22H17NO2
327.1259, found: 327.1256.
4.5. Typical procedure for recovery of DPPT from DPPTea-
mine adducts
4.2. Addition of amines to DPPT
DPPT-p-toluidine (200 mg) was dissolved in CH2Cl2 (5.6 mL).
The solution was washed with 1 M HCl aq (5.6 mLꢂ3). The organic
layer was concentrated in vacuo and the resulting solid was puri-
fied by sublimation at 80 ꢁC in vacuo for 12 h to obtain DPPT
(128 mg, 93%) as a yellow solid.
A typical experimental procedure was as follows. DPPT (11.9 mg,
0.0499 mmol) was dissolved in 0.5 mL of CDCl3 in an NMR tube and
to the solution was added p-toluidine (5.6 mg, 0.052 mmol). The 1H
NMR spectrum was then measured at 25 ꢁC.
Acknowledgements
4.3. Typical procedure for synthesis of DPPTLAmine adducts
This work was supported by JSPS KAKENHI grant number
25288060.
DPPT (270 mg, 1.13 mmol) was dissolved in CH2Cl2 (2.8 mL). To
the solution was added p-toluidine (121 mg, 1.13 mmol), and the
reaction mixture was stirred at ambient temperature for 1 h under
nitrogen atmosphere. To the solution was added anhydrous n-
hexane (28 mL). The resulting precipitate was washed with anhy-
drous n-hexane and dried in vacuo overnight to obtain DPPTLp-
toluidine (287 mg, 73%) as a yellow powder: IR (ATR) 3429, 3344,
1667 cmꢀ1. Anal. Calcd for C22H19NO3: C, 76.50; H, 5.54; N, 4.06.
Found: C, 76.35; H, 5.36; N, 3.95.
Supplementary data
Supplementary data (Detailed X-ray crystal data of DPPTep-
nitroaniline, 1H NMR, 13C NMR, and FTIR spectra) associated with
this article can be found in the online version, at http://dx.doi.org/
10.1016/j.tet.2016.03.093.
DPPTep-anisidine (91%, yellow powder): IR (ATR) 3404, 3356,
1672 cmꢀ1. Anal. Calcd for C22H19NO4: C, 73.12; H, 5.30; N, 3.88.
Found: C, 74.53; H, 5.00; N, 3.97.
DPPTeaniline (74%, yellow powder): IR (ATR) 3416, 3361,
1673 cmꢀ1. Anal. Calcd for C21H17NO3: C, 76.12; H, 5.17; N, 4.23.
Found: C, 76.22; H, 4.94; N, 4.24.
DPPTep-chloroaniline (87%, yellow powder): IR (ATR) 3411,
3337, 1666 cmꢀ1. FABMS [MþH]þ m/z calcd for C21H17ClNO3
366.0891, found: 366.0902.
References and notes
1. (a) Rubin, M. B.; Gleiter, R. Chem. Rev. 2000, 100, 1121e1164; (b) Rubin, M. B.
Chem. Rev. 1975, 75, 177e202.
2. Wasserman, H. H.; Parr, J. Acc. Chem. Res. 2004, 37, 687e701.
3. (a) Hirama, M.; Fukazawa, Y.; Ito, S. Tetrahedron Lett. 1978, 19, 1299e1302; (b)
Moubasher, R.; Othman, A. M. J. Am. Chem. Soc. 1950, 72, 2667e2669.
4. Lepley, A. R.; Thelman, J. P. Tetrahedron 1966, 22, 101e110.
5. (a) Netto-Ferreira, J. C.; Silva, M. T.; Puget, F. P. J. Photochem. Photobiol. A Chem.
1988, 119, 165e170; (b) Silva, M. T.; Braz-Filho, R.; Netto-Ferreira, J. C. J. Braz.
Chem. Soc. 2000, 11, 479e485.
DPPTep-nitroaniline (87%, yellow powder): IR (ATR) 3418,
3320, 1667 cmꢀ1. FABMS [MþH]þ m/z calcd for C21H17N2O5
377.1132, found: 377.1138.
6. (a) Mahran, M. R.; Abdou, W. M.; Sidky, M. M.; Wamhoff, H. Synthesis 1987, 5,
506e508; (b) Sharp, D. B.; Hoffman, H. A. J. Am. Chem. Soc. 1950, 72, 4311e4313.
7. Roberts, J. D.; Smith, D. R.; Lee, C. C. J. Am. Chem. Soc. 1951, 73, 618e625.
8. Gill, G. B.; Idris, M. S. H.; Kirollos, K. S. J. Chem. Soc., Perkin Trans. 1 1992,
2355e2365.
DPPTe4,40-methylenedianiline (88%, yellow powder): IR (ATR)
3423, 3358, 1672 cmꢀ1. Anal. Calcd for C43H34N2O6: C, 76.54; H,
5.08; N, 4.15. Found: C, 77.51; H, 4.90; N, 4.38.
€
9. Schonberg, A.; Singer, E. Chem. Ber. 1970, 103, 3871e3884.
10. (a) Dei, T.; Morino, K.; Sudo, A.; Endo, T. J. Polym. Sci. Part A; Polym. Chem. 2011,
49, 2245e2251; (b) Dei, T.; Morino, K.; Sudo, A.; Endo, T. J. Polym. Sci. Part A;
Polym. Chem. 2012, 50, 2619e2625.
11. (a) Morino, K.; Sudo, A.; Endo, T. Macromolecules 2012, 45, 4494e4499; (b)
Yonekawa, M.; Furusho, Y.; Endo, T. Macromolecules 2012, 45, 6640e6647.
12. Yuki, T.; Yonekawa, M.; Matsumoto, K.; Tomita, I.; Endo, T. Polym. Bull. 2016, 73,
345e356.
DPPTeo-toluidine (not isolated, orange solid): IR (ATR) 3400,
1674 cmꢀ1
.
DPPTe3,5-xylidine (not isolated, orange solid): IR (ATR) 3377,
1667 cmꢀ1
.
13. (a) Yonekawa, M.; Furusho, Y.; Sei, Y.; Takata, T.; Endo, T. Tetrahedron 2013, 69,
4076e4080; (b) Yonekawa, M.; Furusho, Y.; Takata, T.; Endo, T. J. Polym. Sci. Part
A; Polym. Chem. 2014, 52, 921e928.
14. Craig, D. C.; Doughty, A.; Kassiou, M.; MacIntosh, M. G.; Read, R. W. J. Org. Chem.
1993, 58, 5753e5758.
The elemental analysis data for DPPTep-anisidine and for
DPPTe4,40-methylenedianiline did not match the theoretical
values. This is probably due to the dehydration that proceeded to
give the corresponding imines during drying the samples under

T. Yuki et al. / Tetrahedron 72 (2016) 2868e2873
2873
15. (a) Wasserman, H. H.; Fukuyama, J.; Murugesan, N.; Van Duzer, J.; Lombardo, L.;
Rotello, V.; McCarthy, K. J. Am. Chem. Soc. 1989, 111, 371e372; (b) Wasserman,
H. H.; Frechette, R.; Oida, T.; Van Duzer, J. H. J. Org. Chem. 1989, 54, 6012e6014;
(c) Wasserman, H. H.; Cook, J. D.; Vu, C. B. J. Org. Chem. 1990, 55, 1701e1702; (d)
Wasserman, H. H.; Long, Y. O.; Zhang, R.; Carr, A. J.; Parr, J. Tetrahedron Lett.
2002, 43, 3347e3350.
Seffid, M.; Poorhassan, E.; Hassanabadi, A.; Rastegari, F. ARKIVOC 2008,
265e272.
18. Wasserman, H. H.; Blum, C. A. Tetrahedron Lett. 1994, 35, 9787e9790.
19. Crystal data for DPPTep-toluidine: C21H16N2O5: FW¼376.36, triclinic, space
ꢀ
ꢀ
ꢀ
a
group Pe1, a¼6.4402 (14) A, b¼11.239 (2) A, c¼12.713 (3) A,
¼110.629(2),
3
ꢀ
b
¼99.635 (3),
measured, 2936 unique reflections, 2532 observations (I>2.0
(I>2.0 (I)). CCDC 1442328. For more detail on the data,
g
¼90.623 (3), V¼846.6 (3) A , Z¼2, Dcalcd¼1.476, 4041 reflections
16. Barluenga, J.; Tomas, M.; Ballesteros, A.; Kong, J. S.; Garcia-Granda, S.; Aguirre,
A. J. Chem. Soc., Chem. Commun. 1993, 217e218.
s
(I)), R¼0.0422
s
(I)), Rw¼0.1067 (I>2.0
s
17. (a) Poje, M.; Rocic, B. Tetrahedron Lett. 1979, 4781e4782; (b) Wasserman, H. H.;
Han, W. T. J. Am. Chem. Soc. 1985, 107, 1444e1446; (c) Wasserman, H. H.; Han,
W. T. Tetrahedron Lett. 1984, 25, 3747e3750; (d) Lee, B. H.; Biswas, A.; Miller, M.
J. J. Org. Chem. 1986, 51, 106e109; (e) Grodner, J.; Chmielewski, M. Tetrahedron
1995, 51, 829e836; (f) Wasserman, H. H.; Xi, M.; Carr, A. J.; Han, W. T.; Siegel, M.
G. Tetrahedron 2000, 56, 5621e5629; (g) Anary-Abbasinejad, M.; Mazraeh-
see Supplementary data. These data can be obtained free of charge from the
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif.
20. (a) Iwasawa, T.; Hooley, R. J.; Rebek, J., Jr. Science 2007, 317, 493e496; (b) Ka-
wamichi, T.; Haneda, T.; Kawano, M.; Fujita, M. Nature 2009, 461, 633e635; (c)
Xu, L.; Hua, S.; Li, S. Chem. Commun. 2013, 1542e1544.