A new phase transfer catalyst and its applications in organic transformations

Article abstract of DOI:10.1081/SCC-120006462

A new quaternary ammonium bromide salt has been used for the first time in phase transfer catalysis (PTC) reactions such as oxidation of alcohols to carbonyl compounds, alkylation and esterification reactions. Improved yields and reduced reaction times have been achieved by this procedure.

Full text of DOI:10.1081/SCC-120006462

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A NEW PHASE TRANSFER CATALYST AND ITS
APPLICATIONS IN ORGANIC TRANSFORMATIONS*
b
a
a
a
Ch. Venkateshwar Reddy , M. Mahesh , P. V. K. Raju & V. V. Narayana Reddy
a
Organic Chemistry Division-II, Indian Institute of Chemical Technology, Hyderabad, 500007,
India
b
Organic Chemistry Division-II, Indian Institute of Chemical Technology, Hyderabad, 500007,
India
Available online: 18 Oct 2011
To cite this article: Ch. Venkateshwar Reddy, M. Mahesh, P. V. K. Raju & V. V. Narayana Reddy (2002): A NEW PHASE TRANSFER
CATALYST AND ITS APPLICATIONS IN ORGANIC TRANSFORMATIONS*, Synthetic Communications: An International Journal for
Rapid Communication of Synthetic Organic Chemistry, 32:18, 2797-2802
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SYNTHETIC COMMUNICATIONS
Vol. 32, No. 18, pp. 2797–2802, 2002
A NEW PHASE TRANSFER CATALYST
AND ITS APPLICATIONS IN ORGANIC
TRANSFORMATIONS*
Ch. Venkateshwar Reddy,M. Mahesh,P. V. K. Raju,
y
and V. V. Narayana Reddy
Organic Chemistry Division-II, Indian Institute of
Chemical Technology, Hyderabad-500007, India
ABSTRACT
Anew quaternary ammonium bromide salt has been used for
the first time in phase transfer catalysis (PTC) reactions such
as oxidation of alcohols to carbonyl compounds, alkylation
and esterification reactions. Improved yields and reduced
reaction times have been achieved by this procedure.
Phase transfer catalysis find wide applications in oxidation of alcohols,
[
1]
alkylation reactions and esterification reactions, etc. Avariety of quaternary
ammonium salts like tetrabutylammonium bromide (TBAB), tetrabutylam-
monium hydrogen sulphate (TBAHS), benzyltriethylammonium bromide
[
2–4]
(
alysts, they play a vital role for the transfer of anionic species from aqueous to
TEBA), benzyltributylammonium chloride
are used as phase transfer cat-
[
5,6]
organic media and facilitate a variety of organic reactions.
*
IICT Communication No: 4847.
Corresponding author. E-mail: vaddu@iict.ap.nic.in
y
2
797
DOI: 10.1081/SCC-120006462
Copyright & 2002 by Marcel Dekker, Inc.
0039-7911 (Print); 1532-2432 (Online)
www.dekker.com

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2
798
REDDY ET AL.
In the course of our studies on the preferential crystallisation of esfen-
[(S)-a-cyano-3-phenoxybenzyl-(S)-2-(4-chlorophenyl)-3-methyl
valarate,
butyrate] a commercially important synthetic pyrithroid, from its diastereo-
meric mixture [(RS)-a-cyano-3-phenoxybenzyl-(S)-2-(4-chlorophenyl)-3-
methylbutyrate] prepared by making use of known phase transfer catalysts
did not yield good results (Table 1).
Hence, there is a need to search for an efficient phase transfer catalyst
for preparation of the diastereomeric mixture from which one of the
diastereomer is preferentially crystallised. The compound N-butyl-N,N-
dimethyl-a-phenylethylammonium bromide (1c) was prepared starting
from a-phenyl ethyl amine (1a) by using formic acid and formaldehyde
[
7]
to get N,N-dimethyl-a-phenylethylamine (1b) followed by reaction with
n-butyl bromide (Scheme 1).
[8]
This compound has been proved to be a versatile phase transfer cat-
alyst for the crystallisation of esfenvalarate and also a very efficient catalyst
Table 1. Comparison of New PTC with Reported PTCs
Yield of
Esfenvalarate*
Entry
Catalyst
Solvent
1
2
3
4
5
6
TEBAToluene
TEBADCE
TBAB
–
–
–
29%
–
36%
Toluene
DCE
DCE
TBAB
TBAHS
New PTC (1c)
DCE
*
(S)-2-(4-chlorophenyl)-3-methylbutyroylchloridewasreac-
ted with 3-phenoxybenzaldehyde and sodium cyanide using
solvent as indicated above under PTC conditions to yield
after workup, a diastereomeric mixture. From the metho-
nolic solution of this, esfenvalarate has been obtained after
seeding with pure crystals of esfenvalarate.
Scheme 1.

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AMMONIUM BROMIDE SALT AS PTC
2799
for the oxidation of alcohols to the corresponding carbonyl compounds,
alkylation of phenols, amines and active methylene groups.
Aryl carbinols (primary and secondary) were easily converted to cor-
[
9]
responding carbonyl compounds by using excess of 10% aqueous sodium
hypochlorite and 5–8% catalyst (PTC) in refluxing dichloromethane
(
Scheme 2).
However, there was no reaction observed in the absence of the phase
transfer catalyst (PTC). This clearly indicates the role played by the PTC for
the success of the reactions. This method utilizes inexpensive, readily avail-
able reagents and affords high yields of products in a short reaction time.
The results presented in the Table 2 indicate the scope and generality of the
reaction with respect to various alcohols.
Scheme 2.
Table 2. Conversion of Alcohols to Carbonylcompounds Using PTC Oxidation
NaOCl
(mL)
PTC
(mg)
Reaction Time
(min)
Conversion
(% GC)
0
R
Entry
R
1
2
3
4
5
6
7
8
9
H
CH
OCH
Cl
NO
OH
H
CH3
Cl
H
35
35
35
35
45
35
60
60
60
200
200
250
250
300
250
500
500
500
70
70
60
70
120
120
80
80
80
93
95
99
85
50
65
75
85
75
3
H
H
H
H
H
CH
CH3
CH
3
2
3
3
CH
2
OH
1
0
–
40
250
65
99
OPh
CH2OH
1
1
–
40
250
65
98
OCH3
OCH3

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2
800
REDDY ET AL.
Scheme 3.
Table 3. Alkylation of Phenols
0
Entry
R
R
Time (h)
Yield (%)
1
2
3
4
5
H
H
CH3
CH
OCH
C
CH
2
H
5
5
6
6
6
6
6
99
85
95
90
95
3
C H
2
3
CH
CH
3
3
3
It may be noted that the alcohols bearing electron-withdrawing groups
ꢀNO ) in the aromatic ring took longer reaction time (120 min), than the
(
2
simple and electron rich counter parts (ꢀOCH , ꢀOPh) to achieve compar-
3
able yields. These interesting results prompted us to apply this new phase
transfer catalyst for the o-alkylation and esterification reactions.
[
10]
Phenols were efficiently alkylated with dialkyl sulfate and 10% aque-
ous NaOH solution in the presence of 2 mole% phase transfer catalyst in
two-phase system (Scheme 3). The reactions were clean and the products
were obtained in quantitative yields (Table 3).
Similarly, the best results were also obtained in the esterification of
commercially important synthetic pyrithroids like esfenvalarate and cyper-
methrin (Scheme 4) using N-butyl-N,N-dimethyl-a-phenylethylammonium
bromide.
In conclusion, a new PTC is prepared and used for various phase
transfer catalysis reactions such as oxidation of alcohols, o-alkylation and
esterification reactions. Due to its simplicity and efficiency, this new PTC
procedure will definitely find wide applications in organic synthesis.
EXPERIMENTAL
Melting points were determined in open glass capillaries on a Mettler
FP51 melting point apparatus. IR spectra were recorded on FT-IR Perkin

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AMMONIUM BROMIDE SALT AS PTC
2801
Scheme 4.
1
Elmer 1310 IR-spectrophotometer, H NMR spectra were recorded on
Varian Gemini (200 MHz) spectrometer and TMS was used as internal
standard. Mass spectra were recorded on a VG-micro mass 707011 instru-
ment at 70 eV. GC was run on a HP-5890 series-II instrument using capil-
lary column HP-V.
Procedure for the Preparation of PTC
N,N-Dimethyl-a-phenyl ethyl amine (1.49 g, 0.01 mole) and n-butyl
bromide (1.37 g, 0.01 mole) were mixed and stirred at 80 C for 6 h till the
amine disappears, as indicated by TLC to obtain a brown colour solid.
ꢁ
General Procedure for Oxidation of Aryl Carbinols
p-Methyl benzyl alcohol (1.25 g, 0.01 mole) and N-butyl-N,N-dimethyl
a-phenyl ethyl ammonium bromide (0.20 g, 0.0007 mole) were dissolved in
3
0 mL CH Cl , to this solution 35 mL 10% aqueous sodium hypochlorite
2 2
was added. The biphasic mixture was stirred under refluxing tempe-
rature for 80 min, cooled to room temperature and extracted with
dichloroethane (DCM).
General Procedure for Esterification
To the solution of dichloroethane (DCE) (10.0 g) containing 3-phen-
oxy benzaldehyde (1.98 g, 0.01 moles), sodium cyanide (0.784 g, 0.16 moles)

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2
802
REDDY ET AL.
in water and phase transfer catalyst (2.5 mole%) was added under vigorous
ꢁ
stirring. The reaction mixture was cooled to 0 C and the corresponding
acidchloride (2.30 g, 0.01 moles) in dichloroethnae was added dropwise
under vigorous stirring over a period of 45 min. After the addition is over
the stirring was further continued 90 min. After the completion of the
reaction as determined by TLC, the reaction mixture was washed with
water (4 ꢂ 50 mL) and separated dichloroethane layer was dried over
sodium sulfate and concentrated in vaccuo to give (4.1 g) pure diastereo-
meric ester.
ACKNOWLEDGMENTS
Authors are thankful to Dr. K. V. Raghavan, Director, IICT,
Hyderabad for constant encouragement.
REFERENCES
1
2
3
4
. Dehmlow, E.V.; Dehmlow, S.S. Phase Transfer Catalysis, second edi-
tion, 114, 123, 134.
. Borrows, E.T.; (Mrs) Hareaves, B.M.C.; Page, J.E.; Resuggon, J.C.L.;
Robinson, F.A. J. Chem. Soc. 1947, 69, 197.
. Russel C. Lemon; Richard, C. Myrely. U.S.P. 3022349, 1962; CA :
1
5364 h.
. Fieser, M.; Fieser, F.L. Reagents for Organic Synthesis; Wiley,
967–78, 6, 4, 41, 601.
1
5
6
7
8
. Dockx. J. Synthesis 1973, 7, 441.
. Dehmlow, E.V. Angew. Chem. Int. Ed. Eng. 1974, 13, 170.
. Issac Angres and Herman E. Zieger. J. Org. Chem. 1975, 40(10), 1457.
. Condert, R.; Durang, R.R. J. Chem. Phys. Phys. Chem. Biol. 1983,
80(6), 537 (Fr).
9. Lee, G.A.; Freedman, H.H. Tetrahedron Lett. 1976, 20, 1641.
0. Dehmlow, E.V.; Dehmlow, S.S. Phase Transfer Catalysis, 2nd Ed.;
p. 113.
1
Received in the UK July 26, 2001