Intramolecular cycloaddition of geminal dichloroazomethine ylides to multiple carbon-carbon bonds

Article abstract of DOI:10.1007/s11178-005-0204-0

Geminal dichloroazomethine ylides generated by reaction of dichlorocarbene with Schiff bases derived from O-alkenyl- or O-alkynylsalicylaldehyde undergo intramolecular [3 + 2]-cycloaddition with participation of the olefinic or acetylenic dipolarophile to

Full text of DOI:10.1007/s11178-005-0204-0

Russian Journal of Organic Chemistry, Vol. 41, No. 4, 2005, pp. 560–566. Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005,
pp. 571–577.
Original Russian Text Copyright © 2005 by Khlebnikov, Voznyi, Novikov, Kostikov.
Intramolecular Cycloaddition of Geminal Dichloroazomethine
Ylides to Multiple Carbon–Carbon Bonds
A. F. Khlebnikov, I. V. Voznyi, M. S. Novikov, and R. R. Kostikov
1 St. Petersburg State University, Universitetskii pr. 26, St. Petersburg, 198504 Russia
e-mail: Alexander.Khlebnikov@pobox.spbu.ru
Received July 10, 2004
Abstract—Geminal dichloroazomethine ylides generated by reaction of dichlorocarbene with Schiff bases
derived from O-alkenyl- or O-alkynylsalicylaldehyde undergo intramolecular [3+2]-cycloaddition with
participation of the olefinic or acetylenic dipolarophile to afford chromeno[4,3-b]pyrrole and chromeno-
[4,3-b]pyridine derivatives. The greatest yields of the intramolecular cycloaddition products were obtained
from N-methyl-substituted dichloroazomethine ylides, whereas the main stabilization path of N-phenyl and N-
tert-butyl derivatives was cyclization to geminal dichloroaziridines.
Intramolecular 1,3-dipolar cycloadditions of azo-
methine ylides provide a convenient method for the
preparation of various fused and bridged nitrogen-con-
taining polycyclic systems [1], including some natural
compounds, e.g., (+)-α-lycorane [2] and lamellarin K
[3]. Synthetic approaches were developed to building
up martinelline skeleton, as well as those of physo-
stigmine [4], erythrine [5], and other alkaloids [1]. The
development of this synthetic strategy, among other
lines, includes search for new functionalized azo-
methine ylides capable of transferring to the cyclo-
adduct groups which can be useful for further trans-
formations, e.g., halogen atoms or an oxo group. Syn-
thetic equivalents of such reagents may be geminal
dihalo-substituted azomethine ylides; the only example
of intramolecular cycloaddition was reported for gem-
inal difluoro-substituted ylides [6]. Despite dichloro
derivatives are the most accessible from the synthetic
viewpoint and the most studied among dihalo-substi-
tuted ylides, their intramolecular cycloadditions were
not reported.
Schiff bases containing an olefinic or acetylenic di-
polarophile fragment. We recently showed that Schiff
bases I react with difluorocarbene to give difluoro
ylides which undergo intramolecular ring closure
involving the double C=C bond, yielding chromeno-
[4,3-b]pyrrole derivatives II and III (Scheme 1) [6]. It
should be noted that the cycloaddition readily occurs
with difluoro ylides generated from both N-alkyl (R =
Me, t-Bu) and N-aryl derivatives [6], though the trans-
formation direction of halogenated ylides is known to
depend on the substituent on the nitrogen atom [7].
We found that, unlike reactions with difluoro-
carbene, the substituent on the nitrogen atom in Schiff
bases Ia and Ib strongly affected their reactions with
dichlorocarbene generated by thermal decomposition
of sodium trichloroacetate in chloroform in the pres-
ence of benzyltriethylammonium chloride (BTEAC).
For example, ylide IVa generated from N-methyl-
substituted Schiff base Ia and dichlorocarbene was
trapped almost completely by the internal olefinic
dipolarophile to afford two products: chromenopyrrole
Va and chromenopyridine VIa in 34 and 26% yield,
respectively (Scheme 2, see table). Compound Va is
In the present work we examined transformations
of geminal dichloroazomethine ylides generated from
Scheme 1.
O
O
N
O
O
CF2
H
H
+
CO2Et
CO2Et
H
H
N
N
N
CO2Et
CO2Et
R
F2C
R
R
R
F
O
I
II
III
1070-4280/05/4104-0560 © 2005 Pleiades Publishing, Inc.

INTRAMOLECULAR CYCLOADDITION OF GEMINAL DICHLOROAZOMETHINE
561
Scheme 2.
O
N
O
O
CCl2
H
CO2Et
H
N
CO2Et
N
CO2Et
R
Cl2C
R
Cl
R
Cl
Ia, Ib
IVa, IVb
VIIIa, VIIIb
Cl3CCO2Na
O
CO2Et
O
CO2Et
O
Cl
Cl
Cl
H
CO2Et
Cl
H
N
N
N
O
R
R
Ph
Cl
Xa, Xb
IXb
VIIa, VIIb
CCl2
H2O
O
N
O
O
H
H2O
–HCl
H
H
CO2Et
Cl
CO2Et
Cl
CO2Et
H
R
H
H
N
N
R
R
Cl
O
Cl
O
VIa, VIb
Va, Vb
R = Me (a), Ph (b).
tions at double C=C bonds: N-alkyl ylides underwent
intramolecular cycloaddition, whereas N-aryl-substitut-
ed analogs gave rise to aziridine derivatives as a result
of 1,3-cyclization [7]. It should be emphasized that the
intramolecular cycloaddition of dichloroazomethine
ylides generated from Schiff bases Ia and Ib is strictly
stereoselective: the resulting chromenopyrrole deriva-
tives are characterized exclusively by cis-junction of
the pyran and pyrrolidine rings.
Apart from compounds V, VI, and IX, we isolated
from the reaction mixtures azetidinones Xa and Xb;
the latter are formed without participation of dichloro-
carbene, via reaction of Schiff base with trichloro-
formed as a result of hydrolysis of intermediate chloro-
dihydropyrrole VIIa formed by dehydrochlorination of
the primary cycloadduct, chromenopyrrole VIIIa. Di-
chlorocyclopropanation of compound VIIa, followed
by ring expansion and hydrolysis (most probably,
during chromatographic treatment of the reaction mix-
ture), leads to chromenopyridine VIa.
Under analogous conditions, the reaction of N-phe-
nyl-substituted Schiff base Ib with dichlorocarbene
afforded mainly 1,3-cyclization product of interme-
diate ylide IVb, aziridine derivative IXb, while the
yield of chromenopyrrole Vb was as poor as 3%. Thus
replacement of methyl group on the nitrogen atom in
ylide intermediate IV by phenyl changes the direction
of its stabilization: in the first case, intramolecular
cycloaddition occurs exclusively, while in the second,
the predominant reaction pathway is 1,3-cyclization to
aziridine structure. Analogous effect of the substituent
on the nitrogen atom in dichloroazomethine ylides was
observed in their intra- and intermolecular cycloaddi-
Reactions of Schiff bases Ia and Ib with dichlorocarbene
Yield, %
Schiff
base
R
IX
00
60
V
VI
26
X
Me
Ph
34
03
19
05
Ia
Ib
0.02.5
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

KHLEBNIKOV et al.
562
Scheme 3.
OMe
OMe
OMe
MeO
MeO
MeO
CCl2
H
N
R
H
N
N
Cl2C
MeO
R
Cl
XI
R
Cl
OMe
H2O
H
H
N
R
O
XII
R = 4-BrC6H4.
acetyl chloride arising from thermolysis of sodium
trichloroacetate [8]. The formation of azetidin-2-ones
usually accompanies transformations of N-alkyl-N-
benzylideneamines with bulky secondary and tertiary
alkyl groups on the nitrogen atom under conditions of
thermocatalytic decomposition of sodium trichloro-
acetate in chloroform [9]. No examples of formation
of such compounds from N-benzylideneanilines were
reported. Presumably, an appreciable yield of azetidine
derivatives Xa and Xb in the above reactions is
explained by the presence of an ortho substituent in
the benzene ring, which shields the nitrogen center
thus hampering its reaction with dichlorocarbene and
favoring concurrent processes.
spectra and elemental compositions. The cis-junction
of the pyran and piperidine rings in VIa and VIb
follows from the relatively small spin–spin coupling
2
constant J4a,10b = 3.5–4.2 Hz; this is consistent with
the proposed reaction mechanism according to which
compounds Va, Vb and VIa, VIb are formed through
a common dichloropyrrolidine intermediate VIIIa or
VIIIb with the same mode of ring junction.
The reaction of dichlorocarbene (generated from
sodium trichloroacetate) with Schiff base XI having
a nonactivated C=C bond linked to the imine moiety
through a three-atom fragment (Csp
2
–Csp
2
–Csp ) was
3
accompanied by strong tarring, and the intramolecular
cycloaddition product, lactam XII, was formed in
12% yield (Scheme 3). We failed to raise the yield by
using the system CHCl3–KOH–BTEAC for generation
The structure of compounds VI, IX, and X was
1
determined on the basis of their H and 13C NMR
Scheme 4.
O
N
O
N
O
O
CCl2
a
–HCl
N
N
Me
Cl2C
XV
Me
Cl
Me
Me
Cl
Cl
XIII
XVI
XVIII
Cl
Cl
O
O
CCl2
Cl
Cl
Cl
N
N
Me
Cl
Me
Cl
Cl
O
XVII
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

INTRAMOLECULAR CYCLOADDITION OF GEMINAL DICHLOROAZOMETHINE
563
Scheme 5.
O
O
O
CHCl3, KOH
BTEAC
Cl
b
Cl
N
N
N
Bu-t
Cl2C
Bu-t
Bu-t
XIV
XIX
Cl3CCO2Na
CHCl3, BTEAC
a
H2O
O
O
N
O
Cl
Cl
Cl
N
O
O
NHBu-t
t-Bu
t-Bu
XXI
Cl
XXII
XX
of dichlorocarbene; in this case, it was 10%. Neverthe-
less, in both cases the yield of lactam XII exceeded the
overall yield of cycloaddition products Vb and VIb
from ylide IVb. This means that increase in the rigidity
the dichlorocarbene generation mode. In the system
CHCl3–KOH–BTEAC, ylide XIX was formed initial-
ly, and the subsequent cyclization to aziridine deriva-
tive and hydrolysis of the latter gave 43% of α-chloro
amide XX. When dichlorocarbene was generated from
sodium trichloroacetate at higher temperature, decom-
position of unstable N-alkyldichloroaziridine occurred,
and we isolated only azetidinone XXI in 32% yield.
In no case intramolecular cycloaddition product XXII
or its cyclopropanated derivatives were detected.
A probable reason for the observed behavior of N-tert-
butyl-substituted ylide XIX could be shielding by the
tert-butyl group of the carbon reaction centers in the
dipole, which would inhibit cycloaddition at the C≡C
bond. On the other hand, the ylide generated from
Schiff base XIV and difluorocarbene readily under-
goes intramolecular ring closure involving the triple
carbon–carbon bond [6]. Another reason is that the
presence of a bulky tert-butyl group on the nitrogen
atom facilitates concurrent reaction, i.e., formation of
aziridine structure. According to the results of PM3
calculations of the geometric parameters of Z-ylides
XXIII and XXIV derived from the corresponding
E-Schiff bases and dichlorocarbene, replacement of the
of the linker (replacement of the four-atom Csp
2
–Csp
2
–
C
3
sp –O fragment by three-atom Csp –Csp –Csp ) favors
2
2
3
intramolecular cycloaddition to a grater extent than
does activating alkoxycarbonyl group in the dipolaro-
phile moiety.
Thus the transformation pathway of dichloro-sub-
stituted azomethine ylides having an olefinic dipolaro-
phile moiety depends on the substituent on the nitrogen
atom: the contribution of intramolecular cycloaddition
becomes appreciable only for N-alkyl derivatives.
Taking the above into account, we examined the pos-
sibility for intramolecular cycloaddition at the triple
C≡C bond of dichloroazomethine ylides generated
from N-methyl- and N-tert-butyl-2-(2-propynyloxy)-
benzylideneamines XIII and XIV (Schemes 4, 5).
The reaction of Schiff base XIII with dichloro-
carbene generated by thermocatalytic decomposition
of sodium trichloroacetate gave compound XVII
which was formed with participation of three dichloro-
carbene molecules. The reaction sequence leading to
product XVII is analogous to that shown in Scheme 2
for chromeno[4,3-b]pyridine VIa. We failed to isolate
intermediate chloro-substituted chromenopyrrole
XVIII because of its ready dichlorocyclopropanation
at both double C=C bonds in the pyrrole ring; tetra-
cyclic derivative XVII was isolated in 25% yield.
Cl
C2
Me
C
Cl
C2
Me
H
Me
Me
N
Cl
N
Cl
C1
C1
H
XXIII
XXIV
N-tert-Butyl-2-(2-propynyloxy)benzylideneamine
(XIV) behaved differently, and the result depended on
∠C1NC2Cl = 9.4°
∠C1NC2Cl = 22.2°
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

KHLEBNIKOV et al.
564
methyl group on the nitrogen by tert-butyl leads to
a considerable rotation of the dichloromethylene
fragment about the Cl2C–N=C plane, which should
reduce the energy of activation for conrotatory closure
of the aziridine ring. This factor should be even
stronger for ortho-substituted ylide XIV; therefore,
its cyclization to aziridine should be accelerated, as
is the case.
b. Powdered potassium hydroxide, 1.1–1.7 g (20–
30 mmol), was added in portions over a period of
1–2 h under vigorous stirring to a mixture of 1.4 mmol
of Schiff base and 0.16 g (0.7 mmol) of BTEAC in
40 ml of dry chloroform. When the reaction was com-
plete (TLC), the mixture was diluted with 10 ml of
hexane and filtered through a 5-mm layer of silica gel,
the filtrate was evaporated under reduced pressure, and
the residue was purified by recrystallization.
Thus azomethine ylides generated by reaction of
dichlorocarbene with Schiff bases derived from
O-alkenyl- or O-alkynylsalicylaldehyde are capable of
undergoing intramolecular [3+2]-cycloaddition at the
double or triple carbon–carbon bond. The yields of the
cycloaddition products, chromeno[4,3-b]pyrrole and
chromeno[4,3-b]pyridine derivatives, strongly depend
on the substituent on the nitrogen atom. Intramolecular
cycloaddition is the main stabilization pathway of
N-methyl-substituted iminiodichloromethanides. In the
transformations of N-aryl ylides, the contribution of
intramolecular cycloaddition is small, while the major
products (like in the transformations of N-tert-butyl
analogs) are geminal dichloroaziridines or products of
their hydrolysis.
Following method a, from 1.0 g (0.004 mol) of
Schiff base Ia (reaction time 2 h; eluent hexane–
diethyl ether, 3:1) we obtained 0.375 g (34%) of
compound Va, 0.33 g (26%) of VIa, and 0.277 g
(19%) of Xa.
Ethyl (3RS,3aRS,9bSR)-2-oxo-1-methyl-1,2,3,-
3a,4,9b-hexahydrochromeno[4,3-b]pyrrole-3-car-
boxylate (Va). mp 97–98°C (from Et2O) [10].
Ethyl (4aRS,10bSR)-3-chloro-1-methyl-2-oxo-
1,4a,5,10b-tetrahydrochromeno[4,3-b]pyridine-4-
carboxylate (VIa). mp 102–104°C (from Et2O). IR
spectrum (CHCl3), ν, cm–1: 1725, 1660 (C=O).
1H NMR spectrum (CDCl3), δ, ppm: 1.39 t (3H, CCH3,
J = 7.1 Hz), 2.95 s (3H, NCH3), 3.32 d.d.d (1H, 4a-H,
J = 10.6, 4.0, 3.5 Hz), 4.17 t (1H, 5-H, J = 10.6 Hz),
4.38 d.d (2H, CH2, J = 7.1 Hz), 4.36–4.40 m (1H,
5-H), 4.77 d (1H, 10b-H, J = 3.5 Hz), 6.92–7.36 m
(4H, Harom). 13C NMR spectrum (CDCl3), δC, ppm:
13.7 (CH3); 32.2, 35.5 (NCH3, C4a); 53.6 (C10b); 61.9,
62.3 (CH2, C5); 116.2, 117.2, 120.1, 130.6, 131.7,
132.0, 133.8, 153.8 (C3, C4, Carom); 159.0, 163.8 (C=O).
Found, %: C 59.74; H 5.03; N 4.28. C16H16ClNO4.
Calculated, %: C 59.73; H 5.01; N 4.35.
EXPERIMENTAL
The melting points were determined on a Boetius
device and were not corrected. The IR spectra were
recorded on a Carl Zeiss UR-20 instrument using
400-µm cells. The NMR spectra were measured on
1
a Bruker DPX 300 spectrometer at 300 MHz for H
13
and 75 MHz for C. Elemental analysis was perform-
ed on an HP-185B CHN analyzer. The progress of
reactions was monitored by TLC on Silufol UV-254
plates. The reaction mixtures were separated by
column chromatography on LS 5/40 silica gel
(Chemapol). Chloroform was washed with water and
dried by distillation over P2O5.
Ethyl (E)-4-[2-(3,3-dichloro-1-methyl-4-oxoazeti-
din-2-yl)phenoxy]-2-butenoate (Xa). mp 98–100°C
(from Et2O). IR spectrum (CCl4), ν, cm–1: 1790, 1720
1
(C=O). H NMR spectrum (CDCl3), δ, ppm: 1.30 t
(3H, CH3, J = 7.1 Hz), 3.02 s (3H, NCH3), 4.22 q
(2H, CH2, J = 7.1 Hz), 4.72–4.90 m (2N, C4H2), 5.49 s
(1H, CHN), 6.31 d.t (1H, 2-H, J = 15.6, 1.9 Hz), 6.95–
Reactions of Schiff bases with dichlorocarbene
(general procedure). a. A mixture of 1.4 mmol of the
corresponding Schiff base and 1.6 g (0.7 mmol) of
BTEAC in 40 ml of dry chloroform was heated to the
boiling point, and 3.5 g (18.8 mmol) of sodium tri-
chloroacetate was added in portions over a period of
1 h under stirring. The mixture was heated for an ad-
ditional 1 h under reflux (TLC), cooled, and filtered.
The filtrate was evaporated under reduced pressure,
and the residue was subjected to column chromatog-
raphy using hexane–ethyl acetate or hexane–diethyl
ether as eluent. The product was additionally purified
by recrystallization.
13
7.45 m (5H, 3-H, Harom). C NMR spectrum (CDCl3),
δC, ppm: 13.8 (CH3); 28.0 (NCH3); 60.2, 66.6
(OCH2CH3, C4); 70.0 (CHN); 84.6 (CCl2); 111.6,
120.9, 121.3, 122.0, 126.7, 130.3, 141.0, 156.2 (C2, C3,
C
arom); 161.9, 165.5 (C=O). Found, %: C 53.76;
H 4.89; N 3.87. C16H17Cl2NO4. Calculated, %:
C 53.65; H 4.78; N 3.91.
Following method a, from 0.433 g (0.0014 mol) of
Schiff base Ib (reaction time 2 h; eluent hexane–
diethyl ether, 3:1) we obtained 0.014 g (3%) of com-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

INTRAMOLECULAR CYCLOADDITION OF GEMINAL DICHLOROAZOMETHINE
565
(3:1) as eluent. Yield 0.068 g (12%) (a) or 0.057 g
(10%) (b). mp 157–160°C (from CH2Cl2–Et2O) [10].
pound Vb, 0.014 g (2.5%) of VIb, 0.33 g (60%) of
IXb, and 0.028 g (5%) of Xb.
Ethyl (3RS,3aRS,9bSR)-2-oxo-1-phenyl-1,2,3,-
3a,4,9b-hexahydrochromeno[4,3-b]pyrrole-3-car-
boxylate (Vb). mp 148–150°C (from Et2O) [6].
3-Chloro-4a,10b-dichloromethano-1-methyl-1,5-
dihydrochromeno[4,3-b]pyridine-2-one (XVII) was
synthesized from 0.378 g (2.2 mmol) of Schiff base
XIII according to method a (reaction time 3 h); the
product was purified by column chromatography using
hexane–diethyl ether (3:1) as eluent. Yield 0.180 g
(25%). mp 190–192°C (from hexane–Et2O). IR spec-
Ethyl (4aRS,10bSR)-3-chloro-2-oxo-1-phenyl-
1,4a,5,10b-tetrahydrochromeno[4,3-b]pyridine-4-
carboxylate (VIb). mp 143–145°C (from Et2O). IR
spectrum (CHCl3), ν, cm–1: 1730, 1680 (C=O). 1H NMR
spectrum (CDCl3), δ, ppm: 1.42 t (3H, CH3, J =
7.0 Hz), 3.45–3.52 m (1H, 4a-H), 4.42 q (2H, CH2, J =
7.0 Hz), 4.44–4.52 m (2H, 5-H), 5.20 d (1H, 10b-H,
1
trum (CHCl3), ν, cm–1: 1680 (C=O). H NMR spec-
trum (CDCl3), δ, ppm: 3.34 s (3H, NMe), 4.25 d (1H,
5-H, J = 12.4 Hz), 4.55 d (1H, 5-H, J = 12.4 Hz),
13
13
6.75 s (1H, 4-H), 7.02–7.61 m (4H, Harom). C NMR
J = 4.2 Hz), 6.46–7.30 m (9H, Harom). C NMR spec-
spectrum (CDCl3), δC, ppm: 33.6 (NMe); 34.9 (C4a);
48.9 (C10b); 67.2 (CCl2); 71.9 (CH2); 117.7, 118.6,
121.8, 130.1, 130.5, 131.3, 131.4, 157.2 (C3, C4,
Carom); 157.7 (C=O). Found, %: C 50.88; H 3.10;
N 4.00. C14H10Cl3NO2. Calculated, %: C 50.86; H 3.05;
N 4.24.
trum (CDCl3), δC, ppm: 13.6 (CH3); 35.9 (C4a), 55.4
(C10b); 61.8, 62.6 (CH2, C5); 116.4, 119.7, 127.3,
128.0, 128.7, 129.8, 131.4, 131.9, 134.7, 138.7, 153.2
(C3, C4, Carom); 158.6, 163.8 (C=O). Found, %:
C 65.56; H 4.73; N 3.47. C21H18ClNO4. Calculated, %:
C 65.61; H 4.73; N 3.65.
Ethyl (E)-4-[2-(3,3-dichloro-1-phenylaziridin-2-
yl)phenoxy]-2-butenoate (IXb). Oily substance. IR
N-tert-Butyl)-2-chloro-2-[2-(2-propynyloxy)-
phenyl]acetamide (XX) was obtained from 0.640 g
(3.0 mol) of Schiff base XIV according to method b
(reaction time 5.5 h); the product was isolated by
column chromatography using hexane–diethyl ether
(3:1) as eluent. Yield 0.273 g (43%). Oily substance.
IR spectrum (CHCl3), ν, cm–1: 3420 (NH); 3320
1
spectrum (CCl4): ν(C=O) 1720 cm–1. H NMR spec-
trum (CDCl3), δ, ppm: 1.30 t (3H, CH3, J = 7.2 Hz),
4.01 s (1H, CHN), 4.23 q (2H, CH2, J = 7.2 Hz),
4.87 m (2H, CH2), 6.33 d (1H, 2-H, J = 16.4 Hz),
6.95–7.47 m (10H, 3-H, Harom). 13C NMR spectrum
(CDCl3), δC, ppm: 13.9 (CH3); 51.1 (CHN); 60.2, 66.5
(CH2, C4); 75.1 (CCl2); 111.0, 119.5, 121.0, 121.8,
122.1, 123.9, 128.2, 128.7, 129.6, 141.5, 145.0, 156.7
(C2, C3, Carom); 165.7 (C=O).
1
(≡C–H); 2140 (C≡C); 1760, 1715 (C=O). H NMR
spectrum (CDCl3), δ, ppm: 1.41 s (9H, t-Bu), 2.55 t
(1H, ≡CH, J = 2.2 Hz), 4.74 d (2H, CH2, J = 2.2 Hz),
5.64 s (1H, CHCl), 6.63 br.s (1H, NH), 6.99–7.41 m
(4H, Harom). 13C NMR spectrum (CDCl3), δC, ppm:
28.0 (CCH3); 51.4 (CCH3); 55.9 (CH2); 56.4 (CHCl);
75.6 (≡CH); 77.8 (–C≡); 112.2, 121.5, 126.4, 128.9,
129.8, 154.5 (Carom); 166.0 (C=O). In addition, 0.240 g
(50%) of 2-(2-propynyloxy)benzaldehyde was
isolated.
Ethyl (E)-4-[2-(3,3-dichloro-4-oxo-1-phenylazeti-
din-2-yl)phenoxy]-2-butenoate (Xb). mp 127–128°C
(from Et2O). IR spectrum (CCl4), ν, cm–1: 1780, 1715
1
(C=O). H NMR spectrum (CDCl3), δ, ppm: 1.32 t
(3H, CH3, J = 7.1 Hz), 4.25 q (2H, CH2, J = 7.1 Hz),
4.88 m (2H, CH2), 5.93 s (1H, CHN), 6.36 d (1H, 2-H,
J = 15.9 Hz), 6.88–7.51 m (10H, 3-H, Harom). 13C NMR
spectrum (CDCl3), δC, ppm: 13.9 (CH3); 60.3, 66.7
(OCH2, C4); 68.9 (CHN); 83.5 (CCl2); 111.5, 117.7,
120.6, 120.9, 122.2, 125.1, 127.4, 129.0, 130.4, 135.8,
141.0, 156.0 (C2, C3, Carom); 158.3, 165.5 (C=O).
Found, %: C 59.80; H 4.57; N 3.13. C21H19Cl2NO4.
Calculated, %: C 60.01; H 4.56; N 3.33.
1-tert-Butyl-3,3-dichloro-4-[2-(2-propynyloxy)-
phenyl]azetidin-2-one (XXI) was obtained from
0.377 g (1.8 mmol) of Schiff base XIV according to
method a (reaction time 5 h); the product was isolated
by column chromatography using hexane–diethyl ether
(3:1) as eluent. Yield 0.188 g (32%). Oily substance.
IR spectrum (CHCl3), ν, cm–1: 3320 (≡C–H), 2130
1
(C≡C), 1790 (C=O). H NMR spectrum (CDCl3), δ,
(3aRS,8bSR)-1-(4-Bromophenyl)-5,6-dimethoxy-
1,2,3,3a,4,8b-hexahydroindeno[1,2-b]pyrrole-2-one
(XII) was obtained from 0.54 g (1.50 mmol) of Schiff
base XI according to method a (reaction time 2 h) or
from 0.52 g (1.44 mmol) of XI according to method b
(reaction time 3.5 h); the product was isolated by
column chromatography using hexane–ethyl acetate
ppm: 1.37 s (9H, t-Bu), 2.56 t (1H, ≡CH, J = 2.4 Hz),
4.81 t (2H, OCH2, J = 2.4 Hz), 5.58 s (1H, CHN),
13
7.09–7.41 m (4H, Harom). C NMR spectrum (CDCl3),
δC, ppm: 27.4 (CCH3); 55.1 (CCH3); 56.2 (CH2); 66.7
(CHN); 75.6 (≡CH); 77.8 (–C≡); 83.0 (CCl2); 112.2,
120.9, 123.9, 127.9, 129.9, 155.4 (Carom); 161.9 (C=O).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 4 2005

KHLEBNIKOV et al.
566
4. Smith, R. and Livenghouse, T., Tetrahedron, 1985,
In addition, 0.066 g (25%) of 2-(2-propynyloxy)-
benzaldehyde was isolated.
vol. 41, p. 3559.
5. Westling, M., Smith, R., and Livenghouse, T., J. Org.
Chem., 1986, vol. 51, p. 1159.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 05-03-3257a) and by the program “Universities of
Russia” (project no. UR 05.01.316).
6. Novikov, M.S., Khlebnikov, A.F., Besedina, O.V., and
Kostikov, R.R., Tetrahedron Lett., 2001, vol. 42, p. 533.
7. Khlebnikov, A.F. and Kostikov, R.R., Izv. Ross. Akad.
Nauk, Ser. Khim., 1993, p. 646.
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