Monofluoro-substituted azomethine ylides in fluorocarbene reactions with imines. Synthesis and transformations of monofluoroaziridines

Article abstract of DOI:10.1134/S1070428007020224

N-Arylmethylene and N-benzhydrylideneamines react with fluorocarbene yielding fluoro-substituted azomethine ylides that undergo 1,3-π-cyclization into aziridines. Generation of fluoroylides in the presence of dipolarophiles (dimethyl maleate or dimethyl acetylenedicarboxylate) led to the reaction of 1,3-dipolar cycloaddition resulting in substituted 2-pyrrolines or pyrroles. 2-Fluoroaziridines, products of N-alkyl-N-benzhydrylideneamines 1,3-π-cyclization, in the presence of acid catalysts suffer isomerization into α-fluoroimines and 1,3-disubstituted indoles.

Full text of DOI:10.1134/S1070428007020224

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2007, Vol. 43, No. 2, pp. 286−296. © Pleiades Publishing, Ltd. 2007.
Original Russian Text © A.S. Konev, M.S. Novikov, A.F. Khlebnikov, 2007, published in Zhurnal Organicheskoi Khimii, 2007, Vol. 43, No. 2,
pp. 292−302.
Monofluoro-Substituted Azomethine Ylides in Fluorocarbene
Reactions with Imines. Synthesis and Transformations
of Monofluoroaziridines
A. S. Konev, M. S. Novikov, and A. F. Khlebnikov
aSt. Petersburg State University, St. Petersburg, 19850 Russia
e-mail: Alexander.Khlebnikov@pobox.spbu.ru
Received March 22, 2006; revised September 08, 2006
Abstract—N-Arylmethylene and N-benzhydrylideneamines react with fluorocarbene yielding fluoro-substituted
azomethine ylides that undergo 1,3-π-cyclization into aziridines. Generation of fluoroylides in the presence of
dipolarophiles (dimethyl maleate or dimethyl acetylenedicarboxylate) led to the reaction of 1,3-dipolar cycloaddition
resulting in substituted 2-pyrrolines or pyrroles. 2-Fluoroaziridines, products of N-alkyl-N-benzhydrylideneamines
1,3-π-cyclization, in the presence of acid catalysts suffer isomerization into α-fluoroimines and 1,3-disubstituted
indoles.
DOI: 10.1134/S1070428007020224
Halosubstituted iminium ylides, reactive intermediates
formed in reactions of halocarbenes with a C=N bond,
are convenient synthetic building blocks for preparation
of various nitrogen-containing heterocycles [1]. Especially
interesting are fluoro-substituted iminium ylides utilized
in the synthesis of fluoro-containing compounds [2–18].
Introducing one or several fluorine atoms into a molecule
is known to lead as a rule to essential changes in its
geometry and also in its chemical and physical properties
[19]. Therewith the reactivity dependence of the fluoro-
containing molecules on the number of fluorine atoms is
often rather complex [20]. Therefore the chemical
behavior of the fluoro-containing short-living intermediates,
in particular, also ylides, is often difficultly predictable a
priori based on the regular trends known for non-
fluorinated or chloro- and bromo-containing analogs. For
instance, the most thoroughly studied dichloro- and
difluoro-substituted azomethine ylides are quite different
in their chemical behavior [1, 2, 21]. In this connection
monofluoro-substituted azomethine ylides that has not
been previously investigated are interesting from the
theoretical viewpoint since the study of their char-
acteristics makes it possible to reveal the effect of fluorine
atom on the reactivity of ylide intermediates and also for
practice for their π-cyclization and cycloaddition reactions
may present a simple route to some difficultly accessible
fluoro-containing compounds.
We report here on results of the study of generation
and chemical reactions of monofluoro-substituted azo-
methine ylides and also of the products of their 1,3-cycliz-
ation, monofluoroaziridines.
The only efficient method to generate halosubstituted
ylides is based on reactions of halocarbenes with com-
pounds containing a C=N bond. Several methods are
known for generation of monofluorocarbene that has been
applied to preparation of fluorocyclopropanes from alk-
enes [22–28]. However all these procedures involve the
use of strongly basic and highly nucleophilic reagents,
like dimethylzinc or butyllithium, which are incompatible
with substrates containing the C=N bond. We developed
a new method of monofluorocarbene generation under
mild neutral conditions involving a reduction of dibromo-
fluoromethane with active lead in the presence of tetra-
butylammonium bromide under an ultrasonic irradiation
[16]. The active lead was prepared by reducing lead
acetate with sodium borohydride in aqueous acetic acid
[5].
The ultrasonic irradiation of a mixture containing
aromatic ketone imine Ia–Id, active lead, and tetrabutyl-
ammonium bromide in dichloromethane led to a succession
286

MONOFLUORO-SUBSTITUTED AZOMETHINE YLIDES
287
Table 1. Yields of fluoroaziridines in reaction of fluorocarbene
with imines Ia–Ih
Scheme 2.
O
Yield,
%
R1
R2
R3
Aziridine
O
[:CHF]
Imine
N
Ia
Ib
Ic
Id
Ph
Ph
Ph
Ph
Ph
Ph
Me
IIIa
IIIb
IIIc
IIId
47
N
IV
CHF
CH2Ph
34
VI
CH2CO2Me
CH2CH2Ph
47
19a
2,2′-
biphe-
nylene
H
O
O
H
N
O
N
N
H2O/SiO2
H
F
F
Ie
If
Ph
Ph
cis-IIIe
cis-IIIf
4
H
N
H
4-ClC6H4 4-ClC6H4
22
Ig
Ih
Ph
Ph
H
H
CH2Ph
CH2CH2Ph trans-IIIh Tracesb
trans-IIIg 21a
H
O
O
V
a Isolated with initial imine impurity.
1
b Detected by H NMR spectroscopy.
since the trans- and cis-vicinal coupling constants 3JHF
found in monofluoroaziridines are 2.4 and 8.1 Hz respec-
tively [29].
of reactions including fluorocarbene generation, its
addition to the nitrogen atom of the imine, and cyclization
of the arising azomethine ylide IIa–IId (Scheme 1)
resulting in the formation of aziridines IIIa–IIId in 19–
47% yields (Table 1).
It is known that dichloro-substituted ylides generated
from dichlorocarbene and N-alkylimines of arenecarb-
aldehydes with the primary alkyl substituents do not
undergo cyclization into aziridines [30]. In contrast, in
the reaction mixtures of imines Ig and Ih with fluoro-
Scheme 1.
CHFBr2
1
carbene we found by H NMR spectroscopy aziridines
IIIg and IIIh in the form of trans-isomers. Aziridine
IIIg was isolated with an impurity of the initial N-benzyl-
N-benzylideneamine in 21% yield.
Pb*, Bu4NBr
R3
R3
N+ _
R1
R2
Iа_Ih
The configuration of fluoroaziridines IIIg and IIIh
was established from comparison of coupling constants
of vicinal H and F atoms (3JHF 5.5 Hz) with the data
published for monofluoroaziridines [29] and with values
calculated by modified Karplus−Altona equation [31]
(3JHF 1.1–2.5 for cis- and 5.4–8.5 Hz for trans-isomers).
N
R1
R2
IIIа_IIIh
H
[:CHF]
R1
NR3
CHF
R2
F
IIа_IIh
The structure of aziridines IIIa–IIId was establish-
ed from the analysis of 1H and 13C NMR spectra. In the
1H NMR spectra of aziridines synthesized the signal of
aziridine proton appeared as a doublet in the region 5.23–
5.53 ppm (2JHF 77.3–80.9 Hz). The 13C NMR spectra
contain two doublet signals belonging to CF and CAr
atoms of the aziridine ring in the region 87–90 (JCF 243–
254 Hz) and 52–56 ppm (JCF 13–16 Hz).
We obtained an unexpected result in the reaction of
fluorocarbene with dibenzo[b,f][1,4]oxazepine (IV). Here
instead of aziridine was obtained compound V in 17%
yield which might be regarded as a hydrolysis product of
ylide dimer VI (Scheme 2).
The yields of fluoroaziridines are strongly affected by
two factors: the rate of 1,3-cyclization of the correspond-
ing fluoroylide, and the stability of the formed aziridine.
In event of relatively low rate of 1,3-cyclization one of
the reasons of reduced yield of fluoroaziridines IIIa–
IIIi may be a partial oligomerization of the intermediate
azomethine ylides that is indirectly confirmed by formation
of compound V resulting from dimerization of ylide VI.
Cyclizations of fluoroylides generated from aren-carb-
aldehydes imines Ie–Ih may give stereoisomeric aziri-
dines. However in the reaction mixtures obtained from
N-aryl-N-arylmethyleneamines Ie and If under the
conditions of fluorocarbene generation we found by
1H NMR method only cis-aziridines IIIe and IIIf (3JHH
4.4, 3JHF 2.5, 2JHF 79 Hz). The stereochemistry of aziri-
dines IIIe and IIIf follows from the value JHF 2.5 Hz,
At the presence of a little water in the initial compounds
a fast hydrolysis occurs of the intermediate azomethine
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KONEV et al.
288
Scheme 3.
R2
N
R2
N
R1
Ph
R1
R1
Ph
[:CHF]
Iа_Ic, Ie_Ih
O
CH2F
CHF
Ph OH
O H
H
CH3
N
CH3
N
CH3
N
CH3
N
H
O
H
F
[:CHF]
CHF
H
HO
-HF
H O
H
Ii
VII
Scheme 4.
F
Ph
HO
Ph
Ph
Ph
Ph
F
Ph
Catalyst
H2O
SiO2
N
R
HCl
H2O
N
R
CHO
CHO
F
Ph Ph
XIb, XIc
X
Catalyst
(R = CO2Me)
_HF
VIII
IIIb, IIIc
_HF
Catalyst
R
N
Ph
N
CO2Me
Ph
XII
Ph
IXb, IXc
ylide to a carbonyl compound. Actually, virtually in all
performed reactions of imines Ia–Ic, Ie–Ih we isolated
as side products or spectrally detected benzophenone or
arenecarbaldehydes which apparently formed in the ylide
reaction with water involving the protonation of ylide
carbon attached to the fluorine atom (Scheme 3).
gel thus significantly reducing the preparative yields at
purification by column chromatography. To decrease the
losses at separating the reaction products we used silica
gel treated with anhydrous triethylamine. Besides for
crystalline aziridines an isolation procedure was developed
avoiding the use of column chromatography that consisted
in thorough washing of the reaction mixture with water
solution of sodium carbonate followed by the aziridine
crystallization.
The fluorene iminium ylide generated from N-methyl-
fluorene imine (Ii) because of additional stabilization of
the negative charge by the fluorene system possessed
an opposite polarization of the ylide fragment, and its
hydrolysis in the reaction occurring in the presence of
moisture proceeded through a protonation of the fluorenyl
carbon atom.As a result N-methyl-N-fluorenylformamide
(VII) formed in 13% yield.
We also established that fluoroaziridines IIIa–IIIh are
sensitive to the action of Lewis and hydrogen acids. For
instance, in the trifluoroacetic acid or in dichloromethane
in the presence of boron trifluoride etherate aziridine
IIIb suffered fast tarring without formation of any
identifiable products. However after heating at reflux for
3 h solutions of aziridines IIIb and IIIc in dichloromethane
in the presence of catalytic quantities of p-toluenesulfonic
acid the subsequent chromatography on silica gel allowed
separation of α-fluorodiphenylacetaldehyde (VIII) and
indoles IXb and IXc (Scheme 4). At the use as catalyst
of anhydrous zinc chloride or titanium tetrachloride only
There is no published data on the chemical properties
of monofluoroaziridines, and we investigated some
chemical reactions of these compounds in order to
evaluate their synthetic potential. It was established that
fluoroaziridines IIIa–IIIh are stable against heating: they
survive two-hour boiling in dioxane (101°C) or xylene
(144°C). Yet they considerably fast decompose on silica
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MONOFLUORO-SUBSTITUTED AZOMETHINE YLIDES
289
Table 2. Preparative yields of products of acid-catalyzed ring
opening of aziridines IIIb and IIIc in CH2Cl2
indole derivative was obtained (Table 2). In aqueous
dioxane in the presence of catalytic amounts of hydro-
chloric acid aziridine IIIc gave α-hydroxydiphenyl-
acetaldehyde (X) in 77% yield.
Temperature and
duration of
reaction
Yield, %
Aziridine Catalyst
VIII IXb and IXc
Aldehyde VIII formed from hydrolysis of iso-
merization products of fluoroaziridines III, α-fluoroimines
XI. Imines XIb and XIc were detected in the reaction
mixtures at ring opening of aziridines IIIb and IIIc
catalyzed by antimony trifluoride by means of 1H NMR
spectroscopy that revealed characteristic multiplet signals
IIIb
IIIb
TsOH
ZnCl2
40°C, 3 h
31
0
24
42
20°C, 15 h
IIIb
IIIc
TiCl4
20°C, 15 min
40°C, 3 h
0
60
42
TsOH
25
of the imine proton with the coupling constant 3JHF
~
amines with primary alkyl substitiuents, and also gem-
difluoro-substituted ylides do not undergo cyclization into
aziridines, but readily provide products of 1,3-dipolar
cycloaddition with dipolarophiles [1, 2, 30].As seen from
Table 1, cyclization of monofluoro-substituted analogs into
monofluoroaziridines is hardly sensitive to the character
of substituents at the ylide fragment. It is known that
gem-dichloro-substituted azomethine ylides which easily
cyclize into aziridines cannot be involved into 1,3-dipolar
cycloaddition even with the most active dipolarophiles.
To elucidate whether the monofluoro-substituted ylides
can participate in cycloaddition reactions we have reacted
imines Ia, Ie, Ig, and Ih with fluorocarbene in the
presence of dimethyl acetylenedicarboxylate and dimethyl
maleate, the moost often used dipole traps.
10 Hz. Similar opening of a three-membered ring with
halogen migration was observed in gem-dihaloaziridines
[32]. We failed to isolate pure imines XI using as catalysts
for opening the fluoro-substituted aziridine ring TsOH,
ZnCl2, or TiCl4. Antimony trifluoride proved to be
exclusive catalyst:Atreatment with the latter of aziridine
IIIb in dichloromethane at reflux for 11 h led to a nearly
quantitative formation of imine XIb containing 0.6% of
indole IXb and 6% of the initial aziridine.A chromato-
graphic purification on silica gel treated with anhydrous
triethylamine provided analytically pure imine XIb in 55%
yield. Under the same conditions we obtained from imine
IIIc imine XIc in a nearly quantitative yield containing
as an impurity 6 mol % of azadiene XII.
We showed with special experiments that imine XIb
under treatment with SbF3 or p-toluenesulfonic acid in
boiling dichloromethane transformed into indole IXb, but
the rate of indole IXb formation was here much slower
than the rate of its formation from aziridine IIIb. At
treating imine XIb with titanium tetrachloride indole IXb
was found only in traces (1H NMR data). These facts
indicate that acid-catalyzed transformation of aziridine
IIIb into indole IXb does not proceed through α-fluoro-
imine XIb.
At ultrasonic irradiation of a mixture of imine Ie, active
lead, tetrabutylammonium bromide, and dimethyl acetyl-
enedicarboxylate in dichloromethane at 40°C for 100 h
a mixture was obtained that was subjected to column
chromatography to isolate pyrrole XIII in 32% yield
(Scheme 5).Aziridine IIIe disappeared from the reaction
mixture.
Scheme 5.
Ph
N
Ph
N
[:CHF]
The composition of products from aziridine IIIc
transformation is strongly affected by the catalyst, for
aziridine IIIc possesses considerable CH-acidity as
compared to aziridine IIIb. In the presence of hydrogen
acid alongside fluoroimine XIc formed indole IXc, and at
the action of a Lewis acid the cyclization into indole was
totally inhibited.
Ph
Ph
CHF
Ie
IIe
Ph
N
MeO2C
CO2Me
Ph
F
MeO2C
CO2Me
1,3-Cyclization into aziridines is the most characteristic
behavior of gem-dichloro- and and fluorochloro-sub-
stituited azomethine ylides formed in the reaction of
dihalocarbenes with N-alkyl-N-benzhydrylideneamines
and benzylideneanilines [1]. On the contrary, ylides
obtained from dihalocarbenes and N-alkyl-N-benzylidene-
Ph
N
Ph
_HF
MeO2C
CO2Me
XIII
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KONEV et al.
290
Scheme 6.
CH3
N
MeO2C
CO2Me
Ph
Ph
Ph
Ph
CH3
Ph
Ph
CH3
[:CHF]
N
F
N
CHF
MeO2C
CO2Me
IIa
Ia
XV
CH3
N
CH3
N
Ph
Ph
Ph
F
Ph
MeO2C
CO2Me
XIV
IIIa
Scheme 7.
(1) [:CHF]
R
N
R
N
MeO C
CO2Me
(2)
2
R
(3) _HF
Ph
Ph
N
+
Ph
MeO2C
CO2Me
MeO2C
CO2Me
Ig, Ih
cis-XVIg, XVIh
trans-XVIg, XVIh
Similar reactions of imine Ie with dichloro- and
difluorocarbenes in the presence of dimethyl acetylene-
dicarboxylate led to the formation of the corresponding
chloro- and fluoropyrroles in 1.9 and 58% yield respec-
tively, and therewith in the first case the main product
was aziridine [5, 33]. Thus unlike dichloro-substituted
analogs, both difluoro- and monofluoro-substituted azo-
methine ylides prepared from benzalanilines added to the
triple bond of dimethyl acetylenedicarboxylate, the
cycloaddition completely suppressing the 1,3-cyclization
into aziridine.
In going from ylide IIa to ylides IIg and IIh due to
removal of one phenyl substituents the steric hindrances
to the dipolarophile approach were reduced, and this fact
should favor the cycloaddition. Actually, in reactions of
imines Ig and Ih with fluorocarbene in the presence of
dimethyl maleate were obtained only cycloaddition
products: pyrrolines XVIg and XVIh as mixtures of cis-
and trans-isomers, the latter prevailing (Scheme 7).
Compounds XVIg and XVIh were isolated by column
chromatography in an overall yield of 32–35%.
Assignment of the configuration of pyrrolines cis- and
trans- XVIg and XVIh was performed based on the
analysis of the chemical shift values δ of methoxy groups
From the products obtained in reaction of N-benz-
hydrylidene-N-methylamine (Ia) with fluorocarbene in
the presence of less active dipolarophile, dimethyl maleate
we isolated by column chromatography pyrroline XIV
(10%) resulting from dehydrofluorination of pyrrolidine
XV, the primary product of ylide IIa cycloaddition to the
C=C bond (Scheme 6). The analysis of the reaction
mixture by TLC and 1H NMR showed alongside pyrroline
XIV also aziridine IIIa, and the ratio pyrroline : aziridine
was ~1:1, indicating that the rate of ylide IIa cycloaddition
to the C=C bond of dimethyl maleate was comparable
with the rate of its cyclization into aziridine. gem-Dichloro-
substituted analog of ylide IIa does not enter into the
cycloaddition reaction with dimethyl maleate.
1
in the H NMR spectra. The proton signal of methoxy
group at atom C3 in the spectra of cis-2-phenyl-2,3-
dihydropyrrole-3,4-dicarboxylates is shifted upfield on the
average by 0.5 ppm compared to the usual value of 3.6–
3.8 ppm due to the shielding effect of the cis-directed
1
benzene ring [30, 34–37]. In the H NMR spectra of
stereoisomers XVIg and XVIh the δ values for the
methoxy groups at C3 were 3.12–3.15 for cis- and 3.66–
3.67 ppm for trans-isomers.
Thus reaction of fluorocarbene with azomethines
proceeds through intermediate formation of unstable
azomethine ylides whose main transformations are 1,3-
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MONOFLUORO-SUBSTITUTED AZOMETHINE YLIDES
291
cyclization into aziridines, 1,3-dipolar cycloaddition to
electron-deficient multiple carbon–carbon bonds, and
hydrolysis. Besides in some cases monofluoroylides are
capable to give products of formal dimerization. The
cyclization of fluoroylides occurs stereoselectively leading
to the formation of cis-aziridines from N-aryl-substituted
ylides and trans-aziridines from N-alkyl-substituted ylides.
An efficient procedure has been found for selective ring
opening in 2,2-diphenyl-3-fluoroaziridines catalyzed by
antimony trifluoride, therefore the sequence “reaction of
azomethines with fluorocarbene–opening of monofluoro-
substituted aziridine ring” becomes a convenient method
for the synthesis of α-fluoroimines, promising synthetic
building blocks for fluorinated heterocycles. The cyclo-
addition of fluoroylides to dimethyl acetylenedicarboxylate
and dimethyl maleate results in formation of pyrroles and
2-pyrrolines, yet in the case of sterically loaded C,C-di-
substituted ylides the cycloaddition to dipolarophiles
suffers from competition with the cyclization into
aziridines. By the chemical properties the monofluoro-
substituted azomethine ylides take an intermediate position
between difluoro-substituted ylides more prone to 1,3-di-
polar cycloaddition to multiple bonds, and dichloro- and
chlorofluoroylides whose more characteristic reaction is
the 1,3-cyclization.
ratio Pb*–Bu4NBr–imine–CHFBr2 4:4:1:5). On adding
dibromofluoromethane the reaction mixture usually
frothed and slightly heated. The flask was immediately
stoppered, and the stopper was fixed to keep a slight
excessive pressure in the flask. Then the flask was placed
into an ultrasonic bath (160 W) and was subjected to
irradiation at the bath temperature 40°C till total
disappearance of lead. The products were isolated from
the reaction mixtures by two procedures. a. On completion
of the reaction 0.2 ml of triethylamine and silica gel in
amount 2.5 g per 1 g of tetrabutylammonium bromide
was added to the reaction mixture. The solvent was
evaporated in a vacuum at room temperature, the dry
residue was placed on the top of a chromatographic
column packed with silica gel pretreated with triethyl-
amine. The products were eluted by a mixture hexane–
ethyl acetate containing 1 vol% of triethylamine.
b. The reaction mixture was shaken in a separatory
funnel with a water solutio of sodium carbonate
(0.02 mol l−1, 70–80 ml per 50 ml of reaction mixture),
the separated precipitate was filtered off. This procedure
was repeated four times more. The filtrate was dried
over Na2SO4, the solvent was removed in a vacuum, and
the residue was recrystallized.
1-Methyl-2,2-diphenyl-3-fluoroaziridine (IIIa).
A mixture of 0.64 g (3.3 mmol) of N-benzhydrylidene-N-
methylamine (Ia), 2.87 g (14.9 mmol) of dibromo-
fluoromethane, 2.5 g (12.1 mmol) of active lead, and
3.86 g (12.0 mmol) of Bu4NBr in 40 ml of anhydrous
dichloromethane was irradiated for 49 h in an ultrasonic
bath. Yield 0.35 g (47%) by workup a. Characteristics
of this compounds we reported in the preliminary
communication [16].
EXPERIMENTAL
Melting points of substances are measured on a
..
Boetius heating block and are reported without correction.
NMR spectra were registered on a spectrometer Bruker
DPX 300 at operating frequencies 300 (1H) and 75 (13C)
MHz. Elemental analyses were performed on a CHN-
analyzer HP-185B. Mass spectra were taken on MKh-
1303 (ionizing electrons energy 70 eV). The monitoring
of reaction progress was carried out by TLC on Silufol
UV-254 plates. Reaction mixtures were separated by
colum chromatography on silica gel Merck 60/200.
Solvents (CH2Cl2, Et2O, xylene, dioxane) were dried by
standard procedures. Dimethyl acetylenedicarboxylate
was distilled before use. Commercial tetrabutylammonium
bromide was dried in a desiccator over P2O5 before use.
1-Benzyl-2,2-diphenyl-3-fluoroaziridine (IIIb).
A mixture of 0.83 g (3.1 mmol) N-benzhydrylidene-N-
benzylamine (Ib), 2.94 g (15.3 mmol) of dibromo-
fluoromethane, 2.56 g (12.4 mmol) of active lead, and
3.96 g (12.3 mmol) of Bu4NBr in 10 ml of anhydrous
dichloromethane was irradiated for 46 h in an ultrasonic
bath. The reaction product was isolated by means of flash-
chromatography on silica gel treated with triethylamine
(eluent hexane–ethyl). On recrystallization of the crude
product from a mixture ether–hexane, 10:1, we isolated
0.247 g of colorless crystals. Additional 0.032 g of
compound IIIb was isolated from the mother liquor.
Overall yield 0.279 g (30%). The workup of the reaction
mixture by procedure b followed by recrystallization from
ether resulted in the yield of aziridine IIIb of 34%. mp
114–115°C (Et2O). IR spectrum (CHCl3), cm–1: 1500,
Dibromofluoromethane [38], imines Ia–Ic [39], Id, and
Ii [40] were prepared by published procedures. Active
lead was obtained by method from [5].
General procedure of reactions between dibromo-
fluoromethate and actuve lead. Into a flask containing
active lead was charged under an argon atmosphere
anhydrous dichloromethane, tetrabutylammonium
bromide, imine, and dibromofluoromethane (in a molar
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KONEV et al.
292
1180, 1150, 1100, 1090. 1H NMR spectrum (CDCl3), δ,
ppm: 3.53 d.d (1H, CH2, JHH 14.3, JHF 3.7 Hz), 3.64 d.d
(1H, CH2, JHH 14.3, JHF 2.2 Hz), 5.44 d (1H, HCF,
JHF 79.2 Hz), 7.20–7.55 m (15Harom). 13C NMR spectrum
(CDCl3), δ, ppm: 53.7 d (CH2, J 3.1 Hz), 55.5 d (C2,
J 14.5 Hz), 87.0 d (CHF, J 243.9 Hz), 126.8, 126.9, 127.58,
(1H, CH2), 5.53 d (1H, HCF JHF 80.9 Hz), 7.05–7.92 m
(10Harom). 13C NMR spectrum (CDCl3), δ, ppm: 35.9
(PhCH2), 50.4 d (CH2, J 3.3 Hz), 52.5 d (C2, J 13.8 Hz),
89.5 d (CHF, J 253.8 Hz), the signals from the carbon
atoms of aryl systems in the reaction product and the
initial amine overlapped.
127.60, 128.0, 128.1, 128.3, 128.4 (Carom), 130.2 d (Carom
,
(2RS,3SR)-1,2-Diphenyl-3-fluoroaziridine (cis-
IIIe). A mixture of 0.36 g (2.0 mmol) of N-benzyliden-
eaniline (Ie), 1.91 g (10.0 mmol) of dibromofluoro-
methane, 1.64 g (7.9 mmol) of active lead, and 2.56 g
(7.9 mmol) of Bu4NBr in 22 ml of anhydrous dichloro-
methane was irradiated for 69 h in an ultrasonic bath.
The reaction mixture was separated by means of flash-
chromatography on silica gel treated with triethylamine
(eluent hexane–ethyl acetate). On recrystallization of the
crude product from hexane the yield was 0.015 g (3.5%).
Colorless crystals, mp 62–64°C (66–68°C [16]). 1H NMR
spectrum (CDCl3), δ, ppm: 3.34 d.d (1H, C2-H, JHF 2.4,
JHH 4.1 Hz), 5.23 d.d (1H, HCF, JHF 79.2, JHH 4.1 Hz),
7.05–7.60 m (10Harom). 13C NMR spectrum (CDCl3), δ,
ppm: 46.7 d (C2, J 14.0 Hz), 83.9 d (CHF, J 245.3 Hz),
119.7, 124.1, 128.3, 128.5, 128.9, 130.0 (Carom), 134.2 d
(Carom, J 4.0 Hz), 150.3 d (Carom, J 2.0 Hz).
J 2.1 Hz), 134.8 d (Carom, J 4.2 Hz), 137.9 (Carom),
138.3 d (Carom, J 3.1 Hz). Found, %: C 83.00; H 6.03;
N 4.59. C21H18FN. Calculated, %: C 83.14; H 5.98;
N 4.62.
Methyl (2,2-diphenyl-3-fluoroaziridin-1-yl)-
acetate (IIIc).Amixture of 0.585 g (2.3 mmol) of methyl
N-benzhydrylideneglycinate (Ic), 2.09 g (10.9 mmol) of
dibromofluoromethane, 1.8 g(8.7 mmol) of active lead,
and 2.82 g (8.7 mmol) of Bu4NBr in 22 ml of anhydrous
dichloromethane was irradiated for 70 h in an ultrasonic
bath. The workup of the reaction mixture by procedure
b followed by recrystallization from a mixture dichloro-
methane–ether, 2:5, we gave 0.309 g (47%) of compound
IIIc, mp 120–121.5°C. IR spectrum (CHCl3), cm–1: 1750
(C=O). 1H NMR spectrum (CDCl3), δ, ppm: 3.04 d.d
(1H, CH2, JHH 16.8, JHF 3.6 Hz), 3.37 d.d (1H, CH2, JHH
16.8, JHF 2.3 Hz), 3.76 (3H, CH3), 5.42 d (1H, HCF, JHF
77.3 Hz), 7.22–7.44 m (8Harom), 7.56 m (2Harom). 13C
NMR spectrum (CDCl3), δ, ppm: 50.6 d (CH2, J 4.0
Hz), 51.7 (CH3), 55.4 d (C2, J 14.0 Hz), 85.8 d (CHF, J
245.3 Hz), 127.1, 127.7, 128.3, 128.4, 128.6 (Carom), 129.8
d (Carom, J 2.0 Hz), 134.3 d (Carom, J 4.0 Hz), 137.6 d
(Carom, J 4.0 Hz), 169.8 (C=O). Found %: C 71.43; H
5.62; N 5.17. C17H16FNO2. Calculated %: C 71.57; H
5.65; N, 4.91.
(2RS,3SR)-2-Fluoro-1,3-bis(4-chlorophenyl)-
aziridine (cis-IIIg). A mixture of 0.5 g (2 mmol) of
4-chloro-N-(4-chlorobenzylidene)aniline (If), 3.67 g
(19.1 mmol) of dibromofluoromethane, 3.2 g (15.5 mmol)
of active lead, and 4.9 g (15.2 mmol) of Bu4NBr in 15 ml
of anhydrous dichloromethane was irradiated for 34 h in
an ultrasonic bath. The reaction mixture was separated
by means of flash-chromatography on silica gel treated
with triethylamine (eluent hexane–ethyl acetate). Yield
0.126 g (22%), colorless crystals. Characteristics of this
compounds we reported in the preliminary communication
[16].
1-Phenethyl-3-fluoro-9'H-spiro(aziridine-2,9'-
fluorene) (IIId). A mixture of 1.2 g (4.2 mmol) of
fluorenone N-phenethylimine (Id), 4 g (20.8 mmol) of
dibromofluoromethane, 3.5 g (16.9 mmol) of active lead,
and 5.4 g (16.7 mmol) of Bu4NBr in 45 ml of anhydrous
dichloromethane was irradiated for 36 h in an ultrasonic
bath. The reaction mixture was worked up by procedure
a to isolate 1.04 g of a mixture of aziridine (IIId) with
the initial imine. Into the mixture obtained a crystal of the
initial imine was seeded, the precipitated crystals were
filtered off. The filtrate was subjected to chromatography
on 10 g of silica gel pretreated with triethylamine (eluent
hexane). On removing the solvent we obtained 0.36 g of
viscous yellowish fluid containing 70% of aziridine IIId
and 30% of initial imine (1H NMR data).Yield of aziridine
IIId 19%. 1H NMR spectrum (CDCl3), δ, ppm: 2.73 m
(1H, CH2), 2.87 m (1H, CH2), 3.18 m (1H, CH2), 3.46 m
(2RS,3RS)-1-Benzyl-2-phenyl-3-fluoroaziridine
(trans-IIIg). A mixture of 0.812 g (4.2 mmol) of
N-benzyl-N-benzylideneamine (Ig), 6.7 g (34.9 mmol) of
dibromofluoromethane, 3.5 g (16.9 mmol) of active lead,
and 5.4 g (16.7 mmol) of Bu4NBr in 45 ml of anhydrous
dichloromethane was irradiated for 59 h in an ultrasonic
bath. After workup of the reaction mixture by procedure
a aziridine IIIg was obtained in a mixture (400 mg) with
the initial imine.Yield of aziridine 21%. 1H NMR spectrum
(CDCl3), δ, ppm: 3.17 d (1H, C2-H, JHF 5.5 Hz), 3.88 d
(1H, CH2, J 14.0 Hz), 3.94 d (1H, CH2, J 14.0 Hz),
5.17 d (1H, HCF, JHF 78.5 Hz), 7.2–7.5 m (10H,
Harom). 13C NMR spectrum (CDCl3), δ, ppm: 44.7 d (C2,
J 16.1 Hz), 52.4 d (CH2, J 11.4 Hz), 84.3 d (CHF,
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MONOFLUORO-SUBSTITUTED AZOMETHINE YLIDES
293
J 254.3 Hz), 126.7. 127.2, 127.5, 127.6, 127.7, 128.1,
128.3, 138.1 (Carom).
127.4, 127.6, 128.5, 129.0, 140.5, 140.8, 141.0, 141.1
(Carom), 163.1 (HCO), 163.7 (HCO). Mass spectrum, m/
z (Irel, %): 223 (100) [M]+, 208 (47.8) [M – CH3]+, 194
(13.8) [M – HCO]+, 180 (68.5) [M – HCO – CH3]+, 165
(82.6) [M – HCONCH3]+.
(2RS,3RS)-1-Phenethyl-2-phenyl-3-fluoro-
aziridine (trans-IIIh). A mixture of 1 g (4.8 mmol) of
N-benzylidene-N-phenethylamine (Ih), 5.38 g
(28.0 mmol) of dibromofluoromethane, 4.64 g (22.4 mmol)
of active lead, and 7.24 g (22.4 mmol) of Bu4NBr in 25
ml of anhydrous dichloromethane was irradiated for 57 h
in an ultrasonic bath.After workup of the reaction mixture
by procedure a (eluent hexane–ethyl acetate) we obtained
0.015 g of a mixture of compound IIIh with the initial
1-Benzyl-3-phenylindole (IXb) and 2,2-diphenyl-
2-fluoroacetaldehyde (VIII). a. A solution of 0.15 g
(0.5 mmol) of aziridine IIIb in 10 ml of anhydrous dichloro-
methane in the presence of a catalytic quantity of
p-toluenesulfonic acid (1 mg) was heated at reflux for
3 h. After separating the mixture by column chromato-
graphy (eluent hexane–dichloromethane) we obtained
0.033 g (24%) of compound IXb and 0.033 g (31%) of
compound VIII.
1
imine. H NMR spectrum (CDCl3), δ, ppm: 3.19 d (1H,
C2-H, J 5.5 Hz), 5.03 d (1H, CHF, JHF 78.3 Hz).
6,17-Epoxy-6,6a,17,17a-tetrahydrodibenzo-
[b,f]dibenzo[22 ,32 :62 ,72 ][1,4]oxazepino[42 ,52
:4,5]-pyrazino[1,2-d][1,4]oxazepine (V). A mixture of
1.14 g (5.9 mmol) of dibenzo[b,f][1,4]oxazepine (IV),
5.63 g (29.3 mmol) of dibromofluoromethane, 4.86 g
(23.5 mmol) of active lead, and 7.58 g (23.5 mmol) of
Bu4NBr in 50 ml of anhydrous dichloromethane was
irradiated for 10 h in an ultrasonic bath. After workup of
the reaction mixture by procedure b we obtained 0.222 g
(17.4%) of compound V, mp 272–273.5°C. IR spectrum
(CHCl3), cm–1: 1610, 1500, 1460, 1390, 1320, 1285, 1250,
1180, 1110, 1060, 895. 1H NMR spectrum (CDCl3), δ,
ppm: 4.91 (1H, HCAr), 6.21 (1H, HCO), 6.55–7.40 m
(10Harom). 13C NMR spectrum (CDCl3), δ, ppm: 58.5
(HCAr), 70.1 (HCO), 116.8, 119.3, 120.4, 121.5, 124.7,
125.1, 125.9, 129.2, 129.5, 137.8, 144.7, 158.4 (Carom).
Mass spectrum, m/z (Irel, %): 432 (0.1) [M]+, 404 (7)
[M – CO]+, 209 (100) [M – C13H10NO – CO]+, 181
(83). Found, %: C 77.55; H 4.89; N 6.50. C28H20N2O3.
Calculated, %: C 77.76; H 4.66; N 6.48.
Compound IXb, colorless crystals, mp 61–63°C. IR
spectrum (CHCl3), cm–1: 3100–3010 w, 1610 s, 1620,
1550, 1500, 1480 s, 1465, 1400, 1390, 1360, 1340, 1310,
1
1275, 1260–1200, 1190 s, 1090, 1040. H NMR spectrum
(CDCl3), δ, ppm: 5.40 (2H, CH2), 7.20–7.40 m (10Harom),
7.43–7.53 m (2Harom), 7.69–7.80 m (2Harom), 8.00–
8.05 m (1Harom). 13C NMR spectrum (CDCl3), δ, ppm:
49.8 (CH2), 109.7 (C7), 117.1, 119.7, 119.8, 121.8, 125.5,
125.6, 126.1, 126.6, 127.1, 127.4, 128.4, 128.5, 135.2,
136.8, 136.9 (Carom). Found, %: C 88.66; H 6.13; N 5.04.
C21H17N. Calculated, %: C 89.01; H 6.05; N 4.94.
Compound VIII, colorless viscous fluid. IR spectrum
(CHCl3), cm–1: 1760 (C=O). 1H NMR spectrum (CDCl3),
δ, ppm: 7.44 (10Harom), 10.01 d (1H, HCO, JHF 6.5 Hz).
13C NMR spectrum (CDCl3), δ, ppm: 99.8 d (C2,
J 183.5 Hz), 126.6 d (CO, J 7.0 Hz), 128.4 (Cp), 128.9 d
(Cm, J 2.0 Hz), 135.8 d (Ci, J 22.9 Hz), 195.6 d
(HCO, J 38.9 Hz).
b. With 1 ml of thionyl chloride 0.07 g of zinc chloride
was boiled for 30 min, and then the excess thionyl chloride
was removed in a vacuum. Anhydrous zinc chloride thus
prepared (0.05 g, 0.4 mmol) was added to a solution of
0.15 g (0.5 mmol) aziridine IIIb and 0.057 g (0.5 mmol)
of benzylamine in 5 ml of anhydrous dichloromethane,
and the reaction mixture was left overnight. The reaction
products were isolated by column chromatography on
silica gel (eluent hexane–ethyl acetate). We obtained
0.059 g (42%) of 1-benzyl-3-phenylindole (IXb).
N-Methyl-N-(9H-fluoren-9-yl)formamide (VII).
A mixture of 0.186 g (1.0 mmol) N-methyl-N-fluorenyl-
ideenamine (Ii), 0.742 g (3.9 mmol) of dibromofluoro-
methane, 0.6 g (2.9 mmol) of active lead, and 0.94 g
(2.9 mmol) of Bu4NBr in 15 ml of anhydrous dichloro-
methane was irradiated in an ultrasonic bath for 67 h.
After workup of the reaction mixture by procedure b
using in chromatography eluent hexane–ethyl acetate we
obtained compound VII in a yield 0.029 g (13%), mp 104–
114°C. In a chloroform solution compound VII exists as
a rotamers mixture. 1H NMR spectrum (CDCl3), δ, ppm:
2.36 s (1.9H CH3), 2.40 s (1.3H, CH3), 5.57 s (0.6H,
C9−H), 6.69 s (0.4H, C9-H), 7.30–7.50 m (6Harom), 7.81–
7.7 m (2Harom), 8.48 s (0.4H, HCO), 8.71 s (0.6H, HCO).
13C NMR spectrum (CDCl3), δ, ppm: 25.4 (CH3), 29.4
(CH3), 56.7(C9), 63.2 (C9), 119.9, 120.1, 124.2, 124.5,
c. To a solution of 0.04 g (0.13 mmol) of aziridine
IIIb in 5 ml of anhydrous dichloromethane was added
one drop of titanium tetrachloride. The reaction mixture
was stirred for 15 min at room temperature, and then
was filtered through a silica gel bed. The silica gel was
washed with 30 ml of dichloromethane, the filtrate was
evaporated to dryness. We obtained 0.023 g (60%) of 1-
benzyl-3-phenylindole (IXb).
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KONEV et al.
294
Methyl 2-[(2,2-diphenylvinyl)imino]acetate (XII).
Methyl (3-phenylindol-1-yl)acetate (IXc) and 2,2-
a. A mixture of 0.1 g (0.35 mmol) of aziridine IIIc and
0.057 g (0.32 mmol) of SbF3 as fine powder in 20 ml of
dichloromethane was heated at reflux for 6 h. Antimony
trifluoride was filtered off, the solution was evaporated
in a vacuum, anhydrous triethylamine was added to the
residue, and the product was separated by column
chromatography on silica gel treated with anhydrous
triethylamine (eluent hexane– ethyl acetate). Yield 0.02
g (21%). Yellow crystals, mp 109–112°C. IR spectrum
diphenyl-2-fluoroacetaldehyde (VIII). A solution of
0.099 g (0.35 mmol) of aziridine IIIc in 25 ml of anhydrous
dichloromethane containing a catalytic quantity of
p-toluenesulfonic acid monohydrate (1 mg) was heated
at reflux for 3 h. On separating the mixture by column
chromatography (eluent hexane–ethyl acetate) we
obtained 0.023 g (25%) of compound IXc and 0.031 g
(42%) of compound VIII. Compound IXc, viscous fluid.
1H NMR spectrum (CDCl3), δ, ppm: 3.79 (3H, CH3),
4.93 (2H, CH2), 7.20–7.60 m (7Harom), 7.65–7.75 m
(2Harom), 7.95–8.05 m (1Harom). 13C NMR spectrum
(CDCl3), δ, ppm: 47.5 (CH2), 52.3 (CH3), 108.9 117.9,
119.9, 120.1, 122.2, 125.70, 125.71, 126.2, 127.2, 128.4,
134.9, 136.9 (Carom-), 168.5 (C=O).
1
(CHCl3), cm–1: 1750, 1730, 1300. H NMR spectrum
(CDCl3), δ, ppm: 3.87 (3H, CH3), 7.3–7.4 m (11Harom
,
=CH), 7.79 (1H, =CH). 13C NMR spectrum (CDCl3), δ,
ppm: 52.5 (CH3), 127.7, 128.4, 128.6, 128.8, 129.0, 131.7,
137.41, 137.43, 140.7, 148.5, 150.9 (Carom, =CH), 164.6
(C=O). Found %: C 77.18; H 5.92; N 5.23. C17H15NO2.
Calculated %: C 76.96; H 5.70; N 5.28.
2-Hydroxy-2,2-diphenylacetaldehyde (X). To a
solution of 0.105 g (0.37 mmol) of aziridine IIIc in 15 ml
of 1,4-dioxane was added 15 ml of water and 8 drops of
concn. HCl, the mixture obtained was maintained for
10 h at room temperature. The reaction mixture was
diluted with 10 ml of CH2Cl2, the water layer was
separated and washed with 10 ml of dichloromethane.
Combined organic solutions were dried with Na2SO4, and
the solvent was evaporated in a vacuum. The yellow-
brown residue was subjected to column chromatography
(eluent hexane–ethyl acetate) to give 0.06 g (77%) of
compound X. Colorless crystals, mp 52–55°C [41].
1H NMR spectrum (CDCl3), δ, ppm: 4.43 (1H, OH),
7.36–7.47 m (10Harom), 10.01 (1H, CHO). 13C NMR
spectrum (CDCl3), δ, ppm: 83.4 (C–OH), 127.4, 128.5,
128.8, 139.3 (Carom), 198.0 (CHO).
b. A mixture of 0.112 g (0.39 mmol) of aziridine IIIc
and 0.064 g (0.36 mmol) of SbF3 as fine powder in 20 ml
of dichloromethane was heated at reflux for 2 h.Antimony
trifluoride was filtered off, the solution was evaporated
in a vacuum. The obtained light-yellow oily residue
1
(0.112 g) according to H NMR spectrum was methyl
N-(2,2-diphenyl-2-fluoroethylidene)aminoacetate
(XIc) (94 mol %) containing as impurity 6 mol% of
1
azadiene XII. Imine XIc. H NMR spectrum (CDCl3),
δ, ppm: 3.79 (3H, CH3), 4.39 (2H, CH2), 7.2–7.6 m
(10Harom), 8.18 d.d.d (1H, H–CN, JHF 9.8, JHH 2,
JHH 1 Hz). 13C NMR spectrum (CDCl3), δ, ppm: 52.2
(CH3), 61.0 (CH2), 98.3 d (CF, J 174.3 Hz), 127.2 d
(Carom, J 6.7 Hz), 128.3, 128.6 d (Carom, J 2 Hz), 139.2 d
(Carom, J 22.7 Hz), 168.5 d (C=N, J 32.5 Hz), 169.8 (C=O).
N-Benzyl-N-(2,2-diphenyl-2-fluoroethylidene)-
amine (XIb). A mixture of 0.096 g (0.32 mmol) of
aziridine IIIb and 0.07 g (0.39 mmol) of SbF3 as fine
powder in 20 ml of dichloromethane was heated at reflux
for 15 h. The mixture was cooled, SbF3 was filtered off,
the solution was evaporated in a vacuum, and the residue
was subjected to column chromatography on silica gel
treated with anhydrous triethylamine using as eluent a
mixture hexane–ethyl acetate. Yield 0.053 g (55%).
Colorless crystals, mp 29–30°C. IR spectrum (CCl4), cm–
Reaction of imine XIb with p-toluenesulfonic
acid. A mixture of 0.02 g (0.07 mmol) of aziridine IIIb
and 0.012 g (0.07 mmol) of SbF3 as fine powder in 10 ml
of dichloromethane was heated at reflux for 8 h.Antimony
trifluoride was filtered off, the solution was evaporated
in a vacuum, to the residue containing imine XIb 2 ml of
dichloromethane and 1 mg of p-toluenesulfonic acid
monohydrate was added, and the mixture obtained was
boiled for 3 h.According to the 1H NMR data the reaction
mixture contained 93 mol% of imine XIb and 7% of indole
IXb.
1: 3070, 3040, 1690 (C=N), 1500, 1460, 1005. H NMR
1
spectrum (CDCl3), δ, ppm: 4.81 (2H, CH2), 7.2–7.5 m
(15Harom), 8.23 d.t (1H, H–CN, JHF 10.2, JHH 1.5 Hz).
13C NMR spectrum (CDCl3), δ, ppm: 64.4 (CH2), 98.1 d
(CF, J 174.7 Hz), 127.0 d (Carom, J 5.8 Hz), 127.1, 127.9,
128.2, 128.4, 128.5, 138.3 (Carom), 139.8 d (Carom, J 22.7
Hz), 164.3 d (C=N, J 32.5 Hz). Found, %: C 83.12; H
6.12; N 4.56. C21H18FN. Calculated, %: C 83.14; H 5.98;
N, 4.62.
Reaction of imine XIb with SbF3. Amixture of 0.009
g (0.03 mmol) of imine XIb and 0.007 g (0.04 mmol) of
SbF3 in 20 ml of dichloromethane was heated at reflux
for 20 h, and the solvent was evaporated in a vacuum.
1
According to the H NMR data the reaction mixture
contained 9 mol% of indole IXb and 91 mol% of imine
XIb.
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MONOFLUORO-SUBSTITUTED AZOMETHINE YLIDES
295
Dimethyl 1,2-diphenyl-1H-pyrrole-3,4-di-
carboxylate (XIII). A mixture of 0.453 g (2.5 mmol) of
N-benzylideneaniline, 2.4 g (12.5 mmol) of dibromo-
fluoromethane, 0.703 g (5.0 mmol) of dimethyl acetylene-
dicarboxylate, 2.05 g (9.9 mmol) of active lead, and
3.20 g (9.9 mmol) of Bu4NBr in 25 ml of anhydrous
dichloromethane was irradiated for 100 h in an ultrasonic
bath. On separating the reaction products by column
chromatography (eluent hexane–ethyl acetate) the yield
of compound XIII was 0.266 g (32%). Colorless crystals,
mp 114–119°C. IR spectrum (CHCl3), cm–1: 1730 (C=O).
1H NMR spectrum (CDCl3), δ, ppm: 3.77 (3H, CH3),
3.87 (3H, CH3), 7.11–7.05 m (2Harom), 7.32–7.18 m
(8Harom), 7.5 (1H, H5). 13C NMR spectrum (CDCl3), δ,
ppm: 51.2 (CH3O), 51.7 (CH3O), 115.1, 116.4, 125.53,
127.54, 127.60, 127.62, 127.9, 128.8, 129.5, 130.0, 135.1,
138.2 (Carom), 163.6 (C=O), 165.6 (C=O). Found, %:
C 71.76; H 5.23; N, 4.25. C20H17NO4. Calculated, %:
C 71.63; H 5.11; N 4.18.
in CDCl3, and analyzed by 1H NMR method. The ratio
of products originating from 1,3-cyclization and 1,3-cyclo-
addition was estimated using signals of N-methyl groups
of aziridine and pyrroline and the proton signals of the
aziridine and pyrroline rings. The ratio of products of 1,3-
cyclization and 1,3-cycloaddition was 1:1.
(2RS,3SR)- and (2RS,3RS)-Dimethyl 1-benzyl-2-
phenyl-2,3-dihydro-1H-pyrrole-3,4-dicarboxylates
(XVIg). A mixture of 0.74 g (3.8 mmol) of N-benzyl-N-
benzylideneamine (Ib), 3.67 g (19.1 mmol) of dibromo-
fluoromethane, 1.84 g (12.7 mmol) of dimethyl maleate,
3.2 g (15.5 mmol) of active lead, and 4.95 g (15.3 mmol)
Bu4NBr in 45 ml of anhydrous dichloromethane was
irradiated 54 h in an ultrasonic bath. Aliquot of the reac-
tion mixture (about 10%) was charged to the top of
a chromatographic column packed with silica gel, the
products were eluted with ethyl acetate. The solvent was
removed. The ratio of cis-/trans-adducts in the reaction
mixture was 1:3.5 (1H NMR data). The main part of the
reaction mixture was worked up by procedure a to obtain
0.47 g (35%) of a mixture of cis-/trans-adducts as
a viscous fluid. Crystallization from an ether solution of
the isomers mixture with subsequent recrystallization from
ether yielded 0.294 g (22%) of compound trans-XVIg
as colorless crystals, mp 83–85°C (Et2O). IR spectrum
Dimethyl 1-methyl-2,2-diphenyl-2,3-dihydro-1H-
pyrrole-3,4-dicarboxylate (XIV). A mixture of 0.824
g (4.2 mmol) of N-benzhydrylidene-N-methylamine (Ia),
3.25 g (16.9 mmol) of dibromofluoromethane, 2.029 g
(14.1 mmol) of dimethyl maleate, 3.5 g (16.9 mmol) of
active lead, and 5.46 g (16.9 mmol) of Bu4NBr in 40 ml
of anhydrous dichloromethane was irradiated for 45 h in
an ultrasonic bath. Yield 0.142 g (10%) (a). Colorless
crystals, mp 162–165°C (Et2O). IR spectrum (CHCl3),
1
(CHCl3), cm–1: 1755 (C=O), 1690 (C=O). H NMR
spectrum (CDCl3), δ, ppm: 3.67 (3H, CH3O), 3.73 (3H,
CH3O), 3.93 d (1H, H2, J 7.7 Hz), 3.95 d (1H, CH2,
J 14.9 Hz), 4.30 d (1H, CH2, J 14.9 Hz), 4.77 d (1H, H3,
J 7.7 Hz), 7.14–7.45 m (11Harom, H5). 13C NMR spectrum
(CDCl3), δ, ppm: 50.3 (CH3O), 51.3 (CH3O), 52.0 (CH2),
55.6 (C3), 70.5 (C2), 98.3 (C4), 126.6, 127.66, 127.69,
128.2, 128.5, 128.7, 135.2, 139.2 (Carom), 151.0 (C5), 165.3
(C=O), 173.7 (C=O). Found, %: C 71.65; H 6.11; N 3.92.
C21H21NO4. Calculated, %: C 71.78; H 6.02; N 3.99.
Compound cis-XVI g was isolated in a mixture with the
1
cm–1: 1750 (C=O), 1690 (C=O). H NMR spectrum
(CDCl3), δ, ppm: 2.61 (3H, CH3N), 3.07 (3H, CH3O),
3.70 (3H, CH3O), 4.79 (1H, C3-H), 7.20–7.45 m (11Harom
,
H5). 13C NMR spectrum (CDCl3), δ, ppm: 32.8 (CH3N),
50.4 (CH3O), 51.1 (CH3O), 60.7 (C3), 79.7 (C2), 99.0
(C4), 127.31, 127.34, 127.5, 127.9, 128.1, 128.7, 137.4,
141.4 (Carom), 152.1 (C5), 165.3 (C=O), 171.1 (C=O).
Found, %: C 71.66; H 6.06; N 3.93. C21H21NO4.
Calculated, %: C 71.78; H 6.02; N 3.99.Alongside pyrrole
XIV we isolated 0.377 g of a mixture of benzophenone
and aziridine IIIc in a ratio 1:1 (1H NMR data).
1
trans-isomer (0.170 ). H NMR spectrum (CDCl3), δ,
ppm: 3.15 (3H, CH3O), 3.67 (3H, CH3O), 3.88 d (1H,
CH2, J 14.4 Hz), 4.17 d (1H, C2-H, J 12 Hz), 4.33 d (1H,
CH2, J 14.4 Hz), 4.88 d (1H, C3-H, J 12 Hz), 7.14–7.45
m (11Harom, C5-H).
Study of the competition between 1,3-cycloaddi-
tion and 1,3-cyclization.Amixture of 0.154 g (0.8 mmol)
of N-benzhydrylidene-N-methylamine, 0.70 g (3.6 mmol)
of dibromofluoromethane, 0.353 g (2.5 mmol) of dimethyl
maleate, 0.6 g (2.9 mmol) of active lead, and 0.936 g
(2.9 mmol) of Bu4NBr in 7 ml of anhydrous dichloro-
methane was irradiated in an ultrasonic bath for 46 h.
The reaction mixture was twice filtered through a fine-
porous frit funnel, the solvent was evaporated in a vacuum,
the residue was dried in a vacuum (0.1 mm Hg), dissolved
(2RS,3RS)-Dimethyl 2-phenyl-1-phenethyl-2,3-
dihydro-1H-pyrrole-3,4-dicarboxylate (trans-XVIh)
and dimethyl-(2RS,3SR)-2-phenyl-1-phenethyl-2,3-
dihydro-1H-pyrrole-3,4-dicarboxylate (cis-XVIh).
A mixture of 1.36 g (6.5 mmol) of N-benzylidene-N-
phenethylamine (Ih), 7.5 g (39.1 mmol) dibromofluoro-
methane, 2 g (13.9 mmol) dimethyl maleate, 2.66 g
(12.9 mmol) of active lead, and 4.5 g (13.9 mmol) of
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 43 No. 2 2007

KONEV et al.
296
17. Kusei, E.Yu., Novikov, M.S., and Khlebnikov, A.F., Zh.
Obshch. Khim., 2005, vol. 75, p. 1720.
18. Novikov, M.S.,Amer,A.A., and Khlebnikov,A.F., Tetrahe-
dron Lett., 2006, vol. 47, p. 639.
19. Hiyama, T., Organofluorine compounds. Chemistry and,
applications, Springer, 2000, 272 p.
20. Streitwieser, A. Jr., Holtz, D., Ziegler, G.R., Stoffer, J.O.,
Brokaw, M.L., and Guibe, F., J. Am. Chem. Soc., 1976,
vol. 98, p. 5229.
Bu4NBr in 15 ml of anhydrous dichloromethane was
irradiated for 5 h in an ultrasonic bath. The separation of
the mixture by column chromatography (eluent hexane–
ethyl acetate) provided 0.41 g of benzaldehyde, 0.306 g
(12.7% with respect to introduced, 32% with respect to
reacted imine) of trans-XVIh as a viscous fluid, and
0.046 g (2% with respect to introduced, 4.8% with respect
to reacted imine) of cis-XVIh as colorless crystals, mp
153–155°C. Characteristics of compound cis-XVIh are
given in the preliminary communication [16].
21. Khlebnikov, A.F., Novikov, M.S., and Kostikov, R.R.,
Mendeleev Commun., 1997, p. 145.
The study was carried out under a financial support
of the Russian Foundation for Basic Research (grant
no. 05-03-33257) and of the Russian Foundation for Basic
Research – Ministry of Flanders (grant no. 05-03-34811-
MΤ a). A.S. Konev is grateful to ProfessorA. de Meijere
for the granted scholarship.
22. Nishimura, J. and Furakawa, J., J. Chem. Soc., Chem.
Commun., 1971, p. 1375.
23. Tamura, O., Hashimoto, M., Kobayashi, Y., Katoh, T.,
Nakatani, K., Kamada, M., Hayakawa, I., Akiba, T., and
Terashima, S., Tetrahedron, 1994, vol. 50, p. 3889.
24. Kawataba, N., Tanimoto, M., and Fujiwara, S. Tetrahedron,
1979, vol. 35, p. 1919.
25. Hahnfeld, J.L. and Burton, D.J., Tetrahedron Lett., 1975,
p. 1819.
26. Marolewsky, T. and Yang, N.C., J. Chem. Soc., Chem.
Commun., 1967, p. 1225.
REFERENCES
1. Khlebnikov, A.F., Novikov, M.S., and Kostikov, R.R., Usp.
Khim., 2005, vol. 74, p. 183.
2. Khlebnikov,A.F., Novikov, M.S., and Kostikov, R.R., Ros.
Khim. Zh., 1999, vol. 43, no. 1, p. 70.
27. Schlosser, M. and Heinz, G., Angew. Chem., Int. Ed., 1968,
vol. 7, p. 820.
3. Novikov, M.S., Khlebnikov, A.F., Sidorina, E.S., and
Kostikov, R.R., J. Fluor. Chem., 1998, vol. 90, p. 117.
4. Novikov, M.S., Khlebnikov, A.F., Krebs, A., and Kosti-
kov, R.R., Eur. J. Org. Chem., 1998, p. 133.
5. Novikov, M.S., Khlebnikov, A.F., Sidorina, E.S., and
Kostikov, R.R., J. Chem. Soc., Perkin Trans. 1, 2000, p. 231.
6. Novikov, M.S., Khlebnikov, A.F., Besedina, O.V., and
Kostikov, R.R., Tetrahedron Lett., 2001, vol. 42, p. 533.
7. Novikov, M.S., Khlebnikov, A.F., Sidorina, E.S., Masa-
lev, A.E., Kopf, Yu., and Kostikov, R.R., Zh. Org. Khim.,
2002, vol. 38, p. 710.
8. Novikov, M.S., Khlebnikov, A.F, and Kostikov, R.R., Zh.
Org. Khim., 2002, vol. 38, p. 1704.
9. Khlebnikov,A.F., Novikov, M.S., andAmer,A.A., Tetrahe-
dron Lett., 2002, vol. 43, p. 8523.
10. Novikov, M.S., Khlebnikov, A.F., and Shevchenko, M.V.,
J. Fluorine, Chem., 2003, vol. 123, p. 177.
11. Khlebnikov,A.F., Novikov, M.S., andAmer,A.A., Izv. Akad.
Nauk, Ser. Khim., 2004, p. 1049.
12. Voznyi, I.V., Novikov, M.S., Khlebnikov,A.F., Kopf,Yu., and
Kostikov, R.R., Zh. Org. Khim., 2004, vol. 40, p. 226.
13. Novikov, M.S., Khlebnikov,A.F.,Voznyi, I.V., Besedina, O.V.,
and Kostikov, R.R., Zh. Org Khim., 2005, vol. 41, p. 372.
14. Novikov, M.S., Khlebnikov, A.F., Shevchenko, M.V.,
Kostikov, R.R., and Vidovic, D., Zh. Org. Khim., 2005,
vol. 41, p. 1527.
15. Voznyi, I.V., Novikov, M.S., and Khlebnikov,A.F., Synlett.,
2005, p. 1006.
16. Konev,A.S., Novikov, M.S., and Khlebnikov,A.F., Tetrahe-
dron Lett., 2005, vol. 46, p. 8337.
28. Schlosser, M. and Heinz, G., Chem. Ber., 1971, vol. 104,
p. 1934.
29. Usuki, Y., Fukuda, Y., and Iio, H. ITE, Lett. on Batteries,
New Technologies and Medicine, 2001, vol. 2, p. 237; Chem.
Abstr., 2001, vol. 136, 184068.
30. Khlebnikov, A.F., Nikiforova, T.Yu., and Kostikov, R.R.,
Zh. Org. Khim., 1996, vol. 32, p. 746.
31. Thibaudeau, Ch., Plavec, J., and Chattopadhyaya, J., J. Org.
Chem., 1998, vol. 63, p. 4967.
32. Kostikov, R.R., Khlebnikov,A.F., and Ogloblin, K.A., Khim.
Geterotsikl. Soedin., 1978, p. 48.
33. Kostikov, R.R., Khlebnikov, A.F., and Bespalov, V.Ya.,
J. Phys. Org. Chem., 1993, vol. 6, p. 83.
34. Tsuge, O., Ueno, K., Kanemasa, S., and Yorozu, K., Bull.
Chem. Soc. Jpn., 1986, vol. 59, p. 1809.
35. Achiwa, K., Sugiyama, K., and Sekiya, M., Chem. Pharm.
Bull., 1985, vol. 33, p. 1975.
36. Achiwa, K., Sugiyama, K., and Sekiya, M., Tetrahedron
Lett., 1982, vol. 23, p. 2589.
37. Joucla, M., Gree, D., and Hamelin, J., Tetrahedron, 1973,
vol. 29, p. 2315.
38. Seyferth, D. and Hopper, S.P., J. Organometal Chem., 1973,
vol. 51, p. 77.
39. O’Donnell, M.J. and Polt, R.L., J. Org. Chem., 1982, vol. 47,
p. 2663.
40. Padwa, A., Bergwark, W., and Pashayan, D., J. Am. Chem.
Soc., 1969, vol. 91, p. 2659.
41. Favorskaya, I.A. and Remizova, L.A., Zh. Obshch. Khim.,
1953, vol. 23, p. 667.
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