o-benzenedisulfonimide as a soft, efficient, and recyclable catalyst for the acylation of alcohols, phenols, and thiols under solvent-free conditions: Advantages and limitations

Article abstract of DOI:10.1055/s-0028-1083215

o-Benzenedisulfonimide turns out to be a highly efficient Bransted acid catalyst for the acylation of a number of alcohols, phenols, and thiols under a metal- and solvent-free procedure; reaction conditions are mild and yields very good. After the workup, the catalyst can be easily recovered and purified, ready to be reused, with economic and ecological advantages. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0028-1083215

PAPER
3625
o-Benzenedisulfonimide as a Soft, Efficient, and Recyclable Catalyst for the
Acylation of Alcohols, Phenols, and Thiols under Solvent-Free Conditions:
Advantages and Limitations
o
-Benzenedisulfonimid
a
e
as
a
C
ata
r
lyst for
A
g
cylation herita Barbero,* Silvano Cadamuro, Stefano Dughera, Paolo Venturello
Dipartimento di Chimica Generale e Chimica Organica dell’Università, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
Fax +39(11)6707642; E-mail: margherita.barbero@unito.it
Received 28 July 2008; revised 7 August 2008
Protic acid catalysis is less common, both under homoge-
Abstract: o-Benzenedisulfonimide turns out to be a highly efficient
neous and heterogeneous conditions. 4-Toluenesulfonic
Brønsted acid catalyst for the acylation of a number of alcohols,
acid (alcohols; toluene, reflux),30 phosphomolybdic acid
phenols, and thiols under a metal- and solvent-free procedure; reac-
tion conditions are mild and yields very good. After the workup, the
(alcohols, phenols, and amines; neat, r.t., long reaction
catalyst can be easily recovered and purified, ready to be reused, times),31 3-nitrobenzeneboronic acid (alcohols; r.t.),32 and
sulfamic acid (alcohols and phenols)33 have been used.
with economic and ecological advantages.
Key words: o-benzenedisulfonimide, acid catalysis, recyclable cat-
alyst, acylation reaction
Under heterogeneous conditions, solid acids such as
montmorillonite,34 zeolites,35 zirconia,36 Nafion-H,37
macroporous metal oxides,38 solid superacid,39 and het-
eropolyacids,40 have also been exploited for acetylation or
Functional group protection is often essential in organic
synthesis, so many methods and procedures of both pro-
tection and deprotection are continuously proposed in the
literature. Alcohols, phenols, and thiols are routinely pro-
tected by acylation and, despite the high number of known
procedures, new and more efficient methodologies are
still in demand. The most commonly used reagents are
acid anhydrides, although in the reaction one acyl moiety
is lost, and acetic or benzoic anhydrides are the most fre-
quently employed. The reaction with primary and second-
ary alcohols normally requires the presence of a suitable
catalyst, whereas a strong base catalyst is needed for hin-
dered tertiary alcohols.1
acylation (in a few cases) of alcohols, phenols, thiols, and
amines, under solvent-free conditions and at reflux or
room temperature. In other examples of heterogeneous ca-
talysis for O- and N-acetylation, the protic acid catalyst is
supported on a high-surface insoluble inorganic or organ-
ic support, such as sulfated zirconia41a or MoO341b on alu-
mina, and NaHSO4,42a phosphomolybdic acid,42b P2O5,42c
sulfuric acid,42d phosphotungstic acid,42e or fluoroboric
acid42f on silica gel, under solvent-free conditions at room
temperature or reflux.
Ionic liquids have been used as the solvent and catalyst for
the acetylation of alcohols and phenols at room tempera-
ture,43 along with halogenated compounds44 and onium
salts45 as acylation catalysts of alcohols and thiols, in
dichloromethane or under solvent-free conditions, and at
room temperature or with heating.
Taking into consideration only the literature concerning
the acylation of alcohols, phenols, thiols, and amines with
acid anhydrides, the number of recent reports is astonish-
ing, including the use of both homogeneous and heteroge-
neous catalysts. Most methods employ solvent-free
conditions, room temperature (for acetylation with Ac2O)
or heating (for other anhydrides, less commonly used), in
the presence of Brønsted or Lewis acid catalysts.
Furthermore, a few references describe solvent- and cata-
lyst-free reactions, in particular the acylation of amines
and arenethiols at room temperature,46a and the acylation
of alcohols, amines, and thiols at 80–85 °C,46b or micro-
wave induced46c at room temperature.
Various organic and inorganic catalysts have been em-
ployed. The highest number of references deal with the
use of Lewis acids,2 amongst them: Mg(NTf2)2,3
Mg(HSO4)2,4 Al(OTf)3,5 Sc(OTf)3,6 lithium salts,7 distan-
noxane derivatives,8 Er(OTf)3,9 ErCl3,10 SbCl3,11 NbCl5,12
InCl3,13 TaCl5,14 CoCl2,15 tin(IV) porphyrin derivatives,16
La(NO3)3,17 lanthanide(III) tosylates,18 copper salts,19 bis-
muth oxide perchlorate,20 zirconium salts,21 cerium
salts,22 a Mn(III) complex,23 Gd(OTf)3,24 Al(HSO4)3,25
BF3·OEt2,26 cobalt polyoxometalate,27 bismuth salts,28 and
silica derivatives.29
The high number of reported methodologies illustrates the
importance of the development of new simple, low-cost,
and environmentally benign procedures, involving
solvent- and/or metal-free recyclable catalytic systems.
Recently, we reported the use of o-benzenedisulfonimide
(1, Figure 1) as a new Brønsted acid organocatalyst, in
some common acid-catalyzed organic reactions, such as
the synthesis of ethers, esters, and acetals, acetal cleavage
and interconversion, and pinacol rearrangement.47
For the synthesis of 1, described for the first time in
192148 and 1926,49 and more recently with modified pro-
cedures,50–52 the key intermediate is o-benzenedisulfonyl
chloride, which can be prepared starting from o-benzene-
disulfonic acid dipotassium salt,49,52 anthranilic acid,53 2-
SYNTHESIS 2008, No. 22, pp 3625–3632
x
x.
x
x
.
2
0
0
8
Advanced online publication: 10.11.2008
DOI: 10.1055/s-0028-1083215; Art ID: Z17108SS
© Georg Thieme Verlag Stuttgart · New York

3626
M. Barbero et al.
PAPER
tries 21, 22). Furthermore, no racemization was observed
upon reaction of the chiral substrate 2m (entry 20).
SO2
NH
SO2
However, the reaction failed in a few cases. A mixture of
acid-catalyzed isomerization products, acylated or not,
was recovered from the acetylation of linalol (2l) (entry
19) and 1-phenylprop-2-en-1-ol (2p) (entry 23), a mixture
of olefinic products derived from competitive side reac-
tions of elimination and dimerization via a carbocationic
intermediate were isolated from the tertiary alcohol 2u
1
Figure 1
aminobenzenesulfonic acid,48–51,54 and 1,2-bis(methylsul-
fanyl)benzene.55 Now, both o-benzenedisulfonyl chloride
and 1 are commercially available.
In this paper, we wish to report a new application of sul- (entry 31), while with triphenylmethanol the reaction did
fonimide 1 as a nontoxic, nonvolatile, and noncorrosive not proceed, probably stopped at the conversion of 2v into
recyclable catalyst, in an alternative, advantageous meth- the stabilized intermediate triphenylmethyl carbocation.
od for the solvent- and metal-free acylation of alcohols,
phenols, and thiols with acid anhydrides (Scheme 1).
Amines were not reacted because, as well-known and re-
The reaction also gave excellent results in a large-scale
preparation starting from 2e (entry 7, 0.1 mol, yield% in
parentheses).
ported in the literature, their acylation with acid anhy-
The optimized reaction conditions for the O-acetylation
were then applied to the S-acylation of thiophenol (2c)
(entry 5), octane-1-thiol (2f) (entry 10), and phenyl-
methanethiol (2h) (entry 15) with very good results in
short reaction times.
drides does not require use of any catalyst.46a
1
R1XH
(R2CO)2O
R1XCOR2
+
X = O, S
2a–v
3a–c
4a–z
To further explore the applicability of the proposed meth-
od, some substrates were acylated by propanoic anhydride
(3b); carrying out the reactions under the same conditions
(reagent ratio, 5 mol% catalyst, temperature, and reaction
time), we obtained comparable, good yields of pure acy-
lated products 4b,l,v (entries 2, 13, and 25).
Scheme 1
Further valuable aspects of the new procedure are the pos-
sibility of easy recovery of 1 in high yield from the reac-
tion mixture, due to its complete solubility in water, and
its reuse without loss of catalytic activity in further reac-
tions, with economic and ecological advantages.
Finally, we carried out some O- and S-acylations with
benzoic anhydride (3c). Accordingly to literature reports,
the reaction proceeded with success only with heating of
the reagents at 60 °C or 80 °C, in the presence of o-ben-
zenedisulfonimide (5 mol%) as catalyst. The reaction was
applied to 1-naphthol (2a, entry 3, 87% yield), octan-1-ol
(2e, entries 8 and 9, at 60 °C or 80 °C, 70% and 81% yields
respectively; higher temperatures, shorter reaction times,
and improved yield), phenylmethanol (2g, entry 14, 91%),
the hindered 1,1,1-trichloro-2-methylpropan-2-ol (2t, en-
try 30, reagent ratio 2t/3c, 1:2; 71%) and octane-1-thiol
(2f, entry 11, 82%).
To assess the generality of the method, we investigated
the scope and limitations of the reaction by treating vari-
ous alcohols, phenols, and thiols 2a–v, with acetic anhy-
dride (3a), propanoic anhydride (3b), and benzoic
anhydride (3c). Under the optimized conditions, the reac-
tions were very mild: nearly equimolar amounts of re-
agents (2/3, 1:1.1), low catalytic load (1, 5.0 mol%), very
short reaction times (5 min, unless otherwise specified),
and room temperature for the acylation with acetic or pro-
panoic anhydrides, whereas the benzoylation required
heating to 60 or 80 °C. Complete conversion and good
yields were generally obtained. Table 1 lists the substrates
considered for acylation 2a–v, the acid anhydrides em-
ployed 3a–c and the acylation products 4a–z that were
isolated and purified by flash column chromatography.
Quite surprisingly, the reaction failed with 1-phenyl-2-
methylpropan-2-ol (2s); in this case, heating the reaction
mixture favored dehydrative elimination over benzoyla-
tion (entry 28), whereas acetylation run at room tempera-
ture gave 93% of acylated product 4x (entry 27).
In Table 1 we reported the yields of the same products ob-
tained in the Brønsted acid catalyzed acylation starting
from the corresponding alcohols or phenols and acid an-
hydrides. Our yields are comparable or better, considering
that our conditions are milder than those in the literature.
For instance, more than one equivalent of anhydride for
each hydroxy group,32,33,42b,d,e halogenated solvent,33,42a,d,e
and/or longer reaction times42f were required.
Acetylation proceeded with high yields of pure acylation
products, starting both from phenols 2a and 2b (entries 1
and 4), even sterically hindered as 2d, (entry 6), and from
aliphatic and benzylic primary, secondary and tertiary al-
cohols such as 2e and 2g (entries 7 and 12), 2m, 2q, and
2r (entries 20, 24, and 26), and 2s and 2t (entries 27 and
29). High yields were also obtained starting from the ster-
ically hindered phenol 2d and secondary or tertiary alco-
hols 2r, 2s, and 2t, although in the last example the
reagent ratio 2t/3a was 1:2. The reaction worked well also
with primary and secondary allylic alcohols, 2i–k and
2n,o, affording the acylation products in good yields and
with complete stereoselectivity without isomerization or
formation of undesired byproducts (entries 16–18 and en-
In conclusion, we have described a new application of o-
benzenedisulfonimide, a nontoxic, nonvolatile, and un-
corrosive Brønsted acid, as new organocatalyst in an effi-
cient, environmentally friendly, solvent-free acylation of
alcohols, phenols, and thiols.
Synthesis 2008, No. 22, 3625–3632 © Thieme Stuttgart · New York

PAPER
o-Benzenedisulfonimide as a Catalyst for Acylation
3627
Table 1 o-Benzenedisulfonimide-Catalyzed Acylation of Alcohols, Phenols, and Thiolsa
Entry Substrate 2
Anhydride 3 Time Temp Product 4
Yieldb Lit. yieldc
(min) (°C)
(%)
(%)
CH
OCOMe
OCOEt
OCOPh
(MeCO)2O
3a
1
2
3
2a
2a
2a
5
r.t.
r.t.
60
4a
4b
4c
100
90,42d,e 91,42f 9833
(EtCO)2O
3b
5
83
87
(PhCO)2O
3c
2 h
87,42d 89,42e 92,42f
94,41a 97,31 9833
4
5
2b
2c
3a
3a
5
5
r.t.
r.t.
4d
4e
89
OCOMe
SCOMe
OH
100
SH
OH
Cl
Cl
Cl
6
7
2d
2e
3a
3a
4 h
r.t.
4f
95
OCOMe
Cl
96
5
r.t.
60
4g
88,33 90,32,42d 9542e
(98)d
Me(CH2)6CH2OH
Me(CH2)6CH2OCOMe
8
9
2e
2e
2f
2f
3c
3c
3a
3c
4 h
4h
4h
4i
70
81
88
82
Me(CH2)6CH2OCOPh
Me(CH2)6CH2OCOPh
Me(CH2)6CH2SCOMe
Me(CH2)6CH2SCOPh
1.5 h 80
10
11
30
r.t.
60
Me(CH2)6CH2SH
7 h
5
4j
90,42d,71 93,41a 94,42f
95,31 96,42e 99,33
OH
OCOMe
OCOEt
OCOPh
SCOMe
12
13
14
15
2g
2g
2g
2h
3a
3b
3c
3a
r.t.
r.t.
80
r.t.
4k
4l
98
82
91
88
5
1 h
4m
4n
8542f
SH
30
OH
OCOMe
16
17
2i
2j
3a
3a
5
1
r.t.
r.t.
4o
4p
87
84
94,31 9532
9631
OH
OCOMe
18
2k
3a
10
r.t.
4q
90
9142f
OH
OCOMe
e
e
e
19
20
2l
3a
3a
–
r.t.
r.t.
–
–
OH
2m
10
4r
95
83,42f 94,42a 9842b
MeOCO
Synthesis 2008, No. 22, 3625–3632 © Thieme Stuttgart · New York
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3628
M. Barbero et al.
PAPER
Table 1 o-Benzenedisulfonimide-Catalyzed Acylation of Alcohols, Phenols, and Thiolsa (continued)
Entry Substrate 2
Anhydride 3 Time Temp Product 4
Yieldb Lit. yieldc
(min) (°C)
(%)
(%)
OCOMe
OH
21
22
2n
2o
3a
3a
5
5
r.t.
r.t.
4s
4t
80
OH
OH
OCOMe
80
e
e
e
23
2p
3a
–
r.t.
–
–
24
25
2q
2q
3a
3b
5
r.t.
r.t.
4u
4v
94
87,42f 93,31 97,31
OCOMe
OH
15
88
78
OCOEt
OCOMe
OH
90,42d 95,31 98,42e
26
27
2r
2s
3a
3a
2 h
5
r.t.
r.t.
4w
4x
(82)f 9932
93
OH
OCOMe
f
g
g
28
29
2s
2t
3c
3a
–
80
–
–
1 h
5 h
r.t.
4y
4z
86f
71f
Cl3C
OH
Cl3C
Cl3C
OCOMe
30
31
2t
3c
3a
80
OCOPh
h
h
h
2u
–
r.t.
–
–
OH
OH
i
i
i
32
2v
3a
–
r.t.
–
–
a Reaction conditions: 2/3 (1:1.1), o-benzenedisulfonimide (5 mol%).
b Yields refer to pure isolated products (flash chromatography; PE–Et2O, 95:5).
c Literature yields refer to Brønsted acid catalyzed acylation reactions.
d Value in parentheses refers to scaled-up run (see experimental section).
e Under these conditions, GC-MS analyses showed the presence of acylated isomers in a mixture with other unidentified products. In entry 19,
4p and 4q were identified by comparison with the same pure products from entries 17 and 18. In entry 23, two peaks with m/z 176 [M+]),
attributable to the expected acylation product and to the isomerized cinnamyl derivative, were detected.
f Reaction conditions: 2/3 (1:2).
g Dehydration product was identified by GC-MS analyses (m/z 132 [M+]).
h GC-MS analyses showed the presence of only traces of the expected ester (m/z 178 [M+]); olefinic products were identified and isolated as
major products: 2-phenylprop-1-ene [yield: 31%; m/z 118 [M+]; 1H NMR (200 MHz, CDCl3, TMS): d = 2.11 (d, J = 3.6 Hz, 3 H), 5.01–5.04
(m, 1 H), 5.31 (d, J = 3.4 Hz, 1 H), 7.18–7.33 (m, 3 H), 7.39–7.45 (m, 2 H)]56 and 4-methyl-2,4-diphenylpent-1-ene [yield: 45%; m/z 236 [M+];
1H NMR (200 MHz, CDCl3, TMS): d = 1.17 (s, 6 H), 2.78 (s, 2 H), 4.73 (m, 1 H), 5.09 (d, J = 1.8 Hz, 1 H), 7.09–7.26 (m, 10 H)].22a They
probably derive from competitive side reactions of alcohol 2u.
i The reaction does not proceed. Disappearance of 2v was observed, but only traces of acylated product were detected by GC-MS analysis
(m/z 302 [M+]). The reaction probably stops owing to the formation of the highly stabilized triphenylmethyl carbocation.
Synthesis 2008, No. 22, 3625–3632 © Thieme Stuttgart · New York

PAPER
o-Benzenedisulfonimide as a Catalyst for Acylation
3629
13C NMR (50 MHz, CDCl3): d = 9.52, 28.00, 118.28, 121.35,
125.64, 126.12, 126.62 (2 C), 127.11, 128.26, 134.84, 146.89,
173.14.
All the reactions were conducted in vials using analytical grade re-
agents and were monitored by GC and GC-MS spectrometry. GC-
MS data were recorded with an HP 5989B mass selective detector
connected to an HP 5890 GC cross-linked methyl silicone capillary
MS (EI, 70 eV): m/z = 200 (20) [M+], 144 (100).
1
column. H NMR and 13C NMR spectra were recorded in CDCl3
1-Naphthyl Benzoate (4c)59
with a Bruker Avance 200 spectrometer at 200 MHz and 50 MHz,
respectively; chemical shifts are given relative to CDCl3. TLC were
performed on Merck silica plates GF 254; flash chromatography
was carried out on silica gel (particle size 0.032–0.063 mm). Petro-
leum ether (PE) refers to the fraction boiling in the range 40–60 °C.
Structure and purity of all the products were confirmed by compar-
ison of their spectral data (MS and 1H NMR) with those reported in
literature or with those of available commercial samples. Commer-
cially available reagents and solvents were purchased from Aldrich
and were used without purification or distillation prior to use;
Dowex 50X8 ion-exchange resin was purchased from Fluka. o-Ben-
zenedisulfonimide (1) was prepared as described in the literature.57
1H NMR (200 MHz, CDCl3): d = 7.29–7.88 (m, 10 H), 7.90–8.35
(m, 2 H).
13C NMR (50 MHz, CDCl3): d = 118.45, 121.48, 125.69, 126.29,
126.69 (2 C), 127.22, 128.27, 128.94 (2 C), 129.62, 130.53 (2 C),
133.98, 134.90, 147.06, 165.39.
MS (EI, 70 eV): m/z = 248 (15) [M+], 115 (20), 105 (100).
Phenyl Acetate (4d)60
1H NMR (200 MHz, CDCl3): d = 2.24 (s, 3 H), 7.03 and 7.04 (2 d
overlapped, J = 8.6, 8.2 Hz, 2 H), 7.17 (t, J = 7.6 Hz, 1 H), 7.33 (t,
J = 7.2 Hz, 2 H).
Acylation; General Procedure
13C NMR (50 MHz, CDCl3): d = 21.35, 121.78 (2 C), 126.04,
129.64 (2 C), 152.20, 169.73.
MS (EI, 70 eV): m/z = 136 (20) [M+], 94 (100).
A mixture of substrate 2 (2.0 mmol), acid anhydride 3 (2.2 mmol,
1.1 equiv), and o-benzenedisulfonimide (1, 5 mol%, 0.1 mmol,
0.022 g) was stirred at r.t. in a vial. The exothermic reaction was
stopped after 5 min, previous TLC and GC analyses. The mixture
was treated with Et2O and H2O (1:1, 10 mL); organic layer was
washed with 5% aq NaHCO3, dried (Na2SO4), and concentrated un-
der reduced pressure affording virtually pure products 4, purified by
flash chromatography on a short column (silica gel, PE–Et2O,
9.5:0.5).
S-Phenyl Thioacetate (4e)3
1H NMR (200 MHz, CDCl3): d = 2.36 (s, 3 H), 7.30–8.45 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 30.43, 128.14, 129.43 (2 C),
129.66, 134.68 (2C), 194.28.
MS (EI, 70 eV): m/z = 152 (30) [M+], 110 (100).
The aqueous layer from the various reactions were collected and
evaporated under reduced pressure. The residue was passed through
a column of Dowex 50X8 ion-exchange resin (1.6 g for 1 g of prod-
uct), eluting with H2O. After removal of H2O under reduced pres-
sure, virtually pure (1H NMR) o-benzenedisulfonimide (1) was
recovered; mp 192–194 °C (toluene) (Lit.57 192–194 °C).
2,6-Dichlorophenyl Acetate (4f)
Colorless oil; bp 111–112 °C/2.4 mbar.
1H NMR (200 MHz, CDCl3): d = 2.33 (s, 3 H), 7.06 (dd, J = 8.6, 7.4
Hz, 1 H), 7.28 (d, J = 7.8 Hz, 2 H).
13C NMR (50 MHz, CDCl3): d = 20.41, 127.37, 128.82 (2 C),
129.10 (2 C), 144.23, 167.51.
MS (EI, 70 eV): m/z = 204 (20) [M+], 162 (100).
In the case of entry 7, the reaction was carried out on a large scale,
starting from alcohol 2e (13.02 g, 0.1 mol) and Ac2O (3a, 11.22 g,
0.11 mol), in the presence of 5 mol% o-benzenedisulfonimide (1,
1.10 g). The very exothermic reaction was stopped after stirring at
r.t. for 5 min. The usual workup gave virtually pure octyl acetate
(GC, GC-MS, 1H and 13C NMR) (16.84 g; 98%) as a colorless oil
and o-benzenedisulfonimide was recovered in 91% yield (1.00 g;
virtually pure: 1H and 13C NMR).57
Octyl Acetate (4g)61
1H NMR (200 MHz, CDCl3): d = 0.81 (t, J = 5.8 Hz, 3 H), 1.15–
1.35 (m, 10 H), 1.50–1.59 (m, 2 H), 1.97 (s, 3 H), 3.98 (t, J = 6.7
Hz, 2 H).
13C NMR (50 MHz, CDCl3): d = 14.23, 21.17, 22.80, 26.09, 28.78,
29.38 (2 C), 31.95, 64.83, 171.39.
The acylation products 4a–e and 4g–z are known compounds. They
1
were characterized by GC-MS, H and 13C NMR spectra and by
comparison with those reported in literature (for 4e, 4h, 4i, 4j, 4l,
4n, 4s, 4t, 4u, 4v, and 4w) or with those of available commercial
samples (for 4a, 4d, 4g, 4k, 4m, 4o, 4p, 4q, and 4r); spectral prop-
erties for 4b–c and 4x–z are not yet reported in the literature. Details
for the reactions and yields of the pure (GC, GC-MS, TLC, H
NMR) isolated products are listed in Table 1.
MS (EI, 70 eV): m/z = 173 (5) [M+ + 1], 57 (100).
Octyl Benzoate (4h)62
1H NMR (200 MHz, CDCl3): d = 0.82 (t, J = 6.7 Hz, 3 H), 1.20–
1.38 (m, 10 H), 1.63–1.78 (m, 2 H), 4.25 (t, J = 6.7 Hz, 2 H), 7.32–
7.55 (m, 3 H), 7.96–8.03 (m, 2 H).
1
13C NMR (50 MHz, CDCl3): d = 14.30, 22.85, 26.25, 28.92, 29.46
(2 C), 32.00, 65.34, 128.50 (2 C), 129.72 (2 C), 130.73, 132.97,
166.88.
1-Naphthyl Acetate (4a)3
1H NMR (200 MHz, CDCl3): d = 2.41 (s, 3 H), 7.20 (d, J = 7.6 Hz,
1 H), 7.38–7.49 (m, 3 H), 7.70 (d, J = 8.4 Hz, 1 H), 7.80–7.85 (m, 2
H).
13C NMR (50 MHz, CDCl3): d = 21.24, 118.30, 121.33, 125.62,
126.27, 126.67 (2 C), 126.97, 128.276, 134.85, 146.79, 169.78.
MS (EI, 70 eV): m/z = 234 (5) [M+], 123 (100).
S-Octyl Thioacetate (4i)63
1H NMR (200 MHz, CDCl3): d = 0.76–0.83 (m, 3 H), 1.15–1.35 (m,
8 H), 1.40–1.62 (m, 4 H), 2.24 (s, 3 H), 2.78 (t, J = 7.0 Hz, 2 H).
MS (EI, 70 eV): m/z = 186 (25) [M*], 144 (100).
13C NMR (50 MHz, CDCl3): d = 14.27, 22.82, 29.02, 29.33 (3 C),
1-Naphthyl Propanoate (4b)58
1H NMR (200 MHz, CDCl3): d = 1.34 (t, J = 7.6 Hz, 3 H), 2.73 (q,
J = 7.6 Hz, 2 H), 7.22 (d, J = 7.4 Hz, 1 H), 7.38–7.50 (m, 3 H), 7.70
(d, J = 8.2 Hz, 1 H), 7.81–7.86 (m, 2 H).
29.69, 30.81, 31.97, 196.23.
MS (EI, 70 eV): m/z = 188 (15) [M+], 145 (100).
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S-Octyl Thiobenzoate (4j)64
(–)-Menthyl Acetate (4r)3
1H NMR (200 MHz, CDCl3): d = 0.82 (t, J = 6.7 Hz, 3 H), 1.20–
1.35 (m, 10 H), 1.52–1.68 (m, 2 H), 3.01 (t, J = 7.2 Hz, 2 H), 7.32–
7.52 (m, 3 H), 7.88–7.94 (m, 2 H).
1H NMR (200 MHz, CDCl3): d = 0.66 (d, J = 6.8 Hz, 3 H), 0.79 (d,
J = 7.2 Hz, 6 H), 0.80–1.05 (m, 3 H), 1.18–1.40 (m, 2 H), 1.50–1.65
(m, 2 H), 1.72–1.90 (m, 2 H), 1.93 (s, 3 H), 4.57 (dt, J = 10.8, 4.4
Hz, 1 H).
13C NMR (50 MHz, CDCl3): d = 14.28, 22.84, 29.36 (4 C), 29.77,
31.99, 127.36 (2 C), 128.72 (2 C), 133.45, 137.50, 192.26.
MS (EI, 70 eV): m/z = 250 (5) [M+], 105 (100).
13C NMR (50 MHz, CDCl3): d = 16.51, 20.89, 21.45, 22.17, 23.62,
26.44, 31.52, 34.41, 41.08, 47.14, 74.26, 170.80.
MS (EI, 70 eV): m/z = 199 (2) [M+ + 1], 95 (100).
Benzyl Acetate (4k)3
1H NMR (200 MHz, CDCl3): d = 2.04 (s, 3 H), 5.05 (s, 2 H), 7.25–
Oct-1-en-3-yl Acetate (4s)67
7.35 (m, 5 H).
1H NMR (200 MHz, CDCl3): d = 0.81 (t, J = 6.6 Hz, 3 H), 1.16–
1.26 (m, 6 H), 1.50–1.60 (m, 2 H), 1.99 (s, 3 H), 5.06–5.22 (m, 3 H),
5.71 (ddd, J = 17.0, 10.4, 6.3 Hz, 1 H).
13C NMR (50 MHz, CDCl3): d = 21.19, 66.50, 128.44 (3 C), 128.75
(2 C), 136.14, 171.06.
MS (EI, 70 eV): m/z = 150 (50) [M+], 108 (100).
13C NMR (50 MHz, CDCl3): d = 14.15, 21.42, 22.68, 24.89, 31.72,
34.32, 75.04, 116.65, 136.85, 170.55.
Benzyl Propanoate (4l)65
MS (EI, 70 eV): m/z = 155 (2) [M+ – 15], 99 (100).
1H NMR (200 MHz, CDCl3): d = 1.10 (t, J = 7.6 Hz, 3 H), 2.33 (q,
J = 7.6 Hz, 2 H), 5.07 (s, 2 H), 7.30 (m, 5 H).
Cyclohex-2-enyl Acetate (4t)68
1H NMR (200 MHz, CDCl3): d = 1.47–1.84 (m, 6 H), 1.93 (s, 3 H),
5.10–5.15 (m, 1 H), 5.54–5.62 (m, 1 H), 5.79–5.88 (m, 1 H).
13C NMR (50 MHz, CDCl3): d = 9.31, 27.80, 66.33, 128.38 (2 C),
128.75 (2 C), 136.32, 174.50.
MS (EI, 70 eV): m/z = 164 (45) [M+], 91 (100).
13C NMR (50 MHz, CDCl3): d = 18.98, 21.51, 24.99, 28.41, 68.19,
125.83, 132.77, 170.86.
Benzyl Benzoate (4m)66
MS (EI, 70 eV): m/z = 140 (10) [M+], 79 (100).
1H NMR (200 MHz, CDCl3): d = 5.32 (s, 2 H), 7.31–7.69 (m, 8 H),
8.02–8.06 (m, 2 H).
1-Phenylethyl Acetate (4u)3,31
1H NMR (200 MHz, CDCl3): d = 1.48 (d, J = 6.6 Hz, 3 H), 2.02 (s,
3 H), 5.83 (q, J = 6.6 Hz, 1 H), 7.25–7.31 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 66.89, 128.37, 128.44, 128.58,
128.81, 129.92, 130.37, 133.23, 136.29, 166.63.
MS (EI, 70 eV): m/z = 212 (45) [M+], 105 (100).
13C NMR (50 MHz, CDCl3): d = 21.57, 22.41, 72.51, 126.29 (2 C),
128.07, 128.69 (2 C), 141.87, 170.54.
S-Benzyl Thioacetate (4n)3
MS (EI, 70 eV): m/z = 164 (40) [M+], 122 (100).
1H NMR (200 MHz; CDCl3): d = 2.29 (s, 3 H), 4.06 (s, 2 H), 7.20–
7.25 (m, 5 H).
1-Phenylethyl Propanoate (4v)69
1H NMR (200 MHz, CDCl3): d = 1.16 (t, J = 7.4 Hz, 3 H), 1.48 (d,
J = 6.6 Hz, 3 H), 2.30 (q, J = 7.4 Hz, 2 H), 5.85 (q, J = 6.6 Hz, 1 H),
7.22–5.35 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 30.54, 33.65, 127.49, 128.85 (2 C),
129.02 (2 C), 137.81, 195.34.
MS (EI, 70 eV): m/z = 166 (35) [M+], 91 (100).
13C NMR (50 MHz, CDCl3): d = 9.30, 22.50, 28.08, 72.28, 126.25
(2 C), 128.01, 128.69 (2 C), 142.07, 173.90.
MS (EI, 70 eV): m/z = 178 (35) [M+], 105 (100).
3-Phenylprop-2-enyl Acetate (4o)3
1H NMR (200 MHz, CDCl3): d = 2.04 (s, 3 H), 4.67 (d, J = 6.4 Hz,
2 H), 6.24 (dd, J = 16.0, 6.4 Hz, 1 H), 6.60 (d, J = 16.0 Hz, 1 H),
7.19–7.35 (m, 5 H).
Diphenylmethyl Acetate (4w)31
1H NMR (200 MHz, CDCl3): d = 2.12 (s, 3 H), 6.86 (s, 1 H), 7.23–
7.32 (m, 10 H).
13C NMR (50 MHz, CDCl3): d = 21.22, 65.29, 123.35, 126.81 (2 C),
128.28, 128.81 (2 C), 134.41, 136.38, 171.05.
MS (EI, 70 eV): m/z = 176 (45) [M+], 115 (100).
13C NMR (50 MHz, CDCl3): d = 21.52, 77.09, 127.32 (4 C), 128.14
(2 C), 128.74 (4 C), 140.43 (2 C), 170.25.
Geranyl Acetate (4p)3
MS (EI, 70 eV): m/z = 226 (25) [M+], 165 (100).
1H NMR (200 MHz, CDCl3): d = 1.53 (s, 3 H), 1.61 and 1.63 (2 s
overlapped, 6 H), 1.98–2.08 (m, 7 H), 4.518 (d, J = 7.04 Hz, 2 H),
4.98–5.07 (m, 1 H), 5.27 (t, J = 6.8 Hz, 1 H).
2-Methyl-1-phenylpropan-2-yl Acetate (4x)3
1H NMR (200 MHz, CDCl3): d = 1.38 (s, 6 H), 1.91 (s, 3 H), 2.99
(s, 2 H), 7.10–7.23 (m, 5 H).
13C NMR (50 MHz, CDCl3): d = 22.76, 26.17 (2 C), 46.62, 82.26,
126.61, 128.13 (2 C), 130.73 (2 C), 137.53, 170.84.
13C NMR (50 MHz, CDCl3): d = 16.45, 17.86, 21.24, 25.86, 26.46,
39.71, 61.58, 118.40, 123.91, 132.01, 142.46, 171.32.
MS (EI, 70 eV): m/z = 196 (2) [M+], 69 (100).
MS (EI, 70 eV): m/z = 177 (5) [M+ – 15], 132 (94), 91 (100).
Neryl Acetate (4q)3
1H NMR (200 MHz, CDCl3): d = 1.53 (s, 3 H), 1.60 (s, 3 H), 1.69
(s, 3 H), 1.93–2.07 (m, 7 H), 4.48 (d, J = 7.4 Hz, 2 H), 4.95–5.07
(m, 1 H), 5.28 (t, J = 7.3 Hz, 1 H).
1,1,1-Trichloro-2-methylpropan-2-yl Acetate (4y)70
1H NMR (200 MHz, CDCl3): d = 1.84 (s, 6 H), 2.04 (s, 3 H).
13C NMR (50 MHz, CDCl3): d = 21.38 (2 C), 22.40, 88.85, 106.10,
169.30.
MS (EI, 70 eV): m/z = 203 (10) [M+ – 15], 123 (80), 59 (100).
13C NMR (50 MHz, CDCl3): d = 17.82, 21.24, 23.69, 25.86, 26.81,
32.33, 61.29, 119.28, 123.73, 132.35, 142.83, 171.28.
MS (EI, 70 eV): m/z = 196 (2) [M+], 69 (100).
Synthesis 2008, No. 22, 3625–3632 © Thieme Stuttgart · New York

PAPER
o-Benzenedisulfonimide as a Catalyst for Acylation
3631
1,1,1-Trichloro-2-methylpropan-2-yl Benzoate (4z)71
(18) Parac-Vogt, T. N.; Deleersnyder, K.; Binnemans, K. Eur. J.
Org. Chem. 2005, 1810.
1H NMR (200 MHz, CDCl3): d = 1.99 (s, 6 H), 7.39 (t, J = 7.3 Hz,
2 H), 7.50 (app q, J = 7.2 Hz, 1 H), 8.00 (d, J = 7.5 Hz, 2 H).
(19) (a) CuSO4·5H2O: Heravi, M. M.; Behbahani, F. K.;
Zadsirjan, V.; Oskooie, H. A. J. Braz. Chem. Soc. 2006, 17,
1045. (b) Cu(ClO4)2: Jeyakumar, K.; Chand, D. K. J. Mol.
Catal. A: Chem. 2006, 255, 275. (c) Chakraborti, A. K.;
Gulhane, R.; Shivani Synthesis 2004, 111. (d) Cu(OTf)2:
Saravanan, P.; Singh, V. K. Tetrahedron Lett. 1999, 40,
2611.
13C NMR (50 MHz, CDCl3): d = 21.61 (2 C), 89.39, 106.65, 128.66
(2 C), 130.03 (2 C), 130.86, 133.41, 164.62.
MS (EI, 70 eV): m/z = 280 (5) [M+], 105 (100).
Acknowledgment
(20) Chakraborti, A. K.; Gulhane, R.; Shivani Synlett 2003,
1805.
The authors are grateful to Italian MIUR and to Università degli
Studi di Torino for the financial support.
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