Substituted benzaldehydes in the darzens condensation with alkyl dihaloacetates

Article abstract of DOI:10.1007/s11172-006-0440-7

The Darzens reaction of dihaloacetic acid esters with aromatic aldehydes produces either arylhaloglycidic or arylhalopyruvic esters depending on the nature of the substituent in the aromatic ring. Alkyl p- methoxyphenylchloropyruvates undergo spontaneous intermolecular cyclocondensation to form pyranone or furanone derivatives depending on the character of the alkyl fragment.

Full text of DOI:10.1007/s11172-006-0440-7

Russian Chemical Bulletin, International Edition, Vol. 55, No. 8, pp. 1455—1463, August, 2006
1455
Substituted benzaldehydes in the Darzens condensation
with alkyl dihaloacetates
b
c
c
c
a
V. A. Mamedov,a E. A. Berdnikov, S. Tsuboi, H. Hamamoto, T. Komiyama, E. A. Gorbunova,
ꢀ
A. T. Gubaidullin,a and I. A. Litvinova
aA. E. Arbuzov Institute of Organic and Physical Chemistry,
Kazan Research Center of the Russian Academy of Sciences,
8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation.
Fax: +7 (843 2) 73 2253. Eꢀmail: mamedov@iopc.kcn.ru
bKazan State University,
18 ul. Kremlevskaya, 420008 Kazan, Russian Federation
cDepartment of Environmental Chemistry and Materials,
Faculty of Environmental Science and Technology,
Graduate School of Environmental Science, Okayama University,
Tsushima, Okayama 700ꢀ8530, Japan
The Darzens reaction of dihaloacetic acid esters with aromatic aldehydes produces either
arylhaloglycidic or arylhalopyruvic esters depending on the nature of the substituent in the
aromatic ring. Alkyl pꢀmethoxyphenylchloropyruvates undergo spontaneous intermolecular
cyclocondensation to form pyranone or furanone derivatives depending on the character of the
alkyl fragment.
Key words: Darzens reaction, benzaldehydes, dihaloacetic acids, epoxides, glycidic acids,
pyruvic acids, pyranꢀ2,3ꢀdiones, furanꢀ2ꢀones, Xꢀray diffraction study.
The Darzens reaction consists in condensation of alꢀ
dehydes or ketones with αꢀhalocarboxylic acid esters in
the presence of bases to give glycidic esters1,2 (Scheme 1).
the scope of this reaction. The reaction can be directed
to the formation of not only α,αꢀdihalohydrins,18—23
αꢀhaloepoxides,24—26 and αꢀhaloketones21,22,24,27 but also
products, which are not typical of the Darzens reacꢀ
tion,28—33 by varying the nature of the substituents in
aldehyde, a base, and a halogen, as well as the reaction
conditions.
Scheme 1
Earlier,26 the fact that the structure of the products
depends on the nature of the substituent in the aromatic
ring has been exemplified by the reactions of methyl
dichloroacetate with various benzaldehydes. The reacꢀ
tions of unsubstituted benzaldehyde and its 4ꢀchloro
and 4ꢀbromo derivatives produce methyl arylchloroꢀ
pyruvates, whereas the reaction with pꢀnitrobenzaldehyde
stops at the step of formation of intermediate methyl
arylchloroglycidate. These results require a more detailed
investigation of the factors influencing the reaction
pathway.
In the present study, we examined reactions of a broad
range of aromatic aldehydes (1) containing electronꢀwithꢀ
drawing and electronꢀdonating substituents with diꢀ
haloacetic esters (2a—d) under different conditions
(Scheme 2, Table 1). Compounds 3b—g,n—q,v,w and
4h—m,r,s were produced in minor amounts and were not
isolated.
The classical Darzens reaction has attracted interest
because it is widely used in the synthesis of numerous
biologically active natural compounds, including vitamin
A,3 highly selective leukotriene receptor antagonists,4—6
the mosquito pheromone,7 the active component of
8
the antibiotics Virginiamycin M and Roflamycoin9,
amastatin,10 Nꢀsubstituted Lꢀhomophenylalanine,11
thiamꢀ (R = OH)12 and fluorophenicol (R = F),13
gemcitabine,14 the Cꢀ13 side chain of Taxol,15 a calcium
channel blocker of dilthiazem,16 etc.17
The synthesis with the use of esters of α,αꢀdihalo deꢀ
rivatives instead of αꢀhaloacetic esters would be expected
to give reactive haloglycidates, thus substantially extending
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1402—1410, August, 2006.
1066ꢀ5285/06/5508ꢀ1455 © 2006 Springer Science+Business Media, Inc.

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Russ.Chem.Bull., Int.Ed., Vol. 55, No. 8, August, 2006
Mamedov et al.
Scheme 2
Table 1. Reaction products of aromatic aldehydes 1 with
dihaloacetic esters 2a—c
Product
Ester 2
Method
Yield (%)
3h
3i
3j
3k
3l
3m
3r
3s
4a
a
c
a
b
c
d
a
a
a
ii
iii
ii
58
86
84
94
58
64
89
87
81
96
77
70
79
89
62
97
84
65
78
88
55
83
72
56
ii
iii
iii
ii
ii
i
ii
ii
iii
ii
ii
ii
ii
ii
ii
ii
ii
ii
ii
4b
4c
4d
4e
4f
4g
4n
4o
4p
4q
4t
b
c
a
a
a
a
b
b
b
a
a
a
c
c
2
a
b
Hal
Cl
Cl
R
Me
But
2
c
d
Hal
Br
Br
R
Et
Me
3, 4
a
b
c
d
e
f
g
h
i
Ar
Ph
Ph
Ph
R
Hal
Cl
Cl
Br
Cl
Cl
Cl
Cl
Cl
Br
Cl
Cl
Br
3, 4
Ar
R
Hal
Br
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Cl
Br
Br
Me
But
Et
Me
Me
Me
Me
m
n
o
p
q
r
s
t
u
v
4ꢀNO2C6H4 Me
2ꢀMeOC6H4 But
3ꢀMeOC6H4 But
4ꢀMeOC6H4 But
4ꢀMeOC6H4 Me
2ꢀClC6H4
3ꢀClC6H4
4ꢀClC6H4
4ꢀBrC6H4
4ꢀBrC6H4
2ꢀC10H7
2ꢀMeC6H4
3ꢀMeC6H4
4ꢀMeC6H4
3ꢀNO2C6H4 Me
3ꢀNO2C6H4 Et
4ꢀNO2C6H4 Me
4ꢀNO2C6H4 But
4ꢀNO2C6H4
Me
Me
Me
Me
Et
4u
4v
4w
iii
iii
j
k
l
w
2,4ꢀCl2C6H3 Et
Et
Reagents and conditions: i. NaOMe, THF, –80→20 °C;
Table 2. Influence of the amount of ButOK used in the reaction
on the ratio of chloroglycidate 3a to chloroketone 4a (1H NMR)
ii. ButOK, THF, –80→20 °C; iii. ButOK, toluene, –40→20 °C.
Amount of ButOK (equiv.)
3a : 4a
Total yield (%)
As can be seen from Table 1, the reactions of benzalꢀ
dehydes 1 containing electronꢀwithdrawing substituents
afford the corresponding haloglycidates 3, whereas interꢀ
mediate haloglycidates 3 produced in the reactions with
benzaldehydes 1 containing electronꢀdonating substituꢀ
ents, unsubstituted benzaldehyde, or naphthylꢀ2ꢀaldehyde
are isomerized to give halopyruvates 4.
A comparison of the reaction times (see the Experiꢀ
mental section) of thermal isomerization of chloroꢀ
glycidates 3 (in boiling benzene) giving rise to chloroꢀ
pyruvates 4 shows that stability of these chloroglycidates
changes depending on the nature of the substituents in
1.0
2.0
3.0
18 : 82
47 : 53
65 : 35
81
79
84
Scheme 3
the aromatic ring in the following series: 4ꢀNO2
> 3ꢀNO2 >> Cl, Br, H.
>
The ratio of isomers 3 and 4 depends also on the
amount of the base use. As can be seen from Table 2, an
increase in the amount of ButOK used in the reaction
leads to an increase in the percentage of chloroglycidate 3
in the mixture. This can be associated with the fact that
chloride anions, which apparently initiate this isomerizaꢀ
tion, are more rapidly removed from the reaction medium
(Scheme 3).
benzaldehyde in the presence of equimolar amounts of
ButOK and AgNO3 (the latter serves as a scavenger for
chloride anions) produces exclusively chloroglycidate 3a.
This is additionally confirmed by the fact that the
reaction of chloroglycidate 3k with an equimolar amount
of magnesium bromide produces bromopyruvate 4l in
quantitative yield (Scheme 4). Bromopyruvate 4l was also
prepared by thermal isomerization of bromoglycidate 3l.
Therefore, the ratio of haloglycidates 3 to haloꢀ
pyruvates 4 can be controlled by varying the reaction
The influence of chloride anions is evidenced by the
fact that the reaction of methyl dichloroacetate 2a with

Darzens reaction of dihaloacetates
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 8, August, 2006
1457
Scheme 4
conditions and controlling primarily the percentage of
halide ions in the reaction mixture. The ease of isomerꢀ
ization 3 → 4 is determined by the reactivity of the
C(3) atom in glycidate, which decreases in the presence
of electronꢀwithdrawing substituents in the aryl moiety
and increases in the presence of electronꢀdonating subꢀ
stituents.
It is worthy of note that the formation of haloglycidates
3 is stereoselective and the reaction affords only one of
two possible isomers. Xꢀray diffraction study of comꢀ
pounds 3j,l,m (Figs 1—3) showed that haloglycidates adopt
a Z configuration. It should be noted that the reactions of
nitrobenzaldehydes with (+)ꢀ and (–)ꢀmenthyl dichloroꢀ
acetates, which we have performed earlier,34,35 also proꢀ
duced individual Z isomers.
Chloroepoxide 3j (see Ref. 34) and bromoepoxide 3m
form isostructural crystals with similar unit cell paramꢀ
eters and, consequently, these compounds have similar
molecular structures (see Fig. 3), crystal packings, and
systems of intermolecular contacts. In particular, the diꢀ
hedral angle between the benzene ring and the plane of
the epoxide ring in molecules 3j and 3m is 63.4(4) and
62.6(2)°, respectively.
Compounds 3j,34 3l, and 3m form monoclinic cenꢀ
trosymmetric crystals containing one molecule per asymꢀ
metric unit. In the molecules of all three compounds, the
chiral C(2) and C(3) atoms have the same configuration
(R,R or S,S). In chloroepoxide 3j and bromoepoxide 3m,
the plane of the nitro group is twisted with respect to the
plane of the benzene ring by approximately 16°, whereas
this fragment in molecule 3l is flattened.
O(2)
C(25)
O(1)
C(1)
C(24)
C(3)
C(20)
C(23)
O(3)
C(2)
N(23)
O(4)
C(21)
O(10)
C(22)
Br(1)
C(10)
The formation of haloglycidates (3 and entꢀ3) excluꢀ
sively with the Z geometry can be explained with Scheme 5.
Intramolecular cyclization of two enantiomeric oxy
anions A and B, which are generated through the attack of
the dichloroacetate anion on the si and re sides of the
aldehyde group, respectively, occurs apparently through
the sterically more favorable conformers A´ and B´ rather
than through A″ and B″.
Fig. 1. Molecular structure of bromoepoxide 3m in crystals.
C(6)
C(5)
C(4)
O(2)
C(2)
O(72)
N(7)
O(1)
C(7)
C(8)
C(3)
C(1)
C(9)
O(71)
Halopyruvates 4p and 4q, unlike other analogs of this
series, are unstable. For example, spectrally pure chloroꢀ
pyruvate 4q undergoes intermolecular cyclocondensation
at ~20 °C for 1 day to form pyranꢀ2,3ꢀdione derivative 5,*
whereas on attempted vacuum distillation, chloropyruꢀ
vate 4р (brief heating to 100 °C) was converted into fuꢀ
ranꢀ2ꢀone 6 (Scheme 6).
The 13C{1H} and 13C NMR spectra of compound 5
are characterized by the presence of ten signals of two
nonequivalent 4ꢀmethoxycarbonyl fragments, two signals
of the methoxycarbonyl group, two signals of the carboꢀ
nyl groups of the pyran ring, one signal for the quaternary
Br(1)
O(11)
C(13)
C(12)
Fig. 2. Molecular structure of bromoepoxide 3l in crystals.
* Upon prolonged storage, pyrandione 5 undergoes partial transꢀ
formation apparently into isomeric 4ꢀchloroꢀ6ꢀmethoxycarboꢀ
nylꢀ4,5ꢀdi(4ꢀmethoxyphenyl)ꢀ3,4ꢀdihydroꢀ2Hꢀpyranꢀ2,3ꢀdione,
1
which was confirmed by the fact that the H NMR spectrum
Fig. 3. Arbitrary superposition of the molecules of chloroepoxꢀ
ide 3j (dark gray) and bromoepoxide 3m (pale gray).
shows closely positioned signals, whose multiplicities and inteꢀ
grate intensities are analogous to those observed for compound 5.

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Russ.Chem.Bull., Int.Ed., Vol. 55, No. 8, August, 2006
Mamedov et al.
Scheme 5
sp3ꢀhybridized carbon atom, and two signals for the
sp2ꢀhybridized carbon atoms.
The structure of lactone 6 was established by Xꢀray
diffraction (Fig. 4).
The furan ring in molecule 6 is planar within
0.001(1) Å. The dihedral angles between the planes of
the furan ring and two benzene rings C(30)—C(35)
and C(40)—C(45) are 66.9(1) and 16.9(2)°, respecꢀ
tively. The methoxy groups lie in the planes of the
benzene rings (the C(36)—O(33)—C(33)—C(32) and
C(46)—O(43)—C(43)—C(42) torsion angles are 179.9(3)
and –178.5(2)°, respectively). In the crystals, the molꢀ
ecules are linked to each other only by weak C—H...O,
C—H...π, and π...π interactions.
The first step of the formation of products 5 and 6
apparently involves dimerizative dehydrohalogenation givꢀ
ing rise to the intermediate compound C. The reaction of
compound containing R = Me involves the addition of
the Cl– anion followed by cyclization to form pyranꢀ
dione 5. In the case of R = But, the intermediate C, like
other tertꢀbutyl esters,36,37 is transformed into 1,4ꢀdiꢀ
aldehyde D through elimination of isobutylene and deꢀ
carboxylation, and the Cannizzaroꢀtype redox disproporꢀ
tionation of this 1,4ꢀdialdehyde affords lactone 6.
C(46)
C(36)
O(33)
O(43)
C(42)
C(43)
C(34)
C(35)
C(41)
C(40)
C(44)
C(33)
C(30)
C(32)
C(31)
C(45)
C(4)
C(5)
C(3)
C(2)
To summarize, we demonstrated that the pathway of
the Darzens reaction of aromatic aldehydes with dihaloꢀ
acetic esters depends on the structures of the starting comꢀ
pounds. It should be noted that 4ꢀmethoxybenzaldehyde
O(2)
O(1)
Fig. 4. Molecular structure of lactone 6 in crystals.

Darzens reaction of dihaloacetates
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 8, August, 2006
1459
Scheme 6
as a colorless liquid, b.p. 65—67 °C (15 Torr) (cf. lit. data41: b.p.
54—55 °C (8 Torr)). Found (%): C, 38.89; H, 5.58. C6H10Cl2O2.
Calculated (%): C, 38.94; H, 5.45. IR, ν/cm–1: 2986, 1758,
1373, 1307, 1147, 851. 1H NMR (CDCl3), δ: 1.51 (s, 9 H,
OCBut); 5.80 (s, 1 H, CHCl2).
exhibits unusual behavior and gives products, which are
not typical of the Darzens reaction.
Experimental
Darzens condensation of aromatic aldehydes 1 with dihaloꢀ
acetates 2 (general procedure). Potassium tertꢀbutoxide (1.12 g,
10 mmol) was added to a solution of the corresponding dihaloꢀ
acetate (10 mmol) and arylaldehyde (10 mmol) in a dry solvent
(20—25 mL) at –(40—80) °C (for the solvent, see Scheme 2 and
Table 1). The reaction mixture was stirred at this temperature
for 3 h and then kept at ~20 °C for ~14 h. After removal of the
solvent in vacuo, the residue was treated with a 25% aqueous
NaCl solution and extracted with toluene (3×50 mL). The comꢀ
bined organic extracts were dried with MgSO4. After removal of
the solvent, esters of 3ꢀarylꢀ2ꢀhaloꢀ2,3ꢀepoxypropionic acid deꢀ
rivatives 3 or esters of 3ꢀarylꢀ3ꢀhaloꢀ2ꢀoxopropionic acid deꢀ
rivatives 4 were obtained.
The melting points were determined on a Boetius heating
stage. The IR spectra were recorded on JASCO FT/IRꢀ5000 or
Vectorꢀ22 (Bruker) Fourierꢀtransform spectrophotometers in
KBr pellets. The 1H NMR spectra were measured on Varian
Geminiꢀ200 (200.057 MHz), JEOL ALꢀ300 (300.13 MHz),
1
Bruker MSLꢀ400 H (400.13 MHz), and Bruker AVANCEꢀ600
(600.00 MHz) spectrometers. The chemical shifts are given on
the δ scale and were experimentally measured relative to the
signals of the solvents.
All solvents were dried before use according to known proꢀ
cedures.38 The reactions were carried out under nitrogen. Colꢀ
umn chromatography was performed on silica gel 60N (Merck).
Methyl dichloroacetate and methyl dibromoacetate were preꢀ
pared from chloral39 and bromal,40 respectively, according to
known procedures. Ethyl dibromoacetate (Acros Organics) and
potassium tertꢀbutoxide (Lancaster) were used.
tertꢀButyl dichloroacetate (2b). Dichloroacetyl chloride
(88.4 g, 0.60 mol) was added dropwise to a solution of ButOH
(44.4 g, 0.60 mol) and pyridine (47.4 g, 0.60 mol) in THF
(500 mL) at –20 °C, and the reaction mixture was stirred at this
temperature for 8 h. After evaporation of the solvent, the reacꢀ
tion mixture was treated with water and extracted with EtOAc
(3×50 mL). The combined organic layers were washed with a
25% aqueous NaCl solution and concentrated. After vacuum
distillation, compound 2b was obtained in a yield of 112 g (85%)
Methyl 3ꢀchloroꢀ2ꢀoxoꢀ3ꢀphenylpropionate (4a), a yellow oil.
IR, ν/cm–1: 1740, 1458, 1247, 1064, 702. 1H NMR (CDCl3), δ:
3.84 (s, 3 H, OMe); 6.23 (s, 1 H, CH); 7.32—7.38 (m, 5 H, Ph).
tertꢀButyl 3ꢀchloroꢀ2ꢀoxoꢀ3ꢀphenylpropionate (4b), a yellow
oil. Found (%): C, 61.33; H, 5.99. C13H15ClO3. Calculated (%):
C, 61.30; H, 5.94. IR, ν/cm–1: 2984, 1748, 1725, 1458, 1398,
1
1373, 1257, 1158, 1060, 932, 837, 696. H NMR (CDCl3), δ:
1.42 (s, 9 H, OCBut); 6.06 (s, 1 H, CH); 7.39 (m, 5 H, Ar).
Ethyl 3ꢀbromoꢀ2ꢀoxoꢀ3ꢀphenylpropionate (4c), a yellow
oil. Found (%): C, 48.70; H, 4.11; Br, 29.63. C11H11BrO3. Calꢀ
culated (%): C, 48.73; H, 4.09; Br, 29.47. IR, ν/cm–1: 1730,
1
1590, 1489, 1438, 1247, 1061, 1013, 864, 820, 756. H NMR
(CDCl3), δ: 1.19 (t, 3 H, OCH2CH3, J = 6.9 Hz); 4.19 (q,

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Mamedov et al.
2 H, OCH2CH3, J = 6.9 Hz); 6.17 (s, 1 H, CH); 7.26—7.37
(m, 5 H, Ph).
3.57 (s, 3 H, OMe); 4.29 (s, 1 H, CH); 6.88—6.91 and 8.25—8.32
(both m, 2 H each, Ar).
Methyl 3ꢀchloroꢀ3ꢀ(naphthꢀ2ꢀyl)ꢀ2ꢀoxopropionate (4d),
a yellow oil. Found (%): C, 64.32; H, 4.58. C14H11ClO3. Calcuꢀ
lated (%): C, 64.01; H, 4.22. IR, ν/cm–1: 1740, 1458, 1247,
1064, 702. H NMR (CDCl3), δ: 3.75 (s, 3 H, OMe); 6.91 (s,
1 H, CH); 7.43—8.13 (m, 7 H, Ar).
Ethyl 3ꢀbromoꢀ3ꢀ(4ꢀbromophenyl)ꢀ2ꢀoxopropionate (4v),
a yellow oil. Found (%): C, 37.69; H, 2.92; Br, 46.01.
C11H10Br2O3. Calculated (%): C, 37.75; H, 2.88; Br, 45.66. IR,
ν/cm–1: 1740, 1591, 1491, 1439, 1247, 1062, 1013, 861, 820,
756. 1H NMR (CDCl3), δ: 1.25 (t, 3 H, OCH2CH3, J = 7.2 Hz);
4.22 (q, 2 H, OCH2CH3, J = 7.2 Hz); 6.09 (s, 1 H, CH); 7.25
and 7.42 (both d, 2 H each, Ar, J = 8.2 Hz).
Ethyl 3ꢀbromoꢀ3ꢀ(2,4ꢀdichlorophenyl)ꢀ2ꢀoxopropionate (4w),
a yellow oil. Found (%): C, 38.63; H, 2.70; Br, 23.54; Cl, 21.00.
C11H9BrCl2O3. Calculated (%): C, 38.86; H, 2.67; Br, 23.50;
Cl, 20.85. IR, ν/cm–1: 2945, 1752, 1696, 1595, 1477, 1449,
1247, 1072, 940, 853. 1H NMR (CDCl3), δ: 1.35 (t, 3 H,
OCH2CH3, J = 4.9 Hz); 4.22 (q, 2 H, OCH2CH3, J = 4.9 Hz);
6.57 (s, 1 H, CH); 7.24 (d, 1 H, Ar, J = 5.6 Hz); 7.35 (s, 1 H,
Ar); 7.44 (d, 1 H, Ar, J = 5.6 Hz).
1
Methyl 3ꢀchloroꢀ3ꢀ(2ꢀmethylphenyl)ꢀ2ꢀoxopropionate (4e),
a yellow oil. Found (%): C, 58.34; H, 4.76. C11H11ClO3. Calcuꢀ
lated (%): C, 58.29; H, 4.89. IR, ν/cm–1: 2960, 1742, 1543,
1
1419, 1439, 1310, 1249, 913, 861, 698. H NMR (CDCl3), δ:
2.49 (s, 3 H, Me); 3.75 (s, 3 H, OMe); 6.91 (s, 1 H, CH);
7.12—7.21 (m, 4 H, Ar).
Methyl 3ꢀchloroꢀ3ꢀ(3ꢀmethylphenyl)ꢀ2ꢀoxopropionate (4f), a
yellow oil. Found (%): C, 58.24; H, 4.79. C11H11ClO3. Calcuꢀ
lated (%): C, 58.29; H, 4.89. IR, ν/cm–1: 2960, 1823, 1744,
1
1609, 1491, 1437, 1249, 1160, 859, 706. H NMR (CDCl3), δ:
2.38 (s, 3 H, Me); 3.83 (s, 3 H, OMe); 6.13 (s, 1 H, CH);
7.17—7.34 (m, 4 H, Ar).
Methyl 2ꢀchloroꢀ3ꢀphenylꢀ2,3ꢀepoxypropionate (3a) was deꢀ
tected in a mixture with compound 4a, which was prepared by
the reaction of methyl dichloroacetate (2a) with benzaldehyde
in the presence of ButOK (see Table 2). 1H NMR, characteristic
signals (δ): 3.93 (s, 3 H); 4.35 (s, 1 H).
Methyl 3ꢀchloroꢀ3ꢀ(4ꢀmethylphenyl)ꢀ2ꢀoxopropionate (4g),
white crystals, m.p. 56 °C. Found (%): C, 58.25; H, 4.73.
C11H11ClO3. Calculated (%): C, 58.29; H, 4.89. IR, ν/cm–1
:
2960, 1742, 1613, 1514, 1437, 1249, 1064, 864, 816, 795, 706.
1H NMR (CDCl3), δ: 2.36 (s, 3 H, Me); 3.87 (s, 3 H, OMe);
6.14 (s, 1 H, CH); 7.17 and 7.29 (both d, 2 H each, Ar,
J = 8.0 Hz).
tertꢀButyl 3ꢀchloroꢀ3ꢀ(2ꢀmethoxyphenyl)ꢀ2ꢀoxopropionate
(4n), a yellow oil. Found (%): C, 58.79; H, 6.01. C14H17ClO4.
Calculated (%): C, 59.05; H, 6.02. IR, ν/cm–1: 2982, 1719, 1688,
1489, 1468, 1290, 1249, 1162, 1025, 835, 758. 1H NMR (CDCl3),
δ: 1.35 (s, 9 H, OCBut); 3.84 (s, 3 H, OMe); 6.27 (s, 1 H, CH);
6.92 (dd, 2 H, Ar, J = 7.70 Hz, J = 8.8 Hz); 6.99 (dd, 1 H, Ar,
J = 7.6 Hz, J = 8.8 Hz); 7.30 (d, 1 H, Ar, J = 7.6 Hz); 7.83 (d,
1 H, Ar, J = 7.7 Hz).
Methyl 2ꢀchloroꢀ3ꢀ(3ꢀnitrophenyl)ꢀ2,3ꢀepoxypropionate
(3h), a yellow oil. Found (%): C, 46.47; H, 3.05; N, 5.54.
C10H8ClNO5. Calculated (%): C, 46.62; H, 3.13; N, 5.54. IR,
ν/cm–1: 1752, 1606, 1514, 1350, 1282, 1253, 1013, 930, 878,
784, 731. 1H NMR (CDCl3), δ: 3.95 (s, 3 H, OMe); 4.61 (s, 1 H,
CH); 7.73 (dd, 1 H, Ar, J = 8.5 Hz, J = 8.5 Hz); 7.81 and 8.25
(both d, 1 H each, Ar, J = 8.5 Hz); 8.72 (s, 1 H, Ar).
Ethyl 2ꢀbromoꢀ3ꢀ(3ꢀnitrophenyl)ꢀ2,3ꢀepoxypropionate (3i),
a yellow oil. Found (%): C, 41.63; H, 3.12; Br, 25.48; N, 4.40.
C11H10BrNO5. Calculated (%): C, 41.80; H, 3.19; Br, 25.28;
N, 4.43. IR, ν/cm–1: 3116, 3083, 1747, 1707, 1609, 1473,
1320, 1276, 1243, 1198, 1109, 1027, 1016, 948, 882, 865, 835,
1
tertꢀButyl 3ꢀchloroꢀ3ꢀ(3ꢀmethoxyphenyl)ꢀ2ꢀoxopropionate
(4o), a yellow oil. Found (%): C, 58.91; H, 5.97. C14H17ClO4.
Calculated (%): C, 59.05; H, 6.02. IR, ν/cm–1: 2982, 1736,
778, 695, 525. H NMR (CDCl3), δ: 1.27 (t, 3 H, OCH2CH3,
J = 4.5 Hz); 4.36 (q, 2 H, OCH2CH3, J = 4.5 Hz); 4.44 (s,
1 H, CH); 7.52 (dd, 1 H, Ar, J = 5.2 Hz, J = 5.6 Hz); 7.75 (d,
1 H, Ar, J = 5.2 Hz); 8.11 (d, 1 H, Ar, J = 5.6 Hz); 8.25
(s, 1 H, Ar).
Methyl 2ꢀchloroꢀ3ꢀ(4ꢀnitrophenyl)ꢀ2,3ꢀepoxypropionate (3j),
yellow crystals, m.p. 102 °C. Found (%): C, 46.51; H, 3.05;
N, 5.68. C10H8ClNO5. Calculated (%): C, 46.62; H, 3.13;
N, 5.54. IR, ν/cm–1: 1752, 1607, 1522, 1437, 1350, 1282, 1253,
1013, 930, 784, 731. 1H NMR (CDCl3), δ: 3.57 (s, 3 H,
OMe); 4.29 (s, 1 H, CH); 6.88—6.91 and 8.25—8.32 (both m,
2 H each, Ar).
1
1603, 1493, 1460, 1263, 1156, 1052, 837. H NMR (CDCl3), δ:
1.58 (s, 9 H, OCBut); 3.82 (s, 3 H, OMe); 6.03 (s, 1 H, CH);
6.90—7.18 and 7.39—7.47 (both m, 2 H each, Ar).
tertꢀButyl 3ꢀchloroꢀ3ꢀ(4ꢀmethoxyphenyl)ꢀ2ꢀoxopropionate
(4p), a yellow oil. Found (%): C, 59.06; H, 6.02. C14H17ClO4.
Calculated (%): C, 59.05; H, 6.02. IR, ν/cm–1: 2984, 1750, 1609,
1
1580, 1462, 1259, 1160, 1060, 1033, 835. H NMR (CDCl3), δ:
1.43 (s, 9 H, OCBut); 3.89 (s, 3 H, OMe); 6.05 (s, 1 H, CH);
6.89 and 7.30 (both d, 2 H each, Ar, J = 8.8 Hz).
Methyl 3ꢀchloroꢀ3ꢀ(4ꢀmethoxyphenyl)ꢀ2ꢀoxopropionate (4q),
a yellow oil. Found (%): C, 54.42; H, 4.43. C11H11ClO4. Calcuꢀ
lated (%): C, 54.59; H, 4.54. IR, ν/cm–1: 2962, 1742, 1609,
1514, 1441, 1259, 1170, 1033, 696. H NMR (CDCl3), δ: 3.81
and 3.84 (both s, 3 H each, OMe); 6.15 (s, 1 H, CH); 6.91 and
tertꢀButyl 2ꢀchloroꢀ3ꢀ(4ꢀnitrophenyl)ꢀ2,3ꢀepoxypropionate
(3k), yellow crystals, m.p. 60—62 °C. Found (%): C, 52.24;
H, 4.75; Cl, 11.88; N, 4.52. C13H14ClNO5. Calculated (%):
C, 52.10; H, 4.71; Cl, 11.83; N, 4.67. IR, ν/cm–1: 1740, 1611,
1524, 1460, 1427, 1394, 1377, 1350, 1315, 1251, 1201, 1156,
1
1
7.32 (both d, 2 H each, Ar, J = 9.0 Hz).
1100, 1007, 878, 784, 961. H NMR (CDCl3), δ: 1.56 (s, 9 H,
Methyl 3ꢀchloroꢀ3ꢀ(4ꢀchlorophenyl)ꢀ2ꢀoxopropionate (4t),
a yellow oil. Found (%): C, 48.29; H, 3.65. C10H8Cl2O3. Calcuꢀ
lated (%): C, 48.61; H, 3.26. IR, ν/cm–1: 1740, 1591, 1491,
OCBut); 4.53 (s, 1 H, CH); 7.57 and 8.26 (both d, 2 H each, Ar,
J = 8.8 Hz). 13C NMR, δ: 27.74, 61.90, 85.47, 123.36, 128.46,
138.41, 148.14, 148.42, 162.67.
1
1439, 1247, 1062, 861, 820, 756. H NMR (CDCl3), δ: 3.86 (s,
Ethyl 2ꢀbromoꢀ3ꢀ(4ꢀnitrophenyl)ꢀ2,3ꢀepoxypropionate (3l),
yellow crystals. Found (%): C, 41.62; H, 3.22; Br, 25.36; N, 4.21.
C11H10BrNO5. Calculated (%): C, 41.80; H, 3.19; Br, 25.28;
N, 4.43. IR, ν/cm–1: 3116, 3083, 1747, 1707, 1609, 1473, 1320,
1276, 1243, 1198, 1109, 1027, 1016, 948, 882, 865, 835, 778,
3 H, OMe); 6.13 (s, 1 H, CH); 7.36—7.38 (m, 4 H, Ar).
Methyl 3ꢀ(4ꢀbromophenyl)ꢀ3ꢀchloroꢀ2ꢀoxopropionate (4u),
a yellow oil. Found (%): C, 41.24; H, 2.79. C10H8BrClO3. Calꢀ
culated (%): C, 41.20; H, 2.77. IR, ν/cm–1: 1740, 1591, 1491,
1
1
1439, 1247, 1062, 1013, 861, 820, 756. H NMR (CDCl3), δ:
695, 525. H NMR (CDCl3), δ: 1.38 (t, 3 H, OCH2CH3, J =

Darzens reaction of dihaloacetates
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 8, August, 2006
1461
7.2 Hz); 4.37 (q, 2 H, OCH2CH3, J = 7.2 Hz); 4.48 (s, 1 H,
CH); 7.56 and 8.27 (both d, 2 H each, Ar, J = 8.6 Hz).
Methyl 2ꢀbromoꢀ3ꢀ(4ꢀnitrophenyl)ꢀ2,3ꢀepoxypropionate
(3m), yellow crystals. Found (%): C, 39.60; H, 2.62; Br, 26.56;
N, 4.68. C10H8BrNO5. Calculated (%): C, 39.73; H, 2.64;
Br, 26.49; N, 4.63. IR, ν/cm–1: 1748, 1608, 1525, 1446, 1342,
1280, 1249, 1185, 1011, 942, 866, 780, 730, 691. 1H NMF
(CDCl3), δ: 3.59 (s, 3 H, OMe); 4.35 (s, 1 H, CH); 6.96 and
8.31 (both d, 2 H each, Ar, J = 8.6 Hz).
Methyl 2ꢀchloroꢀ3ꢀ(2ꢀchlorophenyl)ꢀ2,3ꢀepoxypropionate
(3r), a yellow oil. Found (%): C, 48.59; H, 3.69. C10H8Cl2O3.
Calculated (%): C, 48.61; H, 3.26. IR, ν/cm–1: 2960, 1742,
1698, 1595, 1477, 1439, 1247, 1068, 940, 864. 1H NMR (CDCl3),
δ: 3.94 (s, 3 H, OMe); 4.69 (s, 1 H, CH); 7.29—7.58 (m, 3 H,
Ar); 7.93 (d, 1 H, Ar, J = 7.6 Hz).
130.59 (CmꢀA); 154.52 (C(4)); 159.77 (CiꢀB); 161.25 (CiꢀA);
174.06 (C=O).
6ꢀChloroꢀ6ꢀmethoxycarbonylꢀ4,5ꢀdi(4ꢀmethoxyphenyl)ꢀ3,6ꢀ
dihydroꢀ2Hꢀpyranꢀ2,3ꢀdione (5). Liquid chloroketone 4q was
transformed into a crystalline product at ~20 °C on standing for
1 day. Recrystallization of this product from a 1 : 1 diethyl
ether—hexane mixture afforded compound 5 in ~100% yield,
m.p. 175—175.5 °C. Found (%): C, 60.54; H, 4.13; Cl, 8.57.
C21H17ClO7. Calculated (%): C, 60.51; H, 4.11; Cl, 8.51. IR,
ν/cm–1: 1746, 1725, 1647, 1605, 1516, 1437, 1303, 1257, 1230,
1170, 1152, 1100, 1021, 917, 886, 797, 764, 745, 704. 1H NMR
(200 MHz, CDCl3), δ: 3.76, 3.85, and 3.88 (all s, 3 H each,
OMe); 6.92 and 6.98 (both d, 2 H each, Ar, J = 9.0 Hz); 7.42 (d,
2 H, Ar, J = 8.8 Hz); 7.65 (d, 2 H, Ar, J = 9.0 Hz). 13C{1H} NMR
(CDCl3), δ: 52.29 (MeOC(O)ꢀA); 55.34 (MeOArꢀC); 55.38
(MeOArꢀB); 113.52 (CoꢀB); 113.60 (CoꢀC); 120.87 (CpꢀB);
123.64 (C—Cl); 126.48 (CpꢀC); 131.00 (CmꢀC); 131.78 (CmꢀB);
132.46 (CiꢀC); 132.53 (CiꢀB); 148.39 (C(5)); 153.77 (C(6));
160.87 (C(2)); 161.14 (MeOC(O)); 162.00 (C(3)). 1H NMR
(600.13 MHz, DMSOꢀd6), δ: 3.67, 3.84, and 3.87 (all s, 3 H each,
OMe); 6.99, 7.07, 7.49, and 7.61 (all d, 2 H each, Ar, J =
8.9 Hz). 13C NMR (DMSOꢀd6), δ: 52.66 (q, MeO—C(O),
Methyl 2ꢀchloroꢀ3ꢀ(3ꢀchlorophenyl)ꢀ2,3ꢀepoxypropionate
(3s), a yellow oil. Found (%): C, 48.23; H, 3.64. C10H8Cl2O3.
Calculated (%): C, 48.61; H, 3.26. IR, ν/cm–1: 2960, 1744,
1
1699, 1595, 1477, 1439, 1247, 1065, 940, 864, 685. H NMR
(CDCl3), δ: 3.92 (s, 3 H, OMe); 4.48 (s, 1 H, CH); 7.25—7.42
(m, 4 H, Ar).
tertꢀButyl 3ꢀbromoꢀ3ꢀ(4ꢀnitrophenyl)ꢀ2ꢀoxopropionate (4k).
A solution of MgBr2•Et2O (3.66 g, 14 mmol) in diethyl ether
(15 mL) cooled to 5 °C was added to an ethereal solution of
chloroglycidate 3k (4.25 g, 14 mmol) at 5—8 °C. After stirring
for 1 min, the reaction mixture was poured onto crushed ice
and extracted with diethyl ether (2×50 mL). The ethereal soluꢀ
tion was dried with MgSO4. After removal of the solvent, the
crude product was chromatographed on a column with the use
of an AcOEt—hexane mixture as the eluent (1 : 1 → 1 : 0). Comꢀ
pound 4k was obtained in a yield of 4.79 g (98%) as an yelꢀ
low oil. Found (%): C, 45.26; H, 4.14; Br, 23.56; N, 3.95.
C13H14BrNO5. Calculated (%): C, 45.37; H, 4.10; Br, 23.22;
N, 4.07. IR, ν/cm–1: 1752, 1607, 1522, 1437, 1350, 1282,
1
1JC,H = 148.0 Hz); 56.10 (q, MeOAr, JC,H = 144.8 Hz); 56.16
1
1
(q, MeOAr, JC,H = 145.0 Hz); 114.29 (dd, JC,H = 161.2 Hz,
3JC,H = 4.9 Hz); 114.34 (dd, 1JC,H = 161.2 Hz, 3JC,H = 4.9 Hz);
3
3
122.09 (dd, JCp,Ho = 8.1 Hz, JCp,Ho = 8.1 Hz); 124.29 (s);
3
3
127.57 (dd, JCp,Ho = 8.1 Hz, JCp,Ho = 8.1 Hz); 129.83, 131.86
1
3
1
(dd, JC,H = 162.2 Hz, JC,H = 6.6 Hz); 132.14 (dd, JC,H
162.2 Hz, JC,H = 7.2 Hz); 133.79 (s); 147.35 (dd, JC,H
4.2 Hz, JC,H = 4.2 Hz); 153.89 (s); 161.08 (s, C(2)); 161.34 (s,
=
=
3
3
3
MeOC(O)); 162.13 (s, C(3)). Upon prolonged storage of comꢀ
1
pound 5, additional signals appeared in the H NMR spectrum
(600.13 MHz, DMSOꢀd6), δ: 3.65, 3.81, and 3.85 (all s, 3 H each,
OMe); 6.92, 7.05, 7.27, and 7.65 (all d, 2 H each, Ar, J = 8.9 Hz).
A mixture of methyl 3ꢀ(4ꢀbromophenyl)ꢀ2ꢀchloroꢀ2,3ꢀepoxyꢀ
propionate (3u) and 3ꢀ(4ꢀbromophenyl)ꢀ3ꢀchloroꢀ2ꢀoxoproꢀ
pionate (4u). Powdered ButOK (1.12 g, 10 mmol) was added
with stirring to a solution of methyl dichloroacetate (1.43 g,
10 mmol) and 4ꢀbromobenzaldehyde (1.84 g, 10 mmol) in THF
(25 mL) at –80 °C. The reaction mixture was stirred at this
temperature for 3 h and then the temperature was gradually
raised to ~20 °C for 3 h. The reaction solution was concentrated
to oneꢀhalf of the initial volume in vacuo using a waterꢀaspirator
pump, treated with a 25% aqueous NaCl solution, and exꢀ
tracted with AcOEt (3×30 mL). The combined organic extracts
were dried with MgSO4, the solvent was removed in vacuo, and a
mixture of chloroglycidate 3u and chloropyruvate 4u was
obtained (physicochemical characteristics are identical to
those reported above). After silica gel column chromatography
(AcOEt—hexane, 20 : 1→8 : 1, as the eluent) of the crude prodꢀ
uct, chloropyruvate 4u and compound 3u were obtained in yields
of 1.16 g (40%) and 1.25 g (43%), respectively.
1
1253, 1013, 930, 784, 731. H NMR (CDCl3), δ: 1.55 (s, 9 H,
OCBut); 6.18 (s, 1 H, CH); 7.64 and 8.24 (both d, 2 H each, Ar,
J = 8.8 Hz).
Ethyl 3ꢀbromoꢀ3ꢀ(4ꢀnitrophenyl)ꢀ2ꢀoxopropionate (4l). Upon
refluxing of bromoglycidate 3l in benzene over a short period of
time (1—2 min), this compound was quantitatively transformed
into bromopyruvate 4l. The yield was ~100%, a yellow oil.
Found (%): C, 41.68; H, 3.22; Br, 25.52; N, 4.39. C11H10BrNO5.
Calculated (%): C, 41.80; H, 3.19; Br, 25.28; N, 4.43. IR,
ν/cm–1: 3116, 3083, 1747, 1707, 1609, 1473, 1320, 1276, 1243,
1198, 1109, 1027, 1016, 948, 882, 865, 835, 778, 695, 525.
1H NMR (CDCl3), δ: 1.38 (t, 3 H, OCH2CH3, J = 7.2 Hz); 4.37
(q, 2 H, OCH2CH3, J = 7.2 Hz); 6.24 (s, 1 H, CH); 7.56 and
8.27 (both d, 2 H each, Ar, J = 8.6 Hz).
3,6ꢀDi(4ꢀmethoxyphenyl)ꢀ2,5ꢀdihydrofuranꢀ2ꢀone (6). Upon
heating of liquid chloropyruvate 4p over a short period of time
(5—8 min) at ∼100 °C (0.1 Torr), a crystalline product was
obtained. Recrystallization of this product from PriOH afforded
compound 6. The yield was 91%, m.p. 178—180 °C. Found (%):
C, 68.02; H, 4.38. C18H16O4. Calculated (%): C, 72.96; H, 5.44.
IR, ν/cm–1: 1734, 1642, 1605, 1574, 1510, 1458, 1340, 1307,
1257, 1183, 1164, 1122, 1067, 1019, 963, 843, 826, 717, 580,
Compound 3u is a yellow oil. Found (%): C, 41.33; H, 2.63.
C10H8BrClO3. Calculated (%): C, 41.20; H, 2.77. IR, ν/cm–1
:
1746, 1695, 1597, 1472, 1439, 934, 864, 702. 1H NMR (CDCl3),
δ: 3.92 (s, 3 H, OMe); 4.46 (s, 1 H, CH); 7.25 and 7.54 (both d,
2 H each, Ar, J = 8.44 Hz).
1
524. H NMR (CDCl3), δ: 3.82 and 3.83 (both s, 3 H each,
MeO); 5.13 (s, 1 H, CH); 6.84, 6.92, 7.25, and 7.37 (all d,
2 H each, Ar, J = 9.0 Hz). 13C NMR, δ: 55.24 (MeOꢀB);
55.33 (MeOꢀA); 70.35 (C(5)); 114.17 (CoꢀA); 114.33 (CoꢀB);
122.74 (C(3)); 123.32 (CpꢀA); 123.80 (CpꢀB); 128.98 (CmꢀB);
Thermal isomerization of 2ꢀhaloꢀ2,3ꢀepoxypropionic ester
3h,j,s,u into 3ꢀhaloꢀ2ꢀoxopropionic esters 4h,j,s,u (general proꢀ
cedure). A solution of 2ꢀhaloꢀ2,3ꢀepoxypropionic ester 3
(10 mmol) in benzene (15 mL) was refluxed until the haloepoxide

1462
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 8, August, 2006
Mamedov et al.
was completely transformed into the corresponding haloketone.
The completion of isomerization was monitored by TLC, which
demonstrated that isomerization of 3h (Rf = 0.30) into 4h
(Rf = 0.10), of 3j (Rf = 0.20) into 4j (Rf = 0.11), of 3s (Rf = 0.30)
into 4s (Rf = 0.15), and of 3u (Rf = 0.35) into 4u (Rf = 0.12) was
completed within ~15, ~25, ~1, and ~5 min, respectively
(EtOAc—hexane, 1 : 4, as the eluent). Under standard condiꢀ
tions of Darzens condensation, the expected chloroepoxide 3a
from the reaction of benzaldehyde with methyl dichloroacetate
was not detected by both TLC and NMR spectroscopy of the
crude product.
Xꢀray diffraction study of compounds 3l,m,j and 6 was perꢀ
formed on automated fourꢀcircle Enraf—Nonius CADꢀ4 difꢀ
fractometers (MoꢀKα (3m,j) and CuꢀKα (3l and 6) radiation) at
20 °C using the ω/2θ scanning technique; the θ scan rate was
variable, 1—16.4 deg min–1. The intensities of check reflections
showed no decrease in the course of Xꢀray data collection. For
the crystals of 3l,j, the absorption correction was applied (for the
crystals of 3m and 6, no absorption corrections were applied
because intense reflections suitable for measurements of ψ curves
were absent). The structures were solved by direct methods usꢀ
ing the SIR program42 and refined first isotropically and then
anisotropically. All hydrogen atoms were revealed in difference
electron density maps. The hydrogen atoms in the structures
of 3j and 6 were refined isotropically. In the structure of 3l, the
contributions of the hydrogen atoms to the structure ampliꢀ
tudes were taken into account with fixed positional and isotropic
thermal displacement parameters. In the structure of 3m, the
coordinates of the hydrogen atoms were calculated based on
stereochemical criteria and refined using a riding model. All
calculations were carried out with the use of the MоlEN proꢀ
gram package43 (3l,j and 6) on an AlfaStation 200 computer and
using the WINGX program package44 (3m). Intermolecular conꢀ
tacts, including hydrogen bonds in the crystals, were analyzed
using the PLATON program.45 The unit cell parameters, details
of Xꢀray diffraction study, and results of structure refinement
are given in Table 3. Crystallographic data for compounds 3l,
3m, 3j, and 6 were deposited with the Cambridge Structural
Table 3. Crystallographic parameters of compounds 3l,m,j and 6 and details of Xꢀray diffraction study
Parameter
3l
3m
3j
6
Color, crystal shape
Colorless,
prismatic
С11H10BrN1O5
316.12
Monoclinic
P21/n
Yellow, rhombohedral
Pale brown,
prismatic
С18H16O4
296.33
Monoclinic
P21/c
Molecular formula
Molecular weight
Crystal system
Space group
Unit cell parameters3
a/Å
С10H8BrN1O5
С10H8ClN1O5
257.63
Monoclinic
P21/n
302.08
Monoclinic
P21/n
10.405(9)
7.743(5)
16.14(1)
104.99(7)
1256(2)
4
1.67
46.14
632
12.058(6)
7.968(2)
12.058(6)
102.93(2)
1129.1(8)
4
11.878(4)
7.929(2)
11.916(4)
102.34(2)
1096.3(2)
4
5.61(1)
29.02(2)
9.37(1)
99.1(1)
1507(2)
4
1.31
7.16
624
b/Å
c/Å
β/deg
Volume/Å3
Z
ρ
calc/g cm–3
1.78
1.56
Absorption coefficient/cm–1
F(000)
36.5
3.53
600
528
Radiation (λ/Å)
CuꢀKα
(1.53184)
5.46 < θ < 57.2
MoꢀKα
(0.71073)
2.71 < θ < 26.3
MoꢀKα
(0.71073)
2.71 < θ < 26.3
CuꢀKα
(1.53184)
5.46 < θ < 57.2
θ Angle range/deg
Standard reflections
Two check reflections distributed in orientation and three check reflections
distributed in intensity after each 200 reflections
Ranges of measured indices
0 < h < 10,
0 < k < 7,
–15 < l < 15
2325
–9 < h < 15,
0 < k < 9,
–15 < l < 9
2297
–14 < h < 14,
–9 < k < 0,
–14 < l < 0
2493
0 < h < 6,
–31 < k < 0,
–10 < l < 10
2346
1960
(I > 3σ(I ))
Ignored
Number of measured reflections
Number of observed independent
reflections
Absorption correction
Method of refinement, leastꢀsquares
1758
1505
1964
(I > 3σ(I ))
Empirical
Against |F |
(MolEN)
(I > 2σ(I ))
Ignored
Against |F |2
(SHELX)
(I > 3σ(I ))
Empirical
Against |F |
(MolEN)
Against |F |
(MolEN)
Final R factors
R
Rw
GOOF
∆/σ
0.049
0.070
3.074
0.002
163
0.049
0.122
0.965
0.000
159
0.040
0.064
2.524
0.000
186
0.050
0.067
2.388
0.008
263
Number of parameters in refinement

Darzens reaction of dihaloacetates
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 8, August, 2006
1463
Database (CCDC 279411, 279413, 279412, and 279410, respecꢀ
tively).
22. V. A. Mamedov, V. N. Valeeva, L. A. Antokhina, A. V.
Chernova, R. R. Shagidullin, G. M. Doroshkina, and I. A.
Nuretdinov, Izv. Akad. Nauk, Ser. Khim., 1994, 1444 [Russ.
Chem. Bull., 1994, 43, 1368 (Engl. Transl.)].
23. J. A. Weigel, J. Org. Chem., 1997, 62, 6108.
24. A. Takeda, S. Wada, M. Fujii, and H. Tanaka, Bull. Chem.
Soc. Jpn, 1970, 43, 2997.
This study was financially supported by the Russian
Foundation for Basic Research (Project Nos 03ꢀ03ꢀ32865
and 05ꢀ03ꢀ33008).
25. S. Tsuboi, H. Furutani, and A. Takeda, Synthesis,
1987, 3, 292.
References
26. V. A. Mamedov and I. A. Nuretdinov, Izv. Akad. Nauk, Ser.
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Received October 10, 2005;
in revised form June 19, 2006