CH3SO3H/P2O5 (4:1) as an efficient reagent for the one-pot synthesis of acylaryl methane sulfonates of phenolic

Article abstract of DOI:10.1080/10426500307808

Methansulfonic acid/di-phosphorus pentoxide (4:1) was found to be an efficient reagent for one-pot synthesis of acylaryl methane sulfonates of phenolic esters via Fries rearrangement. This method is easy, rapid, and high-yielding reactions for the synthesis of acylaryl methane sulfonates.

Full text of DOI:10.1080/10426500307808

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Phosphorus, Sulfur, and Silicon and the Related
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CH 3 SO 3 H/P 2 O 5 (4:1) As An Efficient Reagent for
the One-Pot Synthesis of Acylaryl Methane Sulfonates
of Phenolic
B. Kaboudin a
a Institute for Advanced Studies in Basic Sciences (IASBS) , Gava Zang, Zanjan, Iran
Published online: 27 Oct 2010.
To cite this article: B. Kaboudin (2003) CH 3 SO 3 H/P 2 O 5 (4:1) As An Efficient Reagent for the One-Pot Synthesis of
Acylaryl Methane Sulfonates of Phenolic, Phosphorus, Sulfur, and Silicon and the Related Elements, 178:4, 887-892, DOI:
10.1080/10426500307808
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Phosphorus, Sulfur and Silicon, 2003, Vol. 178:887–892
C
Copyright 2003 Taylor & Francis
1042-6507/03 $12.00 + .00
DOI: 10.1080/10426500390198057
CH3SO3H/P2O5 (4:1) AS AN EFFICIENT REAGENT
FOR THE ONE-POT SYNTHESIS OF ACYLARYL
METHANE SULFONATES OF PHENOLIC
B. Kaboudin
Institute for Advanced Studies in Basic Sciences (IASBS),
Gava Zang, Zanjan, Iran
Methansulfonic acid/di-phosphorus pentoxide (4:1) was found to be an
efficient reagent for one-pot synthesis of acylaryl methane sulfonates of
phenolic esters via Fries rearrangement. This method is easy, rapid, and
high-yielding reactions for the synthesis of acylaryl methane sulfonates.
Keywords: Acylaryl methane sulfonates; di-phosphorus pentoxide;
Fries rearrangement; methansulfonic acid
Acylaryl methane sulfonates have many industrial applications such as
pesticides, insecticides, acaricides,1,2 photosensitizers, and photoinitia-
tor systems for radical and cationic polymerization.3 These compounds
have been prepared by reaction of hydroxyaryl ketones with methane-
sulfonyl chloride in the presence of a base.2 The Fries reaction, used
for the preparation of aryl ketones from phenolic esters, is one of the
most useful rearrangements in aromatic chemistry.4,5 Conducted ther-
mally in the presence of Friedel-Crafts catalysts or photochemically by
irradiation with UV light, reactions typically give mixtures of ortho-
and para-substituted products.6,7 Recently we found that the Fries re-
arrangement of phenolic esters in the presence of MAPO (methanesul-
fonic acid/phosphorus oxychloride),8 gave acylaryl methane sulfonates
products with good yields. This article reports the one-pot synthesis of
acylaryl methane sulfonates via Fries rearrangement of phenolic es-
ters in the presence of a mixture of CH3SO3H/P2O5 (4:1) as an effi-
cient reagent. CH3SO3H/P2O5 first came to our attention when Eaton’s
reagent9 (CH3SO3H/P2O5 with 10:1 ratio) (PPMA) was considered as a
The Institute for Advanced Studies in Basic Scienecs (IASBS) is thanked for support-
ing this work.
Address correspondence to B. Kaboudin, Institute for Advanced Studies in Basic
Sciences, Gava Zang, Zanjan, 45195-159, Iran. E-mail: kaboudin@iasbs.ac.ir
887

888
B. Kaboudin
SCHEME 1
suitable alternative to polyphosphoric acid. The Fries rearrangement
of phenyl benzoate (1a) in the presence of this reagent (10:1), gave
4-benzoylphenyl methane sulfonate (2a) and 2-benzoylphenyl methane
sulfonate (3a) in a 9:1 ratio (Scheme 1) in 35% yield. We speculated that
improved yields of acylaryl methane sulfonates would be obtained by
increasing the amount of P2O5 present (Table I).
1H NMR studies on the Fries rearrangement of 1a at differ-
ent temperatures showed that at the beginning of the reaction, 4-
benzoyloxybenzophenone (4a) is the major product in the presence of
MAPO.8 In a similar experiment, when compound 1a was added to a
mixture of CH3SO3H/P2O5 (4:1) and stirred for 1 h at 100 C, compound
4a was formed in 78% yield (Scheme 2).
SCHEME 2
These results may be explained by considering the initial formation
of 4a, which undergoes decomposition leading to 2a. I examined Fries
rearrangement of phenyl benzoate using this reagent in the presence
of solvent. Phenyl benzoate (1a) was treated with CH3SO3H/P2O5 in
the presence of 1,2-dichloroethane at 80 C for 6 h, afford 4a as the
major product in an 84% yield (isolated yield, based on 2 mmol phenolic
ester that has been used as starting material). Similar results were
obtained in the presence of other solvents such as nitrobenzene and
chlorobenzene.
The same process was successfully extended to other acyloxyarene
derivatives as summarized in Table II. The Fries rearrangement of

Synthesis of Acylaryl Methane Sulfonates of Phenolic
889
TABLE I Progress of Fries Rearrangement of Ester 1a in
the presence of CH3SO3H/P2O5
Ratio of CH3SO3H
to P2O5
Time (hrs)
Yieldsa (%)
Ratio of 2a/3a
10:1
9:1
8:1
7:1
6:1
5:1
4:1
3:1
3
3
3
3
3
3
3
3
35
48
58
70
79
83
86
86
9:1
9:1
9:1
9:1
9.5:0.5
9.5:0.5
9.5:0.5
9.5:0.5
aIsolated yields.
m-tolyl benzoates (1b–e) with this reagent afforded the desired prod-
ucts in 76–89% yields. The results in Table II clearly show that the
reaction seems to be faster when the aryloxy part of the ester carries
electron-donating groups; p-acylaryl methane sulfonates were formed
selectively. The reaction of o-substituted phenolic esters (1f–g) in the
presence of CH3SO3H/P2O5 (4:1) gave p-acylaryl methane sulfonates
as major products. m-Nitro and m-fluoro phenyl benzoate (1h, 1i) with
CH3SO3H/P2O5 (4:1), gave the mesylated phenol (m-nitro and m-fluoro)
(5h, 5i) and the Fries rearrangement did not occur. These results
TABLE II Fries Rearrangement of Acyloxyarene (1) Derivatives in the
Presence of CH3SO3H/P2O5 (4:1) at 100 C
Reaction
time (h)
Yieldsa
(%)
Ratio of
products
Substrate
R
R1
Product(s)
1a
1a
1b
1c
1d
1e
1f
1g
1h
1i
Ph-
Ph-
Ph-
o-ClC6H4-
p-MeC6H4-
m-BrC6H4-
Ph-
Ph-
Ph-
H
H
2a/3a
2a/3a/4a
2b/3b
2c/3c
2d/3d
2e/3e
2f
2g
5g
5i
—
5
1
2.5
6
1.5
8
86
87
86
76
89
78
76
86
90
90
—
—
90
95/5
5/5/90
95/5
92/8
90/10
90/10
—
—
—
—
—
m-Me
m-Me
m-Me
m-Me
o-Cl
o-Me
m-NO2
m-F
8
1
6
6
Ph-
PhCH2
Me-
1j
1k
1l
m-Me
m-Me
m-NO2
1b
1b
1
—
5l
—
—
Me
aIsolated yields.
bUnknown products were produced.

890
B. Kaboudin
clearly indicate that electrophilic substitution did not occur because
electron-withdrawing groups (m-nitro and m-fluoro) deactivate the aro-
matic ring. m-Tolyl-phenylethanoate (1j) and m-tolyl etanoate (1k)
upon treatment with CH3SO3H/P2O5 at 100 C, gave unknown products
at 100 C after 1 h. m-Nitrophenyl acetate (1l), with CH3SO3H/P2O5,
gave 5l as the major product (Scheme 3).
SCHEME 3
In summary, methanesulfonic acid/phosphorus pentoxide (4:1) has
been shown to be an efficient reagent in the Fries rearrangement of
acyloxybenzene derivatives to acylarylmethane sulfonates.
EXPERIMENTAL
Chemicals were purchased from Fluka and Merck chemical companies.
IR spectra were recorded on Perkin Elmer 781 spectrometer. 1H-NMR
spectra were obtained on a Bruker Avance DPX 250 MHz and a Hitachi,
R-2413, 60 MHz spectrophotometers. All melting points were obtained
by a Buchi 510 and are uncorrected. The purity of the substrates was
determined by TLC on silica gel polygram SIL 6/UV 254 plates.
Fries Rearrangement of Acyloxybenzene Derivatives
in the Presence of Methanesulfonic Acid/Phosphorus
Pentoxide (4:1)
General Procedure
The acyloxybenzene derivative (0.003 mmol) was added to a 2 mL of
mixture of methanesulfonic acid and phosphorus pentoxide (4:1 w/w)
at 100 C. The reaction mixture was stirred for the time period reported
in Table I. The reaction mixture was poured into water, extracted with
chloroform (2 25 mL), washed with sodium hydrogen carbonate so-
lution (2 30 mL), dried (CaCl2), filtered, and evaporated. The crude

Synthesis of Acylaryl Methane Sulfonates of Phenolic
891
product was isolated in a pure state by simple filtration chromatography
through a short plug of silica gel with n-hexane-ethylacetate (90:10).
The solvent was evaporated. Known compounds were characterized by
comparison of their physical data with those prepared in accordance
with literature procedures.8
4-Benzoylphenyl methane sulfonate (2a): White crystals, m.p.
78–79 C (n-hexane/CH2Cl2). Rf 0.66 (n-hexane/EtOAc 60:40); IR (KBr):
1
1
1655 (C O), 1600 (Ar), 1375 and 1175 cm (S O). H NMR (CDCl3):
3.15 (s, 3H), 7.1–7.9 (m, 9H).
4-Benzoyl-3-methylphenyl methane sulfonate (2b): Viscous oil,
Rf 0.69 (n-hexane/EtOAc 60:40); IR (neat): 1668 (C O), 1603 (Ar), 1372
1
1
and 1185 cm (S O). H NMR (CDCl3): 2.3 (s, 3H), 3.10 (s, 3H),
7.0–7.75 (m, 8H).
4-(2-Chlorobenzoyl)-3-methylphenyl methane sulfonate (2c):
Viscous oil, Rf 0.68 (n-hexane/EtOAc 60:40); IR (neat): 1678 (C O), 1608
1
1
(Ar), 1372 and 1185 cm (S O). H NMR (CDCl3): 2.5 (s, 3H), 3.10
(s, 3H), 7–7.45 (m, 7H).
4-(4-Methylbenzoyl)-3-methylphenyl methane sulfonate (2d):
Viscous oil, Rf 0.74 (n-hexane/EtOAc 60:40); IR (neat): 1663 (C O), 1608
1
(Ar), 1370 and 1182 cm (S O). 1H NMR (CDCl3): 2.25 (s, 3H), 2.35
(s, 3H), 3.15 (s, 3H), 6.95–7.6 (m, 7H).
4-(3-Bromobenzoyl)-3-methylphenyl methane sulfonate (2e):
White crystals, m.p. 84 C (n-hexane/CH2Cl2). Rf 0.73 (n-hexane/EtOAc
1
60:40); IR (KBr): 1678 (C O), 1605 (Ar), 1368 and 1188 cm (S O).
1H NMR (CDCl3): 2.3 (s, 3H), 3.12 (s, 3H), 7.0–7.8 (m, 7H).
4-Benzoyl-2-chlorophenyl methane sulfonate (2f): Viscous oil,
Rf 0.75 (n-hexane/EtOAc 60:40); IR (neat): 1670 (C O), 1600 (Ar), 1383
1
and 1180 cm (S O). 1H NMR (CDCl3): 3.20 (s, 3H), 7–8.1 (m, 8H).
4-Benzoyl-2-methylphenyl methane sulfonate (2g): White crys-
tals, m.p. 57 C (n-hexane/CH2Cl2). Rf 0.80 (n-hexane/EtOAc 60:40); IR
1
1
(neat): 1675 (C O), 1600 (Ar), 1388 and 1170 cm (S O). H NMR
(CDCl3): 2.35 (s, 3H), 3.20 (s, 3H), 7.1–7.80 (m, 8H).
2-Benzoylphenyl methane sulfonate (3a): Viscous oil, Rf 0.89
(n-hexane/EtOAc 60:40); IR (neat): 1673 (C O), 1610 (Ar), 1373 and
1
1180 cm (S O). 1H NMR (CDCl3): 3.2 (s, 3H), 7.2–7.8 (m, 9H).
2-Benzoyl-5-methylphenyl methane sulfonate (3b): Viscous oil,
Rf 0.86 (n-hexane/EtOAc 60:40); IR (neat): 1670 (C O), 1615 (Ar), 1370
1
1
and 1183 cm (S O). H NMR (CDCl3): 2.45 (s, 3H), 3.2 (s, 3H),
7.2–7.75 (m, 8H).
2-(2-Chlorobenzoyl)-5-methylphenyl methane sulfonate (3c):
White crystals, m.p. 64 C (n-hexane/CH2Cl2). Rf 0.71 (n-hexane/EtOAc
1
60:40); IR (KBr): 1670 (C O), 1610 (Ar), 1370 and 1180 cm (S O).
1H NMR (CDCl3): 2.52 (s, 3H), 3.11 (s, 3H), 7.2–7.9 (m, 7H).

892
B. Kaboudin
2-(4-Methylbenzoyl)-5-methylphenyl methane sulfonate (3d):
Viscous oil, Rf 0.88 (n-hexane/EtOAc 60:40); IR (neat): 1668 (C O), 1612
1
1
(Ar), 1370 and 1180 cm (S O). H NMR (CDCl3): 2.2 (s, 3H), 2.28
(s, 3H), 3.1 (s, 3H), 7.1–7.65 (m, 7H).
2-(3-Bromobenzoyl)-5-methylphenyl methane sulfonate (3e):
Orange viscous oil, Rf 0.76 (n-hexane/EtOAc 60:40); IR (neat): 1675
1
1
(C O), 1615 (Ar), 1370 and 1185 cm (S O). H NMR (CDCl3), 2.5
(s, 3H), 3.06 (s, 3H), 7.0–7.98 (m, 7H).
3-Nitrophenyl methane sulfonate (5g): White crystals, m.p. 60 C
(n-hexane/CH2Cl2). Rf 0.58 (n-hexane/EtOAc 60:40); IR (KBr): 1600
1
1
(Ar), 1530 (N O), 1375, 1175 cm (S O). H NMR (CDCl3), 3.15
(s, 3H), 7.4–8.3 (m, 4H).
3-Fluorophenyl methane sulfonate (5i): Red viscous oil, Rf 0.78
1
(n-hexane/EtOAc 60:40). IR (neat): 1610 (Ar), 1375 and 1190 cm
(S O). 1H NMR (CDCl3), 3.15 (s, 3H), 6.8–7.4 (m, 4H).
4-Benzoyloxybenzophenone (4a): White crystals, m.p. 83 C
1
(n-hexane/EtOAc 90:10). IR (KBr): 1760 (C O), 1675 (C O), 1600 cm
(Ar). 1H NMR (CDCl3): 7.0–7.8 (m, 11H), 8.05 (dd, J 6 and 2Hz, 2H).
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