Thermal oligomerization of methyl 4-(1,3-dioxo-2,3-dihydro-1H-isoindol-2- yl)buta-2,3-dienoate

Article abstract of DOI:10.1134/S1070428012060085

Dimeric compounds formed as a result of thermal oligomerization of methyl 4-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)buta-2,3-dienoate were identified.

Full text of DOI:10.1134/S1070428012060085

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2012, Vol. 48, No. 6, pp. 793–798. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © I.M. Sakhautdinov, I.R. Batyrshin, A.A. Fatykhov, F.Z. Galin, M.S. Yunusov, 2012, published in Zhurnal Organicheskoi Khimii,
2012, Vol. 48, No. 6, pp. 797–802.
Thermal Oligomerization of Methyl 4-(1,3-Dioxo-2,3-dihydro-
1H-isoindol-2-yl)buta-2,3-dienoate
I. M. Sakhautdinova, I. R. Batyrshina, A. A. Fatykhova, F. Z. Galina, b, and M. S. Yunusova
a Institute of Organic Chemistry, Ufa Research Center, Russian Academy of Sciences,
pr. Oktyabrya 71, Ufa, 450054 Bashkortostan, Russia
e-mail: ims@anrb.ru
b Bashkir State University, Ufa, Bashkortostan, Russia
Received November 21, 2011
Abstract—Dimeric compounds formed as a result of thermal oligomerization of methyl 4-(1,3-dioxo-2,3-
dihydro-1H-isoindol-2-yl)buta-2,3-dienoate were identified.
DOI: 10.1134/S1070428012060085
Cyclobutane derivatives attract increased attention
of many researchers. This is related to both specific
structure and chemical properties of compounds con-
taining a cyclobutane ring and their possible applica-
tion in medicine, primarily as antiviral and antitumor
drugs [1, 2]. Interest in such structures stimulates
development of simple, inexpensive, and general
procedures for their preparation with a view to obtain
new derivatives, taking into account that the number of
available cyclobutane compounds is not large. Substi-
tuted allenes were shown [3] to be promising as
starting compounds for the synthesis of cyclobutane
derivatives [3].
allene fragment, and the allene carbon atoms gave
signals at δC 91.75, 96.66 (–CH=), and 209.97 ppm
(=C=) in the 13C NMR spectrum.
It is known that thermal activation of allene leads to
its dimerization [3, 4]. Heating of allene II in boiling
toluene under microwave irradiation and without it, as
well as under polymerization conditions in the pres-
ence of azobis(isobutyronitrile) (AIBN) and in the
absence of initiator, gave substituted cyclobutanes IV–
VI (Scheme 2). Joint oligomerization of allenes with
unsaturated compounds is known to produce methyl-
enecyclobutane and methylenecyclobutene derivatives
[3, 4]. In our case, the reaction of allene II with di-
methyl acetylenedicarboxylate resulted in dimerization
of the allene rather than in co-oligomerization (see
table). The structure of the dimeric products was deter-
mined by IR and NMR spectroscopy, mass spec-
trometry, and elemental analysis.
In the present work we studied transformations of
allene II having a phthalimide fragment, which was
synthesized by the Wittig reaction of N-phthaloyl-
glycine (I) prepared in turn by direct fusion of phthalic
anhydride with glycine (Scheme 1). The Wittig reac-
tion of I afforded 63% of allene II and 5% of ylide III.
The structure of the products was proved by spectral
1
The H NMR spectra of IV and V contained two
three-proton singlets from methyl protons in the two
nonequivalent ester groups at δ 3.29, 3.79 and 3.37,
3.76 ppm, respectively, which indicated formation of
1
data. The H NMR spectrum of II contained doublet
signals at δ 6.21 and 7.25 ppm due to protons in the
Scheme 1.
O
O
O
O
O
O
PPh3
(1) SOCl2
(2) P3P=CHCOOMe, Et3N
OH
·
OMe
+
N
N
N
OMe
O
O
O
O
I
II
III
793

SAKHAUTDINOV et al.
794
Scheme 2.
OMe
H
OMe
O
O
O
O
Hd
O
O
Ha
N
H
O
O
Hc
N
N
·
OMe
a–f
H
+
N
N
O
OMe
Hb
H
O
O
O
O
OMe
O
O
II
IV
V
OMe
H
O
O
H
N
O
+
O
N
H
OMe
H
O
O
VI
a dimer. Also, characteristic were two doublets from
protons in the cyclobutane ring, located at δ 4.61 (Hd)
and δ 5.99 ppm (Hc) in the spectrum of IV and at
δ 4.96 and 5.79 ppm, respectively, in the spectrum of
V [5–9]. The two-dimensional HSQC spectrum of un-
symmetrical dimer IV revealed couplings of protons at
the double bonds (Ha and Hb, δ 6.82, 5.68 ppm) with
the olefinic carbon atoms resonating at δC 115.80 and
118.13 ppm, respectively; the Hc (δ 5.99 ppm) and Hd
protons (δ 4.61 ppm) gave cross peaks with tertiary
carbon atoms in the cyclobutane ring (δC 50.16 and
49.00 ppm, respectively) [10, 11]. Unsymmetrical
structure of IV also follows from the presence in the
1H–15N HMBC spectrum of cross peaks of Ha and
Hc with nitrogen atoms in the phthalimide fragments
(δ/δN 5.99/161 and 6.82/172 ppm).
(δ 5.68/5.99 ppm). The Hd proton also displayed
coupling with the neighboring Hc proton in the cyclo-
butane ring. The latter protons were found to interact
in the NOESY spectrum, which indicated their cis
orientation with respect to each other. In the HMBC
spectrum we observed a cross peak between Ha and
imide carbon atom (δ/δC 6.82/164.74 ppm), whereas
the Hb proton was coupled with the ester carbonyl
carbon atom (δ/δC 5.68/165.31 ppm), and the latter
showed a cross peak with methoxy protons
(δ 3.79 ppm). The structure of the cyclobutane frag-
ment was confirmed by correlations of Ha and Hb with
quaternary carbon atoms at the double bonds in the
HMBC spectrum (δ/δC 5.68/127.46, 5.68/151.94,
6.82/127.46, 6.82/151.94 ppm). The two-dimensional
NOESY spectrum showed interaction between Hd and
Ha, in keeping with syn orientation of these protons,
whereas Ha, Hb, and Hc displayed no NOE. This means
that these protons are fairly distant from each other.
The Ha proton (δ 6.82 ppm) was coupled with Hd
(δ 4.61 ppm) in the H–H COSY spectrum; analogous
correlation was observed for the Hb and Hc protons
Thermal cyclodimerization of methyl 4-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)buta-2,3-dienoate (II)
Yield, %
Reaction
time, h
Conversion
of II, %
Reaction conditions
IV
V
VI
a: CHCl3, AIBN (3 wt %), 80–90°C
50
50
60
65
63
85
80
87
10
22
27
39
16
40
07
08
10
18
04
05
07
14
24
–
b: CHCl3, AIBN (3 wt %), reduced pressure, 80–90°C
c: CHCl3, reduced pressure, 80–90°C
d: PhMe, 110°C
50
40
e: Microwave irradiation, 750 W, PhMe, 110°C
f: Dimethyl acetylenedicarboxylate, PhH, 80°C
0.00.5
03
13
–
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 6 2012

THERMAL OLIGOMERIZATION OF METHYL 4-(1,3-DIOXO-2,3-DIHYDRO-...
795
Scheme 3.
O
O
O
OMe
H
OMe
O
O
O
O
O
Ultrasound
PhMe
·
OMe
N
N
+
N
N
N
O
O
O
O
H
MeO
O
MeO
VIII, 4%
O
O
II
VII, 26%
Analogous NMR spectra were recorded for minor
compound V. The NOESY experiment revealed spatial
interaction between proton in the cyclobutane ring at
the ester group and proton at the double bond in the
α-position with respect to the imide fragment. How-
ever, no coupling was observed between two protons at
neighboring carbon atoms in the cyclobutane ring,
indicating their trans orientation with respect to each
other. No coupling was observed between other
protons.
In the 1H NMR spectrum of symmetric cyclobutane
derivative VI signals from six protons in the ester
methoxy groups, two protons in the cyclobutane frag-
ment, and two protons at the double bonds were
observed at δ 3.81, 4.43, and 6.42 ppm, respectively.
According to published data [5–12] and NMR spectra,
protons at the double bonds (δ 6.42 ppm) appear in the
vicinity of the phthalimide fragments, and protons in
the cyclobutane ring (δ 4.43 ppm) are located in the
α-positions with respect to the ester groups and are
oriented cis with respect to each other, as follows from
their equivalence due to molecular symmetry.
carbon atom (δ/δC 3.51/168.40 ppm) in the HMBC
spectrum. NOE experiment showed spatial interaction
between the olefinic and methylene protons, indicating
trans orientation of the phthalimide and ester frag-
ments. We failed to determine configuration of the
double bonds in minor product VIII because of its
poor yield (Scheme 3).
To conclude, we have synthesized new cyclobutane
derivatives by dimerization of methyl 4-(1,3-dioxo-
2,3-dihydro-1H-isoindo-2-yl)buta-2,3-dienoate and
determined their structure. Dimerization of this allene
in toluene under ultrasonic irradiation was found to
produce two symmetric dienes containing no cyclo-
butane ring.
EXPERIMENTAL
The IR spectra were measured on a Spesord M-80
spectrometer from thin films or suspensions in mineral
1
oil. The H and 13C NMR spectra were recorded on
a Bruker AM-500 spectrometer at 500.13 and
125.76 MHz, respectively, using tetramethylsilane as
internal reference. Signals in the NMR spectra of com-
pounds IV, V, and VII were assigned using two-
dimensional homo- and heteronuclear correlation
techniques (COSY, NOESY, HSQC, HMBC). The
progress of reactions was monitored by thin-layer
chromatography on Sorbfil PTSKh-AF-A plates; spots
were detected by UV irradiation, treatment with iodine
vapor, or spraying with a solution of ninhydrin or
p-methoxybenzaldehyde with subsequent heating to
100–120°C. The mass spectra (atmospheric pressure
chemical ionization) were obtained on a Shimadzu
LCMS-2010EV instrument. Microwave-assisted reac-
tions were carried out in a 50-ml quartz reactor placed
in a modified multimode cavity based on a SAM-
OM75S-(31) magnetron (2.45×109 Hz, 750 W); the
mechanical stirrer drive unit and reflux condenser
were mounted outside the microwave radiation zone.
Ultrasound was generated using a UZDN-2T setup
with an operating frequency of 22 kHz.
Dimerization of allene II under ultrasonic activa-
tion in toluene at 110°C (10 h) gave two isomeric
dienes VII and VIII. According to spectral data,
among possible diene structures, only two symmetric
isomers were obtained. Signals from the methylene
1
and olefinic protons appeared in the H NMR spectra
as singlets. The upfield position of the CH2 signal of
VII (δ 3.51 ppm) as compared to VIII (δ 5.21 ppm)
suggests that the methylene group in VII is neigh-
boring to the ester fragment rather than phthalimide as
in VIII [5–11]. The symmetric structure of VII is also
confirmed by the presence of only one cross peak in
1
the H–15N HMBC spectrum (δ/δN 6.48/165), as well
as by correlations of the olefinic proton with the
carbonyl carbon atom in the phthalimide fragment
(δ/δC 6.48/165.47 ppm), quaternary carbon atom at the
double bond (δC 117.98 ppm), and methylene carbon
atom (δC 42.53 ppm). In addition, a cross peak was
observed between the CH2 protons and ester carbonyl
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 6 2012

SAKHAUTDINOV et al.
796
Acetone, methylene chloride, and ethyl acetate
(CHarom), 128.56 (CHarom), 131.77 (CHarom), 132.58
(Carom), 133.32 (CHarom), 168.11 (C=O), 168.37 (C=O),
187.98 (C=O). Found, %: C 71.23; H 4.76; N 2.89;
P 6.21. C31H24NO5P. Calculated, %: C 71.40; H 4.64;
N 2.69; P 5.94.
were distilled over P2O5. Toluene, tetrahydrofuran, and
petroleum ether were heated under reflux over metallic
sodium and then distilled. Thionyl chloride of analyt-
ical grade and dimethyl acetylenedicarboxylate were
used without additional purification. The products
were isolated by column chromatography on silica gel
(40–100 and 100–160 μm; Chemapol).
Dimerization of compound II. a. Compound II,
243 mg (1 mmol), was dissolved in 20 ml of anhy-
drous chloroform, 3 wt % of AIBN was added, and the
mixture was heated for 50 h at 80–90°C in a sealed
ampule. The solution was separated by decanting, the
solvent was distilled off, and the products were
isolated by column chromatography on silica gel.
N-Phthaloylglycine (I) was synthesized according
to [13], and (2-methoxy-2-oxoethyl)triphenylphospho-
nium bromide and methyl (triphenyl-λ5-phosphanyli-
dene)acetate were prepared as described in [14]; their
physical constants were consistent with published data.
b. Compound II, 243 mg (1 mmol), was dissolved
in 20 ml of anhydrous chloroform, 3 wt % of AIBN
was added, the mixture was placed into an ampule and
evacuated, and the ampule was sealed and heated for
50 h at 80–90°C. The solution was separated by
decanting, the solvent was distilled off, and the
products were isolated by column chromatography on
silica gel.
Methyl 4-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-
yl)buta-2,3-dienoate (II) and methyl 4-(1,3-dioxo-
2,3-dihydro-1H-isoindol-2-yl)-3-oxo-2-(triphenyl-λ5-
phosphanylidene)butanoate (III). N-Phthaloyl-
glycine (I), 1 g (4.9 mmol), was dispersed in 10 ml of
anhydrous benzene, fivefold excess of thionyl chloride
was added, and the mixture was heated for 3 h under
reflux. The solvent and excess thionyl chloride were
distilled off on a rotary evaporator, and the residue
(phthalimidoacetyl chloride) was used without addi-
tional purification. An equimolar amount of triethyl-
amine was added to a solution of methyl (triphenyl-λ5-
phosphanylidene)acetate in THF, the mixture was
cooled to –10°C, and a cold solution of phthalimido-
acetyl chloride was slowly added dropwise. The
mixture was stirred for 12.5 h at 0°C, the precipitate
was filtered off, the solvent was distilled off from
the filtrate, and the residue was subjected to column
chromatography on silica gel using petroleum ether–
ethyl acetate (4:1) as eluent.
c. Compound II, 243 mg (1 mmol), was dissolved
in 20 ml of anhydrous chloroform, the solution was
placed into an ampule and evacuated, and the ampule
was sealed and heated for 50 h at 80–90°C. The
solution was separated by decanting, the solvent was
distilled off, and the products were isolated by column
chromatography on silica gel.
d. A suspension of 243 mg (1 mmol) of compound
II in 20 ml of anhydrous toluene was heated for 40 h
under reflux. The solvent was distilled off, and the
products were isolated by column chromatography on
silica gel.
e. A suspension of 243 mg (1 mmol) of compound
II in 20 ml of anhydrous 1,4-dioxane was heated for
0.5 h under microwave irradiation. The solution was
separated by decanting, the solvent was distilled off,
and the products were isolated by column chromatog-
raphy on silica gel.
Compound II. Yield 0.75 g (63%), white crystals,
mp 95–97°C. IR spectrum, ν, cm–1: 1782, 1763.
1H NMR spectrum (CDCl3), δ, ppm: 3.74 s (3H, CH3),
6.21 d (1H, CH, J = 5.1 Hz), 7.25 d (1H, CH, J =
13
5.1 Hz), 7.74–7.83 m (4H, C6H4). C NMR spectrum
(CDCl3), δC, ppm: 54.37 (CH3), 91.75 (CH), 96.66
(CH), 123.61 (CHarom), 131.49 (Carom), 133.86
(CHarom), 164.45 (C=O), 164.65 (C=O), 209.97 (=C=).
Mass spectrum: m/z 244 [M + H]+, 243 [M]–. Found,
%: C 63.75; H 3.64; N 5.71. C13H9NO4. Calculated, %:
C 64.20; H 3.59; N 5.76. M 243.21.
f. Compound II, 243 mg (1 mmol), was dispersed
in 20 ml of anhydrous benzene, an equimolar amount
of dimethyl acetylenedicarboxylate was added, and the
mixture was heated for 3 h under reflux.
Methyl (1S,2S,3Z,4Z)-2-(1,3-dioxo-2,3-dihydro-
1H-isoindol-2-yl)-4-[(1,3-dioxo-2,3-dihydro-1H-iso-
indol-2-yl)methylidene]-3-(2-methoxy-2-oxoethyli-
dene)cyclobutane-1-carboxylate (IV) was isolated
using petroleum ether–ethyl acetate (1:1) as eluent.
Yellow crystals, mp 196–197°C. IR spectrum, ν, cm–1:
1729, 1718, 1687. 1H NMR spectrum (CDCl3), δ, ppm:
Compound III. Yield 0.13 g (5%), yellow oily
substance. IR spectrum, ν, cm–1: 1724, 1539, 1458.
1H NMR spectrum (CDCl3), δ, ppm: 3.32 s (3H, CH3),
5.11 s (2H, CH2), 7.41–7.81 m (19H, Harom). 13C NMR
spectrum (CDCl3), δC, ppm: 46.29 (CH2), 49.64 (CH3),
69.55 (C=Ph), 122.93 (CHarom), 124.86 (Carom), 128.38
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 48 No. 6 2012

THERMAL OLIGOMERIZATION OF METHYL 4-(1,3-DIOXO-2,3-DIHYDRO-...
797
3.29 s (3H, CH3), 3.79 s (3H, CH3), 4.61 d.d (1H, 1-H,
J = 2.3, 2.6 Hz), 5.68 d (1H, CH, J = 2.7 Hz), 5.99 d.d
(1H, 2-H, J = 2.3, 2.6 Hz), 6.82 d (1H, CH, J =
isolated by column chromatography on silica gel using
petroleum ether–ethyl acetate (9:1) as eluent.
Dimethyl (3Z,4Z)-3,4-bis[(1,3-dioxo-2,3-dihydro-
1H-isoindol-2-yl)methylidene]hexanedioate (VII).
Yield 78 mg (26%), yellow crystals, mp 115–117°C.
13
2.4 Hz), 7.77–7.96 m (8H, C6H4). C NMR spectrum
(CDCl3), δC, ppm: 49.00 (C1), 50.16 (C2), 51.87 (CH3),
53.16 (CH3), 115.80 (=CH), 118.13 (=CH), 123.93
(CHarom), 124.20 (CHarom), 127.46 (C4), 131.57 (Carom),
131.84 (Carom), 134.17 (CHarom), 134.91 (CHarom),
151.94 (C3), 164.74 (C=O), 165.31 (C=O), 167.14
(C=O), 170.04 (C=O). Mass spectrum: m/z 486 [M]–.
Found, %: C 64.13; H 3.67; N 5.73. C26H18N2O8. Cal-
culated, %: C 64.20; H 3.73; N 5.76. M 486.43.
1
IR spectrum, ν, cm–1: 1722, 1387, 1261. H NMR
spectrum (CDCl3), δ, ppm: 3.51 s (4H, CH2), 3.73 s
(6H, CH3), 6.48 s (2H, CH), 7.70–7.86 m (8H, C6H4).
13C NMR spectrum (CDCl3), δC, ppm: 42.53 (CH2),
52.59 (CH3), 117.98 (=CH), 123.85 (CHarom), 130.96
(CHarom), 131.29 (=C), 131.86 (Carom), 134.45 (CHarom),
165.47 (NC=O), 168.40 (C=O). Mass spectrum:
m/z 488 [M]–. Found, %: C 63.85; H 3.97; N 5.71.
C26H20N2O8. Calculated, %: C 63.93; H 4.13; N 5.74.
M 488.45.
Methyl (1S,2R,3Z,4Z)-2-(1,3-dioxo-2,3-dihydro-
1H-isoindol-2-yl)-4-[(1,3-dioxo-2,3-dihydro-1H-iso-
indol-2-yl)methylidene]-3-(2-methoxy-2-oxoethyli-
dene)cyclobutanecarboxylate (V) was isolated using
petroleum ether–ethyl acetate (1:1) as eluent. Yellow
crystals, mp 193–195°C. IR spectrum, ν, cm–1: 1719,
Dimethyl 3,4-bis[(1,3-dioxo-2,3-dihydro-1H-iso-
indol-2-yl)methyl]hexa-2,4-dienedioate (VIII). Yield
12 mg (4%), yellow crystals, mp 185–187°C. IR spec-
1
trum, ν, cm–1: 1760, 1399, 1281. H NMR spectrum
1
1703, 1693. H NMR spectrum (CDCl3), δ, ppm:
(CDCl3), δ, ppm: 3.82 s (6H, CH3), 5.21 s (4H, CH2),
6.31 s (2H, CH), 7.71–7.98 m (8H, C6H4). 13C NMR
spectrum (CDCl3), δC, ppm: 39.50 (CH2), 51.94 (CH3),
121.31 (=CH), 123.59 (CHarom), 131.88 (=C), 134.21
(CHarom), 134.45 (Carom), 149.35 (NC=O), 167.41
(C=O). Mass spectrum: m/z 488 [M]–. Found, %:
C 63.75; H 3.89; N 5.69. C26H20N2O8. Calculated, %:
C 63.93; H 4.13; N 5.74. M 488.45.
3.37 s (3H, CH3), 3.76 s (3H, CH3), 4.96 d.d (1H, 1-H,
J = 6.6, 2.7 Hz), 5.71 d (1H, CH, J = 1.5 Hz), 5.79 d.d
(2-H, J = 6.6, 2.7 Hz), 7.03 d (1H, CH, J = 1.4 Hz),
13
7.64–7.88 m (8H, C6H4). C NMR spectrum (CDCl3),
δC, ppm: 47.09 (C1), 50.49 (C2), 51.04 (CH3), 52.63
(CH3), 113.25 (=CH), 116.82 (=CH), 123.67 (CHarom),
123.72 (CHarom), 123.99 (C3 or C4), 131.66 (Carom),
132.31 (Carom), 134.36 (CHarom), 134.44 (CHarom),
151.15 (C4 or C3), 165.29 (C=O), 167.13 (C=O),
169.68 (C=O), 170.72 (C=O). Mass spectrum: m/z 486
[M]–. Found, %: C 64.09; H 3.59; N 5.71. C26H18N2O8.
Calculated, %: C 64.20; H 3.73; N 5.76. M 486.43.
This study was performed under financial support
by the President of the Russian Federation (program
for support of leading scientific schools, project
no. NSh-7014.2012.3) and by the Federal Special-
Purpose Program “Scientific and Scientific–Pedagog-
ical Staff of Innovation Russia 2009–2013” (state
contract no. 14.740.11.0367).
Dimethyl 2,4-bis[(1,3-dioxo-2,3-dihydro-1H-iso-
indol-2-yl)methylidene]cyclobutane-1,3-dicarbox-
ylate (VI) was isolated using petroleum ether–ethyl
acetate (1:1) as eluent. Yellow crystals, mp 169–
171°C. IR spectrum, ν, cm–1: 1714, 1688, 1678.
1H NMR spectrum (CDCl3), δ, ppm: 3.81 s (6H, CH3),
4.43 s (2H, 1-H, 3-H), 6.42 s (2H, CH), 7.33–7.49 m
(8H, C6H4). 13C NMR spectrum (CDCl3), δC, ppm:
45.11 (C1, C3), 52.60 (CH3), 112.57 (CH), 123.25
(CHarom), 131.29 (Carom), 132.30 (C2, C4), 133.86
(CHarom), 163.58 (C=O), 170.15 (C=O). Mass spec-
trum: m/z 486 [M]–. Found, %: C 64.15; H 3.69;
N 5.74. C26H18N2O8. Calculated, %: C 64.20; H 3.73;
N 5.76. M 486.43.
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Dimerization of allene II under ultrasonic irra-
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in 10 ml of anhydrous toluene was subjected to
ultrasonic irradiation over a period of 10 h at 110°C.
The solvent was distilled off, and the products were
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SAKHAUTDINOV et al.
798
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