Oxidative addition of N-aminophthalimide to 2-alkenyl-1,3,4-oxadiazoles. Synthesis of aziridinyloxadiazoles

Article abstract of DOI:10.1134/S1070428007070172

Oxidation of N-aminophthalimide with lead tetraacetate in the presence of 2-[(E)-2-arylethenyl]-5-phenyl-1,3,4-oxadiazoles gives the corresponding 2-(3-aryl-1-phthalimidoaziridin-2-yl)-5-phenyl-1,3,4-oxadiazoles. From 2-phenyl-5-[(1E,3E)-4-phenylbuta-1,3-

Full text of DOI:10.1134/S1070428007070172

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 7, pp. 1042–1047. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © O.A. Ignatenko, M.A. Kuznetsov, S.I. Selivanov, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 7,
pp. 1048–1053.
Oxidative Addition of N-Aminophthalimide to 2-Alkenyl-
1,3,4-oxadiazoles. Synthesis of Aziridinyloxadiazoles
O. A. Ignatenko, M. A. Kuznetsov, and S. I. Selivanov
St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504 Russia
e-mail: mak@org.chem.lgu.spb.su
Received June 21, 2006
Abstract—Oxidation of N-aminophthalimide with lead tetraacetate in the presence of 2-[(E)-2-arylethenyl]-5-
phenyl-1,3,4-oxadiazoles gives the corresponding 2-(3-aryl-1-phthalimidoaziridin-2-yl)-5-phenyl-1,3,4-
oxadiazoles. From 2-phenyl-5-[(1E,3E)-4-phenylbuta-1,3-dien-1-yl]-1,3,4-oxadiazole only the addition product
at both C=C bonds was obtained, while in the reaction with 2,5-bis[(E)-2-phenylethenyl]-1,3,4-oxadiazole both
mono- and bis-adducts were isolated.
DOI: 10.1134/S1070428007070172
We recently reported on a sharp difference in the re-
sults of oxidative phthalimidoaziridination of alkenyl-
dihydropyrazoles and alkenylpyrazoles, which con-
firmed our assumption that the reaction successfully
occurs with unsaturated compounds having a C=N
bond only if the latter is a part of an aromatic system
[1]. Presumably, in other cases intermediate aminoni-
trenoid (or aminonitrene) attacks primarily just the
C=N bond (most probably, at the lone electron pair on
the nitrogen atom) to give a product incapable of form-
ing adducts at C=C bonds. In order to verify whether
the observed relation is general we examined analo-
gous reactions with alkenyl-substituted 1,3,4-oxadia-
zoles. Unlike pyrazoles, the heteroring in 1,3,4-oxa-
diazoles is π-acceptor; in addition, it contains one more
heteroatom (oxygen) whose lone electron pair may
also be attacked by intermediate nitrenoid.
substituted cinnamoyl chlorides; hydrazide Id was ob-
tained from cinnamoyl chloride and hydrazine hydrate.
Oxadiazole IIe was synthesized following the same
scheme from 5-phenylpenta-2,4-dienoic acid and ben-
zohydrazide without isolation of intermediate diacyl-
hydrazine.
Styryl-substituted oxadiazoles IIa–IIe showed in
the 1H NMR spectra doublets due to olefinic protons in
the region δ 6.6–7.9 ppm with a coupling constant
3J of about 16 Hz, indicating that their original trans-
orientation did not change during the cyclization
process. The 13C NMR spectra of newly synthesized
compounds IIb and IIe characteristically contained
signals at δC 160–165 ppm from carbon atoms in the
oxadiazole ring.
The oxidative addition of N-aminophthalimide to
alkenyloxadiazoles IIa–IIe was carried out by adding
alternately in small portions N-aminophthalimide and
lead tetraacetate to a solution of unsaturated substrate
in methylene chloride. In first experiments, the reac-
tion mixture was cooled to –15°C (as in reactions with
styrylpyrazoles [1]); however, in these cases the conver-
sion of initial unsaturated compounds II was poor, and
the yield of adducts III did not exceed 15–20%. When
the reactions were performed at room temperature (18–
23°C), the conversion of styryloxadiazoles and the
yield of compounds IIIa–IIIf increased considerably.
The product structure was confirmed by elemental
Initial alkenyl-substituted 1,3,4-oxadiazoles IIa–
IId were synthesized by cyclization of diacylhydra-
zines Ia–Id according to known procedures [2, 3]
(Scheme 1). Compounds Ia–Ic were prepared in turn
by acylation of benzohydrazide with the corresponding
Scheme 1.
O
O
H
R
POCl3
N
R'
R'
R
N
H
N
N
O
Ia–Ie
IIa–IIe
1
analysis, H and 13C NMR spectroscopy, and mass
R = Ph, R′ = Ph (a), 4-MeOC6H4 (b), 4-O2NC6H4 (c),
PhCH=CH (e); R = PhCH=CH, R′ = Ph (d).
spectrometry. From monostyryl-substituted oxadia-
1042

OXIDATIVE ADDITION OF N-AMINOPHTHALIMIDE
1043
Scheme 3.
zoles IIa–IIc we obtained 42–46% of the correspond-
ing addition products at the exocyclic C=C bonds, first
representatives of the aziridinyloxadiazole series IIIa–
IIIc (Scheme 2).
Ph
N
O
Ph
NPhth
a: 1:1
N
N
Scheme 2.
PhthNNH2
Pb(OAc)4
IIId
R
IId
PhthNNH2
Ph
Ph
Pb(OAc)4
O
R
IIa–IIc
N
O
NPhth
N
N
N
N
PhthN
NPhth
b: 1:3
N
N
IIIa–IIIc
IIIe
O
The reaction of 2,5-distyryloxadiazole IId with
PhthN =
N
.
equimolar amounts of N-aminophthalimide and lead
tetraacetate (a) gave only the corresponding adduct
IIId at one C=C bond of the substrate (yield 46%),
while in the reaction with 3 equiv of N-aminophthal-
imide and 3 equiv of the oxidant (b) we succeeded in
isolating 37% of bis-adduct IIIe (Scheme 3). The spec-
tral parameters of compounds IIId and IIIe were anal-
ogous to those of aziridinyloxadiazoles IIIa–IIIc with
O
R = Ph (a), 4-MeOC6H4 (b), 4-O2NC6H4 (c).
In the 1H NMR spectra of compounds IIIa–IIIc we
observed four doublets in the region δ 3.9–5.3 ppm,
which belong to protons in the aziridine ring of two
invertomers (due to low inversion of the aziridine ni-
trogen atom on the NMR time scale [4]). The corre-
sponding vicinal coupling constants (3J = 5.3–5.8 Hz)
indicate trans orientation of protons in the aziridine
ring. This is not surprising, for oxidative aminoaziri-
dination is known to always retain original configura-
tion of substituents at the double bond in the addition
products [5, 6]. The invertomer ratio ranges from
~5:1 to ~20:1, and signals from the aziridine protons
of the major invertomer appear in a stronger field
relative to the corresponding signals of the minor one.
Taking into account that the effective volume of the
five-membered heteroring is clearly smaller than that
of the aryl group, the major invertomers in solution are
likely to be those with syn orientation of the heteroring
and phthalimide fragment.
In the 13C NMR spectra of aziridinyloxadiazoles
IIIa–IIIc we clearly distinguished signals from the
phthaloyl carbonyl carbon atoms (δC 165–166 ppm),
carbon atoms in the aziridine ring (δC 41–51 ppm), and
carbon atoms in the five-membered heteroring
(δC 160–165 ppm). The other signals are located in
the region typical of aromatic carbon atoms (δC 114–
141 ppm). Compounds IIIa–IIIc showed in the elec-
tron impact mass spectra fairly strong molecular ion
peaks, peaks of the [M – 146]+ and/or [M – 147]+ ions
arising from elimination of the phthalimide fragment
(which are characteristic of N-phthalimidoaziridines),
and the phthalimide ion peak with m/z 147.
1
the difference that the H NMR spectrum of IIIe con-
tained at least three pairs of doublets from aziridine
protons with an intensity ratio of ~84:8:8. In all cases,
the corresponding coupling constants did not exceed
6 Hz, indicating trans orientation of protons in the
three-membered rings. This means that the presence of
several signals does not result from the lack of cis-
stereoselectivity in the addition process but from
(1) formation of two diastereoisomeric adducts (addi-
tion at the same or different sides of the formal plane
of distyryloxadiazole molecule IId) and/or (2) slow
inversion of the aziridine nitrogen atoms. Each of the
two diastereoisomers could give rise to three inverto-
mers which, in keeping with the relative orientation of
the heteroring and phthalimido groups, may be denoted
as anti–anti, anti–syn, and syn–syn. The anti–syn in-
1
vertomer should display in the H NMR spectrum two
pairs of signals with equal intensities from the aziri-
dine protons, while the symmetrical structures (anti–
anti and syn–syn) should be characterized by a single
pair of signals. Obviously, the stronger doublets at
1
δ 4.14 and 4.67 ppm in the H NMR spectrum of IIIe
belong to more stable symmetric invertomer of one
diastereoisomer; on the basis of steric considerations,
we can presume that the major invertomer in solution
has syn–syn structure.
Our attempts to separate product IIIe into two pos-
sible diastereoisomers by chromatography using sev-
eral solvent systems were unsuccessful. Therefore, it
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 7 2007

IGNATENKO et al.
1044
The fraction of the anti–syn invertomer of IIIe in
solution is approximately 5 times lower (16:84) than
that of the more stable syn–syn invertomer. With ac-
count taken of statistical factor (anti–syn invertomer is
identical to syn–anti), these data are very consistent
with the syn/anti ratio found for aziridine IIIa (9:1).
The fraction of the least stable anti–anti invertomer
should be lower by a factor of ~20 than the fraction of
anti–syn (<1%); therefore, it is not surprising that we
failed to distinguish signals from the anti–anti inver-
seemed more probable that we have not a mixture of
diastereoisomers but a mixture of invertomers of only
one diastereoisomer. This assumption is confirmed by
the two-dimensional EXSY-NOESY data for a solution
of bis-aziridine IIIe in CDCl3 at 45°C. At that tem-
perature, the rate of inversion of the aziridine nitrogen
atoms is still insufficient to induce appreciable changes
in a routine 1H NMR spectrum but sufficient to distin-
guish signals from protons belonging to different inter-
convertible forms. Raising the temperature to 60°C
leads to appreciable broadening of signals from
aziridine protons, but their complete coalescence is not
achieved.
1
tomer. Nevertheless, the H NMR spectrum of IIIe
contained a weak doublet signal at δ 4.02 ppm (3J =
5.3 Hz) which is likely to correlate with the signal at
δ 4.79 ppm, the latter being partially overlapped by the
signal at δ 4.81 ppm from the anti–syn invertomer.
Since both these signals showed no correlation with
the other aziridine proton signals in the EXSY-NOESY
spectrum, they may be assigned to the syn–syn inverto-
mer of the other diastereoisomer whose concentration
does not exceed 3%. The reason for the high diastereo-
selectivity in the formation of compound IIIe still
remains unclear.
The EXSY-NOESY data showed that the doublet at
δ 4.14 ppm, belonging to the major invertomer, cor-
relates with signals at δ 4.22 and 5.26 ppm and that the
doublet at δ 4.70 ppm is related to signals at δ 4.28 and
4.81 ppm. This means that two low-intense pairs of
doublets correspond to the anti–syn invertomer of the
same diastereoisomer as for the syn–syn invertomer.
Insofar as inversion of the nitrogen atom should
strongly affects the chemical shifts of protons just in
the corresponding ring, while variations of the chem-
ical shifts of protons in the other ring should be small,
we assigned doublets at δ 4.22 and 4.81 ppm to the
syn-fragment, and those at δ 5.26 and 4.28 ppm, to the
anti-fragment of the anti–syn invertomer. It is seen that
the inversion leads to transposition of signals from
protons in the inverted ring: the upfield signal in the
syn-fragment (δ 4.14 ppm for the syn–syn invertomer)
becomes the most downfield (δ 5.26 ppm), whereas
the downfield signal (δ 4.67 ppm) shifts upfield to
δ 4.28 ppm. Taking into account that the phthalimide
fragment in N-phthalimidoaziridines usually strongly
deshields protons oriented syn with respect to it and
shields anti-oriented protons [4], signals from the aziri-
dine protons in the syn–syn and anti–syn invertomers
of bis-adduct IIIe were assigned as follows:
In the reaction with oxadiazole IIe having a diene
fragment, as with similarly substituted 5-phenyl-3-(4-
phenylbuta-1,3-dien-1-yl)pyrazole [1], we succeeded
in isolating in a poor yield only the addition product at
both C=C bonds, despite equimolar reactant ratio. The
use of 2 equiv of the reagents allowed us to raise the
yield of bis-adduct IIIf to 32% (Scheme 4). No olefin-
1
ic proton signals were present in the H NMR spec-
trum of IIIf, and in the region δ 3–5 ppm we observed
three sets of aziridine proton signals with an intensity
ratio of ~10:10:1, the overall intensity corresponding
to four rather than two protons. The coupling constants
for all doublets ranged from 5 to 6 Hz, in keeping with
trans arrangement of protons in the aziridine rings. As
in the reaction with IId, the formation of two dia-
stereoisomers of IIIf is possible, and each of them may
be a mixture of four invertomers.
PhthN
NPhth
N
N
Scheme 4.
N
N
Ph
4.70 (5.5)
H
O
NPhth
N
H
H
H
PhthNNH2
Pb(OAc)4
Ph
Ph
4.14 (5.5)
syn–syn
IIe
O
Ph
N
NPhth
NPhth
N
N
4.28 (5.8)
N
N
N
N
H
IIIf
4.81 (5.5)
H
O
Ph
PhthN
H
H
5.26 (5.8)
Ph
4.22 (5.5)
The ratio of stereoisomeric bis-adducts IIIf is fairly
anti–syn
similar to the ratio of structurally related bis-adducts
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 7 2007

OXIDATIVE ADDITION OF N-AMINOPHTHALIMIDE
1045
obtained from 5-phenyl-3-(4-phenylbuta-1,3-dien-1-
yl)pyrazole (~6:6:1 [1]). The coupling constants for
protons in the neighboring aziridine rings in the two
major structures differ by a factor of more than 1.5
(8.5 and 5.4 Hz), indicating different equilibrium con-
formations of these stereoisomers. We made no at-
tempts to separate possible diastereoisomers of IIIf by
chromatography because of the low stability of this
compound over silica gel.
1H NMR spectrum, δ, ppm: 3.84 s (3H, MeO), 6.95 d
(1H, =CH, J = 15.8 Hz), 6.97–7.60 m (8H, 7Harom
,
=CH), 8.10 d (2H, 5-Ph, o-H, J = 7.3 Hz). 13C NMR
spectrum, δC, ppm: 55.34 (MeO); 107.51 (2-CH=);
114.43 (p-C6H4, Cm); 123.92 (Ci); 126.82, 127.49 (Ci);
128.98, 129.02, 131.55, 138.48 (=CHAr); 161.07,
162.26, 163.72 (CO, C=N). Mass spectrum (EI), m/z
(Irel, %): 278 (33) [M]+, 277 (100) [M – H]+, 161 (15),
105 (23), 77 (21). Found, %: C 73.34; H 5.18;
N 10.10. C17H14N2O2. Calculated, %: C 73.37; H 5.04;
N 10.07.
Thus oxidative phthalimidoaziridination of alkenyl-
substituted 1,3,4-oxadiazoles IIa–IIe gives the corre-
sponding aziridinyloxadiazoles rather than products re-
sulting from attack by phthalimidonitrene or the corre-
sponding nitrenoid at the lone electron pairs on the
nitrogen or oxygen atoms in the heteroring. Com-
parison of the reaction conditions and yields shows
that the C=C bond in alkenyloxadiazoles IIa and IIb is
less reactive than the same bond in similarly substi-
tuted pyrazoles [1], which may be due to stronger
π-acceptor power of the 1,3,4-oxadiazole ring.
2-[(E)-2-(4-Nitrophenyl)ethenyl]-5-phenyl-1,3,4-
oxadiazole (IIc). Yield 75%, mp 242–244°C; pub-
1
lished data [9]: mp 247–249°C. H NMR spectrum, δ,
ppm: 7.57–7.63 m (4H, 3Harom, =CH), 7.84 d (1H,
=CH, J = 16.0 Hz), 8.03 d (2H, 4-O2NC6H4, 2-H,
J = 8.7 Hz), 8.11 m (2H, 5-Ph, o-H), 8.26 d (2H,
4-O2NC6H4, 3-H, J = 8.7 Hz). Found, %: C 65.69;
H 4.01; N 14.10. C16H11N3O3. Calculated, %: C 65.53;
H 3.75; N 14.33.
2,5-Bis[(E)-2-phenylethenyl]-1,3,4-oxadiazole
(IId). Yield 70%, mp 152–153°C; published data [10]:
mp 150–151°C. H NMR spectrum, δ, ppm: 7.05 d
EXPERIMENTAL
1
The elemental analyses were obtained on
a Hewlett–Packard 185B C,H,N analyzer. The H and
(2H, =CH, J = 16.0 Hz), 7.39–7.64 m (12H, Ph, =CH).
1
13C NMR spectra were recorded on a Bruker DPX-300
spectrometer at 300 and 75.4 MHz, respectively,
using CDCl3 as solvent and reference (δ 7.26 ppm;
δC 77.0 ppm). Signals in the 13C NMR spectra were as-
signed using DEPT technique. The mass spectra were
run on MKh-1321 (electron impact, 70 eV) and Finni-
gan MAT 95 instruments (electrospray ionization; sol-
vent methanol). The reaction mixtures were analyzed,
and the purity of the products was checked, by TLC on
Alugram SIL G/UV plates. N-Aminophthalimide was
synthesized as described in [7].
2-Phenyl-5-[(1E,3E)-4-phenylbuta-1,3-dien-1-
yl]-1,3,4-oxadiazole (IIe). 5-Phenylpenta-2,4-dienoic
acid, 3.48 g (20 mmol), was dispersed in 30 ml of
methylene chloride, 1.5 ml (2.5 g, 21 mmol) of SOCl2
and a few drops of DMF were added, and the mixture
was heated for 30 min under reflux. The solvent was
evaporated, the residue was dissolved in 10 ml of
dioxane, and a solution of 2.72 g (20 mmol) of benzo-
hydrazide and 2.5 ml (2.3 g, 22.8 mmol) of N-methyl-
morpholine in 20 ml of dioxane were added. The
mixture was heated to the boiling point, cooled, and
diluted with 150 ml of water. The residue was filtered
off, dried, and transferred into a round-bottom flask,
20 ml (32.9 g, 0.21 mol) of phosphoryl chloride was
added, and the mixture was heated to the boiling point
(it became homogeneous) and was then heated under
reflux for 20 min. The solution was cooled, poured
onto ice, and treated with 50 ml of methylene chloride.
The organic phase was separated, and the aqueous
phase was extracted with methylene chloride (2×
50 ml). The extracts were combined with the organic
phase, dried over MgSO4, and passed through a layer
of silica gel. The solvent was removed, and the residue
was recrystallized from ethanol. Yield 1.09 g (20%),
Styryl-1,3,4-oxadiazoles IIa–IId (general proce-
dure). A mixture of 10 mmol of diacylhydrazine Ia–Id
and 20 ml (32.9 g, 0.21 mol) of POCl3 was heated for
2 h under reflux, cooled, and poured onto ice. The
precipitate was filtered off and dried in air. The crude
product was purified by flash chromatography, fol-
lowed by recrystallization from ethanol.
2-Phenyl-5-[(E)-2-phenylethenyl]-1,3,4-oxadia-
zole (IIa). Yield 83%, mp 122–123°C; published data
[8]: mp 128°C. 1H NMR spectrum, δ, ppm: 7.25 d (1H,
=CH, J = 16.2 Hz), 7.37–7.70 m (9H, 8Harom, =CH),
8.08 m (2H, 5-Ph, o-H).
1
mp 103–104°C. H NMR spectrum, δ, ppm: 6.63 d
(1H, =CH, J = 16.0 Hz), 6.87–7.03 m (2H, =CH),
2-[(E)-2-(4-Methoxyphenyl)ethenyl]-5-phenyl-
1,3,4-oxadiazole (IIb). Yield 64%, mp 118–119°C.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 7 2007

IGNATENKO et al.
1046
1
7.30–7.51 m (9H, 8Harom, =CH), 8.10 m (2H, 2-Ph,
o-H). 13C NMR spectrum, δC, ppm: 112.74 (=CH),
123.82 (Ci), 126.78, 126.84, 127.05, 128.79, 128.91,
128.99, 131.62 (=CH), 136.00 (4-Ph, Ci), 138.99
(=CH), 139.07 (=CH), 163.86 (CHt), 164.22 (CHt).
Mass spectrum (EI), m/z (Irel, %): 275 (4), 274 (23)
[M]+, 273 (8) [M – H]+, 198 (14), 197 (100), 128 (10),
105 (10), 77 (10). Found, %: C 78.70; H 5.19;
N 10.16. C18H14N2O. Calculated, %: C 78.81; H 5.14;
N 10.21.
(83:17). H NMR spectrum, δ, ppm: 3.83 s and 3.85 s
(3H, MeO, major and minor invertomers), 4.17 d and
4.79 d (Hazir, major invertomer, J = 5.6 Hz), 4.40 d and
5.37 d (Hazir, minor invertomer, J = 5.8 Hz), 6.81 d and
6.96 d (2H, p-C6H4, 3-H, minor and major inverto-
mers, J = 8.7 Hz), 7.33 d (p-C6H4, 2-H, minor inver-
tomer, J = 8.7 Hz), 7.50 d (p-C6H4, 2-H, major inver-
tomer, J = 8.7 Hz), 7.4–7.6 m (5H, 5-Ph, m-H, p-H);
7.64–7.72 m (4H, PhthN), 8.01 m and 8.12 m (2H,
5-Ph, o-H, major and minor invertomers). 13C NMR
spectrum, δC, ppm: major invertomer: 41.78, 50.17
(2Cazir); 55.32 (MeO), 114.22 (p-C6H4, Cm), 123.37
(Cb), 126.96, 128.50, 129.03, 129.98 (Ca), 130.86,
131.94, 134.14 (Cc); 160.06 (CHt), 160.41, 162.28
(CHt); 165.66 (C=O). Mass spectrum (EI), m/z (Irel, %):
438 (6) [M]+, 305 (56), 291 (56), 271 (20), 266 (11),
188 (9), 161 (8), 147 (60), 133 (100), 113 (9), 105
(40), 103 (29), 90 (17), 76 (56), 63 (8), 50 (24). Found,
%: C 68.51; H 4.28; N 12.68. C25H18N4O4. Calculated,
%: C 68.49; H 4.14; N 12.78.
General procedure for the oxidative addition of
N-aminophthalimide to styryl-substituted 1,3,4-oxa-
diazoles IIa–IId. Compound IIa–IId, 1 mmol, was
dissolved in 50 ml of methylene chloride, 0.69 g
(5 mmol) of potassium carbonate was added, and
162 mg (1 mmol) of N-aminophthalimide and 443 mg
(1 mmol) of lead tetraacetate were added alternately in
small portions to the suspension over a period of
15 min under stirring at room temperature. The mix-
ture was stirred for 30 min, and the inorganic precip-
itate was filtered off and washed with methylene chlo-
ride until colorless filtrate. The solvent was removed,
and the residue was treated with diethyl ether for crys-
tallization. The product was filtered off, washed with
diethyl ether, and recrystallized from ethanol. Com-
pound IIIc was purified by flash chromatography,
followed by recrystallization. Compound IIId was
repeatedly recrystallized until complete removal of the
initial olefin impurity.
2-[(E)-3-(4-Nitrophenyl)-1-phthalimidoaziridin-
2-yl]-5-phenyl-1,3,4-oxadiazole (IIIc). Yield 42%,
mp 209–210°C (decomp.); a mixture of two inverto-
1
mers (~95:5). H NMR spectrum, δ, ppm: 4.17 d and
4.92 d (Hazir, major invertomer, J = 5.3 Hz), 4.53 d and
5.42 d (Hazir, minor invertomer, J = 5.5 Hz); 7.45–
7.62 m (3H, 5-Ph, m-H, p-H), 7.66–7.77 m (6H,
PhthN, 4-O2NC6H4, 2-H), 8.02 m and 8.12 m (2H,
5-Ph, o-H, major and minor invertomers), 8.31 d (2H,
4-O2NC6H4, 3-H, J = 8.7 Hz). 13C NMR spectrum, δC,
ppm: major invertomer: 41.24, 48.40 (2Cazir), 122.46,
122.84, 122.94, 125.92, 127.60, 128,30, 128.75, 129.78
(Ca), 133.69 (Cc), 140.71; 163.64, 164.77 (2CHt), 165.21
(C=O). Mass spectrum (EI), m/z (Irel, %): 454 (5)
[M + 1]+, 453 (20) [M]+, 435 (5), 307 (20), 306 (17),
305 (66), 304 (5), 248 (7), 173 (11), 148 (18), 147
(11), 144 (7), 132 (17), 130 (11), 105 (100), 104 (76),
103 (37), 90 (8), 77 (46), 76 (34), 51 (5), 50 (8).
Found, %: C 63.68; H 3.47; N 15.22. C24H15N5O5. Cal-
culated, %: C 63.58; H 3.33; N 15.45.
2-Phenyl-5-[(E)-3-phenyl-1-phthalimidoaziridin-
2-yl]-1,3,4-oxadiazole (IIIa). Yield 44%, mp 155–
1
156°C, a mixture of two invertomers (90:10). H NMR
spectrum, δ, ppm: 4.20 d and 4.86 d (Hazir, major
invertomer, J = 5.5 Hz), 4.47 d and 5.45 d (Hazir
,
minor, invertomer, J = 5.7 Hz), 7.4–7.6 m (8H, 3-Ph
and 2-Ph, m-H, p-H), 7.63–7.75 m (4H, PhthN), 8.03 m
and 8.14 m(2H, 2-Ph, o-H, major and minor inverto-
mers, respectively). 13C NMR spectrum (major inver-
tomer), δ, ppm: 41.95 and 50.33 (2Cazir), 123.28 (Cb),
126.99, 127.19, 128.77, 128.83, 129.04, 129.98 (Ca),
134.16 (Cc); 160.31 and 164.8 (2CHt), 165.73 (C=O).
Mass spectrum (EI), m/z (Irel, %): 408 (11) [M]+, 407
(3), 305 (35), 262 (29), 248 (12), 236 (21), 203 (12),
173 (14), 147 (44), 130 (11), 103 (100), 90 (8), 76
(65), 63 (7), 50 (25). Found, %: C 70.36; H 4.08;
N 13.53. C24H16N4O3. Calculated, %: C 70.58; H 3.95;
N 13.72.
2-[(E)-3-Phenyl-1-phthalimidoaziridin-2-yl]-5-
[(E)-2-phenylethenyl]-1,3,4-oxadiazole (IIId). Yield
46%, mp 143–145°C; a mixture of two invertomers
1
(90:10). H NMR spectrum, δ, ppm: 4.14 d and 4.81 d
(Hazir, major invertomer, J = 5.5 Hz), 4.43 d and 5.42 d
(Hazir, minor invertomer, J = 5.8 Hz), 6.96 d (J =
16.5 Hz, =CHPh, major invertomer), 7.26–7.58 m
(12H, 2Ph, =CHPh, minor invertomer, =CHHt), 7.61–
7.75 m (4H, PhthN). 13C NMR spectrum, δC, ppm:
major invertomer: 41.93, 50.32 (2Cazir); 109.38, 123.29
2-[(E)-3-(4-Methoxyphenyl)-1-phthalimidoaziri-
din-2-yl]-5-phenyl-1,3,4-oxadiazole (IIIb). Yield
46%, mp 149–150°C, a mixture of two invertomers
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 7 2007

OXIDATIVE ADDITION OF N-AMINOPHTHALIMIDE
1047
(Cb), 128.46, 128.76, 128.83, 128.94, 129.49, 129.95,
130.11, 134.18 (Cc), 161.60, 164.78 (2CHt), 165.37
(C=O). Mass spectrum (ES), m/z (Irel, %): 923 (21)
[2M + Na + MeOH]+, 891(100) [2M + Na]+, 489 (9)
[M + Na + MeOH]+, 457(21) [M + Na]+. Found, %:
C 71.68; H 4.36; N 12.59. C26H18N4O3. Calculated, %:
C 71.88; H 4.18; N 12.90.
5 ml of methylene chloride, and the precipitate was
filtered off. Yield 32%, mp 242–245°C (decomp.);
a mixture of three stereoisomers (~10:10:1). The prod-
uct decomposed on attempted recrystallization from
1
ethanol. H NMR spectrum, δ, ppm: 2.88 d.d (J = 8.5,
5.0 Hz), 3.78 d.d (J = 8.5, 5.5 Hz), 4.26 d (J = 5.5 Hz),
and 4.57 d (J = 5.0 Hz) (Hazir, major stereoisomer);
4.13 d (J = 5.7 Hz), 4.21 d.d (J = 5.4, 5.4 Hz), 4.44 d.d
and 4.45 d (overlapping signals, J = 5.4–5.9 Hz) (Hazir,
another major stereoisomer); 3.65 m, 3.95 d (J =
5.2 Hz), 4.50 m, and 5.05 d (J = 4.9 Hz) (Hazir, minor
isomer), (4H total); 7.25–7.78 m (16H, 5-Ph, m-H,
p-H, Ph, 2PhthN); 8.03–8.07 m (5-Ph, o-H, major
stereoisomers) and 8.11 m (5-Ph, o-H, minor stereo-
isomer) (2H total). 13C NMR spectrum, δC, ppm: two
major stereoisomers: 38.12, 40.66, 43.01, 47.11, 48.51,
49.14, 49.20, 50.15 (8Cazir), 122.99, 123.23, 123.33
(2C), 123.41 (Cb), 127.06, 127.14, 127.24, 128.22,
128.27, 128.59, 129.07, 129.57, 129.81 (2C), 129.97
(2C, Ca), 130.47, 131.98, 132.03, 134.01 (2C), 134.20
(2C, Cc), 159.86, 160.07, 164.77, 164.62 (4 CHt);
165.38 (C=O). Mass spectrum (ES), m/z (Irel, %): 1869
(18) [3M + Na + 2MeOH]+, 1837 (14) [3M + Na +
MeOH]+, 1805 (7) [3M + Na]+, 1275 (66) [2M + Na +
2MeOH]+, 1243 (68) [2M + Na + MeOH]+, 1211 (22)
[2M + Na]+, 681 (38) [M + Na + 2MeOH]+, 649 (100)
[M + Na + MeOH]+, 617 (55) [M + Na]+. Found, %:
C 68.69; H 3.69; N 14.01. C34H22N6O5. Calculated, %:
C 68.68; H 3.73; N 14.13.
2,5-Bis[(E)-3-phenyl-1-phthalimidoaziridin-2-
yl]-1,3,4-oxadiazole (IIIe). Potassium carbonate,
5 mmol, was dispersed in a solution of 274 mg
(1 mmol) of oxadiazole IId in 50 ml of methylene
chloride, 486 mg (3 mmol) of N-aminophthalimide and
1.329 g (3 mmol) of lead tetraacetate were added
alternately in small portions over a period of 15 min
under stirring at room temperature, and the mixture
was stirred for 30 min. The inorganic precipitate was
filtered off and washed with methylene chloride until
colorless filtrate, the solvent was removed, and the res-
idue was recrystallized from ethanol with addition of
DMF. Yield 220 mg (37%), mp 220–222°C (decomp.);
1
a mixture of three stereoisomers (~82:15:3). H NMR
spectrum, δ, ppm: 4.14 d and 4.70 d (Hazir, major
isomer, J = 5.5 Hz); 4.22 d (J = 5.5 Hz), 4.28 d (J =
5.8 Hz), 4.79 d (J 5.5 Hz), and 5.26 d (J = 5.8 Hz)
(Hazir, medium-fraction component); 4.03 d (J = 5.3 Hz)
and ~4.79 d (Hazir, minor isomer) (4H total); 7.26–
7.57 m (10H, 2Ph), 7.60–7.77 m (8H, 2PhthN).
13C NMR spectrum, δC, ppm: major component: 41.59,
50.30 (2Cazir); 123.32 (Cb), 127.20, 128.75, 128.94,
129.94 (Ca), 133.86, 134.20 (Cc); 161.59 and 164.73
(2CHt). Mass spectrum (ES), m/z (Irel, %): 1869 (18)
[3M + Na + 2MeOH]+, 1837 (38) [3M + Na + MeOH]+,
1805 (38) [3 M + Na]+, 1275 (36) [2 M + Na +
2MeOH]+, 1243 (84) [2M + Na + MeOH]+, 1211 (80)
[2M + Na]+, 681 (15) [M + Na + 2MeOH]+, 649 (64)
[M + Na + MeOH]+, 617 (100) [M + Na]+. Found, %:
C 68.60; H 3.70; N 14.13. C34H22N6O5. Calculated, %:
C 68.68; H 3.73; N 14.13.
REFERENCES
1. Ignatenko, O.A., Blandov, A.N., and Kuznetsov, M.A.,
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3. Kerr, V.N., Ott, D.G., and Hayes, F.N., J. Am. Chem.
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2-{(E)-3-[(E)-3-Phenyl-1-phthalimidoaziridin-2-
yl]-1-phthalimidoaziridin-2-yl}-5-phenyl-1,3,4-oxa-
diazole (IIIf). Potassium carbonate, 0.69 g (5 mmol),
was dispersed in a solution of 274 mg (1 mmol) of
oxadiazole IIe in 50 ml of methylene chloride, 324 mg
(2 mmol) of N-aminophthalimide and 886 mg
(2 mmol) of lead tetraacetate were added alternately in
small portions over a period of 15 min under stirring at
room temperature, and the mixture was stirred for
30 min. The inorganic precipitate was filtered off and
washed with methylene chloride until colorless filtrate.
The solvent was removed, the residue was treated with
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 7 2007