Novel method for the synthesis of α-bromocinnamaldehydes

Article abstract of DOI:10.1007/s11172-006-0030-8

A novel method for the synthesis of α-bromocinnamaldehydes from aromatic aldehydes was developed. The catalytic olefination of hydrazones of aromatic aldehydes with 2-tribromomethyl-1,3-dioxolane affords ethylene acetals of the target products in yields f

Full text of DOI:10.1007/s11172-006-0030-8

Russian Chemical Bulletin, International Edition, Vol. 54, No. 7, pp. 1733—1736, July, 2005
1733
Novel method for the synthesis of αꢀbromocinnamaldehydes
A. V. Shastin,a A. L. Reznichenko,b O. N. Lenkova,b E. S. Balenkova,b and V. G. Nenaidenkob
ꢀ
aInstitute of Problems of Chemical Physics, Russian Academy of Sciences,
142432 Chernogolovka, Moscow Region, Russian Federation.
Eꢀmail: shastin@icp.ac.ru
bDepartment of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (095) 932 8846. Eꢀmail: nen@acylium.chem.msu.ru
A novel method for the synthesis of αꢀbromocinnamaldehydes from aromatic aldehydes
was developed. The catalytic olefination of hydrazones of aromatic aldehydes with 2ꢀtriꢀ
bromomethylꢀ1,3ꢀdioxolane affords ethylene acetals of the target products in yields from
moderate to good.
Key words: αꢀbromocinnamaldehydes, acetals, catalytic olefination, catalysis, copper salts,
2ꢀtribromomethylꢀ1,3ꢀdioxolane, hydrazones.
Olefination of carbonyl compounds is a versatile route
for the syntheses of substituted alkenes.1 Although many
approaches are presently available, the development of
new simple and efficient methods of olefination remains a
typical task.2
We have previously3 shown that Nꢀunsubstituted
hydrazones of aldehydes and ketones react with polyhaloꢀ
alkanes in the presence of catalytic amounts of copper
salts to transform into the corresponding substituted alkꢀ
enes. Based on the catalytic olefination, we developed
methods for syntheses of dihaloalkenes, vinyl halides, fluoꢀ
rineꢀcontaining alkenes, and chlorocinnamic nitriles and
esters. A possible reaction mechanism has been discussed
earlier.4
The highest yield of unsaturated aldehyde acetal was obꢀ
served for the reaction in DMSO with threefold excess of
acetal 1, ethylenediamine as a base, and copper(I) chloꢀ
ride (10 mol.%). It should be mentioned that the reaction
is rather fast (it takes about 3 h according to TLC). The
reaction can also be performed as a oneꢀpot process. In
the case of the reaction with 4ꢀchlorobenzaldehyde, the
yield of the target product was virtually independent of
whether the hydrazone was obtained in situ or isolated
preliminarily.
Scheme 1
In the present work, we propose a novel method for
the synthesis of αꢀbromocinnamaldehydes using catalytic
olefination, which is a convenient alternative to the known
methods for the preparation of these compounds, such as
the Wittig reaction,5 elimination of HBr from 2,3ꢀdiꢀ
bromoꢀ3ꢀarylpropionaldehydes,6,7 and bromination of
cinnamaldehydes.8 αꢀBromocinnamaldehydes are valuꢀ
able bifunctional building blocks and can be used in synꢀ
theses of heterocyclic systems.9
We showed that treatment of 4ꢀchlorobenzaldehyde
with bromal produced no 2ꢀbromoꢀ3ꢀ(4ꢀchloropheꢀ
nyl)acrylaldehyde, and symmetrical 4ꢀchlorobenzaldeꢀ
hyde azine was the only reaction product according to the
GLCꢀMS data. To prevent the transformation of hydraꢀ
zone into azine, we used bromal acetal, viz., 2ꢀtriꢀ
bromomethylꢀ1,3ꢀdioxolane (1), as the polyhalogenꢀconꢀ
taining reagent (Scheme 1). The influence of conditions
(the nature of solvent and base, the amount of catalyst
and reactant 1) on the course of the reaction was studied.
We applied the developed method to synthesize ethylꢀ
ene acetals of different αꢀbromocinnamaldehydes 2 from
aromatic and heteroaromatic aldehydes (Table 1). Subseꢀ
quent treatment of ethylene acetals 2 with 5% HCl in
THF afforded the corresponding αꢀbromocinnamaldeꢀ
hydes 3a—i in high yields (see Table 1). According to the
GLCꢀMS data, the ratio of Zꢀ to Eꢀisomers remains unꢀ
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1683—1686, July, 2005.
1066ꢀ5285/05/5407ꢀ1733 © 2005 Springer Science+Business Media, Inc.

1734
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 7, July, 2005
Shastin et al.
Table 1. Yields of αꢀbromocinnamaldehydes 3 and their ethylꢀ
ene acetals 2
3 mmol) in DMSO (1 mL). The mixture was stirred until the
starting aldehyde disappeared (TLC). Ethylenediamine (1.0 mL,
15 mmol) and freshly purified12 CuCl (30 mg, 0.3 mmol) were
added to the solution of the resulting hydrazone, and then a
solution of 1 (2.9 g, 9 mmol) in DMSO (2 mL) was added
dropwise for 2 min at 18—20 °С (cooling). The reaction mixture
was stirred for 3 h and treated with 0.1 M HCl (150 mL). The
reaction products were extracted with CH2Cl2 (3×50 mL), and
the combined extracts were dried with Na2SO4. The solvent was
distilled off in vacuo, and the reaction products were isolated by
column chromatography.
Compoꢀ
unds
Ar
Yield (%)
Ratio of
Zꢀ : Eꢀisomers
2
3
2a, 3a
2b, 3b
2c, 3c
2d, 3d
2e, 3e
2f, 3f
2g, 3g
2h, 3h
2i, 3i
Ph
62
69
66
48
51
52
93
95
89
92
94
94
95
93
90
9 : 1
12 : 1
10 : 1
10 : 1
9 : 1
9 : 1
14 : 1
9 : 1
4ꢀMeOC6H4
4ꢀClC6H4
4ꢀNO2C6H4
3ꢀNO2C6H4
2ꢀNO2C6H4
3,4ꢀ(MeO)2C6H3 68
2ꢀNaphthyl
3ꢀPyridyl
2ꢀ(1ꢀBromoꢀ2ꢀphenylvinyl)ꢀ1,3ꢀdioxolane (2a), mixture of
isomers (Z : E = 9 : 1), white crystals, m.p. 77 °C, Rf 0.42. IR,
1
ν/cm–1: 1641 (С=C). H NMR of Zꢀisomer, δ: 7.68—7.64 (m,
66
54
2 H); 7.39—7.30 (m, 3 H); 7.22 (s, 1 H, HC=); 5.47 (s, 1 H);
4.22—4.14, 4.07—3.99 (both m, 2 H each). 13C NMR of
Zꢀisomer, δ: 134.3, 131.3, 129.3, 128.6, 128.2, 123.2, 105.1, 65.8
(CH2). Mass spectrum, m/z (Irel (%)): 254 [M]+ (17), 175
[M – Br]+ (100), 131 [M – Br – C2H4O] (35), 77 [С6H5]+ (13),
73 [С3H5O2]+ (74). Found (%): С, 51.85; H, 4.33. C11H11BrO2.
Calculated (%): С, 51.79; H, 4.35.
2ꢀ[1ꢀBromoꢀ2ꢀ(4ꢀmethoxyphenyl)vinyl]ꢀ1,3ꢀdioxolane (2b),
mixture of isomers (Z : E = 12 : 1), white crystals, m.p. 82 °C,
Rf 0.22. IR, ν/cm–1: 1622 (С=С). 1H NMR of Zꢀisomer, δ: 7.67
(d, 2 H, J = 9.0 Hz); 7.14 (s, 1 H, HC=); 6.89 (d, 2 H, J =
9.0 Hz); 5.44 (s, 1 H); 4.21—4.13, 4.06—3.98 (both m, 2 H
each); 3.82 (s, 1 H, Me). 13C NMR of Zꢀisomer, δ: 159.8, 130.9,
126.7, 120.9, 113.6, 105.4, 65.8 (CH2), 55.2 (Me). Mass specꢀ
trum, m/z (Irel (%)): 284 [M]+ (33), 253 [M – Me]+ (14), 205
[M – Br]+ (100), 161 [M – Br – C2H4O]+ (47), 73 [С3H5O2]+
(68). Found (%): С, 50.85; H, 4.78. C12H13BrO3. Calcuꢀ
lated (%): С, 50.55; H, 4.60.
2ꢀ[1ꢀBromoꢀ2ꢀ(4ꢀchlorophenyl)vinyl]ꢀ1,3ꢀdioxolane (2c),
mixture of isomers (Z : E = 10 : 1), white crystals, m.p. 62—64 °C,
Rf 0.44. IR, ν/cm–1: 1640 (С=С). 1H NMR of Zꢀisomer, δ:
7.60, 7.33 (both d, 2 H each, J = 8.6 Hz); 7.17 (s, 1 H, HC=);
5.45 (s, 1 H); 4.21—4.14, 4.07—4.00 (both m, 2 H each).
13C NMR of Zꢀisomer, δ: 134.5, 132.8, 130.6, 130.0, 128.5,
124.1, 105.0, 65.8 (CH2). Mass spectrum, m/z (Irel (%)):
288 [M]+ (14), 253 [M – Cl]+ (15), 209 [M – Br]+ (77), 73
[С3H5O2]+ (100). Found (%): С, 45.58; H, 3.49. C11H10BrClO2.
Calculated (%): С, 45.63; H, 3.48.
2ꢀ[1ꢀBromoꢀ2ꢀ(4ꢀnitrophenyl)vinyl]ꢀ1,3ꢀdioxolane (2d),
mixture of isomers (Z : E = 10 : 1), yellow crystals, m.p.
138—140 °C, Rf 0.26. IR, ν/cm–1: 1520 (NO2), 1350 (NO2).
1H NMR of Zꢀisomer, δ: 8.22, 7.79 (both d, 2 H each, J =
8.8 Hz); 7.29 (s, 1 H, HC=); 5.49 (s, 1 H); 4.20—4.14, 4.09—4.03
(both m, 2 H each). 13C NMR of Zꢀisomer, δ: 147.3, 140.9,
130.0, 129.0, 127.6, 123.5, 104.6, 65.9 (CH2). Mass spectrum,
m/z (Irel (%)): 299 [M]+ (4), 207 [M – Br – С2H4O]+ (20), 220
[M – Br]+ (100), 73 [С3H5O2]+ (89). Found (%): С, 43.94;
H, 3.16. C11H10BrNO4. Calculated (%): С, 44.02; H, 3.36.
2ꢀ[1ꢀBromoꢀ2ꢀ(3ꢀnitrophenyl)vinyl]ꢀ1,3ꢀdioxolane (2e),
mixture of isomers (Z : E = 9 : 1), brown crystals, m.p. 42 °C,
Rf 0.31. IR, ν/cm–1: 1538 (NO2), 1355 (NO2). 1H NMR of
Zꢀisomer, δ: 8.52 (s, 1 H); 8.17, 7.95 (both d, 1 H each, J =
7.9 Hz); 7.54 (t, 1 H, J = 7.9 Hz); 7.28 (s, 1 H, HC=); 5.49
(s, 1 H); 4.20—4.14, 4.09—4.03 (both m, 2 H each). 13C NMR
of Zꢀisomer, δ: 147.3, 133.3, 131.8, 131.1, 129.1, 128.4, 126.7,
124.7, 103.8, 65.5 (CH2). Mass spectrum, m/z (Irel (%)):
299 [M]+ (3), 220 [M – Br]+ (87), 73 [С3H5O2]+ (100).
9 : 1
changed on going from acetals to aldehydes. As shown by
a comparison of the chemical shifts in the 13C NMR
spectra of the main isomer of compound 3a with the
earlier published data,10 the main reaction product is
the Zꢀisomer. Based on the characteristic signals of
the C atoms of the double bond (δ 146.7—151.8 and
123.5—125.7) and aldehyde group (δ 186.3—187.0), we
assigned all the other compounds to Zꢀisomers. It should
be mentioned that the stereoselectivity of catalytic olefiꢀ
nation with 2ꢀtribromomethyldioxolane is higher, on the
average, than that with trichloroacetonitrile and ethyl
trichloroacetate.3
Thus, a novel efficient method for the synthesis of
different αꢀbromocinnamaldehydes and their acetals from
accessible reagents under mild conditions was developed.
The high stereoselectivity of formation of the target prodꢀ
ucts is one of the most important advantages of the reacꢀ
tion proposed.
Experimental
IR spectra were obtained on a URꢀ20 spectrophotometer in
Nujol. 1Н and 13С NMR spectra were obtained on a Varian
VXRꢀ400 spectrometer (400 and 100 MHz) in СDCl3 using
Me4Si as the internal standard. Mass spectra were recorded on a
Finnigan SSQ 7000 mass spectrometer (EI, 70 eV) connected
with a Varian 3400 GC gas chromatograph equipped with a
DBꢀ5MS column (30 m × 0.2 mm, helium as carrier gas).
The m/z values are presented for 79Br and 35Cl isotopes.
Merck 60 F254 plates were used for TLC (hexane—CH2Cl2,
1 : 2), and column chromatography was carried out on silica gel
Merck (63—200 mesh). Melting points were measured for mixꢀ
tures of isomers without recrystallization.
2ꢀTribromomethylꢀ1,3ꢀdioxolane (1) was synthesized acꢀ
cording to a previously published procedure.11
Commercial reagents and solvents were used. DMSO was
reagent grade. The purity of the aldehydes used was not below
than 95%.
Synthesis of ethylene acetals of αꢀbromocinnamaldehydes (2).
A solution of an aldehyde (3 mmol) in DMSO (1 mL) was added
dropwise with stirring to a solution of hydrazinehydrate (0.15 mL,

Novel synthesis of αꢀbromocinnamaldehydes
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 7, July, 2005
1735
Found (%): С, 43.90; H, 3.19. C11H10BrNO4. Calculated (%):
С, 44.02; H, 3.36.
СНО); 8.02 (d, 2 H, J = 8.8 Hz); 7.80 (s, 1 H, HC=); 6.99 (d,
2 H, J = 8.8 Hz); 3.87 (s, 3 Н, Me). 13C NMR of Zꢀisomer, δ:
186.9 (СНО), 162.4, 148.8, 133.3, 125.6, 121.7, 114.2, 55.5
(Me). Mass spectrum, m/z (Irel (%)): 240 [M]+ (69), 161
[M – Br]+ (100), 108 [С7H8O]+ (63). Found (%): С, 49.65;
H, 3.80. C10H9BrO2. Calculated (%): С, 49.82; H, 3.76.
2ꢀBromoꢀ3ꢀ(4ꢀchlorophenyl)propꢀ2ꢀenal (3c) (Z : E = 10 : 1),
white crystals, m.p. 91 °C, Rf 0.44. IR, ν/cm–1: 1690 (С=О).
1H NMR of Zꢀisomer, δ: 9.33 (s, 1 Н, СНО); 7.94 (d, 2 H,
J = 8.6 Hz); 7.84 (s, 1 H, HC=); 7.45 (d, 2 H, J = 8.6 Hz).
13C NMR of Zꢀisomer, δ: 186.8 (СНО), 147.3, 132.1, 131.3,
129.1, 124.8. Mass spectrum, m/z (Irel (%)): 244 [M]+ (29), 209
[M – Cl]+ (49), 165 [M – Br]+ (15), 75 [С6H3]+ (100).
Found (%): С, 44.15; H, 2.47. C9H6СlBrO. Calculated (%):
С, 44.03; H, 2.46.
2ꢀBromoꢀ3ꢀ(4ꢀnitrophenyl)propꢀ2ꢀenal (3d) (Z : E = 10 : 1),
white crystals, m.p. 136 °C, Rf 0.31. IR, ν/cm–1: 1695 (С=О),
1522 (NO2), 1350 (NO2). 1H NMR of Zꢀisomer, δ: 9.40 (s, 1 Н,
СНО); 8.32, 8.10 (both d, 2 H each, J = 8.8 Hz); 7.96 (s, 1 H,
HC=). 13C NMR of Zꢀisomer, δ: 186.4 (СНО), 148.7, 145.2,
138.9, 131.2, 127.9, 123.8. Mass spectrum, m/z (Irel (%)):
255 [M]+ (12), 209 [M – NO2]+ (11), 176 [M – Br]+ (12),
28 [СO]+ (100). Found (%): С, 42.15; H, 2.50. C9H6BrNO3.
Calculated (%): С, 42.22; H, 2.36.
2ꢀBromoꢀ3ꢀ(3ꢀnitrophenyl)propꢀ2ꢀenal (3e) (Z : E = 9 : 1),
white crystals, m.p. 89—91 °C, Rf 0.33. IR, ν/cm–1: 1695 (С=О),
1528 (NO2), 1352 (NO2). 1H NMR of Zꢀisomer, δ: 9.40 (s, 1 Н,
СНО); 8.85 (s, 1 H); 8.34, 8.27 (both d, 1 Н each, J = 8.0 Hz);
7.97 (s, 1 Н, НС=); 7.68 (y, 1 Н, J = 8.0 Hz). 13C NMR of
Zꢀisomer, δ: 186.3 (СНО), 148.4, 145.1, 135.9, 134.5, 129.9,
127.1, 125.5, 125.1. Mass spectrum, m/z (Irel (%)): 255 [M]+
(25), 238 [M – O – H]+ (79), 208 [M – NO2]+ (30), 176
[M – Br]+ (20), 102 [C8H6]+ (100). Found (%): С, 42.14;
H, 2.21. C9H6BrNO3. Calculated (%): С, 42.22; H, 2.36.
2ꢀBromoꢀ3ꢀ(2ꢀnitrophenyl)propꢀ2ꢀenal (3f) (Z : E = 9 : 1),
white crystals, m.p. 94 °C, Rf 0.35. IR, ν/cm–1: 1700 (С=О),
1525 (NO2), 1352 (NO2). 1H NMR of Zꢀisomer, δ: 9.46 (s, 1 Н,
СНО); 8.33 (s, 1 H); 8.23 (d, 1 Н, J = 8.4 Hz); 7.77—7.75 (m,
2 Н); 7.67—7.61 (m, 1 Н). 13C NMR of Zꢀisomer, δ: 186.0
(СНО), 146.7, 146.4, 133.8, 131.0, 130.8, 129.5, 128.1, 125.1.
Mass spectrum, m/z (Irel (%)): 255 [M]+ (1), 176 [M – Br]+
(20), 92 [CHBr]+ (100). Found (%): С, 42.50; H, 2.38.
C9H6BrNO3. Calculated (%): С, 42.22; H, 2.36.
2ꢀBromoꢀ3ꢀ(3,4ꢀdimethoxyphenyl)propꢀ2ꢀenal (3g) (Z : E =
14 : 1), white crystals, m.p. 62 °C, Rf 0.11. IR, ν/cm–1: 1685
(С=О). 1H NMR of Zꢀisomer, δ: 9.29 (s, 1 Н, СНО); 7.80 (br.s,
2 H, Ar and HC=); 7.52, 6.95 (both d, 1 H each, J = 8.4 Hz);
3.94, 3.93 (both s, 3 Н each, Me). 13C NMR of Zꢀisomer, δ:
186.9 (СНО), 152.1, 149.1, 148.7, 126.6, 125.7, 121.6, 112.8,
110.8, 56.0 (Me), 55.9 (Me). Mass spectrum, m/z (Irel (%)): 270
[M]+ (68), 191 [M – Br]+ (51), 120 [M – Br – C2H2O – MeO]+
(89), 92 [С6H2O]+ (100). Found (%): С, 48.25; H, 4.42.
2ꢀ[1ꢀBromoꢀ2ꢀ(2ꢀnitrophenyl)vinyl]ꢀ1,3ꢀdioxolane (2f), mixꢀ
ture of isomers (Z : E = 9 : 1), yellow crystals, m.p. 68 °C,
Rf 0.24. IR, ν/cm–1: 1535 (NO2), 1350 (NO2). 1H NMR of
Zꢀisomer, δ: 8.11 (d, 1 H, J = 8.2 Hz); 7.65—7.61 (m, 2 H); 7.57
(s, 1 H, HC=); 7.50 (t, 1 H, J = 8.2 Hz); 5.59 (s, 1 H); 4.19—4.14,
4.08—4.03 (both m, 2 H each). 13C NMR of Zꢀisomer, δ: 148.1,
136.1, 135.0, 129.2, 128.6, 126.8, 124.0, 123.2, 104.6, 65.8 (CH2).
Mass spectrum, m/z (Irel (%)): 299 [M]+ (1), 220 [M – Br]+ (3),
73 [С3H5O2]+ (100). Found (%): С, 43.84; H, 3.30.
C
11H10BrNO4. Calculated (%): С, 44.02; H, 3.36.
2ꢀ[1ꢀBromoꢀ2ꢀ(3,4ꢀdimethoxyphenyl)vinyl]ꢀ1,3ꢀdioxolane
(2g), mixture of isomers (Z : E = 14 : 1), white crystals, m.p.
60 °C, Rf 0.11. IR, ν/cm–1: 1633 (С=C). 1H NMR of Zꢀisomer,
δ: 7.40 (s, 1 H); 7.21 (d, 1 H, J = 8.4 Hz); 7.14 (s, 1 H, HC=);
6.85 (d, 1 H, J = 8.4 Hz); 5.44 (s, 1 H); 4.19—4.14, 4.06—3.99
(both m, 2 H each); 3.88 (s, 6 H, Me). 13C NMR of Zꢀisomer, δ:
149.4, 148.3, 130.9, 126.9, 123.0, 121.0, 112.1, 110.6, 105.4, 65.8
(CH2), 55.84 (Me), 55.82 (Me). Mass spectrum, m/z (Irel (%)):
314 [M]+ (26), 283 [M – MeО]+ (25), 235 [M – Br]+ (45), 73
[С3H5O2]+ (100). Found (%): С, 49.83; H, 4.88. C13H15BrO4.
Calculated (%): С, 49.54; H, 4.80.
2ꢀ[1ꢀBromoꢀ2ꢀ(2ꢀnaphthyl)vinyl]ꢀ1,3ꢀdioxolane (2h), mixꢀ
ture of isomers (Z : E = 9 : 1), white crystals, m.p. 102—104 °C,
Rf 0.55. IR, ν/cm–1: 1635 (С=C). 1H NMR of Zꢀisomer, δ: 8.15
(s, 1 Н); 7.86—7.77 (m, 4 H); 7.51—7.45 (m, 2 Н); 7.39 (s, 1 H,
HC=); 5.53 (s, 1 H); 4.25—4.16, 4.10—4.00 (both m, 2 H each).
13C NMR of Zꢀisomer, δ: 133.2, 132.9, 131.8, 131.3, 129.1,
128.3, 127.69, 127.63, 126.64, 126.57, 126.3, 123.62, 105.2, 65.8
(CH2). Mass spectrum, m/z (Irel (%)): 304 [M]+ (70), 225
[M – Br]+ (83), 151 [M – Br – C3H5O2]+ (33), 73 [С3H5O2]+
(74). Found (%): С, 59.15; H, 4.60. C15H13BrO2. Calcuꢀ
lated (%): С, 59.04; H, 4.29.
2ꢀ[1ꢀBromoꢀ2ꢀ(3ꢀpyridyl)vinyl]ꢀ1,3ꢀdioxolane (2i), mixture
of isomers (Z : E = 9 : 1), yellow crystals, m.p. 38 °C, Rf 0.45
(ethyl acetate). IR, ν/cm–1: 1642 (С=C). 1H NMR of Zꢀisomer,
δ: 8.74 (s, 1 H); 8.54 (d, 1 H, J = 4.7 Hz); 8.11 (d, 1 H, J =
8.0 Hz); 7.29 (dd, 1 H, J = 8.0 Hz, J = 4.7 Hz); 7.20 (s, 1 H,
HC=); 5.47 (s, 1 H); 4.18—4.12, 4.07—4.01 (both m, 2 H each).
13C NMR of Zꢀisomer, δ: 150.6, 149.4, 135.8, 130.4, 127.7,
126.1, 123.0, 104.7, 65.8 (CH2). Mass spectrum, m/z (Irel (%)):
255 [M]+ (7), 176 [M – Br]+ (100), 73 [С3H5O2]+ (61).
Found (%): С, 46.06; H, 4.00. C10H10BrNO2. Calculated (%):
С, 46.90; H, 3.94.
Synthesis of αꢀbromocinnamaldehydes 3. To a solution of
ethylene acetal 2 (1 mmol) in THF (2 mL), 5% HCl (1 mL) was
added. The reaction mixture was stirred for 5 h at 65 °C, after
which water (30 mL) was added. The reaction products were
extracted with CH2Cl2 (3×20 mL), and the combined extracts
were dried with Na2SO4. The solvent was distilled off in vacuo.
Aldehydes 3 were obtained as mixtures of Z,Eꢀisomers.
2ꢀBromoꢀ3ꢀphenylpropꢀ2ꢀenal (3a) (Z : E = 9 : 1), white
C
11H11BrO3. Calculated (%): С, 48.73; H, 4.09.
1
crystals, m.p. 70—71 °C. H NMR of Zꢀisomer, δ: 9.34 (s, 1 H,
2ꢀBromoꢀ3ꢀ(2ꢀnaphthyl)propꢀ2ꢀenal (3h) (Z : E = 9 : 1),
СНО); 8.03—7.98 (m, 2 H); 7.89 (s, 1 H, HC=); 7.50—7.47
(m, 3 H). 13C NMR of Zꢀisomer, δ: 187.0 (СНО), 149.1, 132.9,
131.6, 130.9, 128.7, 124.2. The NMR spectra correspond to
published data.10
2ꢀBromoꢀ3ꢀ(4ꢀmethoxyphenyl)propꢀ2ꢀenal (3b) (Z : E =
12 : 1), white crystals, m.p. 61 °C, Rf 0.22. IR, ν/cm–1: 1715
(C=O), 1635 (C=C). 1H NMR of Zꢀisomer, δ: 9.29 (s, 1 Н,
white crystals, m.p. 125—126 °C, Rf 0.38. IR, ν/cm–1: 1700
(С=О). 1H NMR of Zꢀisomer, δ: 9.39 (s, 1 Н, СНО); 8.49
(s, 1 Н); 8.10—8.04 (m, 2 H); 7.94—7.85 (m, 3 H); 7.61—7.53
(m, 2 H). 13C NMR of Zꢀisomer, δ: 187.0 (СНО), 149.1, 134.5,
132.8, 132.3, 130.4, 129.1, 128.4, 128.3, 127.8, 126.9, 126.7,
124.2. Mass spectrum, m/z (Irel (%)): 260 [M]+ (41), 181
[M – Br]+ (26), 151 [M – Br – CHO]+ (100), 28 [СO]+ (100).

1736
Russ.Chem.Bull., Int.Ed., Vol. 54, No. 7, July, 2005
Shastin et al.
Found (%): С, 59.35; H, 3.80. C13H9BrO. Calculated (%):
С, 59.80; H, 3.47.
3. A. V. Shastin, V. N. Korotchenko, V. G. Nenaidenko, and
E. S. Balenkova, Izv. Akad. Nauk, Ser. Khim., 1999, 2210
[Russ. Chem. Bull., 1999, 48, 2184 (Engl. Transl.)].
4. V. G. Nenaidenko, V. N. Korotchenko, A. V. Shastin, and
E. S. Balenkova, Izv. Akad. Nauk, Ser. Khim., 2004, 991
[Russ. Chem. Bull., Int. Ed., 2004, 53, 1034].
5. G. Maerkl, Chem. Ber., 1962, 95, 3003.
6. C. Kowalski, A. Weber, and K. Fields, J. Org. Chem., 1982,
47, 5088.
7. W. Bowman, C. Bridge, M. Cloonan, and D. Leach, Synlett,
2001, 765.
8. S. Ley and A. Whittle, Tetrahedron Lett., 1981, 3301.
9. A. Yu. Rulev, Usp. Khim., 1998, 67, 317 [Russ. Chem. Rev.,
1998, 67, 279 (Engl. Transl.)].
10. A. Yu. Rulev, A. S. Mokov, L. B. Krivdin, N. A. Keiko, and
M. G. Voronkov, Zh. Org. Khim., 1995, 31, 1634 [Russ.
J. Org. Chem., 1995, 31, 1465 (Engl. Transl.)].
11. A. N. Meldrum and G. M. Vad, J. Indian Chem. Soc., 1936,
13, 119.
2ꢀBromoꢀ3ꢀ(3ꢀpyridyl)propꢀ2ꢀenal (3i) (Z : E = 10 : 1), brown
crystals, m.p. 55 °C, Rf 0.38 (ethyl acetate). IR, ν/cm–1: 1689
(C=O), 1609 (С=C). 1H NMR of Zꢀisomer, δ: 9.37 (s, 1 Н,
СНО); 8.99 (s, 1 H); 8.69 (d, 1 Н, J = 4.7 Hz); 8.50 (d, 1 Н, J =
7.8 Hz); 7.90 (s, 1 Н, HC=); 7.43 (dd, 1 H, J = 7.8 Hz, J =
4.7 Hz). 13C NMR of Zꢀisomer, δ: 186.4 (СНО), 152.0, 151.8,
144.9, 136.7, 129.2, 126.5, 123.5. Mass spectrum, m/z (Irel (%)):
211 [M]+ (66), 132 [M – Br]+ (100), 7 [C5H3N]+ (51).
Found (%): С, 45.15; H, 2.80. C8H6BrNO. Calculated (%):
С, 45.31; H, 2.85.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 03ꢀ03ꢀ
32052ꢀa).
References
12. Handbuch der praparativen anorganischen Chemie,
Herausgegeben von G. Brauer, Verdinand Enke Verlag,
Stuttgart, 1975.
1. T. Takeda, Modern Carbonyl Olefination, Wiley,
Weinheim, 2004.
2. V. N. Korotchenko, V. G. Nenaidenko, E. S. Balenkova,
and A. V. Shastin, Usp. Khim., 2004, 73, 1039 [Russ. Chem.
Rev., 2004, 73, 957 (Engl. Transl.)].
Received February 8, 2005;
in revised form May 27, 2005