Lanthanide triiodide-catalyzed amination of phthalonitrile. the structure of 1-isopropylamino-3-(isopropylimino)isoindole

Article abstract of DOI:10.1007/s11172-008-0293-3

The reactions of phthalonitrile with MeNH₂, Pr ⁿNH₂, and PrⁱNH₂ in the presence of catalytic amounts of LnI₃ (Ln = Nd or Dy) or LnI₃(THF) ₃ (Ln = Gd or Nd) afford 1,3-

Full text of DOI:10.1007/s11172-008-0293-3

Russian Chemical Bulletin, International Edition, Vol. 57, No. 10, pp. 2162—2167, October, 2008
2162
Lanthanide triiodideꢀcatalyzed amination of phthalonitrile.
The structure of 1ꢀisopropylaminoꢀ3ꢀ(isopropylimino)isoindole*
M. N. Bochkarev, T. V. Balashova, A. A. Maleev, I. I. Pestova,
G. K. Fukin, E. V. Baranov, and Yu. A. Kurskii
G. A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences,
49 ul. Tropinina, 603950 Nizhny Novgorod, Russian Federation.
Fax: +7 (831) 462 7497. Eꢀmail: mboch@iomc.ras.ru
The reactions of phthalonitrile with MeNH2, PrnNH2, and PriNH2 in the presence of cataꢀ
lytic amounts of LnI3 (Ln = Nd or Dy) or LnI3(THF)3 (Ln = Gd or Nd) afford 1,3ꢀbis(alkylꢀ
imino)isoindolines (Alk = Me (1), Prn (2), or Pri (3), respectively). Under analogous conditions,
2ꢀaminopyridine gives 1,3ꢀbis(2ꢀpyridylimino)isoindoline (4). The Xꢀray diffraction study of
compound 3 showed that, in the crystalline state, this compound exists as the isomer, 1ꢀisopropylꢀ
aminoꢀ3ꢀ(isopropylimino)isoindole.
Key words: alkyliminoisoindolines, amines, lanthanide triiodides, primary amines,
pyridyliminoisoindoline, catalysis.
1,3ꢀBis(alkylimino)isoindolines have attracted attenꢀ
of phthalonitrile, discuss the possible reaction pathway,
and describe the structure of one of the isoindolines.
tion as specific tridentate ligands, whose rigid planar strucꢀ
ture hinders the formation of a tetrahedral core with the
result that complexes with another structure can be synꢀ
thesized.1,2 In addition, these compounds serve as comꢀ
ponents for the template synthesis of phthalocyanines and
their metal complexes3 used in many fields of medicine
and engineering. Recently, isoindole derivatives have
found new use. Thus, it was found that phenylꢀsubstituted
ethylcarbazolylisoindole has good chargeꢀtransport propꢀ
erties,4 whereas indolizino[3,4,5ꢀab]isoindole derivatives
show high electroluminescence activity.5 Hence, these
heterocyclic compounds can be considered as promising
materials for organic lightꢀemitting diodes. Nevertheless,
in spite of considerable interest in isoindolines and their
derivatives, the structures and physical properties of these
compounds are poorly known. There are several methods
for the synthesis of diiminoisoindolines.6—10 The simplest
method is based on the reaction of primary amines with
phthalonitrile in the presence of catalytic amounts of
alkalineꢀearth metal salts9 or sulfur.10 Recently, it has
been found that lanthanide triiodides efficiently catalyze
the amination of acetonitrile and benzonitrile giving rise
to monoꢀ and N,N´ꢀdisubstituted amidines.11 As a conꢀ
tinuation of this research, we found that lanthanide
triiodides catalyze also the addition of amines to phthaloꢀ
nitrile; however, these reactions afford 1,3ꢀbis(alkylimino)ꢀ
isoindolines. In the present study, we report the amination
Results and Discussion
The reactions of phthalonitrile with excess RNH2
(R = Me, PrnNH2, or PriNH2) in the presence of the
NdI3, DyI3, NdI3(THF)3, or GdI3(THF)3 salts (1—1.5 mol)
afford the corresponding 1,3ꢀbis(alkylimino)isoindolines
1—3. The reactions performed at room temperature for
6—8 h give products in 55—85% yields. However, the GLC
monitoring showed that the 100% conversion of phthaloꢀ
nitrile in the reactions with PriNH2/C6H4(CN)2/NdI3 is
achieved within 1 h at 40 °C. The addition of 2ꢀaminoꢀ
pyridine at the C≡N bond of phthalonitrile proceeds with
difficulty. After heating of the reaction mixture (a soluꢀ
tion of the reagents in benzene) at 80 °C for 20 h, more
than 30% of 2ꢀaminopyridine remained unconsumed, and
the yield of 1,3ꢀbis(2ꢀpyridylimino)isoindoline (4) was at
most 20%. After removal of the excess amine and the
resulting isoindoline, a waxꢀlike emeraldꢀgreen compound
was always obtained as a residue in 5—10% yield based on
the starting amount of C6H4(CN)2. The UV spectra of this
compound show a set of bands characteristic of phthaloꢀ
cyanine. It should be noted that the formation of phthaloꢀ
cyanine as a byꢀproduct is observed also in reactions cataꢀ
lyzed by alkaline earth metal salts.9
Lanthanide salts used as catalysts are isolated (after
completion of the reactions) as complexes with amine
and isoindoline that is formed in the reaction. These salts
have the formulas LnI3(PriNH2)4 (Ln = Nd, Gd, or Dy),
* Dedicated to Professor V. I. Bregadze on the occasion of his
70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2121—2125, October, 2008.
1066ꢀ5285/08/5710ꢀ2162 © 2008 Springer Science+Business Media, Inc.

Synthesis of 1,3ꢀbis(alkylimino)isoindolines
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
2163
Scheme 1
R = Me (1), Prn (2), Pri (3), 2ꢀC5H5N (4)
NdI3(PrnNH2)5, and NdI3(MeNH2)(L) (L is 1,3ꢀbisꢀ
(methylimino)isoindoline (1)). We suggested that these
complexes serve as catalysts in the processes under conꢀ
sideration. To confirm this hypothesis, we performed the
reaction of phthalonitrile with PriNH2 in the presence of
NdI3(PriNH2)4 at room temperature. After 6 h, this reacꢀ
tion afforded 1,3ꢀbis(isopropylimino)isoindoline (3) in
73% yield. The intermediates in these reactions were not
identified. However, taking into account the similarity of
the reactions of amines with acetonitrile11 and phthaloꢀ
nitrile, the general reaction pathway for the formation of
isoindoline can be represented by Scheme 1.
Ammonia that is eliminated in the last step of the
reaction can be detected as ammonium chloride, which is
formed upon the treatment of volatile products with HCl.
Apparently, ammonia partially (5—10%) reacts with
phthalonitrile to give phthalocyanine.
Isoindolines 2 and 3 can easily be isolated from the
reaction mixture as colorless crystals by sublimation in
vacuo. Products 1 and 4 can also be isolated by sublimaꢀ
tion in vacuo; however, the reaction mixture should be
pretreated with methanol (after the removal of the cataꢀ
lyst and excess amine).
Isoindoline 3 was studied by Xꢀray diffraction. Inforꢀ
mation on the structures of free 1,3ꢀbis(imino)isoindoꢀ
lines12—14 and transition metal and mainꢀgroup metal comꢀ
plexes with isoindoline ligands1,2,15—17 from the Cambridge
Structural Database can be used for comparison with the
structure of 3. The Xꢀray diffraction study of compound 3
showed that there are two independent molecules with
similar geometry per asymmetric unit (Table 1). The geoꢀ
metric characteristics of only one of these molecules are
discussed below. The structure of the molecular core
clearly indicates that, in the crystalline state, compound 3
exists as the isomer A with the hydrogen atom at the side
nitrogen atom (Fig. 1).
Although the N(1)—C(1) and C(1)—N(2) bonds
(1.324(2) and 1.330(1) Å, respectively) are shorter than
the other C—N bonds, they are substantially longer than
the true C=N double bond (C(8)—N(3), 1.285(2) Å),
which is indicative of the substantial electron density
delocalization in the N(1)—C(1)—N(2) fragment. In
the N(1)—C(8)—N(3) group, the electron density deloꢀ
calization is less pronounced. Thus, the N(1)—C(8) bond
is 1.401(1) Å (1.403(1) Å), but the C(8)—N(3) bond is
1.285(2) Å (1.286(2) Å). The molecular structure of 3
Table 1. Selected bond lengths (d) and bond angles (ω) in
two crystallographically independent molecules (I and II) of
1ꢀisopropylaminoꢀ3ꢀ(isopropylimino)isoindole (3)
Parameter
Value
I
II
Bond
d/Å
N(1)—C(1)
N(1)—C(8)
N(2)—C(1)
N(2)—C(9)
N(3)—C(8)
N(3)—C(12)
C(1)—C(2)
C(7)—C(8)
1.324(2)
1.401(1)
1.330(1)
1.474(2)
1.285(2)
1.477(2)
1.487(2)
1.491(2)
1.323(2)
1.403(1)
1.333(1)
1.473(2)
1.286(2)
1.474(2)
1.482(2)
1.484(2)
Angle
ω/deg
C(1)—N(2)—C(9)
N(1)—C(1)—C(2)
C(1)—N(1)—C(8)
N(1)—C(8)—C(7)
C(8)—N(3)—C(12)
121.2(1)
112.8(1)
106.5(1)
109.3(1)
116.7(1)
122.1(1)
112.8(1)
106.6(1)
109.3(1)
117.0(1)

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Bochkarev et al.
tallize as the isomer B.18 In the zinc and copper comꢀ
plexes with 1,3ꢀbis[(5ꢀmethylꢀ2ꢀpyridyl)imino]isoindoꢀ
line ligands,1 the differences in the C(1)—N(1) and
N(1)—C(8) bond lengths (0.01 and 0.008 Å, respectively),
as well as the differences in the C(1)—N(2) (0.017 Å) and
C(8)—N(3) bond lengths (0.004 Å), are substantially
smaller than the corresponding differences in isoindoline
3, which is indicative of the substantial electron density
delocalization in the ligands coordinated to the metal
center.
In the crystal structure, molecules 3 form double chains
through intermolecular N…H hydrogen bonds (Fig. 2).
Along the chains, these bonds are formed between the
imino N atoms and the amino N atoms (N(3AA)...H(2BA)
and N(3AC)...H(2BB), 2.120(15) Å; N(3BA)...H(2AB)
and N(3BC)...H(2AC), 2.119(8) Å). These bonds are
shorter than 2.3 Å and correspond to typical N—H
hydrogen bonds.19 The lateral bonds in the double
chains (N(1AA)...H(11B), N(1AC)…...H(11A), and
N(1AB)... H(11C), 2.553(17) Å) are formed between
the N atoms of the isoindole fragment from one chain
and one of the H atoms of the methyl groups of the
amino fragment from another chain. The length of
these contacts (2.553(17) Å) is close to the length of the
van der Waals intermolecular interaction (2.64 Å).19
The signals for the protons of the N—H groups in the
1H NMR spectra of compounds 1, 2, and 3 (δ 5.2, 7.38,
and 2.4, respectively) are substantially broadened, which
confirms the wellꢀknown equilibrium between the isoꢀ
mers A and B of isoindolines in solution.
C(10)
C(11)
C(9)
N(2)
H(2)
N(1)
C(1)
C(14)
C(12)
N(3)
C(8)
C(2)
C(13)
C(3)
C(4)
C(7)
C(6)
C(5)
Fig. 1. Molecular structure of 1,3ꢀbis(isopropylimino)isoꢀ
indole (3).
is similar (except for the geometry of the substituents)
to the structures of free 1,3ꢀbis(imino)isoindoline,12
5ꢀ(1ꢀaminoisoindolꢀ3ꢀylideneamino)ꢀ1,3,4ꢀthiadiazoleꢀ
2(3H)ꢀthione,13 and antiꢀ1ꢀaminoꢀ3ꢀ(phenylimino)isoꢀ
indoline,14 although the electron density delocalization
in the N(2)—C(1)—N(1)—C(8)—N(3) fragment in these
compounds is somewhat different (judging from the bond
lengths). It is interesting that isoindolines containing aroꢀ
matic substituents, such as 1,3ꢀbis(phenylimino)isoꢀ
indoline14 and 1,3ꢀbis(2ꢀpyridylimino)isoindoline, crysꢀ
Unlike the aboveꢀmentioned indolizinoisoindole deꢀ
rivatives, the isoindolines synthesized in the present study
do not show photoꢀ and electroluminescence properties,
N(3AA)
H(2BA)
H(2AA)
Pri
H(2AB)
N(3AB)
Pri
N(3BA)
Pri
N(1AA)
N(2AA)
Pri
N(1AB)
H(11C)
N(2AB)
N(2BA)
Pri
N(1BA)
H(11B)
Pri
Pri
N(1BB)
N(2BB)
Pri
N(2AC)
H(2AC)
Pri
N(1BC)
N(2BC)
N(1AC)
N(3BB)
H(2BB)
N(3BC)
N(3AC)
H(2BC)
Fig. 2. Association of isoindoline molecules 3 in the crystal structure.

Synthesis of 1,3ꢀbis(alkylimino)isoindolines
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
2165
AA´BB´, 4 H, C6H4). IR, ν/cm–1: 3197, 3139 (N—H); 3050
(C—H); 1665 (C=N); 1584, 1531 (C=C, N—H); 1405, 1120,
1026, 860, 772 (C—H). UV (MeCN, 10–4 mol L–1), λmax/nm
(ε•10–3): 258.8 (10.2), 305 (4.9).
but exhibit noticeable pꢀtype conductivity. The reacꢀ
tions of these compounds with lanthanide silylamides
Ln[N(SiMe3)2]3 afforded new complexes of composition
Ln(L)3 (L is 1,3ꢀbis(imino)isoindoline). Investigations of
the properties and structures of the latter compounds are
presently underway.
Hence, we found that lanthanide triiodides LnI3 effiꢀ
ciently catalyze the amination of phthalonitrile giving rise
to 1,3ꢀbis(alkylimino)isoindolines. Iodides containing
coordinated THF have the same catalytic activity. The
Xꢀray diffraction study of isoindoline 3 showed that, in
the crystalline state, this compound exists as the isomer
with the hydrogen atom at the terminal nitrogen atom,
viz., as 1ꢀisopropylaminoꢀ3ꢀ(isopropylimino)isoindole.
1,3ꢀBis(propylimino)isoindoline (2). A mixture of phthaloꢀ
nitrile (1.39 g, 10.85 mmol), PrnNH2 (4,59 g, 77.65 mmol), and
a NdI3 powder (0.72 g, 1.37 mmol) was stirred at room temperaꢀ
ture for 8 h, after which a green solution and a precipitate of
NdI3(PrnNH2)5 were obtained. The precipitate was filtered off,
washed with amine, and dried in vacuo; the yield was 1.077 g
(96%). Found (%): I, 46.76; Nd, 17.79. C15H45N5I3Nd (820.5).
Calculated (%): I, 46.40; Nd, 17.58. IR, ν/cm–1: 3462, 3293,
3235 (N—H); 1631 (C=N); 1565 (C—C); 1042, 938, 807, 700
(C—H). Propylamine and volatile products were removed from
the filtrate by vacuum condensation. The residue was sublimed at
140 °C (0.2 Torr). 1,3ꢀBis(propylimino)isoindoline 2 was obtained
in a yield of 0.671 g (27%) as colorless crystals, m.p. 110 °C.
Found (%): C, 73.30; H, 8.52; N, 18.18. C14H19N3 (229.32).
Calculated (%): C, 73.32; H, 8.35; N, 18.32. 1H NMR (CD3CN,
200 MHz), δ: 1.01 (t, 6 H, CH3; J = 7.4 Hz); 1.83 (m, 4 H, βꢀCH2);
3.79 (t, 4 H, αꢀCH2, J = 7.1 Hz); 7.38 (s, NH); 7.68—8.21 (m,
AA´BB´, 4 H, C6H4). IR, ν/cm–1: 3293, 3181 (N—H); 3031
(C—H); 1619 (C=N); 1311, 1234, 1157, 1096, 1011, 973, 769,
711, 669, 642. UV (MeCN, 10–4 mol L–1), λmax/nm (ε•10–3):
261 (26.5), 312 (14.4).
Experimental
Materials and methods. All reactions and operations were
carried out in vacuo using the standard Schlenk technique. Comꢀ
mercial phthalonitrile and amines (Aldrich) were used. Methyꢀ
lamine was prepared from MeNH2•HCl by distillation over
NaOH followed by condensation into a cold trap. The amine
was treated with 5 mol.% NdI2 before use. Other amines were
dried with NdI2 (3—5 mol.%, 10 min) immediately before use
and then condensed into a reaction vessel in vacuo. Unsolvated
lanthanide iodides LnI3 were prepared by burning a Ln/I2 mixꢀ
ture;20 GdI3(THF)3 and NdI3(THF)3 were prepared by crystalꢀ
lization of GdI3 and NdI3, respectively, from THF. The 1H NMR
spectra were recorded in CD3CN or CDCl3 at 298 K on a
Bruker DPX 200 spectrometer; the chemical shifts are expressed
in ppm with respect to the chemical shifts of the residual protons
of deuterated solvents. The IR spectra were recorded on a FSM
1201 Fourierꢀtransform IR spectrometer as Nujol mulls. The
UVꢀVis spectra were measured on a Perkin Elmer Lambda 25
spectrometer. The GLC analysis of volatile products was carried
out on a Tsvetꢀ530 chromatograph. The melting points (uncorꢀ
rected) were determined in sealed tubes.
1,3ꢀBis(methylimino)isoindoline (1). A NdI3 powder (0.439 g,
0.84 mmol) was added to a solution of phthalonitrile (0.516 g,
4.03 mmol) in MeNH2 (2.5 g, 80.5 mmol). The reaction mixture
was stirred at 10 °C for 6 h, during which the solution turned
emeraldꢀgreen. The crystalline precipitate was filtered off and
dried in vacuo. The product NdI3(MeNH2)(L) (L is 1,3ꢀbisꢀ
(methylimino)isoindoline) was obtained in a yield of 0.48 g
(79%). Found (%): I, 52.93; Nd, 19.87. C11H16N4I3Nd (729.128).
Calculated (%): I, 52.21; Nd, 19.78. IR, ν/cm–1: 3147 (N—H);
1630 (C=N); 1588 (N—H); 1527 (C—C); 1115, 1020, 853, 711
(C—H). Volatile products and MeNH2 were separated from
the green filtrate by vacuum condensation. The nonꢀcrystalline
yellow precipitate was treated with MeOH. The solution was
separated from the precipitate by decantation. Then volatile
products were removed from the solution by vacuum condensaꢀ
tion. The yellow precipitate was sublimed at 100—120 °C (0.2 Torr).
Isoindoline 1 was obtained in a yield of 0.361 g (52%) as colorꢀ
less crystals, m.p. 175—177 °C (decomp.) (cf. lit. data6: m.p. 172 °C
(decomp.)). Found (%): C, 69.30; H, 6.33. C10H11N3 (173.118).
Calculated (%): C, 69.38; H, 6.40. 1H NMR (CDCl3, 200 MHz),
δ: 3.46 (s, 6 H, CH3); 5.2 (br.s, 1 H, NH); 7.41—7.66 (m,
1,3ꢀBis(isopropylimino)isoindoline (3). A NdI3 powder (0.36 g,
0.9 mmol) was added with stirring to a solution of phthalonitrile
(0.774 g, 6.04 mmol) in PriNH2 (5.842 g, 98.8 mmol). The
reaction mixture was magnetically stirred at room temperature
for 8 h. The white crystalline precipitate of NdI3(PriNH2)4 was
filtered off, washed with PriNH2 (2Ѕ5 mL), and dried in vacuo.
The yield was 0.457 g (75.2%). Found (%): I, 50.33; Nd, 19.25.
C12H36N4I3Nd (761.39). Calculated (%): I, 50.00; Nd, 18.94.
IR, ν/cm–1: 3451, 3317 (N—H); 3038 (C—H); 1657 (C=C);
1603 (C=N); 1193, 720, 489. Unconsumed PriNH2 and volatile
products were removed from the filtrate by vacuum condensaꢀ
tion. The residue was sublimed at 140 °C (0.2 Torr). Isoindoline
3 was obtained in a yield of 0.713 g (52%) as colorless crystals,
m.p. 159 °C. One crystal was used for Xꢀray diffraction study.
Found (%): C, 73.33; H, 8.43. C14H19N3 (229.32). Calculated
1
(%): C, 73.32; H, 8.35. H NMR (CD3CN, 200 MHz), δ: 1.26
(d, 12 H, CH(CH3)2, J = 6.4 Hz); 2.4 (br.s, NH); 4.46 (sept,
2 H, CH(CH3)2, J = 6.4 Hz); 7.45—7.68 (m, AA´BB´, 4 H, C6H4).
IR, ν/cm–1: 3223 (N—H); 3022 (C—H); 1649 (C=N); 1568,
1525 (C—H, N—H); 1342, 1324, 1283, 1225, 1154, 1140, 1129,
1098, 1017, 983, 947, 886, 843, 775, 715, 662, 646, 557, 555,
472. UV (MeCN, 10–4 mol L–1), λmax/nm (ε•10–3): 261 (9.4),
312 (5.1).
Isoindoline 3 was synthesized analogously from phthalonitrile
(0.716 g, 5.6 mmol), PriNH2 (5.09 g, 86.1 mmol), and DyI3
(0.137 g, 0.25 mmol) in a yield of 0.93 g (73%). 1,3ꢀBis(isopropylꢀ
imino)isoindoline 3 was synthesized analogously from phthaloꢀ
nitrile (1.5 g, 1.2 mmol), PriNH2 (6.94 g, 117.4 mmol), and
GdI3(THF)3 (0.9 g, 1.2 mmol) in a yield of 2.08 g (78%). Comꢀ
pound 3 was synthesized also from phthalonitrile (1.076 g,
8.4 mmol), PriNH2 (6.94 g, 117.4 mmol), and NdI3(THF)3
(1.058 g, 1.4 mmol) in a yield of 1.632 g (85%).
1,3ꢀBis(2ꢀpyridylimino)isoindoline (4). A NdI3 powder (0.84 g,
1.6 mmol) was added to a solution of phthalonitrile (0.526 g,
4.11 mmol) and 2ꢀaminopyridine (0.773 g, 8.21 mmol) in benꢀ

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Bochkarev et al.
Table 2. Crystallographic parameters and the Xꢀray diffraction
data collection and refinement statistics for compound 3
Table 2. The intensities were integrated using the SAINT proꢀ
gram.21 Absorption corrections were applied with the use of the
SADABS program.22 All calculations for the structure of 3 were
performed with the use of the SHELXTL program package.23
The positional and thermal parameters of nonhydrogen atoms
were refined anisotropically. The hydrogen atoms were located
in Fourier maps and refined isotropically. Two crystallographiꢀ
cally independent molecules 3 occupy general positions.
The atomic coordinates and complete data on the bond
lengths and bond angles were deposited with the Cambridge
Structural Database (CCDC 668002).
Parameter
Characteristics
Molecular formula
Molecular weight
T/K
Crystal system
C14H19N3
229.32
100(2)
Triclinic
Pꢀ1
Space group
Unit cell parameters
a/Å
b/Å
c/Å
α/deg
8.5909(3)
12.9617(5)
13.4752(5)
104.7590(10)
108.4750(10)
101.3230(10)
1311.91(8)
4
We thank M. A. Lopatin, T. I. Lopatina, and
O. V. Kuznetsova (G. A. Razuvaev Institute of Organoꢀ
metallic Chemistry, Russian Academy of Sciences) for
performing spectroscopic and chromatographic analysis.
This study was financially supported by the Russian
Foundation for Basic Research (Project No. 07ꢀ03ꢀ00248).
β/deg
γ/deg
V/Å3
Z
dcalc /g cm–3
1.161
0.071
μ/mm–1
References
F(000)
496
Crystal dimensions/mm3
θꢀScan range/deg
Number of observed reflections
Number of independent reflections
Rint
0.20×0.13×0.07
1.69—26.00
11431
5136
0.0334
99.7
5136/1/459
1.001
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Completeness of Xꢀray data (%)
Number of refined parameters
Goodnessꢀofꢀfit on F2
R1/wR2 (I > 2σ(I))
R1/wR2 (based on all parameters)
Residual electron
0.0470/0.1036
0.0759/0.1140
0.243/–0.174
density (e Å–3), ρmax/ρ
min
7. H. Hopff, P. Gallegra, Helv. Chim. Acta, 1968, 51, 253.
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Papers, XII Nizhny Novgorod Young Scientists Session],
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zene (10 mL). The reaction mixture was magnetically stirred at
80 °C for 20 h, after which a green solution and a precipitate
were obtained. The solution was removed by decantation, The
precipitate was washed with benzene and dried in vacuo. Benꢀ
zene and unconsumed 2ꢀaminopyridine (0.274 g, 35%) were
separated by condensation and sublimation in vacuo. The yellow
precipitate was treated with MeOH (5 mL) and H2O (5 mL).
The yellow powder insoluble in water was dried and sublimed at
140—160 °C (0.2 Torr). Isoindoline 4 was obtained in a yield of
0.2 g (16%) as yellow crystals, m.p. 178—180 °C (cf. lit data9:
m.p. 181—183 °C). Found (%): C, 72.66; H, 4.69; N, 22.65.
C18H13N5 (299.33). Calculated (%): C, 72.23; H, 4.38; N, 23.40.
1H NMR (CDCl3, 200 MHz), δ: pyridine protons 8.62 (dd, 1 H,
J = 4.8 Hz, J = 1.3 Hz); 7.76 (td, 1 H, J = 7.5 Hz, J = 1.8 Hz);
7.46 (d, 1 H, J = 8.0 Hz); 7.12 (m, 1 H); 8.08 (m, AA´, 2 H,
C6H4); 7.65 (m, BB´, 2 H, C6H4). IR, ν/cm–1: 3254, 3200
(N—H); 3062, 3050, 3037 (C—H); 1630 (C=N); 1606 (N—H);
1583, 1553 (C—C, N—H); 1430, 1110, 1035, 853, 786 (C—H).
Xꢀray diffraction study. Single crystals of compound 3 were
grown by sublimation. The Xꢀray diffraction data were collected
on a SMART APEX diffractometer (graphite monochromator,
λ(MoꢀKα) = 0.71073 Å, 100 К, ω—ϕ scanning technique). The
crystallographic parameters and the Xꢀray diffraction data colꢀ
lection and refinement statistics for compound 3 are given in
15. D. M. Baird, K. Y. Shih, J. H. Welch, R. D. Bereman,
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Chem., 1983, 22, 3944.
18. W. Schilf, J. Mol. Struct., 2004, 691, 141.

Synthesis of 1,3ꢀbis(alkylimino)isoindolines
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 10, October, 2008
2167
19. Yu. V. Zefirov, P. M. Zorkii, Usp. Khim., 1995, 64, 446
[Russ. Chem. Rev., 1995, 64, 415 (Engl. Transl.)].
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v.6.02a, Bruker AXS, Madison, WI, USA, 2000.
23. G. M. Sheldrick, SHELXTL v.6.12, Structure Determination
Software Suite, Bruker AXS, Madison, WI, USA, 2000.
22. G. M. Sheldrick, SADABS v. 2.01, Bruker/Siemens Area Detector
Absorption Correction Program, Bruker AXS, Madison, WI,
USA, 1998.
Received January 15, 2008;
in revised form February 26, 2008