One-pot synthesis of ω-chloroesters via the reaction of acid chlorides with tetrahydrofuran in the presence of trichloroborane

Article abstract of DOI:10.1081/SCC-120004849

The reaction of acid chlorides with tetrahydrofuran in the presence of trichloroborane produces ω-chloroesters in excellent yields.

Full text of DOI:10.1081/SCC-120004849

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ONE-POT SYNTHESIS OF ω-CHLOROESTERS
VIA THE REACTION OF ACID CHLORIDES WITH
TETRAHYDROFURAN IN THE PRESENCE OF
TRICHLOROBORANE
a
b
Rama R. Malladi & George W. Kabalka
a
Departments of Chemistry and Radiology , The University of Tennessee , Knoxville, TN,
7996-1600, U.S.A.
3
b
Departments of Chemistry and Radiology , The University of Tennessee , Knoxville, TN,
7996-1600, U.S.A.
3
Published online: 16 Aug 2006.
To cite this article: Rama R. Malladi & George W. Kabalka (2002) ONE-POT SYNTHESIS OF ω-CHLOROESTERS VIA
THE REACTION OF ACID CHLORIDES WITH TETRAHYDROFURAN IN THE PRESENCE OF TRICHLOROBORANE, Synthetic
Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry, 32:13, 1997-2001, DOI:
10.1081/SCC-120004849
To link to this article: http://dx.doi.org/10.1081/SCC-120004849
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SYNTHETIC COMMUNICATIONS, 32(13), 1997–2001 (2002)
ONE-POT SYNTHESIS OF
v-CHLOROESTERS VIA THE REACTION
OF ACID CHLORIDES WITH
TETRAHYDROFURAN IN THE PRESENCE
OF TRICHLOROBORANE
Rama R. Malladi and George W. Kabalka*
Departments of Chemistry and Radiology, The
University of Tennessee, Knoxville, TN 37996-1600, USA
ABSTRACT
The reaction of acid chlorides with tetrahydrofuran in the
presence of trichloroborane produces !-chloroesters in excel-
lent yields.
Key Words: Boron trichloride; Ether cleavage; Chloroesters;
Ester formation
The exothermic formation of addition complexes from ethers is a well
[1]
known phenomenon. Thermal decomposition of these complexes often
[
1]
leads to the formation of ꢀ,!-dihaloalkanes (Eq. 1). Aluminum,
ð1Þ
*
Corresponding author. E-mail: kabalka@utk.edu
997
1
Copyright & 2002 by Marcel Dekker, Inc.
www.dekker.com

1
998
MALLADI AND KABALKA
[2]
[3]
boron, and silicon reagents have all been employed in these cleavage
[4]
reactions. Ethers can also be converted to their corresponding esters in
the presence of acylating reagents and it has been shown that such trans-
[
5]
formations can be achieved in presence of transition metals and organo-
[6]
lanthanide complexes.
Our continued interest in boron halide induced cleavage reactions of
[
ethers and geminal diacetates, lactones, and esters as well as our use of
7]
[8]
[9]
[
10]
acid chlorides for preparing ketones prompted us to report a simple one-
pot synthesis of !-chloroesters via the reaction of acid chlorides with tetra-
hydrofuran in the presence of trichloroborane (Eq. 2).
ð2Þ
Tetrahydrofuran readily reacts with either aromatic or aliphatic acid
chlorides in the presence of trichloroborane to yield !-chloroesters. The
results are summarized in the Table 1.
We carried out a study to determine reaction conditions leading to
ꢀ
maximum yields and found that a reaction temperature of 65 C results in a
convenient reaction time of 3 h. A shorter time results in incomplete reaction
and recovery of starting material whereas a longer time leads to the forma-
tion of higher homologs of the desired chloroesters (8–20%).
Although, no mechanistic study has been carried out, the reaction
presumably occurs via the formation of a boron ether complex followed
by nucleophilic attack of a chloride ion. Cyclic amines and acyclic ethers
do not lead to the desired cleavage products.
EXPERIMENTAL
All reactions were performed in oven-dried glassware under a nitrogen
atmosphere with magnetic stirring. Air and moisture sensitive compounds
were introduced via syringe through a rubber septum.THF was dried and
distilled prior to use. Products were purified by flash chromatography using
1
13
˚
30–400 mesh ASTM 60 A silica gel. All H and C NMR spectra were
2
recorded on a 250 MHz spectrometer in CDCl solution, chemical shifts
3
are given in ppm (d) relative to TMS. All GC/MS data were obtained
using a Hewlett Packard 6890 series GC system equipped with a 5973
Mass Selective Detector or a Hewlett Packard 5890 Series GC system
equipped with a 5970 Mass Selective Detector.
[
6]
1
Benzoic Acid 4-Chlorobutyl Ester:
H NMR (CDCl /TMS)
3
d 1.81–1.86 (m, 4H), 3.48–3.53 (t, 2H), 4.23–4.27 (t, 2H), 7.31–7.37 (t,

SYNTHESIS OF v-CHLOROESTERS
1999
a
Table 1. Reaction of Acid Chlorides with THF in the Presence of Trichloroborane
b
c
Acid Chloride
Product
Yield(%)
9
8
0
8
8
0
6
7
8
8
8
2
a
Boron trichloride (1 mmol) added to the acid chloride (3 mmol) in THF and the
mixture refluxed for 3 h.
b
The products exhibited physical and spectral data in accord with literature values.
Isolated yield.
c
1
3
2
4
H), 7.43–7.49 (t, 1H), 7.94–7.97 (d, 2H); C NMR (CDCl ) d 25.98, 29.07,
3
4.28, 63.87, 128.16, 129.31, 130.04, 132.74, 166.22; GC/MS (EI) m/z (rela-
þ
tive intensity) 215 (3), 213 (M , 2), 212 (5), 177 (18), 122 (68), 105 (100), 77
(
71), 51 (23).
-Methylbenzoic acid 4-Chlorobutyl Ester:
d 1.81–1.86 (m, 4H), 2.30 (s, 3H), 3.48–3.53 (t, 2H), 4.21–4.26 (t, 2H), 7.12–
[
6] 1
4
H NMR (CDCl /TMS)
3
1
3
7
.15 (d, 2H), 7.81–7.85 (d, 2H); C NMR (CDCl ) d 21.48, 26.06, 29.16,
3
44.37, 63.75, 127.37, 128.95, 129.43, 143.45, 166.40; GC/MS (EI) m/z (rela-
þ
tive intensity) 229 (3) 227 (M , 2) 226 (5), 191 (10), 136 (75), 119 (100), 91
(
49), 65 (19), 55 (11).
Isobutyric Acid 4-Chlorobutyl Ester:
[
11]
1
H NMR (CDCl /TMS)
3
d 1.08–1.11 (d, 6H), 1.69–1.81 (m, 4H), 2.42–2.50 (m, 1H), 3.48–3.53
1
3
(
t, 2H), 4.00–4.06 (t, 2H); C NMR (CDCl ) d 18.87, 26.02, 29.08, 33.90,
3

2
000
MALLADI AND KABALKA
þ
4
4.36, 63.26, 176.95; GC/MS (EI) m/z (relative intensity) 181 (3), 179 (M , 5),
1
43 (19), 134 (25), 91 (100), 85 (22), 71 (73), 55 (64).
[
12] 1
Trichloroacetic Acid 4-Chlorobutyl Ester:
H NMR (CDCl /TMS)
3
1
3
d 1.64–1.81 (m, 4H), 3.49–3.54 (t, 2H), 4.02–4.08 (t, 2H); C NMR
(
tive intensity) 257 (2), 255 (M ,5), 223 (11), 165 (13), 149 (29), 1233 (24), 91
CDCl ) d 26.15, 29.45, 44.55, 61.90, 89.10, 164.25; GC/MS (EI) m/z (rela-
3
þ
(
100), 71 (48), 55 (67).
,2-Dimethylpropionic Acid 4-Chlorobutyl Ester:
CDCl /TMS) d 1.31 (s, 9H), 1.67–1.87 (m, 4H), 3.47–3.53 (t, 2H), 4.03–
[
13]
1
2
H NMR
(
3
1
3
4
1
1
.09 (t, 2H); C NMR (CDCl ) d 25.87, 26.49, 29.00, 41.60, 44.40, 63.45,
3
þ
76.05; GC/MS (EI) m/z (relative intensity) 195 (3), 193 (M , 6) 156 (38),
35 (29), 119 (17), 91 (100), 71 (42), 55 (59).
1
Undecenoic Acid 4-Chlorobutyl Ester: H NMR (CDCl /TMS) d 1.30–
3
1
3
.64 (m, 12H), 1.76–1.88 (m, 4H), 1.99–2.07 (q, 2H), 2.26–2.32 (t, 2H), 3.54–
.58 (6, 2H), 4.08–4.12 (t, 2H), 4.89–5.02 (dd, 2H), 5.78–5.81 ( m, 1H);
1
3
C NMR (CDCl ) d 24.82, 25.99, 28.75, 28.91, 29.06, 33.64, 34.13, 44.25,
3
6
3.17, 114.00, 138.94, 173.56; GC/MS (EI) m/z (relative intensity) 275
þ
(
M , 2), 241 (3), 163 (10), 134 (20), 91 (100), 71 (27), 55 (71).
ACKNOWLEDGMENT
We thank the U.S. Department of Energy and the Robert H. Cole
Foundation for support of this research.
REFERENCES
1
2
3
. Johnson, F. Reactions of Ethers and Cyclic Ethers. In Friedel–Crafts
And Related Reactions; Olah, G.A.,Ed.; Interscience: New York, 1965;
, 1–109.
. Guindon, Y.; Yoakim, C.; Horton, H.E. Cleavage of Carbon–Oxygen
Bonds. Dimethylboron Bromide. A New Reagent for Ether Cleavage.
Tetrahedron Lett. 1983, 24, 2969–2072.
. Bhatt, M.V.; El-Morey, S.S. Silicon Tetrachloride/Sodium Iodide as a
Convenient and Highly Regioselective Ether Cleaving Reagent.
Synthesis. 1982, 12, 1048–1050.
4
4. Bhatt, M.V.; Konkani, S.U. Cleavage of Ethers. Synthesis. 1983, 4,
249–282.
5. Iqbal, J.; Srivastava, R.R. Cobalt(II)Chloride Catalyzed Cleavage of
Ethers with Acyl Halides: Scope and Mechanism. Tetrahedron 1991,
47, 3155–3170.

SYNTHESIS OF v-CHLOROESTERS
2001
6. Qian, C.; Qiu, A.; Huang, Y.; Chen, W.J. Reaction of
Dicyclopentadienylyttrium Chloride with Acyl Chlorides in Tetra-
hydrofuran. Acylative Cleavage of the Cp–Y ꢁ-bond and Tetrahydro-
furan Ring. J. Organomet. Chem. 1991, 412, 53–59
7
8
9
. Narayana, C.; Padmanabhan, S.; Kabalka, G.W. Cleavage of Ethers
and Geminal Diacetates Using the Boron Triiodide-N,N-Diethylani-
line Complex. Tetrahedron Lett. 1990, 31, 6977–6978.
. Narayana, C.; Reddy, N.K.; Kabalka, G.W. An Efficient Cleavage of
Lactones with Boron Triiodide-N,N-Diethylaniline Complex.
Tetrahedron Lett. 1991, 32, 6855–6856.
. Kabalka, G.W.; Narayana, C.; Reddy, N.K. Boron Triiodide-N-N-
Diethylaniline Complex: A New Reagent for Cleaving Esters. Syn.
Comm. 1992, 22, 1793–1798.
1
0. Kabalka, G.W.; Malladi, R.R.; Tejedor, D.; Kelley, S. Preparation of
Ketones via the Palladium-Catalyzed Cross-Coupling of Acid
Chlorides with Trialkylboranes. Tetrahedron Lett. 2000, 41, 999–1001.
1. Bhar, S.; Ranu, B.C. Zinc-Promoted Selective Cleavage of Ethers in
Presence of Acyl Chloride. J. Org. Chem. 1995, 60, 745–747.
2. Korhonen, I.O.O. Gas–Liquid Chromatographic Analyses. IX. Glass
Capillary Gas Chromatography of Aliphatic C1-C8n-Alkyl Mono-
chloro Esters of Acetic, Chloroacetic, Dichloroacetic and Trichloro-
acetic Acids. J. Chromatogr. 1982, 248, 69–88.
1
1
1
3. Kotsuki, H.; Ichikawa, Y.; Nishizawa, H. High Pressure Organic
Chemistry. 9. Non-Catalyzed Cleavage Reactions with Acyl Halides
Under High Pressure Conditions. Chem. Lett. 1988, 4, 673–676.
Received in the USA June 23, 2001