One-step preparation of α-chlorostyrenes

Article abstract of DOI:10.1016/j.tetlet.2007.05.065

α-Chlorostyrenes were prepared via a one-step method involving Friedel-Crafts reaction of various aromatic substrates with acid chlorides in the presence of a heterogeneous Si-Fe catalyst.

Full text of DOI:10.1016/j.tetlet.2007.05.065

Tetrahedron Letters 48 (2007) 4869–4872
One-step preparation of a-chlorostyrenes
b,
a
Hanumant B. Borate,a,* Abaji G. Gaikwad, Suleman R. Maujan,
*
Sangmeshwer P. Sawargavea and Kamalakar M. Kalala
aDivision of Organic Chemistry: Technology, National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India
bChemical Engineering and Process Development Division, National Chemical Laboratory, Dr. Homi Bhabha Road,
Pune 411 008, India
Received 3 April 2007; revised 3 May 2007; accepted 10 May 2007
Available online 17 May 2007
Abstract—a-Chlorostyrenes were prepared via a one-step method involving Friedel–Crafts reaction of various aromatic substrates
with acid chlorides in the presence of a heterogeneous Si–Fe catalyst.
ꢀ 2007 Elsevier Ltd. All rights reserved.
a-Chlorostyrenes are used as intermediates in the prepa-
ration of a-halomethyl ketones,1 1-diarylphosphino-2-
arylethylenes,2 2-arylallyltitanocenes,3 a-thiocyanato-
stilbenes,4 arylacetylenes,5 etc. They can be prepared by
reaction of aryl alkyl ketones with PCl5 followed by dis-
tillation,6 pyrolysis of a mixture of dihaloethylene and
alkanes,7 Wittig reaction of ketones with Ph3P@CHCl8
or addition of HCl to acetylenes in the presence of zinc
chloride,8 reaction of diethyl chlorobenzylphosphonate
with ketones,9 heating aryltrichloromethanes with
P(OMe)3 in CCl4 to give the intermediate aryldichloro-
ethane and further conversion to a-chlorostyrenes,10
reaction of benzeneselenenyl chloride with olefins the in
presence of aluminium chloride,11 reaction of phenylsele-
nium trichloride with olefins followed by selenoxide elim-
ination,12 reaction of acid chlorides with aromatic
substrates in the presence of acid-treated Montmorillon-
ite–FeCl3 catalyst,13 halogenation of acetophenones with
acid halides in the presence of Lewis acid,14 etc. These
methods suffer from the disadvantages such as heating
at high temperatures,7 costly or rare reagents,9–12 and
low yields.13
geneous catalysts offer a number of advantages over
homogeneous catalysts such as ease of work-up, recycla-
bility of catalyst, and effluent treatment. During the
course of our studies, we found that a heterogeneous
Si–Fe catalyst catalyzed the Friedel–Crafts acylation
of aromatic compounds.19 a-Chlorostyrenes were
obtained in one-step as the major product in the case
of acid chlorides having a-methylene groups. Our results
are reported herein.
Initially anisole was reacted with benzoyl chloride in the
presence of various catalysts. The Si–Fe catalyst,19,20
prepared from sodium trisilicate and ferric nitrate in
the presence of ammonia and ammonium carbonate,
afforded the corresponding Friedel–Crafts acylation
product in 70% isolated yield on stirring the neat reac-
tion mixture at rt (Table 1, entry 1). The reactions of
various acid chlorides with anisole and thiophene
resulted in the formation of acylated products21 (Table
1) in 70–77% yields. When anisole was reacted with pro-
pionyl chloride, a mixture of two products was obtained
which was easily separated by column chromatogra-
phy.22 The slower moving product obtained in 28% yield
was found to be the Friedel–Crafts acylation product
while the faster moving product, isolated in 65% yield,
turned out to be the corresponding a-chlorostyrene.8
(Table 2, entry 1). A literature survey revealed that
a-chlorostyrenes were obtained as side products in
Friedel–Crafts acylations using acid-treated Montmoril-
lonite–FeCl3 catalyst13 in 1–9% yields. The higher yield
obtained in our reaction prompted us to develop this
method for the one-step preparation of a-chlorostyr-
enes. Accordingly, reactions of various aliphatic acid
As a part of our ongoing efforts to explore the utility of
heterogeneous catalysts for various organic reac-
tions,15–18 we have studied various heterogeneous
catalysts for applications in organic chemistry. Hetero-
Keywords: a-Chlorostyrenes; Friedel–Crafts acylation; Heterogeneous
catalysts; Acid chlorides.
*
Corresponding authors. Fax: +91 2025902629 (H.B.B.); e-mail:
hb.borate@ncl.res.in
0040-4039/$ - see front matter ꢀ 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2007.05.065

4870
H. B. Borate et al. / Tetrahedron Letters 48 (2007) 4869–4872
Table 1. Friedel–Crafts acylation with aromatic acid chlorides
Cl
Ar
R
+
Si-Fe cat, 25 ºC
R
Ar
O
O
Entry
1
Substrate
Acid chloride
Product (% yield)
MeO
MeO
Cl
O
(70)
(76)
O
O
OMe
MeO
OMe
MeO
MeO
2
Cl
O
OMe
Cl
3
4
5
(75)
(79)
(77)
S
S
O
O
Cl
O
S
S
S
S
O
O
OMe
OMe
Cl
O
Table 2. Preparation of a-chlorostyrenes
Cl
CH2R'
Si-Fe cat, 25 ºC
R
+
+
R
R
CH2R'
O
R'
Cl
O
1
2
Entry
1
Substrate
Acid chloride
Product 1 (% yield)
Product 2 (% yield)
MeO
MeO
MeO
MeO
Cl
C2H5
C4H9
C3H7
MeO
(65)
(28)
(25)
C2H5
O
O
CH3
Cl
Cl
MeO
MeO
MeO
H3C
H3C
H3C
H3C
2
3
4
5
6
7
8
(67)
(43)
(41)
(60)
(36)
(57)
(46)
C4H9
O
C3H7
Cl
O
O
MeO
MeO
H3C
H3C
H3C
H3C
MeO
MeO
H3C
H3C
H3C
H3C
Cl
Cl
(49)
(48)
(30)
(40)
(32)
(28)
C3H7
O
C2H5
Cl
(CH2)3Cl
(CH2)3Cl
O
(CH2)2Cl
Cl
O
O
Cl
Cl
Cl
C2H5
C2H5
O
CH3
Cl
C4H9
C4H9
O
C3H7
Cl
O
O
O
C3H7
C3H7
O
C2H5
Cl
(CH2)3Cl
Cl
(CH2)3Cl
O
(CH2)2Cl
Cl

H. B. Borate et al. / Tetrahedron Letters 48 (2007) 4869–4872
4871
Table 2 (continued)
Entry
Substrate
Acid chloride
Product 1 (% yield)
Product 2 (% yield)
C3H7
Cl
Cl
Cl
C3H7
O
9
(26)
(66)
S
S
S
S
S
C2H5
S
S
S
O
O
Cl
C4H9
C4H9
O
10
11
(17)a
(19)a
(73)
(68)
C3H7
Cl
(CH2)3Cl
(CH2)3Cl
O
S
(CH2)2Cl
O
Cl
a The reactions had to be worked-up in 10 min in order to isolate the a-chlorostyrenes.
chlorides with aromatic substrates were carried out to
Acknowledgement
afford the corresponding a-chlorostyrenes in good
yields. Comparison of 1H NMR data of the faster
moving products obtained in the reactions of anisole
and toluene with propionyl chloride (Table 2, entries 1
and 5) showed that the products were (Z)-1-chloro-1-
(4-methoxyphenyl)-1-propene and (Z)-1-chloro-1-(4-
methylphenyl)-1-propene, respectively.8
S.R.M. and S.P.S. thank CSIR, New Delhi, for grants of
SRF and JRF, respectively.
References and notes
1. Morton, H. E.; Leanna, M. R. Tetrahedron Lett. 1993, 34,
4481–4484.
2. Khachatryan, R. A.; Grigoryan, N. Y.; Indzhikyan, M. G.
Zh. Obshch. Khim. 1994, 64, 1260–1265; Chem. Abstr. 122,
290971.
The a-chlorostyrenes were easily separated from the cor-
responding Friedel–Crafts acylation products by col-
umn chromatography. These compounds had variable
stability ranging from 1–2 days to 1–2 weeks after which
they either decomposed or were converted into the cor-
responding Friedel–Crafts acylation products.
3. Hanzawa, Y.; Kowase, N.; Taguchi, T. Tetrahedron Lett.
1998, 39, 583–586.
4. Bila, E. E.; Obushak, M. D.; Ganushchak, M. I. Pol. J.
Chem. 2000, 74, 1567–1573.
5. Murthy, K. S. K.; Rey, A. W. Can. Pat. Appl. CA
2510093 A1 2006; Chem. Abstr. 146, 62443.
6. Yuldashev, K. Y.; Abdukadirov, A. VINITI 1978, 2034–
2038; Chem. Abstr. 91, 210993.
Clark et al. have proposed a mechanism for the forma-
tion of a-chlorostyrenes from aromatic substrates13
involving a chlorovinyl cation or chlorohydroxy cation.
We envisage that the Fe3+ present in Si–Fe catalyst
helps the formation of cation A from the acid chloride,
which on reaction with the substrate leads to the forma-
tion of cation B and a Fe2+ species. Cation B is trans-
formed to the a-chlorostyrene and Fe3+ is regenerated
(Scheme 1).
7. Milner, D. J. Brit. UK Pat. Appl. GB 2046246 1980;
Chem. Abstr. 95, 24502.
8. Hanack, M.; Weber, E. Chem. Ber. 1983, 116, 777–797.
9. Xu, L.; Tao, F.; Wu, J. Gaodeng Xuexiao Huaxue Xuebao
1984, 5, 129–132; Chem. Abstr. 100, 209253.
10. Ballester Boix, M.; Castaner Gargallo, J.; Riera Figueras,
J.; Fernandez-Llamazares Rodriguez, C.; Onrubia Miguel,
C. Span. ES 542695 A1, 1985, 12 pp; Chem. Abstr. 106,
32523.
In conclusion, a-chlorostyrenes were prepared by a one-
step method from aromatics and acid chlorides using a
heterogeneous, Si–Fe catalyst at room temperature with
or without solvent.
11. Kamigata, N.; Satoh, T.; Yoshida, M.; Kobayashi, M.
Chem. Lett. 1987, 345–346.
12. Engman, L. J. Org. Chem. 1987, 52, 4086–4094.
13. Bastock, T. W.; Clark, J. H.; Landon, P.; Martin, K. J.
Chem. Res. Synop. 1994, 3, 104–105.
14. Kodomari, M.; Fukuoka, N.; Takeda, T. Jpn. Kokai
Tokkyo Koho JP 2001261585 A2 2001, 16 pp; Chem.
Abstr. 135, 257036.
15. Jadhav, V. H.; Dumbre, D. K.; Phapale, V. B.; Borate, H.
B.; Wakharkar, R. D. Catal. Commun. 2007, 8, 65–68.
16. Shinde, P. D.; Mahajan, V. A.; Borate, H. B.; Tillu, V. H.;
Bal, R.; Chandwadkar, A.; Wakharkar, R. D. J. Mol.
Catal. A: Chem. 2004, 216, 115–119.
17. Tillu, V. H.; Jadhav, V. H.; Borate, H. B.; Wakharkar,
R. D. ARKIVOC 2004, xiv, 83–88.
18. Choudhary, V. R.; Tillu, V. H.; Narkhede, V. S.; Borate,
H. B.; Wakharkar, R. D. Catal. Commun. 2003, 4, 449–
453.
19. Part of this work was presented as a poster during the 9th
CRSI National Symposium in Chemistry, Delhi Univer-
sity, New Delhi, February 1–4, 2007.
Scheme 1.

4872
H. B. Borate et al. / Tetrahedron Letters 48 (2007) 4869–4872
20. To a solution of sodium trisilicate (24.21 g, 0.3 mol) in
water (250 ml), a solution of ferric nitrate (40.4 g, 0.1 mol)
in water (75 ml) and a solution of ammonium carbonate
containing ammonia [ammonium carbonate (2.34 g,
0.05 mol), 25% ammonia solution (34 ml, 0.5 mol) diluted
to 75 ml] were added simultaneously at room temperature
with stirring. The solid mass formed in the aqueous solution
was stirred for 12 h, filtered, dried at 120 ꢁC for 12 h,
calcined at 500 ꢁC for 3 h, powdered and used for reactions.
This iron silicate type catalyst had an acidity of 0.4 mmol/g
(by the ammonia method), surface area 271 m2/g (by BET
method) and atomic weight ratio C = 4.14%, O = 64.6%,
Si = 18.11% and Fe = 13.15% (by EDAX).
filtrate and washings were combined, washed with water,
dried over sodium sulfate and concentrated to give a crude
product. Purification by column chromatography over
silica gel afforded (Z)-1-chloro-1-(4-methoxyphenyl)-1-
propene8 (220 mg, 65%) as the faster moving spot. 1H
NMR (CDCl3, 200 MHz): d 1.94 (d, J = 8 Hz, 3H), 3.83 (s,
3H), 6.09 (q, J = 8 Hz, 1H), 6.88 (d, J = 10 Hz, 2H), 7.50
(d, J = 10 Hz, 2H); 13C NMR (50 MHz, CDCl3+CCl4): d
15.11, 55.22, 113.57 (2C), 120.38, 127.60 (2C), 131.21,
133.66, 160.63; GC–MS: m/z 184 (26%, M+) and 182 (79,
M+), 147 (100), 131 (20), 115 (45), 103 (32), 91 (54), 77 (40).
Anal. Calcd for C10H11ClO: C, 65.75; H, 6.03; Cl, 19.45.
Found: C, 65.58; H, 5.91; Cl, 19.64.
21. All the products showed satisfactory spectral data.
22. Typical experimental procedure: To a two-neck flask
equipped with a guard tube (CaCl2), activated (150 ꢁC,
2 h) catalyst (10% by weight, 20 mg) was added. To this
was added anisole (0.2 ml, 1.85 mmol) followed by the
addition of propionyl chloride (0.16 ml, 1.85 mmol). The
reaction mixture was allowed to stir at 25 ꢁC for 10 h.
The reaction mixture was then filtered to remove the
catalyst and washed with ethyl acetate (2 · 3 ml). The
Further elution afforded 1-(4-methoxyphenyl)-propan-1-
one (85 mg, 28%) as a thick liquid. 1H NMR (CDCl3,
200 MHz): d 1.21 (t, J = 8 Hz, 3H), 2.96 (q, J = 8 Hz, 2H),
3.87 (s, 3H), 6.93 (d, J = 10 Hz, 2H), 7.95 (d, J = 10 Hz,
2H); 13C NMR (50 MHz, CDCl3): d 8.36, 31.33, 55.36,
113.58 (2C), 129.92, 130.13 (2C), 163.21, 199.43; GC–MS:
m/z 164 (11%, M+), 135 (100), 107 (16), 92 (19), 77 (30).
Anal. Calcd for C10H12O2: C, 73.17; H, 7.32. Found: C,
72.87; H, 7.42.