New reaction of ethenetetracarbonitrile with N-arylisoindolines

Article abstract of DOI:10.1016/S0040-4020(03)00735-X

N-Arylisoindolines 1a-i react with ethenetetracarbonitrile 2 in aerated benzene by formation of [3-(2-aryl-3-dicyanomethylene-2,3-dihydro-1H-isoindol-1-ylidene)-2-aryl-2, 3-dihydro-1H-isoindol-1-ylidene]propanedinitriles 8a-i (20-36%), N-aryl-3-dicyanomethylene-isoindol-2-ones 9a-i (15-21%) and N-arylphthalimides 10a-i (4-9%) as well as 1,1,2,2-tetracyanoethane 11 (35-55%). The structure of 8d has been unambiguously confirmed by a single crystal X-ray structure analysis. A rationale for the formation of products 8-11 is presented.

Full text of DOI:10.1016/S0040-4020(03)00735-X

Tetrahedron 59 (2003) 5073–5081
New reaction of ethenetetracarbonitrile with N-arylisoindolines
a,*
b
Dietrich D o¨ pp, Alaa A. Hassan, Aboul-Fetouh E. Mourad, Ahmed M. Nour El-Din,
b
b
c
Klaus Angermund, Carl Kr u¨ ger, Christian W. Lehmann and J o¨ rg Rust
c
c
c
a
Institut f u¨ r Chemie, Universit a¨ t Duisburg-Essen, D-47048 Duisburg, Germany
Department of Chemistry, Faculty of Science, El-Minia University, El-Minia, A.R. Egypt
Max-Planck-Institut f u¨ r Kohlenforschung, D-45466 M u¨ lheim (Ruhr), Germany
b
c
Received 7 January 2003; revised 22 April 2003; accepted 2 May 2003
Abstract—N-Arylisoindolines 1a–i react with ethenetetracarbonitrile 2 in aerated benzene by formation of [3-(2-aryl-3-dicyanomethylene-
,3-dihydro-1H-isoindol-1-ylidene)-2-aryl-2,3-dihydro-1H-isoindol-1-ylidene]propanedinitriles 8a–i (20–36%), N-aryl-3-dicyano-
2
methylene-isoindol-2-ones 9a–i (15–21%) and N-arylphthalimides 10a–i (4–9%) as well as 1,1,2,2-tetracyanoethane 11 (35–55%).
The structure of 8d has been unambiguously confirmed by a single crystal X-ray structure analysis. A rationale for the formation of products
8
–11 is presented. q 2003 Elsevier Science Ltd. All rights reserved.
1
. Introduction
with (2,4,7-trinitro-9H-fluoren-9-ylidene)propanedinitrile
in pyridine with admission of air via a net a-H-atom
abstraction to give 2-arylisoindole-1,3-di-(N-arylimines) 3
and isoindigoid products like 4 and 5 as well as 6 as a
result of an oxidative condensation. The latter type of
products is also obtained from the interaction of 1,4-benzo-
Ethenetetracarbonitrile (previously referred to as tetra-
cyanoethylene, 2) shows a great affinity for electrons, and
is thus a fairly good dehydrogenating agent towards
dihydroaromatic and dihydroheteroaromatic systems. It
behaves as a strong electron acceptor towards suitable
1
1
4 – 16
or 1,4-naphthoquinones with N-arylisoindolines.
2 -Arylspiro[1,3-benzodioxole-2 -isoindoline]-3 -ones were
1
–4
0
0
observed from the reaction of N-arylisoindolines with
0
electron donors.
intermolecular charge-transfer interaction,
monoelectronic reduction results in the formation of the
It forms molecular complexes by an
1
,4–6
and the
1
7
tetrachloro-1,2-benzoquinone. On the other hand, iso-
indolines reacted with (1,3-dioxo-2,3-dihydro-1H-inden-2-
1
,6
fairly long-lived radical anion. Tetracyanoethylene reacts
with N,N-dialkylanilines or analogous electron rich arenes
(with free p-position) to products of p-tricyanovinylation.
Indole derivatives would undergo this reaction at—
depending on conditions—either C-2 or C-3, primary
1
aromatic amines on nitrogen, whereas the secondary amine
0
arylisoindol-1,3-ylene)-di(1,4-naphthoquinone-3-carbo-
ylidene)propanedinitrile in aerated pyridine to give 2,2 -(2-
1
,7,8
1
8
nitriles) 7 (Chart 1).
9
2
C-6. Compounds with active methylene groups perform a
,2,4-trimethyl-1,2-dihydroquinoline shows that reaction on
1
2. Results and discussion
0
Michael-type addition, giving rise to a-(1,1,2,2-tetra-
1
In the present work we describe the reaction of N-aryl-
isoindolines 1a–i with tetracyanoethylene 2. Upon addition
of doubled molar amounts of 2 to a solution of N-aryl-
isoindolines 1a–i in benzene with admission of air, the
1
cyanoethyl)-derivatives. This addition may be followed
by elimination of malononitrile and formation of dicyano-
1
,12
methylene derivatives.
1
9
green colour of a transient charge-transfer complex is
observed which quickly gives way to a brown and finally to
a characteristic blue colour, and formation of crude
tetracyanoethane as precipitate. The concentration residue
of the filtrate was subjected to vacuum sublimation to
remove any unreacted 2. Chromatographic separation of the
residue gave numerous coloured zones, from which
products 8–11 could be isolated (Chart 2).
N-Arylisoindolines 1, featuring reactive benzylic hydrogens
in a comparatively rigid five-membered ring, show a
different behaviour towards tetracyanoethylene deviating
from the behaviour of tertiary arylamines or indole.
1
3
We recently reported that N-arylisoindolines 1 reacted
Keywords: cyano compounds; isoindoles; oxygenation; strained
compounds.
Structural assignments of compounds 8–11 are based on
spectral data, on combustion analyses and on chemical
evidence. Compounds 8a–i show a characteristic blue
*
Corresponding author. Tel.: þ49-203-3793304;
e-mail: doepp@uni-duisburg.de
0040–4020/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0040-4020(03)00735-X

5074
D. D o¨ pp et al. / Tetrahedron 59 (2003) 5073–5081
Chart 1.
colour in solution, attributable to the local push–pull
systems of conjugated double bonds and lone pairs. The
lmax values (584–570 nm) for various substituted com-
pounds 8a–i are similar due to the same molecular gross
structure and configuration. The IR spectrum of (for
example) 8b in KBr shows a sharp absorption characteristic
of conjugated CuN groups at 2210 cm2 and several peaks
at 1610 and 1530 for skeletal vibrations of the aryl groups.
isomers which are not interconvertible at the temperatures
applied. Likely a priori possibilities might be atrop-
isomerism with respect to the N-aryl bonds (see below) or
the coexistence of two conformers with respect to the
central double bond, one being twisted, the other one being
anti-pyramidalized at its termini. Such a situation has been
observed recently with bi[1,3-bis(dicyanomethylene)indan-
2-ylidene] and in other cases, but does not seem to play a
role in the cases reported here (see below). The HPLC-
analysis of 8b using acetonitrile/methanol (9:1 v/v) shows
one compound peak only.
1
2
0
1
The H NMR spectra (CD NO , 300 MHz) of 8a–i clearly
2
3
show the absence of methylene protons and the presence of
phenyl and (if applicable) methyl protons only. In some
cases (8a–e,i) the substituents (o-, m-OCH ; o-, m-, p-CH ;
3
3
p-COCH ) on the N-aryl group give rise to more than one
3
singlet for the CH -protons. In the case of 8b at 303 K, a
3
shoulder at 3.86 ppm and a sharp singlet at 3.78 ppm are
present. Upon warming to 333 or 343 K the shoulder is
replaced by a second singlet at 3.86 ppm. This behaviour
suggests the presence of two very closely related stereo-
The molecular formulas of compounds 8a–i are supported
by the mass spectra which gave the predicted molecular ion
peaks as base peaks. It should also be noted that the mass
spectra of compounds 8a–i are characterized by loss of the
C(CN) moiety from the molecular ions but the correspon-
2
dent fragment peaks are of relatively low intensity.
Chart 2.

D. D o¨ pp et al. / Tetrahedron 59 (2003) 5073–5081
5075
Moreover, the structure of 8d has been unambiguously
confirmed by a single crystal X-ray structure analysis
The gross formulas of 9a–i were confirmed by the
elemental analyses and the mass spectra, which exhibited
the expected molecular ion peaks in high intensity. The
IR-spectra showed absorptions uniformly near 2220 (CN)
and between 1745 and 1770 cm2 (CO) (see Section 4). The
structures of the N-arylphthalimides 10 and of tetra-
cyanoethane (11) were confirmed by comparison with
authentic samples.
(
Figs. 1 and 2, Table 1). The characteristic feature with
respect to the C1–C21 double bond (note that the crystal-
lographic numbering does not correspond to the systematic
1
IUPAC numbering rules), showing a bond length of
˚
1
.379(2) A and thus being slightly elongated, is cisoid
twisted geometry with a dihedral angle N1–C1–C2–N21
of 233.93(30)8. This value clearly indicates that com-
pounds 8 are sterically crowded due to steric repulsion
between the hydrogen atoms at the peri-positions C3 and
Since the reactions reported very likely require numerous
steps, moderate yields (based throughout on the amount of
starting materials used, see Section 4) have to be regarded as
acceptable.
˚
C23 which are in a 3.15 A distance, and the calculated
3
˚
H–23H distance is 2.390(1) A. Also, compounds 8 are
considerably encumbered due to the vicinity of the
dicyanomethylene groups and the nearly sandwiched
N-phenyl-rings. This is documented by the deviation of
the C9–C11–N3 and C29–C31–N23 bond angles by 8.48
and 8.68, respectively, from 1808 (Table 1). Also, carbon
atoms 1,8,9,21,28, and 29 are planar, since the bond angles
surrounding these centres all sum up to 3608 within the
limits of accuracy, and the sums of bond angles at N1 and
N21 are only a few degrees lower than 3608, so the
isoindolic N-atoms show very little if any pyramidalization.
In order to rationalize the formation of products 8–11,
1
dehydrogenation of 1 by 2 may be regarded as the initial
event, whereby CT-complexes may (but not have to) be
intermediate stages, forming tetracyanoethane (11) and the
corresponding isoindoles 12, which, however, were not
isolated (Scheme 1). Whenever didehydrogenation is
unfavourable for structural reasons, e.g. in higher ring
homologues of 1, hydride abstraction is observed followed
2
2
by cyanation of the cyclic iminium ions.
It should be noted that the crystal structure of 8d does show
some degree of disorder affecting the m-methylphenyl
groups attached to N1 and N21. Two conformations, related
via a 1808 rotation around the N21–C32 bond, are found.
The disorder concerning N1 is more complex in so far as
two discrete m-methylphenyl groups are found in a ratio of
Compounds with active methylene groups are known to
react with 2 by a Michael-type addition followed by release
of malononitrile giving rise to dicyanomethylene com-
1
pounds. Since isoindoles may be seen as vinylogous
enamines, a behaviour towards 2 similar to that of
1
methylene active ketones may be expected. Thus, addition
8
(
4:16. Thus, 8d exists as a mixture of two atropisomers
Fig. 1).
of 2 to C1 of 12 may generate 13 which undergoes
protonation/deprotonation giving rise to 14 which has two
options: (i) release of HCN giving a product (15) of
tricyanovinylation of 1; (ii) an ‘elimination type of
dimerization’ (reminescent of the ‘oxidative dimerization’
Similar typical cisoid arrangements are demonstrated in the
X-ray crystal structure analyses of 1-methyl-3-(1-methyl-2-
phenylindol-3-yl)-2-phenylindole (with the phenyl groups
being nearly sandwiched and the peri-hydrogen atoms in
close contact),
biisothianaphtylidene.
2
3
typical for isoindoles ).
2
1a
21b
of a fused biisoindolylidene,
2
and a
Option (i) does not seem to be the preferred mode of 14
bearing N-aryl groups, however, if the aryl group is replaced
1c
Figure 1. Molecular structure of 8d in the crystal. The crystallographic numbering does not reflect the systematic IUPAC numbering. Anisotropic displacement
parameters are shown at 50% probability level. C39 is the disordered equivalent of C38, C91 to C97 represent a disordered part of the molecule.

5076
D. D o¨ pp et al. / Tetrahedron 59 (2003) 5073–5081
Figure 2. Crystal packing of compound 8d (view along axis a).
by e.g. t-butyl, the corresponding tricyanovinylation
2
the release of two molecules of malononitrile (Scheme 1).
The latter is never isolated as such due to build-up
4
product may be isolated. On the other hand, loss of
malononitrile from a tetracyanoethyl-substituted indole
2
5
of higher cyanocarbons
by reacting with 2. No
1
2
derivative has been demonstrated earlier.
attempt has been made to isolate these highly polar
materials from the complex mixture of by-products.
There is, so far, no indication of a [4þ2] cycloaddition
of 2 to 1.
The formation of 8 via 14 by pathway (ii) thus requires
two molecules of 1 and two molecules of 2 and leads to
Table 1. Selected bond distances and bond angles of compound 8d (major atropisomer, the crystallographic numbering does not reflect the systematic IUPAC
numbering)
˚
Bond distances (A)
C8–C9
C1–N1
1.393(2)
1.413(2)
C28–C29
C21–N21
1.388(3)
1.409(2)
N1–C8
C1–C21
1.375(2)
1.379(3)
N21–C28
1.380(2)
Bond angles (8)
C8–C9–C10
C28–C29–C30
N1–C8–C7
N21–C28–C27
N1–C1–C2
N21–C21–C22
C12–N1–C8
C32–N21–C28
C9–C10–N2
C29–C31–N23
121.18(16)
120.01(17)
107.00(15)
106.71(15)
105.69(16)
105.64(16)
123.41(15)
122.55(15)
175.28(19)
171.4(2)
C8–C9–C11
C28–C29–C31
N1–C8–C9
N21–C28–C29
N1–C1–C21
N21–C21–C1
C12–N1–C1
C32–N21–C21
C9–C11–N3
127.81(17)
128.70(18)
126.50(16)
126.32(17)
128.89(16)
129.05(16)
122.12(16)
124.54(15)
171.6(2)
C10–C9–C11
C30–C29–C31
C7–C8–C9
C27–C28–C29
C2–C1–C21
C1–C21–C22
C1–N1–C8
111.00(16)
111.25(16)
126.32(17)
126.75(17)
125.42(16)
125.23(16)
110.89(14)
111.18(14)
176.7(2)
C21–N21–C28
C29–C30–N22

D. D o¨ pp et al. / Tetrahedron 59 (2003) 5073–5081
5077
Scheme 1. For the meaning of Ar, see Charts 1 and 2.
The oxygenated products 9 and 10 may arise from action of
air oxygen on either 12 or 14 for which reaction the
formation of an intermediate 1,3-endoperoxide has been
breakage of the central double bond and oxygen uptake by
either the radical anion of 8 or by any fragments thereof. It is
not possible, though, to delineate the exact course of the
reaction on the basis of these findings alone.
2
3
suggested. Phthalimides as 10 may be formed in this way
2
3
even when C1 and C3 of the isoindole are alkylated. The
build-up of compounds 9, on the other hand, seems feasible
by two routes (Scheme 2): (i) formation of a hydroperoxide
3. Conclusion
1
looses malononitrile to give 9. It had been reported earlier
8 which with another molecule of 14 forms 19 which again
2
6
In a fairly complex and multistep process two types of
dicyanomethylenated products are formed from various
N-arylisoindolines 1 and ethenetetracarbonitrile (2). The
latter has a dual functioning role as a dehydrogenating agent
and as a source of the dicyanomethylene units. The
predominant products 8a–i have an interesting twisted
and strained isoindigoid structure and resemble analogues
that the action of t-butoxide on a selection of compounds 8
in dry DMSO generates the radical anions of the latter, the
ESR signals of which are degraded upon admission of air,
giving way to the ESR-signal of the radical anions of the
corresponding compounds 9. This finding requires the
2
7
of the family of heterocyclic tetracyanoquinodimethanes.
Tricyanovinylation of the proposed intermediate isoindoles,
although certainly feasible, is not observed. While being
interpretable by precedence and analogy, the reactions
reported add to the very rich chemistry of tetracyano-
ethylene (2) with electron donating organic compounds.
4. Experimental
4.1. General
Mp’s were determined with a Reichert Thermovar hot stage
microscope and are uncorrected. The UV/Vis spectra were
recorded on a Perkin–Elmer 554 spectrophotometer, the IR
spectra on Perkin–Elmer 397 and Perkin–Elmer 283
1
13
spectrophotometers. The 300 MHz H and 75 MHz
C
NMR spectra were recorded on a Bruker WM 300
instrument, chemical shifts are expressed as d (ppm) with
tetramethylsilane as internal reference, s¼singlet, m¼
1
3
Scheme 2. For the meaning of Ar, see Charts 1 and 2.
multiplet; C assignments have been made with the aid

5078
D. D o¨ pp et al. / Tetrahedron 59 (2003) 5073–5081
of DEPT 135/90 spectra. The mass spectra (70 eV, electron
impact mode) were obtained on a Varian MAT 311 A
instrument. Elemental analyses were carried out with a
Carlo Erba Mod. 1106 CHN analyzer. The High Pressure
Liquid Chromatography was run on a Waters Associates
phenyl)-2,3-dihydro-1H-isoindol-1-ylidene}propane-
dintrile (8a). Blue-black crystals (acetonitrile), mp 323–
3258C, (175 mg, 24%); UV/Vis (acetonitrile): lmax¼582
nm, log 1¼4.67; IR: n¼2210 (CN), 1610 (CvC), 1580
(aryl) cm2 , H NMR (CD NO ): d¼3.85–3.92 (m, 6H,
1 1
3
2
4
2
40 modular equipment using an absorbance detector with
54 nm filter. For preparative layer chromatography 48 cm
2OCH ), 6.88–7.08 (m, 2H, Ar-H), 7.15–7.75 (m, 12H, Ar-
3
þ
H), 8.46–8.63 (m, 2H, aryl-H); MS: m/z (%)¼570 (M ,
wide and 20 cm tall glass plates, covered with a 1 mm thick
layer of slurry applied and air-dried silica gel Merck PF254
100), 555 (8), 539 (15), 506 (23), 463 (10), 285 (25), 270
(31), 254 (6), 221 (15), 76 (22). Anal. calcd for C H N O
22 6 2
,
36
were used. Zones were detected by their colour or by
quenching of indicator fluorescence upon exposure to
(570.6): C, 75.77; H, 3.88; N, 14.72. Found: C, 75.61; H,
3.76; N, 14.63.
2
54 nm light.
4
.2.2. {3-[2-(3-Methoxyphenyl)-3-(dicyanomethylene)-
4
.1.1. Starting materials. 2-Aryl-2,3-dihydro-1H-iso-
indoles 1a–i were prepared according to published
2,3-dihydro-1H-isoindol-1-ylidene]-2-(3-methoxy-
phenyl)-2,3-dihydro-1H-isoindol-1-ylidene}propane-
dinitrile (8b). Blue-black crystals (acetonitrile), mp 268–
2708C, (241 mg, 33%); UV/Vis (acetonitrile): lmax¼580
nm, log 1¼4.84; IR: n¼2210 (CN), 1610 (CvC), 1530
1
5,28,29
28,29
procedures.
1a: bp 136–1388C/0.13 mb (lit.
28
1
1
1
1
1
1
34–1378C/0.13 mb); 1b: mp 112–1138C (lit. 112–
2
9
138C); 1c: bp 118–1208C/0.013 mb (lit.
9
117–
208C/0.013 mb); 1d: mp 115–1168C (lit. 115–1178C);
2
21 1
(aryl) cm ; H NMR (CD NO ): d¼3.78–3.86 (m, 6H,
3
2
2
9
29
e: mp 190–1928C (lit. 1938C); 1f: mp 170–1718C (lit.
72–1738C); 1g: bp 120–1228C/0.013 mb (lit.
208C/0.013 mb); 1h: mp 100–1028C (lit. 1018C), 1i:
1
2OCH ), 6.80–6.90 (m, 4H, Ar-H), 7.00–7.05 (m, 2H, Ar-
3
2
9
H), 7.24–7.30 (m, 2H, Ar-H), 7.58–7.65 (m, 4H, Ar-H),
7.94–8.10 (m, 2H, Ar-H), 8.52–8.58 (m, 2H, Ar-H); MS:
2
9
5
þ
mp 182–1848C (lit. 182–1848C). Compounds 1a,1c and
g were purified by two consecutive bulb-to-bulb distilla-
tions. Ethenetetracarbonitrile (2, Merck) was purified by
m/z (%)¼570 (M , 100), 555 (14), 539 (10), 506 (21), 463
1
(7), 285 (10), 270 (3), 254 (7), 221(15), 76 (21). Anal. calcd
for C H N O (570.6): C, 75.77; H, 3.88; N, 14.72.
Found: C, 75.74; H, 3.83; N, 14.76.
3
6 22 6 2
crystallization from chlorobenzene and sublimed, mp
1
98–1998C.
4
.2.3. {3-[2-(2-Methylphenyl)-3-(dicyanomethylene)-2,3-
dihydro-1H-isoindol-1-ylidene]-2-(2-methylphenyl)-2,3-
dihydro-1H-isoindol-1-ylidene}propanedinitrile (8c).
4
.2. Reaction of N-arylisoindolines 1a–i with 2
A solution of N-arylisoindolines 1a–i (2.56 mmol) in dry
benzene (30 mL) was added dropwise with stirring at room
temperature to 2 (5.12 mmol) in benzene (40 mL). The
reaction colour changed quickly from green to brown which
gradually gave way to a blue colour. The stirring was
continued for 48 h with admission of air to complete the
reaction. The reaction mixture was filtered and the
precipitate was washed several times with cold benzene
until the washings remained colourless. The filtrate was
concentrated to dryness and the residue sublimed at 808C
under vacuum to remove all unreacted 2. The residue was
then separated by preparative layer chromatography
Blue-black crystals (acetonitrile), mp 317–3198C,
(193 mg, 28%); UV/Vis (acetonitrile): lmax¼580 nm,
log 1¼4.48; IR: n¼2200 (CN), 1600 (CvC), 1580
(aryl) cm2 ; H NMR (CD NO ): d¼2.25–2.40 (m, 6H,
1 1
3
2
2CH ), 6.90–7.55 (m, 10H, Ar-H), 7.70–7.80 (m, 2H, Ar-
3
H), 7.94–8.08 (m, 2H, Ar-H), 8.42–8.62 (m, 2H, Ar-H);
þ
MS: m/z (%)¼538 (M , 100), 474 (25), 447 (3), 432 (2),
380 (6), 369 (4), 357 (3), 269 (17), 243 (16), 205 (13), 91
(31). Anal. calcd for C H N (538.6): C, 80.28; H, 4.11;
N, 15.60. Found: C, 80.20; H, 4.07; N, 15.50.
3
6 22 6
4.2.4. {3-[2-(3-Methylphenyl)-3-(dicyanomethylene)-2,3-
dihydro-1H-isoindol-1-ylidene]-2-(3-methylphenyl)-2,3-
(
100 mg per plate) using a suitable solvent mixture as
eluent (cyclohexane/ethyl acetate 5:1 for the reactions of 2
with 1a,1c,1g and 1h; cyclohexane/ethyl acetate 3:1 for the
reactions of 2 with 1b,1d, and 1f, cyclohexane/ethyl acetate
dihydro-1H-isoindol-1-ylidene}propanedinitrile
(8d).
Blue-black crystals (acetonitrile), mp 326–3288C,
(268 mg, 39%); UV/Vis (acetonitrile): lmax¼579 nm,
log 1¼4.54; IR: n¼2210 (CN), 1615 (CvC), 1530 (Ar-
2
:1 for the reactions of 2 with 1e and 1i) to give numerous
CH) cm2 ; H NMR (CD NO ): d¼2.30–2.46 (m, 6H,
1
1
coloured zones, the three intense of which were removed
and extracted. The fastest migrating one contained the
N-arylphthalimides 10a–i, the second zone, which
quenched all indicator fluorescence upon exposure to
3
2
2CH ), 6.74–7.50 (m, 8H, Ar-H), 7.56–7.60 (m, 4H, Ar-H),
3
7.84–8.10 (m, 2H, Ar-H), 8.50–8.54 (m, 2H, Ar-H); MS:
m/z (%)¼538 (M , 100), 474 (31), 447 (4), 380 (7), 369 (5),
þ
357 (2), 269 (21), 243 (7), 91 (46). Anal. calcd for C H N
2
54 nm UV-light, contained compounds 9a–i, and finally
3
6
22
6
the slowest migrating zone (which is always characterized
by deep blue colour) contained the ‘dimers’ 8a–i. Extrac-
tion of the zones with acetone gave a residue, which was
rechromatographed to separate the pure compounds. The
precipitate was washed several times with cold benzene,
dried and sublimed at 1358C under vacuum to give
colourless crystals of 1,1,2,2-tetracyanoethane which
(538.6): C, 80.28; H, 4.11; N, 15.60. Found: C, 80.37; H,
4.09; N, 15.70.
4.2.5. {3-[2-(4-Methylphenyl)-3-(dicyanomethylene)-2,3-
dihydro-1H-isoindol-1-ylidene]-2-(4-methylphenyl)-2,3-
dihydro-1H-isoindol-1-ylidene}propanedinitrile
(8e).
Blue-black crystals (acetonitrile), dec. 330–3328C,
(214 mg, 31%); UV/Vis (acetonitrile): lmax¼584 nm,
log 1¼4.33; IR: n¼2200 (CN), 1600 (CvC), 1550
3
0
decomposed at 165–1708C (lit. 165–1708C).
(aryl) cm2 ; H NMR (CD NO ): d¼2.25–2.40 (m, 6H,
2CH ), 6.65–6.80 (m, 2H, Ar-H), 6.90–7.84 (m, 12H,
3
1 1
4
2
.2.1. {3-[2-(2-Methoxyphenyl)-3-(dicyanomethylene)-
,3-dihydro-1H-isoindol-1-ylid-ene]-2-(2-methoxy-
3
2

D. D o¨ pp et al. / Tetrahedron 59 (2003) 5073–5081
5079
þ
Ar-H), 8.52–8.75 (m, 2H, Ar-H); MS: m/z (%)¼538 (M ,
(13), 242 (10), 232 (13), 206 (30), 152 (25), 104 (33), 76
(27). Anal. calcd for C H N O (301.3): C, 71.75; H, 3.67;
N, 13.94. Found: C, 71.79; H, 3.58; N, 14.02.
1
9
4
00), 474 (10), 447 (5), 369 (2), 357 (22), 269 (13), 243 (6),
1 (24). Anal. calcd for C H N (538.6): C, 80.28; H,
.11; N, 15.60. Found: C, 80.33; H, 4.11; N, 15.67.
1
8 11 3 2
3
6 22 6
4.2.11. N-(3-Methoxyphenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9b). Yellow crystals
4
.2.6. [3-(2-Phenyl-3-dicyanomethylene-2,3-dihydro-1H-
isoindol-1-ylidene)-2-phenyl-2,3-dihydro-1H-isoindol-1-
ylidene]propanedinitrile (8f). Blue-black crystals (aceto-
nitrile), mp 301–3038C, (189 mg, 29%); UV/Vis (aceto-
(ethanol), mp 224–2268C, (154 mg, 20%); IR: n¼2220
1 1
(CN), 1745 (CO) cm2 ; H NMR (CDCl ): d¼3.85 (s, 3H,
3
OCH ), 6.85–7.68 (m, 4H, Ar-H), 7.78–8.10 (m, 3H, Ar-
3
1
3
nitrile): l ¼578 nm, log 1¼4.51; IR: n¼2210 (CN), 1580
max
H), 8.56–8.70 (m, 1H, Ar-H); C NMR (CDCl ): d¼55.62
3
(
Ar-H), 7.45–7.75 (m, 12H, Ar-H), 8.30–8.70 (m, 4H, Ar-
aryl) cm2 ; H NMR (CD NO ): d¼6.65–6.70 (m, 2H,
1
1
(OCH ), 61.48 [C(CN) ], 109.98 (CN), 113.81 (CN);
3
3
2
2
115.09, 116.89, 121.37, 125.42, 125.49, 130.55, 134.35,
135.01 (8 aryl CH); 127.53, 132.54, 132.90, 160.59 (4
quaternary C), 158.05 (C-3), 165.81 (CvO); MS: m/z
þ
H); MS: m/z (%)¼510 (M , 100), 446 (5), 433 (5), 255 (22),
2
29 (11), 77 (44). Anal. calcd for C H N (510.6) C,
34 18 6
þ
7
9.98; H, 3.55; N, 16.46. Found: C, 79.75; H, 3.46; N, 16.41.
(%)¼301 (M , 100), 286 (6), 270 (28), 258 (10), 242 (9),
232 (10), 206 (3), 152 (5), 104 (20), 76 (15). Anal. calcd for
4
.2.7. {3-[2-(2-Chlorophenyl)-3-(dicyanomethylene)-2,3-
C H N O (301.3): C, 71.75; H, 3.67; N, 13.94. Found: C,
18 11 3 2
dihydro-1H-isoindol-1-ylidene]-2-(2-chlorophenyl)-2,3-
dihydro-1H-isoindol-1-ylidene}propanedinitrile (8g).
Blue-black crystals (acetonitrile), mp 254–2568C,
71.62; H, 3.46; N, 13.84.
4.2.12. N-(2-Methylphenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9c). Yellow crystals (benzene/
pentane), mp 175–1778C, (131 mg, 18%); IR: n¼2210
(
148 mg, 20%); UV/Vis (acetonitrile): lmax¼570 nm,
2
1
1
log 1¼4.40; IR: n¼2200 (CN), 1525 (aryl) cm
; H
(CN), 1750 (CO) cm2 ; H NMR (CDCl ): d¼2.25 (s, 3H,
1 1
NMR (CD NO ): d¼6.55–6.70 (m, 2H, Ar-H), 6.95–7.95
3
2
3
(m, 12H, Ar-H), 8.45–8.60 (m, 2H, Ar-H); MS: m/z
(%)¼583 (18), 581 (36), 579 (M , 100), 543 (52), 508
(
CH ), 7.15–7.55 (m, 4H, Ar-H), 7.80–8.10 (m, 3H, Ar-H),
3
þ
15), 482 (9), 467 (9), 289 (15), 254 (24), 76 (15). Anal.
þ
8.60–8.75 (m, 1H, Ar-H); MS: m/z (%)¼285 (M , 100),
270 (11), 259 (74), 231 (6), 205 (2), 166 (11), 152 (6), 104
(7), 76 (24). Anal. calcd for C H N O (285.3): C, 75.77;
H, 3.88; N, 14.72. Found: C, 75.62; H, 3.70; N, 14.61.
calcd for C H N Cl (579.4): C, 70.47; H, 2.78; N, 14.50.
2
3
4
16
6
18 11 3
Found: 70.31; H, 2.82; N, 14.44.
4
.2.8. {3-[2-(3-Chlorophenyl)-3-(dicyanomethylene)-2,3-
dihydro-1H-isoindol-1-ylidene]-2-(3-chlorophenyl)-2,3-
dihydro-1H-isoindol-1-ylidene}propanedinitrile (8h).
Blue-black crystals (acetonitrile), mp 323–3258C,
267 mg, 36%); UV/Vis (acetonitrile): lmax¼574 nm,
4.2.13. N-(3-Methylphenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9d). Yellow crystals (cyclo-
hexane), mp 217–2188C, (153 mg, 21%); IR: n¼2200
(CN), 1745–1770 (CO) cm2 ; H NMR (CDCl ): d¼2.45
1 1
3
(
(s, 3H, CH ), 7.10–7.50 (m, 4H, Ar-H), 7.78–8.10 (m, 3H,
3
1
3
log 1¼4.48; IR: n¼2210 (CN), 1610 (CvC), 1540
Ar-H), 8.55–8.70 (m, 1H, Ar-H); C NMR (CDCl3):
aryl) cm2 ; H NMR (CD NO ): d¼6.75–7.05 (m, 2H,
1
1
d¼21.37 (CH ), 61.37 [C(CN) ], 109.97 (CN), 113.83
(
Ar-H), 7.35–8.07 (m, 10H, Ar-H), 8.45–8.62 (m, 4H, Ar-
3
2
3
2
(CN); 125.37, 125.46, 126.23, 129.58, 129.67, 132.07,
134.30, 134.95 (8 aryl-CH); 127.56, 131.49, 132.90, 140.09
(4 quaternary C); 158.18 (C-3), 165.94 (CvO); MS: m/z
þ
2),543 (9), 515 (7), 467 (10), 453 (3), 289 (34), 263 (15),
H); MS: m/z (%)¼583 (20), 581 (39), 579 (M , 100), 553
(
þ
2
54 (12), 225 (14), 76 (21). Anal. calcd for C H N Cl
2
(%)¼285 (M , 100), 270 (33), 259 (37), 231 (8), 205 (2),
3
4
16
6
(
2
579.4): C, 70.47; H, 2.78; N, 14.50. Found: C, 70.36; H,
.84; N, 14.49.
166 (27), 152 (17), 104 (2), 76 (53). Anal. calcd for
C H N O (285.3): C, 75.77; H, 3.88; N, 14.72. Found: C,
1
8 11 3
75.61; H, 3.72; N, 14.50.
4
.2.9. {3-[2-(4-Acetylphenyl)-3-(dicyanomethylene)-2,3-
dihydro-1H-isoindol-1-ylid-ene]-2-(4-acetylphenyl)-2,3-
dihydro-1H-isoindol-1-ylidene}propanedinitrile (8i).
Blue-black crystals (acetonitrile), mp 274–2768C,
266 mg, 35%); UV/Vis (acetonitrile): lmax¼576 nm,
4.2.14. N-(4-Methylphenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9e). Colourless crystals
(ethanol), mp 238–2408C, (133 mg, 18%); IR: n¼2220
(CN), 1750–1780 (CO) cm2 ; H NMR (CDCl ): d¼2.47
1 1
(
3
log 1¼4.38; IR: n¼2200 (CN), 1600 (CvC),
(s, 3H, CH ), 7.15–7.45 (m, 4H, Ar-H), 7.75–8.10 (m, 3H,
3
1
6
685(CO) cm2
H, Ar-H), 6.95–7.00 (m, 2H, Ar-H), 7.50–8.22 (m, 12H,
1
;
1
H NMR (CD NO ): d¼2.60–2.70 (s,
Ar-H), 8.58–8.70 (m, 1H, Ar-H); C NMR (CDCl3):
13
3
2
d¼21.50 (CH ), 61.29 [C(CN) ], 110.06 (CN), 113.87
3
2
þ
Ar-H), 8.46–8.64 (m, 2H, Ar-H); MS: m/z (%)¼594 (M ,
(CN); 125.35, 125.45, 128.92 (2C), 130.49 (2C), 134.28,
134.92 (8 aryl-CH); 127.52, 132.91, 141.65 (3 of 4
quaternary C, one signal not detectable); 158.33 (C-3),
1
(
(
00), 579 (12), 553 (9), 479 (10), 297 (60), 282 (10), 254
20), 233 (15), 119 (30). Anal. calcd for C H N O
8 22 6 2
3
þ
594.6): C, 76.75; H, 3.72; N, 14.13. Found: C, 76.59; H,
.61; N, 14.19.
166.02 (CvO); MS: m/z (%)¼285 (M , 100), 270 (17), 259
3
(11), 231 (2), 205 (1), 166 (5), 152 (2), 129 (14), 104 (21),
76 (11). Anal. calcd for C H N O (285.3): C, 75.77; H,
3.88; N, 14.72. Found: C, 75.63; H, 3.90; N, 14.63.
18 11 3
4
.2.10. N-(2-Methoxyphenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9a). Yellow crystals (aceto-
nitrile), mp 182–1838C, (116 mg, 15%); IR: n¼2220 (CN),
4.2.15. N-Phenyl-3-dicyanomethylene-2,3-dihydro-1H-
isoindol-1-one (9f). Colourless crystals (acetonitrile), mp
274–2768C, (139 mg, 20%); IR: n¼2220 (CN), 1750–1770
2
1 1
1
OCH ), 7.00–8.08 (m, 7H, Ar-H), 8.55–8.70 (m, 1H, Ar-
770–1750 (CO) cm ; H NMR (CDCl ): d¼3.85 (s, 3H,
3
3
þ
21
1
H); MS: m/z (%)¼301 (M , 100), 286 (4), 270 (23), 258
(CO) cm ; H NMR (CD NO ): d¼7.38–7.70 (m, 5H,
3
2

5080
D. D o¨ pp et al. / Tetrahedron 59 (2003) 5073–5081
Ar-H), 7.85–8.10 (m, 3H, Ar-H), 8.52–8.70 (m, 1H, Ar-H);
MS: m/z (%)¼271 (M , 100), 245 (89), 217 (8), 191 (2),
4.3. Single crystal X-ray structure determination of 8d
þ
79 (24), 163 (4), 152 (17), 131 (54), 104 (41), 76 (46).
1
Anal. calcd for C H N O (271.3): C, 75.26; H, 3.34; N,
Suitable crystals were obtained by recrystallization from
acetonitrile. Data were recorded using an Enraf-Nonius
Kappa CCD diffractometer with graphite-monochromated
1
7 9 3
1
5.48. Found: C, 75.53; H, 3.30; N, 15.31.
˚
Mo K -radiation (l¼0.71073 A). The crystal was mounted
a
4
.2.16. N-(2-Chlorophenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9g). Pale yellow crystals
in a stream of cold nitrogen gas. The structure was solved by
direct methods (SHELXS-97 ) and refined by full matrix
3
3
2
34
(
(
7
ethanol), mp 158–1598C, (113 mg, 13%); IR: n¼2220
least squares techniques against F (SHELXL-97 ). Hydro-
gen atoms were inserted from geometry consideration using
the HFIX option of the program.
2
1 1
CN), 1750–1770 (CO) cm ; H NMR (CDCl ): d¼7.35–
3
.70 (m, 4H, Ar-H), 7.75–8.10 (m, 3H, Ar-H), 8.60–8.75
þ
(m, 1H, Ar-H); MS: m/z (%)¼307 (13), 305 (M , 70), 270
(100), 244 (11), 216 (14), 201 (18), 190 (5), 125 (14), 104
(9), 76 (77). Anal. calcd for C H N OCl (305.7): C, 66.78;
2
1
Crystal and intensity data. C H N , M ¼538.60 g mol
,
¯
3
6
22
6
r
blue-black, crystal size 0.35£0.21£0.12 mm, triclinic, P1
1
7 8 3
˚
H, 2.63; N, 13.74. Found: C, 66.57; H, 2.59; N, 13.78.
[No. 2], a¼7.77510(10), b¼11.0928(2), c¼16.5963(3) A,
a¼108.4270(10), b¼92.7020(10), g¼90.7120(10)8,
˚
3
23
4.2.17. N-(3-Chlorophenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9h). Colourless crystals
V¼13.55.93(4) A , Z¼2,
D
¼1.319 Mg m
,
m¼
calc
0.080 mm2 , T¼100 K, 33170 reflections collected, 6207
1
(
(
(
1
(
ethanol), mp 228–2308C, (149 mg, 19%); IR: n¼2220
independent reflections, 4795 reflections with I.2s(I),
umax¼27.508, 394 refined parameters, R¼0.058, R ¼0.154,
2
1 1
CN), 1750 (CO) cm ; H NMR (CDCl ): d¼7.35–7.60
3
w
˚
3
m, 4H, Ar-H), 7.70–8.12 (m, 3H, Ar-H), 8.60–8.75 (m,
H, Ar-H); MS: m/z (%)¼307 (11), 305 (M , 100), 270
S¼1.021, largest diff. peak and hole¼0.6/20.6 e A .
þ
50), 244 (23), 216 (18), 201 (2), 190 (13), 125 (8), 104 (7),
Crystallographic data (excluding structure factors) have
been deposited with the Cambridge Crystallographic
Data Centre as supplementary publication number
CCDC 190218. Copies of the data can be obtained, free of
charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK, (fax: þ44-1223-336033 or
e-mail: deposit@ccdc.cam.ac.uk).
7
2
6 (76). Anal. calcd for C H N OCl (305.7): C, 66.78; H,
17 8 3
.63; N, 13.74. Found: C 66.68; H, 2.55; N, 13.66.
4.2.18. N-(4-Acetylphenyl)-3-dicyanomethylene-2,3-
dihydro-1H-isoindol-1-one (9i). Pale yellow crystals
(
acetonitrile), mp 223–2248C, (136 mg, 17%); IR:
21
n¼2220 (CN), 1660–1680, 1700, 1750–1770 (CO) cm
;
1
H NMR (DMSO-d ): d¼2.65 (s, 3H, COCH ), 7.65–8.20
6
3
(
(
m, 7H, Ar-H), 8.45–8.55 (m, 1H, Ar-H); MS: m/z
%)¼313 (M , 33), 298 (100), 270 (17), 244 (5), 216 (8),
þ
09 (25), 181 (12), 119 (30), 104 (28), 76 (50). Anal. calcd
Acknowledgements
2
for C H N O (313.3): C, 72.83; H, 3.53; N, 13.41.
Found: C, 72.92; H, 3.46; N, 13.22.
A. A. Hassan is indebted to Alexander-von-Humboldt-
Foundation for a fellowship. Generous support of this work
by Fonds der Chemischen Industrie is gratefully
acknowledged.
1
9 11 3 2
4
Methoxyphenyl)-, mp 156–1578C (lit. 1588C), 26 mg (4%).
.2.19. Phthalimides 10a–i. Compound 10a. N-(2-
3
1
Compound 10b. N-(3-Methoxyphenyl)-, mp 124–1258C
3
1
(
lit. 1268C), 32 mg (5%).
References
3
1
Compound 10c. N-(2-Methylphenyl)-, mp 184–1868C (lit.
858C), 30 mg (5%).
1. Fatiadi, A. J. Synthesis 1986, 249–284, and references cited
therein.
1
2
. Fatiadi, A. J. Synthesis 1987, 749–789, and references cited
therein.
Compound 10d. N-(3-Methylphenyl)-, mp 176–1788C
3
1
(
lit. 1758C), 49 mg (8%).
3. Nishio, T.; Okuda, N. J. Org. Chem. 1992, 57, 4000–4005.
4
. Bruni, P.; Tosi, G. Gazz. Chim. Ital. 1997, 127, 435–459, and
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3
2
Compound 10e. N-(4-Methylphenyl)-, mp 204–2068C (lit.
058C), 30 mg (5%).
2
5. Bocelli, G.; Cardellini, C. R.; De Meo, G.; Ricci, A.; Rizzoli,
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3
1
Compound 10f. N-Phenyl-, mp 209–2108C (lit. 2128C),
0 mg (7%).
4
3
3
1
2
2
5
Compound 10g. N-(2-Chlorophenyl)-, mp 1448C (lit.
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8
. Rappoport, Z.; Horowitz, A. J. Chem. Soc. 1964, 1348–1359.
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48–2508C), 55 mg (8%).
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