Synthesis and reactivity of π-electron-deficient (arylsulfonyl)acetates

Article abstract of DOI:10.1002/hlca.200290013

Different π-electron-deficient (arylsulfonyl)acetates 9 were synthesized (Scheme 1, Table 1), and their behavior as soft nucleophiles in the dialkylation reaction under phase-transfer catalysis conditions was studied (Schemes 2 and 3, Tables 2 and 3). The [3,5-bis(trifluoromethyl)phenyl]sulfonyl group was shown to be the best substituent for the stereoselective synthesis of (E)-aconitates 18 via an alkylation hydro-sulfonyl-elimination integrated process under very mild phase-transfer-catalysis conditions (Scheme 5, Table 4). Sulfonylacetates 9h,i also underwent smooth Diels-Alder reactions with acyclic and cyclic dienes via in situ formation of the appropriate dienophile through a Knoevenagel condensation with paraformaldehyde (Scheme 6). Reductive desulfonylation with Zn and NH₄Cl in THF was shown to be an efficient method for removal of the synthetically useful sulfonyl moiety (Scheme 7).

Full text of DOI:10.1002/hlca.200290013

Helvetica Chimica Acta Vol. 85 (2002)
4287
Synthesis and Reactivity of p-Electron-Deficient (Arylsulfonyl)acetates
by Diego A. Alonso, Carmen Na¬jera*, and Montserrat Varea
¬
Departamento de QuÌmica Organica, Universidad de Alicante Apartado 99, E-03080 Alicante
(phone: ‡34-965903728; fax: ‡34-965903549; e-mail: cnajera@ua.es)
Dedicated to Professor Dieter Seebach on the occasion of his 65th birthday
Different p-electron-deficient (arylsulfonyl)acetates 9 were synthesized (Scheme 1, Table 1), and their
behavior as soft nucleophiles in the dialkylation reaction under phase-transfer catalysis conditions was studied
(Schemes 2 and 3, Tables 2 and 3). The [3,5-bis(trifluoromethyl)phenyl]sulfonyl group was shown to be the best
substituent for the stereoselective synthesis of (E)-aconitates 18 via an alkylation hydro-sulfonyl-elimination
integrated process under very mild phase-transfer-catalysis conditions (Scheme 5, Table 4). Sulfonylacetates 9h,i
also underwent smooth Diels-Alder reactions with acyclic and cyclic dienes via in situ formation of the
appropriate dienophile through a Knoevenagel condensation with paraformaldehyde (Scheme 6). Reductive
desulfonylation with Zn and NH4Cl in THF was shown to be an efficient method for removal of the synthetically
useful sulfonyl moiety (Scheme 7).
1. Introduction.
The sulfonyl group is a well-established activating moiety
introduced in an intermediate molecule for the construction of CÀC bonds and other
transformations [1]. During the last years, the use of sulfones in organic synthesis has
been a common synthetic methodology in many total syntheses and in the preparation
of an infinite collection of functionalized compounds. The ability of the sulfonyl group
to stabilize carbanions is one of the best known features of these compounds [2], they
can act also as radical stabilizers [3] and as cationic synthons [4]. Since removal of
the sulfonyl group, generally by a reductive process or via a base-promoted
b-elimination route [5], is simple, sulfones have become a very popular tool for
organic chemists.
Electron-deficient sulfonyl groups are of particular interest in synthetic chemistry
as they represent one of the strongest neutral electron-withdrawing functionalities
known. The presence of electron-withdrawing substituents at the sulfonyl moiety
increases to a large extent the acidity of H-atoms at the a position, facilitating
deprotonation and subsequent desulfonylation steps.
(Perfluoroalkyl)sulfonyl groups [6], such as triflones (ˆ(trifluoromethyl)sulfones),
are used as electron-deficient sulfonyl moieties for the stabilization of carbanions [7],
as a tool to activate olefins in nucleophilic additions or cycloaddition reactions, and as
nucleofuge leaving groups [8]. However, they have to be prepared from sodium
triflinate (ˆsodium trifluoromethanesulfinate)1), which is not commercially available,
and have a great tendency to decompose by sulfur dioxide extrusion [5]. On the other
hand, p-electron deficient arylsulfonyl derivatives are very stable compounds and are
1
)
Sodium triflinate is usually prepared from the unaccessible trifluorobromomethane [9].

4288
Helvetica Chimica Acta Vol. 85 (2002)
usually prepared from commercially available starting materials. They have been
successfully used as base-labile amino-protecting groups2) for peptide synthesis as an
alternative to the most popular (9H-fluoren-9-ylmethoxy)carbonyl (Fmoc) group [11].
Some representative examples depicted in Figure are the 4-nitro- (Nsc) [12], 4-bromo-
(Bsc) [13], 4-(methylsulfonyl)- (Mpc) [13][14], and 2,4-dinitro-substituted [15]
[(phenylsulfonyl)ethoxy]carbonyl groups 1 4. p-Electron-deficient arylsulfones have
also been employed to improve the desulfonylation processes; the 4-fluorophenyl and
2-naphthyl sulfones have been shown to increase the rate and yield of the reaction
under typical sodium-amalgam desulfonylation conditions when compared with phenyl
or 4-methylphenyl sulfones [16]. Besides, the very efficient stannyl-radical-mediated
cleavage of p-electron-deficient heterocyclic sulfones such as 5 (Fig.) has recently been
developed for the synthesis of a-fluorinated esters and phosphonates [17]. Pyridin-2-yl
sulfones such as 6 (Fig.) have been used as glycosylation agents in the presence of SmII
and SmIII species as reducing agents [18]. Although the ability of the sulfone group to
stabilize carbanions is known, only a few examples of p-electron-deficient sulfones
have been reported in the literature. Acetal carbanions derived from 7 substituted with
an electron-withdrawing group (EWG) can be mainly dialkylated in the case of the
(nitrophenyl)sulfonyl systems [19]. In the total synthesis of rhizoxin D, a natural
macrolactone with potent antitumor and antifungal activity, the (3,4-dichlorophenyl)-
sulfonyl group has been introduced to improve the yield in the alkylation of the lithium
diisopropylamide generated carbanion derived from compound 8 and for the hydro-
sulfonyl elimination step (1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1058) in com-
parison with the phenylsulfonyl moiety [20].
Figure. p-Electron-deficient sulfones
In a preliminary publication [21], we have recently reported the use of p-electron-
deficient (arylsulfonyl)acetates 9 as soft nucleophiles for the stereoselective synthesis
of (E)-aconitates via an alkylation/hydro-sulfonyl-elimination sequence under very
mild phase-transfer-catalysis (PTC) conditions. Herein, we report the full account of
the synthesis and reactivity of a complete series of p-electron-deficient (arylsulfonyl)-
acetates 9.
2
)
For a recent review on N-protecting groups, see [10].

Helvetica Chimica Acta Vol. 85 (2002)
4289
2. Results and Discussion. The series of p-electron deficient (arylsulfonyl)acetates
9 was synthesized via an alkylation/oxidation sequence of the corresponding arylthiols
10 (Scheme 1, Table 1). (Arylthio)acetates 11 were readily accessible and obtained in
quantitative yields by reaction with alkyl bromoacetates with either NaH or Et3N as the
base in MeCN at room temperature for 1 d. Only the alkylation of pentafluorothio-
phenol with benzyl bromoacetate (Table 1, Entry 3) proceeded in low yield to give 11c
along with uncharacterizable by-products probably obtained from nucleophilic
aromatic substitution reactions of the starting thiol with the reaction product3). The
¾
oxidation of (arylthio)acetates 11 was carried out with Oxone in MeOH/H2O or 3-
chloroperbenzoic acid (MCPBA) in CH2Cl2 at room temperature for 1 d. A variety of
p-electron-deficient (arylsulfonyl)acetates 9a i were prepared in good to excellent
yields (Table 1, Entries 1 9) as well as the 4-methylphenyl derivative 9j4) (Table 1,
Entry 10).
Scheme 1. Synthesis of (Arylsulfonyl)acetates
a) See Table 1 for Ar and R.
Table 1. Synthesis of (Arylsulfonyl)acetates 9
Entry
Ar
Base
R
(Arylthio)acetate 11
Oxidant
(Arylsulfonyl)acetate 9
No.
Yield [%]a)
No.
Yield [%]b)
1
2
3
3-CF3-C6H4
4-NO2-C6H4
C6F5
NaH
NaH
NaH
Bn
Bn
Bn
11a
11b
11c
90
95
30
Oxone
Oxone
Oxone
9a
9b
9c
83
47
68
4
Et3N
Bn
11d
90
Oxone
9d
30
5
6
7
8
9
Pyridin-2-yl
Et3N
Et3N
Et3N
NaH
NaH
Bn
Bn
iPr
Bn
iPr
iPr
11e
11f
11g
11h
11i
80
85
90
98
99
MCPBA
MCPBA
Oxone
Oxone
Oxone
9e
9f
9g
9h
9i
56
62
73
75
Pyrimidin-2-yl
3,4-(Cl)2C6H3
3,5-(CF3)2C6H3
3,5-(CF3)2C6H3
4-Me-C6H4
92
10
9j
80c)
a) Isolated yield determined for the crude reaction mixture after 1 d reaction time. All the crude
(arylthio)acetates 11 showed a high purity (> 95%) as determined by H-NMR (300 MHz). b) Isolated yield
1
after flash chromatography, based on starting 11 after 1 d reaction time. c) Isopropyl (4-methylphenyl)sulfo-
nyl]acetate (9j) was prepared in 80% yield by reaction of the corresponding sodium 4-methylbenzene sulfinate
with isopropyl bromoacetate in DMF at r.t. for 1 d.
3
)
It is known that pentafluorophenyl compounds containing electron-withdrawing groups react with
nucleophilic reagents to give 1,4-disubstituted compounds [22].
Isopropyl [(4-methylphenyl)sulfonyl]acetate (9j) was prepared in 80% yield by reaction of the
corresponding sodium 4-methylbenzenesulfinate with isopropyl bromoacetate in DMF at room
temperature for 1 d (see Exper. Part).
4
)

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Helvetica Chimica Acta Vol. 85 (2002)
First, we studied the effect of the different electron-withdrawing groups in the
alkylation reaction of the sulfonyl-substituted substrates under PTC conditions5). The
reaction was studied treating the different (arylsulfonyl)acetates 9 with benzyl bromide
in the presence of K2CO3 or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as base and
Bu4NBr as phase-transfer catalyst in MeCN for 1 d at room temperature (Scheme 2,
Table 2). In the case of the (4-methylphenyl)sulfonyl derivative 9j, the alkylation
Scheme 2. Dibenzylation of (Arylsulfonyl)acetates
a) See Table2 for Ar and R.
Table 2. Dibenzylation of (Arylsulfonyl)acetates 9
Entry
Ar
R
Base
Product
Yield [%]a)
1
2
3
3-CF3-C6H4
4-NO2-C6H4
C6F5
Bn
Bn
Bn
K2CO3
K2CO3
K2CO3
12a
12b
12c
30
66
28
b
4
Bn
K2CO3
12d
)
5
6
7
8
9
Pyridin-2-yl
Bn
Bn
iPr
Bn
iPr
iPr
K2CO3
K2CO3
DBU
K2CO3
K2CO3
K2CO3
12e
12f
12g
12h
12i
64
Pyrimidin-2-yl
3,4-(Cl)2C6H3
3,5-(CF3)2C6H3
3,5-(CF3)2C6H3
4-Me-C6H4
58
30c)
58
71
10
12j
50d)
a) Isolated yield after flash chromatography, based on starting 9 after 1 d reaction time. b) Only decomposition
products were detected by 1H-NMR analysis (300 MHz) of the crude reaction mixture. c) The reaction did not
work in the presence of inorganic bases such as K2CO3 and KOH. d) Monoalkylated isopropyl 2-[(4-
methylphenyl)sulfonyl]-3-phenylpropanoate was also obtained in 50% yield.
reaction afforded a 1:1 mixture of mono- and dibenzylated products (Table 2,
Entry 10). Under the same conditions, p-electron-deficient (arylsulfonyl)acetates 9a i
furnished the corresponding dialkylated products 12a i in good yields, except for the
(1-oxidopyridin-2-yl)sulfonyl derivative 12d, which decomposed (Table 2, Entry 4). In
the case of [(pentafluorophenyl)sulfonyl]acetate 9c, a very low 28% yield of
dialkylated product was obtained. The dialkylation of the [(3,4-dichlorophenyl)sulfo-
nyl]acetate 9g was unproductive in the presence of K2CO3 and other inorganic bases
such as KOH. When DBU was used as base, a very low 30% yield was obtained after 2 d
5
)
For a study of the substituent effects on the pKa values of different substituted aryl phenacyl sulfones, see
[23].

Helvetica Chimica Acta Vol. 85 (2002)
4291
(Table 2, Entry 7). The best yields in the dialkylation reaction were obtained with the 4-
nitrophenyl, pyridin-2-yl, pyrimidin-2-yl, and [3,5-bis(trifluoromethyl)phenyl]sulfonyl
derivatives (Table 2, Entries 2, 5, 6, 8, and 9). The isopropyl acetate 9i afforded the
highest yield (71%) in the dialkylation process (Table 2, Entry 9).
A variety of electrophiles were found to undergo this useful dialkylation reaction
under PTC conditions with the [3,5-bis(trifluoromethyl)phenyl]sulfonyl derivatives
9h,i, which had been shown to contain the best activating group. These substrates
underwent dialkylation upon deprotonation with 3 equiv. of K2CO3 in MeCN at room
temperature to give functionalized p-electron-deficient arylsulfonyl derivatives in
moderate to excellent yields (Scheme 3, Table 3). Different alkyl halides such as methyl
iodide, allyl bromide, and prop-2-ynyl bromide furnished the corresponding products
13a d in good yields (Table 3, Entries 1 4). When the alkylation reaction was carried
out with methyl (2E)-4-bromobut-2-enoate (Scheme 3, Table 3, Entry 5), a 42%
isolated yield of the monoallylated product 14a was obtained. When methyl 2-
(bromomethyl)prop-2-enoate was used as electrophile, 6 equiv. of base had to be used
to afford the dialkylated product in 58% yield (Table 3, Entry 6). Dialkylated sulfonyl
derivatives 13c and 13g were subjected to a PdII-catalyzed cycloisomerization [24]. As
shown in Scheme 4, palladium acetate (5 mol-%) catalyzed the cyclization of both 1,6-
dienic sulfonyl derivatives in a HCl-saturated CHCl3 solution at 608 to afford, after
12 h, the cyclopentene derivatives with high regio- and stereoselectivity and in
moderate yields. The relative configuration of the cyclic sulfonyl derivatives 15 and 16
was determined by NOESY experiments. (Arylsulfonyl)cyclopentanecarboxylates
were also synthesized in very good yields with 1,4-dihalides as electrophiles (Table 3,
Entries 9 12). Cyclopentenecarboxylate 13i with a phenylsulfonyl group has been
used as starting material for the generation of ethyl 3-oxocyclopenta-1,4-diene-1-
carboxylate, a very reactive dienophile [25].
Scheme 3. Dialkylation of {[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}acetates
a) See Table 3 for R and X.
Michael diaddition of sulfonylacetate 9i with different acceptors was studied under
two different reaction conditions (Scheme 3 and Table 3). Method A consisted in the
use of substoichiometric amounts of DBU (0.2 equiv.) at 608 in MeCN for 1 d.
Method B involved the use of Si(OEt)4 and CsF as base at 608 for 1 d [26]. Entries 13
and 14 of Table 3 show that the Michael diaddition delivered better yields with
Method A in the case of methyl and tert-butyl prop-2-enoates as electrophiles. Under
the same reaction conditions, methyl vinyl ketone led to the expected dialkylated

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Helvetica Chimica Acta Vol. 85 (2002)
Table 3. Dialkylation of {[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}acetates 9h,i
‡
Entry
R
E
Product 13 or 14
No.
X
Yield [%]a)
1
2
3
4
5
6
7
8
9
Bn
Bn
iPr
Bn
iPr
iPr
iPr
iPr
Bn
Bn
MeI
13a
13b
13c
13d
14a
13e
13f
13g
13h
13i
Me
89
74
81
67
CH2ˆCHCH2Br
CH2ˆCHCH2Br
HCꢀCCH2Br
CH2ˆCHCH2
CH2ˆCHCH2
HCꢀCCH2
(E)-MeO2CCHˆCHCH2Br
MeO2CC(ˆCH2)CH2Br
(E)-PhCHˆCHCH2Br
Me2CˆCHCH2Br
I(CH2)4I
(E)-MeO2CCHˆCHCH2
MeO2CC(ˆCH2)CH2
(E)-PhCHˆCHCH2
Me2CˆCHCH2
(CH2)4
42b)
58c)
48b)
78b)
73
10
(Z)-BrCH2CHˆCHCH2Br
(Z)-CH2CHˆCHCH2
92
11
12
Bn
iPr
13j
13k
57
65
13
14
15
16
iPr
iPr
iPr
iPr
CH2ˆCHCO2Et
13l
CH2CH2CO2Et
CH2CH2CO2 Bu
CH2CH2COMe
CH2CH2CONH2
54d), 35e)
74d), 62e)
58
t
t
CH2ˆCHCO2 Bu
13m
13n
14c
CH2ˆCHCOMe
CH2ˆCHCONH2
47b)
a) Isolated yield after flash chromatography based on starting sulfonylacetate after 1 d reaction time. b) 2 Equiv.
of K2CO3 were used. c) 6 Equiv, of K2CO3 were used. With 3 equiv. of base, monoalkylated product 14b (see
Exper. Part) was obtained as the only product in 41% yield. d) Method A: DBU (0.2 equiv.), LiBr, THF, 608, 1 d.
e) Method B: Si(OEt)4, CsF, 608, 1 d.
Scheme 4. Cycloisomerization Reactions
compound in 58% yield (Table 3, Entry 15). The reaction carried out with prop-2-
enamide afforded only the monoalkylated derivative 14c in 47% yield (Table 3,
Entry 16).
When the dialkylation/reaction was carried out with ethyl bromoacetate as the
electrophile under the same PTC conditions as described above but in the presence of
6 equiv. of base (Scheme 5, Table 4), sulfonylacetates 9a,b,f cleanly underwent a
dialkylation elimination process to provide stereoselectively the (E)-aconitate (ˆ(1E)-

Helvetica Chimica Acta Vol. 85 (2002)
4293
prop-1-ene-1,2,3-tricarboxylate 18a6) in moderate yields (Table 4, Entries 1, 2, and
4)7). The 3,5-[bis(trifluoromethyl)phenyl]sulfonyl group showed again the best
activating effect; thus sulfonylacetate 9h gave aconitate 18a after 3 d at room
temperature with higher yield (Table 4, Entry 5). The integrated process was faster
when the reaction was carried out with isopropyl {[3,5-bis(trifluoromethyl)phenyl]sul-
fonyl}acetate (9i). Aconitate 18b was then obtained in 71% yield after 3 d at room
temperature (Table 4, Entry 6) and in 60% yield when the mixture was warmed up to
608 for 1 d (Table 4, Entry 7)8). These results can be compared with those obtained
with [(4-methylphenyl)sulfonyl]acetate 9j, which afforded 18b in a poor 35% isolated
yield after 2 d at 608 (Table 4, Entry 8). The integrated process was unsuccessful in the
case of [(pyridin-2-yl)sulfonyl]acetate 9e, which afforded the corresponding dialky-
lated product 17 in moderate yield (Scheme 5, Table 4, Entry 3).
Scheme 5. Synthesis of Aconitates 18
a) For Ar, R, and yields, see Table 4.
Table 4. Synthesis of Aconitates 18
Entry
Starting ester 9
T [8]
Time [d]
Aconitate 18
Ar
R
No.
No.
Yield [%]a)
1
2
3
4
5
6
7
8
3-CF3-C6H4
4-NO2-C6H4
Pyridin-2-yl
Pyrimidin-2-yl
3,5-(CF3)2C6H3
3,5-(CF3)2C6H3
3,5-(CF3)2C6H3
4-Me-C6H4
Bn
Bn
Bn
Bn
Bn
iPr
iPr
iPr
9a
9b
9e
9f
9h
9i
r.t.
r.t.
r.t.
r.t.
r.t.
r.t.
60
4
3
7
7
3
3
1
2
18a
18a
17
18a
18a
18b
18b
18b
50
20
50
30
64
71
60
35
9i
9j
60
a) Isolated yield after flash chromatography based on starting sulfonylacetate 9.
(Arylsulfonyl)acetates 9 have been shown to be very efficient precursors of reactive
methylenic dienophiles in a Knoevenagel condensation reaction with paraformalde-
hyde (Scheme 6). This is a very interesting transformation as the chemistry of 1,1-
disubstituted alkenes containing two electron-withdrawing groups have received
significant attention in recent years [29]. The Knoevenagel condensation of sulfony-
6
)
)
)
The configurations of aconitates 18 were determined with the aid of NOESY and non-decoupled 13C-NMR
experiments (3J(HCˆC, CH2CˆC) ˆ 7.7 Hz for the (E) isomer and 5.5 Hz for the (Z) isomer.
Trimethyl aconitates have recently been used as versatile synthetic building blocks in the synthesis of
heterocycles by means of domino reactions [27].
7
8
A similar synthesis of triethyl aconitates has been performed by reaction of sodium triflinate and ethyl
i
bromoacetate in the presence of KI and Pr2EtN in N,N-dimethylacetamide at 808 for 145 h in 67% yield
(see [28]).

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Helvetica Chimica Acta Vol. 85 (2002)
lacetate 9h with paraformaldehyde in the presence of 2,3-dimethylbuta-1,3-diene gave
the corresponding Diels-Alder adduct 19 in 83% yield after 5 h (Scheme 6). Under the
same conditions, derivative 9i reacted with paraformaldehyde in the presence of cyclic
1,3-dienes such as cyclopenta-1,3-diene and cyclohexa-1,3-diene, affording bicyclic
Diels-Alder adducts 20 and 21 in good yields and moderate diastereoselectivity (endo/
exo 3 :1) (Scheme 6)9). The first step of the reaction is the formation of the
corresponding dienophile intermediates, which are very unstable and were not isolated.
The cycloaddition reactions were carried out in sealed tubes at 1008 in AcOH as solvent
and with Cu(OAc)2 as catalyst [30].
Scheme 6. Diels-Alder Cycloadditions
Finally, the reduction of dibenzylated ester 12i was carried out with Zn in the
presence of ammonium chloride in refluxing THF for 1 d to give ester 22 in 70% yield
(Scheme 7).
Scheme 7. Reduction of Sulfonylacetate 12i with Zinc
In conclusion, of all synthesized p-electron-deficient (arylsulfonyl)acetates 9, the
[3,5-bis(trifluoromethyl)phenyl]sulfonyl group was shown to be the best substituent for
the dialkylation of these acetates and the alkylation/hydro-sulfonyl-elimination
sequence under very mild phase-transfer-catalysis conditions, allowing the stereo-
selective synthesis of (E)-aconitates. Sulfonylacetates 9h,i also underwent smooth
Diels-Alder reactions with acyclic and cyclic dienes via in situ formation of the
appropriate dienophile by a Knoevenagel condensation with paraformaldehyde.
9
)
The configuration of bicyclic derivatives 20 and 21 was determined by NOESY experiments.

Helvetica Chimica Acta Vol. 85 (2002)
4295
Reductive desulfonylation with Zn and NH4Cl in THF was shown to be an efficient
method for the removal of the synthetically useful sulfonyl moiety.
¬
This work was supported by the DGES of the Spanish Ministerio de Educacion y Cultura (MEC) (PB97-
0123). We thank the Unidad de Resonancia of Alicante University for specific NMR measurements. D. A. A.
¬
thanks MEC for a contract under the program Acciones para la Incorporacion a Espanƒa de Doctores y
¬
Tecnologos.
Experimental Part
1. General. Commercial chemicals and solvents were used without further purification unless otherwise
¾
stated. Flash chromatography (FC): silica gel 60 (0.040 0.063 mm; Merck). TLC: Polygram -SIL-G/UV254
plates; elution with hexane/AcOEt 2 :1. M.p.: Reichert Thermovar. IR Spectra: Nicolet Impact-400D-FT
spectrophotometer; in cmÀ1. NMR Spectra: Bruker AC-300 or Avance-DRX-500 spectrometer; in CDCl3; d in
ppm rel. to SiMe4 (ˆ0 ppm), J in Hz. EI-MS: mass-selective detector G2579A from Agilent Technolo-
gies 5973N; in m/z (rel. intensity in % of the base peak). HR-MS: Finningan MAT95S apparatus. Elemental
analyses: Carlo Erba EA 1108 (CHNS-O); performed by the corresponding services at the University of
Alicante.
2. (Arylthio)acetates 11a c, 11h, and 11i. To a soln. of the corresponding thiol 10 (5 mmol) and 95% of NaH
(150 mg, 6 mmol) in MeCN (15 ml) under N2 was added at 08 the corresponding alkyl bromoacetate (5.5 mmol).
The mixture was stirred at r.t. for 1 d. After quenching with H2O (20 ml), the mixture was extracted with AcOEt
(2 Â 20 ml). The combined org. layers were dried (Na2SO4) and evaporated: (arylthio)acetates 11, which were
used for the next step without further purification.
Benzyl {[3-(Trifluoromethyl)phenyl]thio}acetate (11a). Yield 1.467 g (90%). Rf 0.70. IR: 1735, 1275, 1128.
1H-NMR: 7.62 (s, 1 arom. H); 7.74 (d, J ˆ 7.3, 1 arom. H); 7.40 (d, J ˆ 7.9, 1 arom. H); 7.31 7.25 (m, 6 arom. H);
5.10 (s, CH2O); 3.66 (s, CH2S). 13C-NMR: 168.81 (CˆO); 136.39, 135.00 (arom. C); 131.12 (q, J(C,F) ˆ 31.7,
CCF3); 132.35, 129.23, 128.36, 128.24, 128.11, 125.76, 123.23 (arom. CH); 120.02 (q, J(C,F) ˆ 271.7, CF3); 67.18
‡
(CH2O); 35.77 (CH2S). EI-MS: 326 (10, M ), 191 (40), 171 (10), 91 (100), 65 (11). HR-EI-MS: 326.0513
‡
(C16H13SO2F3 ; calc. 326.0588).
Benzyl [(4-Nitrophenyl)thio]acetate (11b). Yield 1.439 g (95%). Rf 0.60. IR: 1735, 1517, 1342, 1267, 11.80.
1H-NMR: 8.05 (d, J ˆ 8.5, 2 arom. H); 7.36 7.25 (m, 7 arom. H); 5.17 (s, CH2O); 3.79 (s, CH2S). 13C-NMR:
166.78(C ˆO); 140.92, 140.79, 134.22 (arom. C); 131.38, 128.90, 128.72, 128.58, 128.51, 127.67, 127.01, 124.15
‡
(arom. CH); 65.28(CH 2O); 54.72 (CH2S). EI-MS: 303 (5, M ), 168(19), 121 (12), 100 (100). HR-EI-MS:
‡
303.0621 (C15H13NO4S ; calc. 303.0565).
Benzyl [(2,3,4,5,6-Pentafluorophenyl)thio]acetate (11c). Yield 522 mg (30%). Rf 0.65. IR: 1738, 1273, 1128.
1H-NMR: 7.39 7.19 (m, 5 arom. H); 5.09 (s, CH2O); 3.57 (s, CH2S). 13C-NMR: 168.19 (CˆO); 134.81
‡
(arom. C); 128.63, 128.57, 128.52 (arom. CH); 67.63 (CH2O); 35.58(CH 2S). EI-MS: 348(19, M ), 203 (22),
‡
105 (18), 92 (17), 91 (100), 77 (19), 65 (32), 51 (17), 46 (10), 45 (37). HR-EI-MS: 348.0217 (C15H9F5O2S ; calc.
348.0243).
Benzyl {[3,5-Bis(trifluoromethyl)phenyl]thio}acetate (11h). Yield 1.930 g (98%). Rf 0.69. IR: 1738, 1280,
1137. 1H-NMR: 7.77 (s, 2 arom. H); 7.67 (s, 1 arom. H); 7.32 7.24 (m, 5 arom. H); 5.14 (s, CH2O); 3.76
(s, CH2S). 13C-NMR: 168.17 (CˆO); 138.75, 134.86 (arom. C); 132.43 (q, J(C,F) ˆ 32.2, 2 CCF3); 128.67, 128.56,
128.48, 127.70, 126.97 (arom. CH); 122.85 (q, J(C,F) ˆ 271.7, 2 CF3); 67.76 (CH2O); 35.47 (CH2S). EI-MS: 394
‡
‡
(4, M ), 259 (10), 91 (100). HR-EI-MS: 394.0472 (C17H12F6O2S ; calc. 394.0462).
Isopropyl {[3,5-Bis(trifluoromethyl)phenyl]thio}acetate (11i). Yield 1.713 g (99%). Rf 0.71. IR: 1735, 1282,
1138. 1H-NMR: 7.82 (s, 2 arom. H); 7.70 (s, 1 arom. H); 5.11 5.01 (m, Me2CH); 3.72 (s, CH2S); 1.22 (d, J ˆ 6.7,
Me2CH). 13C-NMR: 168.17 (CˆO); 139.19 (arom. C); 132.21 (q, J(C,F) ˆ 32.2, 2 CCF3); 128.27, 128.24, 119.99
(arom. CH); 122.95 (q, J(C,F) ˆ 271.7, 2 CF3); 69.91 (Me2CH); 35.69 (CH2S); 21.46 (Me2CH). EI-MS: 346 (49,
‡
‡
M ), 285 (11), 260 (26), 259 (100), 239 (30). HR-EI-MS: 346.0479 (C13H12F6O2S ; calc. 346.0462).
3. (Arylthio)acetates 11d g. To a soln. of the corresponding thiol 10 (5 mmol) and Et3N (1425 ml, 10 mmol)
in MeCN (15 ml) was added the corresponding alkyl bromoacetate. The mixture was stirred at r.t. for 1 d. After
quenching the mixture with a sat. aq. NH4Cl soln. (20 ml), the mixture was extracted with AcOEt (2 Â 20 ml).
The combined org. layers were dried (Na2SO4) and evaporated: (arylthio)acetates 11, which were used in the
next step without further purification.
Benzyl [(1-Oxidopyridin-2-yl)thio]acetate (11d). Yield 1.238g (90%). M.p. 94 95 8. IR: 1728, 1245, 1141.
1H-NMR: 8.18 (d, J ˆ 6.0, 1 arom. H); 7.35 7.18( m, 7 arom. H); 7.14 (t, J ˆ 8.5, 1 arom. H); 5.16 (s, CH2O);

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3.76 (s, CH2S). 13C-NMR: 168.81 (CˆO); 150.25, 134.59 (arom. C); 128.21, 128.16, 128.00, 125.65, 121.83,
‡
120.89, 113.89 (arom. CH); 67.18 (CH2O); 35.77 (CH2S). EI-MS: 275 (1, M ), 168(11), 127 (14), 125 (13), 124
‡
(64), 120 (19), 111 (31), 91 (100), 79 (14), 78(42), 77 (11), 65 (15), 51 (18). Anal. calc. for C 14H13NO3S (275):
C 61.08, H 4.76, N 5.09, S 11.64; found: C 60.74, H 5.00, N 5.14, S 11.46.
Benzyl (Pyridin-2-ylthio)acetate (11e). Yield 1.036 g (80%). Rf 0.69. IR: 1728, 1270, 1148. 1H-NMR: 8.30
(d, J ˆ 3.7, 1 arom. H); 7.60 7.31 (m, 6 arom. H); 7.19 (d, J ˆ 7.9, 1 arom. H); 6.96 6.93 (m, 1 arom. H); 5.16
(s, CH2O); 4.00 (s, CH2S). 13C-NMR: 169.40 (CˆO); 135.42, 128.13 (arom. C); 149.07, 135.80, 128.22, 127.95,
‡
127.90, 121.68, 119.54 (arom. CH); 66.82 (CH2O); 32.02 (CH2S). EI-MS: 259 (6, M ), 168(14), 125 (17), 124
‡
(89), 120 (28), 111 (41), 91 (100), 79 (11), 78 (43), 65 (15), 51 (17). HR-EI-MS: 259.0681 (C14H13NO2S ; calc.
259.0667).
Benzyl (Pyrimidin-2-ylthio)acetate (11f). Yield 1.105 g (85%). Rf 0.60. IR: 1740, 1295, 1151. 1H-NMR: 8.43
(d, J ˆ 4.9, 2 arom. H); 7.36 7.29 (m, 5 arom. H); 6.95 (t, J ˆ 4.9, 1 arom. H); 5.19 (s, CH2O); 3.97 (s, CH2S).
13C-NMR: 168.92 (CˆO); 170.44, 135.41 (arom. C); 157.07, 128.31, 128.08, 116.70 (arom. CH); 66.99 (CH2O);
‡
33.26 (CH2S). EI-MS: 259 (6, M ), 154 (19), 126 (11), 125 (68), 112 (40), 98 (11), 91 (100), 65 (13). HR-EI-MS:
‡
260.0690 (C13H12N2O2S ; calc. 260.0619).
Isopropyl [(3,4-Dichlorophenyl)thio]acetate (11g). Yield 1.251 g (90%). Rf 0.71. IR: 1730, 1282, 1141.
1H-NMR: 7.56 7.19 (m, 3 arom. H); 5.06 4.97 (m, Me2CH); 3.60 (s, CH2S); 1.22 (d, J ˆ 6.1, Me2CH).
13C-NMR: 168.40 (CˆO); 135.33, 128.93, 126.55 (arom. C); 130.76, 130.44, 128.65 (arom. CH); 69.36 (Me2CH);
‡
36.40 (CH2S); 21.50 (Me2CH). EI-MS: 278(73, M ), 236 (13), 195 (13), 193 (68), 192 (13), 191 (100), 142 (18).
‡
HR-EI-MS: 277.9895 (C11H12Cl2O2S ; calc. 277.9935).
4. (Arylsulfonyl)acetates 9a d and 9g i. To a soln. of the corresponding (arylthio)acetate 11 (5 mmol) in
¾
MeOH/H2O 1:1 (40 ml) was added portionwise Oxone (30.75 g, 50 mmol) at 08. The mixture was stirred
vigorously at r.t. for 1 d. The MeOH was evaporated and the residue diluted with CH2Cl2 (40 ml) and washed
with brine (3 Â 50 ml). The org. layer was dried (Na2SO4) and evaporated and the crude product purified by FC
(hexane/AcOEt): (arylsulfonyl)acetates 9.
Benzyl {[3-(Trifluoromethyl)phenyl]sulfonyl}acetate (9a). Yield 1.486 g (83%). Rf 0.38. IR: 1745, 1327,
1285, 1163, 1142. 1H-NMR: 8.18 (s, 1 arom. H); 8.03 (d, J ˆ 7.9, 1 arom. H); 7.85 (d, J ˆ 7.9, 1 arom. H); 7.59
(t, J ˆ 7.3, 1 arom. H); 7.33 7.21 (m, 5 arom. H); 5.09 (s, CH2O); 4.21 (s, CH2S). 13C-NMR: 161.79 (CˆO);
139.59, 134.15 (arom. C); 131.88, 130.65, 129.88, 128.57, 128.45, 128.36, 125.44 (arom. CH); 132.16 (q, J(C,F) ˆ
‡
30.5, CCF3); 122.88 (q, J(C,F) ˆ 271.7,CF3); 67.93 (CH2O); 60.39 (CH2S). DIP-MS: 358(6, M ), 338(29), 336
(45), 303 (12), 285 (13), 282 (18), 271 (17), 269 (100), 267 (78), 265 (35), 253 (22), 252 (42), 251 (25), 249 (16),
247 (12), 235 (12), 233 (40), 231 (74), 229 (68), 227 (16), 225 (10), 219 (15), 218 (11), 217 (17), 216 (10), 213
(27), 212 (17), 211 (36), 210 (28), 209 (15), 205 (33), 204 (85), 203 (68), 202 (10), 199 (18), 197 (62), 196 (21),
195 (34), 194 (75), 193 (39), 192 (20), 185 (20), 183 (43), 182 (17), 181 (43), 180 (15), 179 (12), 177 (46), 175
(56), 173 (12), 171 (13), 169 (16), 165 (39), 163 (18), 162 (26), 161 (59), 160 (29), 159 (40), 158 (18), 157 (18),
151 (10), 149 (59), 148(25), 147 (75), 146 (31), 144 (12), 143 (25), 141 (20), 140 (12), 137 (17), 135 (28), 133
(22), 127 (36), 126 (46), 125 (35), 123 (21), 121 (29), 119 (52), 117 (46), 115 (19), 114 (27), 113 (41), 112 (58),
111 (69), 110 (38), 109 (69), 108 (12), 107 (53), 101 (15), 99 (40), 95 (75), 89 (26), 87 (22), 85 (65), 83 (71), 82
(10), 79 (22), 78 (16), 77 (81), 76 (59), 75 (57), 73 (13), 64 (11), 63 (21), 51 (27). HR-DIP-MS: 358.0486
‡
(C16H13F3O4S ; calc. 358.0486).
Benzyl [(4-Nitrophenyl)sulfonyl]acetate (9b). Yield 787 mg (47%). M.p. 83 848. IR: 1734, 1533, 1341,
1308, 1276, 1158, 1108. 1H-NMR: 8.23 (d, J ˆ 8.5, 2 arom. H); 7.98 (d, J ˆ 8.5, 2 arom. H); 7.38 7.23
(m, 5 arom. H); 5.10 (s, CH2O); 4.22 (s, CH2S). 13C-NMR: 161.62 (CˆO); 150.90, 143.64, 134.03 (arom. C);
130.05, 129.03, 128.90, 128.66, 124.18 (arom. CH); 68.33 (CH2O); 60.58(CH 2S). DIP-MS: 224 (1, [M À
‡
CH2Ph] ), 211 (18), 170 (78), 150 (36), 149 (85), 148 (27), 141 (28), 125 (22), 124 (10), 123 (10), 122 (55),
120 (74), 109 (18), 108 (51), 107 (100), 106 (72), 105 (85), 92 (12), 91 (31), 90 (49), 79 (84), 78 (12), 77 (57), 75
(30), 65 (24), 63 (17), 51 (46). Anal. calc. for C15H13NO6S (335): C 53.73, H3.91, N 4.18, S 9.56; found: C 53.64,
H 4.09, N 4.00, S 8.78.
Benzyl [(2,3,4,5,6-Pentafluorophenyl)sulfonyl]acetate (9c). Yield 1.292 g (68%). M.p. 1198. IR: 1758, 1354,
1286, 1120, 1158. 1H-NMR: 7.36 7.23 (m, 5 arom. H); 5.14 (s, CH2O); 4.33 (s, CH2S). 13C-NMR: 163.53 (CˆO);
‡
134.14 (arom. C); 128.89, 128.81, 128.58 (arom. CH); 68.02 (CH2O); 56.86 (CH2S). DIP-MS: 380 (100, M ), 233
(29), 232 (12), 231 (66), 216 (17), 215 (63), 195 (12), 184 (15), 183 (63), 181 (35), 168 (73), 167 (36), 155 (15),
150 (77), 149 (37), 148(37), 1121 (12), 120 (33), 119 (12), 177 (47), 109 (15), 108(42), 107 (21), 106 (70), 105
(57), 104 (13), 99 (12), 93 (13), 92 (48), 91 (23), 90 (46), 89 (47), 80 (27), 79 (31), 78 (24), 77 (38), 65 (18), 64
(24), 63 (32), 52 (21), 51 (34). Anal. calc. for C15H9F5O4S (380): C 47.38, H 2.39, S 8.43; found: C 47.83, H 2.59,
S 7.99.

Helvetica Chimica Acta Vol. 85 (2002)
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Benzyl [(1-Oxidopyridin-2-yl)sulfonyl]acetate (9d). Yield 460 mg (30%). Rf 0.20. IR: 1715, 1366, 1266,
1
1161, 1141. H-NMR: 8.20 (d, J ˆ 6.7, 1 arom. H); 7.92 (dd, J ˆ 7.9, 1.2, 1 arom. H); 7.41 (t, J ˆ 6.1, 1 arom. H);
7.34 7.20 (m, 6 arom. H); 5.06 (s, CH2O); 4.89 (s, CH2S). 13C-NMR: 162.13 (CˆO); 146.05, 134.10 (arom. C);
‡
140.68, 129.67, 128.69, 128.58, 127.76, 125.49 (arom. CH); 68.02 (CH2O); 57.09 (CH2S). DIP-MS: 307 (0.3, M ),
254 (10), 252 (22), 250 (13), 248(39), 235 (25), 234 (10), 232 (10), 220 (40), 219 (18), 218(30), 217 (21), 216
(24), 201 (10), 200 (38), 186 (22), 185 (73), 184 (10), 183 (10), 182 (16), 181 (13), 172 (12), 168 (52), 167 (32),
160 (17), 159 (53), 158(70), 156 (49), 155 (42), 154 (43), 145 (19), 144 (53), 143 (25), 142 (26), 128(11), 127
(49), 126 (56), 125 (11), 114 (11), 113 (14), 112 (100), 111 (10), 110 (60), 108(16), 107 (51), 106 (34), 105 (81),
96 (86), 93 (14), 92 (26), 91 (36), 90 (79), 89 (78), 80 (37), 79 (15), 78 (17), 77 (29), 76 (18), 67 (11), 66 (36), 65
‡
(22), 64 (44), 63 (71), 53 (11), 52 (50), 51 (15). HR-DIP-MS: 307.0536 (C14H13NO5S ; calc. 307.0514).
Isopropyl [(3,4-Dichlorophenyl)sulfonyl]acetate (9g). Yield 1.132 g (73%). M.p. 79 808. IR: 1733, 1336,
1
1288, 1143, 1088. H-NMR: 8.04 (s, 1 arom. H); 7.78( d, J ˆ 7.9, 1 arom. H); 7.67 (d, J ˆ 7.9, 1 arom. H); 5.05
4.97 (m, Me2CH); 4.11 (s, CH2S); 1.22 (d, J ˆ 6.1, Me2CH). 13C-NMR: 161.48(C ˆO); 138.33, 133.92 (arom. C);
‡
131.22, 130.70, 127.72 (arom. CH); 70.82 (CH2O); 61.08(CH 2S); 21.46 (Me2CH). DIP-MS: 310 (9, M ), 253
(44), 251 (75), 228(25), 226 (43), 213 (14), 211 (88), 209 (100), 208(12), 206 (91), 205 (12), 204 (90), 193 (11),
164 (26), 162 (44), 161 (25), 159 (34), 149 (12), 147 (83), 146 (12), 145 (94), 111 (21), 110 (17), 109 (60), 85
(10), 75 (29), 74 (23), 59 (27). Anal. calc. for C11H12Cl2O4S (310): C 42.46, H 3.89, S 10.30; found: C 39.94,
H 3.83, S 10.01.
Benzyl {[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}acetate (9h). Yield 1.598g (75%). M.p. 96 98 8. IR: 1732,
1318, 1294, 1148, 1135. 1H-NMR: 8.37 (s, 2 arom. H); 8.12 (s, 1 arom. H); 7.35 7.22 (m, 5 arom. H); 5.12
(s, CH2O); 4.25 (s, CH2S). 13C-NMR: 161.55 (CˆO); 141.23, 132.89 (arom. C); 133.29 (q, J(C,F) ˆ 35.4,
2 CCF3); 128.68, 128.45 (arom. CH); 122.30 (q, J(C,F) ˆ 271.7, 2 CF3); 68.41 (CH2O); 60.34 (CH2S). DIP-MS:
‡
426 (86, M ), 407 (35), 365 (21), 335 (12), 279 (10), 277 (31), 262 (12), 261 (80), 214 (23), 183 (21), 182 (11),
163 (30), 150 (35), 149 (27), 148(47), 147 (10), 144 (21), 121 (24), 120 (94), 109 (21), 108(35), 107 (19), 106
(100), 105 (56), 103 (14), 92 (57), 91 (13), 90 (78), 89 (31), 79 (63), 78 (27, 77 (52)), 63 (16), 51 (42). Anal. calc.
for C17H12F6O4S (426): C 46.38, H 2.92, S 7.74; found: C 46.27, H 2.80, S 7.39.
Isopropyl {[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}acetate (9i). Yield 1.739 g (92%). M.p. 109 1108. IR:
1727, 1361, 1288, 1184, 1141. 1H-NMR: 8.43 (s, 2 arom. H); 8.19 (s, 1 arom. H); 5.08 4.97 ( m, Me2CH); 4.19
(s, CH2S); 1.21 (d, J ˆ 6.7, Me2CH). 13C-NMR: 161.21 (CˆO); 141.49 (arom. C); 133.09 (q, J(C,F) ˆ 35.4,
2CCF3); 129.31, 127.82 (arom. CH); 122.32 (q, J(C,F) ˆ 271.7, 2 CF3); 71.18(Me 2CH); 60.86 (CH2S); 21.37
‡
(Me2CH). DIP-MS: 378(12, M ), 359 (35), 320 (36), 319 (100), 318(13), 317 (41), 293 (10), 279 (30), 278(11),
272 (58), 243 (10), 214 (13), 213 (22), 194 (24), 163 (23), 125 (19), 100 (10), 85 (20), 77 (10), 71 (10), 69 (15), 59
(33), 56 (10), 55 (18). Anal. calc. for C13H12F6O4S (378): C 41.28, H 3.20, S 8.48; found: C 41.10, H 3.19, S 7.93.
5. (Arylsulfonyl)acetates 9e f. To a soln. of the corresponding (arylthio)acetate 11 (5 mmol) in CH2Cl2
(50 ml), was added portionwise NaHCO3 (2.948g, 35 mmol) and MCPBA (3.365 g, 15 mmol) at 0 8. The mixture
was stirred vigorously at r.t. for 2 h. The mixture was then washed with sat. aq. Na2S2O3 soln. (2 Â 60 ml), sat. aq.
NaHCO3 soln. (2 Â 60 ml), and brine (2 Â 60 ml). The org. layer was dried (Na2SO4) and evaporated and the
crude product purified by FC (hexane/AcOEt): (arylsulfonyl)acetates 9e,f.
Benzyl (Pyridin-2-ylsulfonyl)acetate (9e). Yield 815 mg (56%). Rf 0.33. IR: 1742, 1325, 1276, 1166, 1110.
1H-NMR: 8.65 (s, J ˆ 4.3, 1 arom. H); 7.95 (d, J ˆ 7.9, 1 arom. H); 7.82 (2d, J ˆ 7.9, 7.3, 1 arom. H); 7.48( dd, J ˆ
7.3, 4.9, 1 arom. H); 7.36 7.17 (m, 1 arom. H); 5.06 (s, CH2O); 4.51 (s, CH2S). 13C-NMR: 162.05 (CˆO); 156.19,
134.23 (arom. C); 149.90, 137.96, 128.42, 128.37, 128.29, 127.45, 122.10 (arom. CH); 67.67 (CH2O); 55.89 (CH2S).
‡
DIP-MS: 291 (2, M ), 185 (29), 184 (100), 143 (65), 107 (17), 93 (73), 92 (11), 91 (16), 90 (26), 80 (32), 79 (14),
‡
78(52), 77 (64), 65 (78), 63 (11), 52 (33), 51 (45). HR-DIP-MS: 291.0546 (C 14H13NO4S ; calc. 291.0565).
Benzyl (Pyrimidin-2-ylsulfonyl)acetate (9f). Yield 905 mg (62%). M.p. 99 1008. IR: 1742, 1333, 1273,
1140, 1123. 1H-NMR: 8.80 (d, J ˆ 4.9, 2 arom. H); 7.46 (t, J ˆ 4.9, 1 arom. H); 7.31 7.18( m, 5 arom. H); 5.07
(s, CH2O); 4.64 (s, CH2S). 13C-NMR: 164.51 (CˆO); 161.87, 133.98 (arom. C); 158.29, 128.37, 128.31, 128.27,
‡
123.78(arom. CH); 67.75 (CH 2O); 55.15 (CH2S). DIP-MS: 292 (0.3, M ), 186 (36), 169 (23), 107 (28), 106 (11),
94 (66), 92 (23), 91 (52), 89 (10), 81 (50), 80 (100), 78 (32), 77 (50), 65 (38), 53 (57), 52 (44), 51 (32). Anal.
calc. for C13H12N2O4S (292): C 53.42, H 4.41, N 9.58, S 10.97; found: C 51.77, H 3.99, N 9.50, S 10.55.
6. Isopropyl [(4-Methylphenyl)sulfonyl]acetate (9j). A DMF soln. (30 ml) of sodium 4-methylbenzene-
sulfinate (1.430 g, 8mmol) and isopropyl bromoacetate (260 ml, 2 mmol) was stirred vigorously at r.t. for 1 d.
The mixture was diluted with AcOEt (20 ml) and washed with H2O (5 Â 60 ml). The org. layer was dried
(Na2SO4) and evaporated and the crude product purified by FC (hexane/AcOEt): 410 mg (80%) of pure 9j.
M.p. 62 638. IR: 1733, 1325, 1288, 1151, 1104. 1H-NMR: 7.82 (d, J ˆ 7.9, 2 arom. H); 7.37 (d, J ˆ 7.9, 2 arom. H);
5.01 4.92 (m, Me2CH); 4.08( s, CH2S); 2.45 (s, MeC6H4); 1.17 (d, J ˆ 6.1, Me2CH). 13C-NMR: 161.77 (CˆO);

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Helvetica Chimica Acta Vol. 85 (2002)
145.16, 135.65 (arom. C); 129.58, 128.36 (arom. CH); 70.09 (Me2CH); 61.46 (CH2S); 21.22 (Me2CH). DIP-MS:
‡
256 (6, M ), 197 (50), 192 (50), 173 (55), 172 (28), 157 (32), 156 (52), 155 (64), 151 (52), 149 (77), 139 (74), 122
(14), 121 (18), 119 (14), 108 (29), 107 (46), 106 (32), 105 (51), 103 (20), 92 (34), 91 (66), 90 (35), 89 (55), 80
(10), 79 (69), 78(45), 77 (52), 66 (39), 65 (52), 64 (42), 62 (13), 59 (100), 56 (19), 53 (17), 51 (14). Anal. calc.
for C12H16O4S (256): C 5623, H 6.29, S 12.51; found: C 55.59, H 4.48, S 12.35.
7. Dialkylation of (Arylsulfonyl)acetates with Alkyl Halides: General Procedure. To a THF soln. (3 ml) of
the corresponding (arylsulfonyl)acetate 9 (0.2 mmol),K2CO3 (87 mg, 0.6 mmol), and Bu4NBr (7 mg,
0.02 mmol) was added the corresponding alkyl halide (0.44 mmol). The mixture was stirred at r.t. for 1 d and
then the reaction quenched with sat. aq. NH4Cl soln. The aq. phase was extracted with AcOEt (2 Â 10 ml), the
combined org. phase dried (Na2SO4) and evaporated, and the crude product purified by FC (hexane/AcOEt):
alkylated compounds 12 14.
Benzyl 2-Benzyl-3-phenyl-2-{[3-(trifluoromethyl)phenyl]sulfonyl}propanoate (12a). Yield 32 mg (30%).
Rf 0.33. IR: 1735, 1326, 1278, 1177, 1140. 1H-NMR: 8.04 (s, 1 arom. H); 7.80 (2d, J ˆ 7.9, 2 arom. H); 7.44 (t, J ˆ
7.9, 1 arom. H); 7.36 7.07 (m, 15 arom. H); 5.12 (s, CH2O); 3.48, 3.41 (2d, J ˆ 14.3, 2 CH2C). 13C-NMR: 167.42
(CˆO); 139.24, 133.09, 131.28(arom. C); 131.97 ( q, J(C,F) ˆ 35.4, CCF3); 130.93, 130.26, 130.21, 129.05, 128.86,
128.68, 128.10, 127.82, 127.77, 127.32 (arom. CH); 122.30 (q, J(C,F) ˆ 271.2, CF3); 78.62 (CS); 68.17 (CH2O);
‡
39.10 (2 CH2C). DIP-MS: 538(0.06, M ), 237 (30), 219 (16), 193 (21), 192 (20), 191 (15), 178(13), 159 (20), 145
‡
(33), 131 (11), 116 (10), 115 (40), 92 (37), 91 (100), 77 (11), 65 (19). HR-DIP-MS: 538.1462 (C30H25F3O4S ;
calc. 538.1426).
Benzyl 2-Benzyl-2-[(4-nitrophenyl)sulfonyl]-3-phenylpropanoate (12b). Yield 68mg (66%). Rf 0.39. IR:
1735, 1532, 1349, 1280, 1144, 1140. 1H-NMR: 8.02 (d, J ˆ 9.2, 2 arom. H); 7.76 (d, J ˆ 8.5, 2 arom. H); 7.39 7.12
(m, 15 arom. H); 5.11 (s, CH2O); 3.50, 3.43 (2d, J ˆ 14.0, 2 CH2C). 13C-NMR: 167.24 (CˆO); 150.34, 143.48,
133.87, 133.64 (arom. C); 132.09, 130.93, 129.23, 129.13, 128.74, 128.19, 127.45, 123.12 (arom. CH); 78.94 (CS);
‡
68.44 (CH2O); 39.23 (2 CH2C). DIP-MS: 515 (0.4, M ), 75 (20), 76 (30), 79 (13), 105 (14), 107 (21), 115 (64),
116 (60), 117 (100), 118(30), 119 (56), 135 (83), 145 (57), 146 (13), 190 (97), 191 (28). HR-DIP-MS: 515.1419
‡
(C29H25NO6S ; calc. 515.1403).
Benzyl 2-Benzyl-2-[(2,3,4,5,6-pentafluorophenyl)sulfonyl]-3-phenylpropanoate (12c). Yield 31 mg (28%).
Rf 0.74. IR: 1730, 1320, 1280, 1140, 1120. 1H-NMR: 7.38 7.62 ( m, 15 arom. H); 5.19 (s, CH2O); 3.56, 3.46
(2d, J ˆ 14.0, 2 CH2C). 13C-NMR: 166.69 (CˆO); 133.72, 133.38, 129.21, 128.89, 128.82, 128.64, 128.11, 127.22
(arom. C, 5 CF); 130.83, 128.98, 128.69, 128.18, 128.04, 127.42 (arom. CH); 80.18 (CS); 68.96 (CH2O); 37.32
‡
(2 CH2C). DIP-MS: 560 (2, M ), 467 (22), 466 (95), 402 (16), 393 (17), 392 (80), 343 (10), 331 (43), 330 (17),
328(15), 313 (20), 312 (17), 307 (10), 306 (12), 283 (20), 253 (11), 252 (34), 251 (50), 250 (17), 239 (33), 238
(12), 237 (34), 233 (19), 222 (17), 221 (28), 220 (35), 219 (32), 209 (10), 205 (23), 195 (15), 194 (58), 193 (19),
192 (27), 191 (32), 190 (17), 189 (32), 187 (21), 182 (15), 181 (27), 180 (45), 179 (57), 178 (64), 177 (35), 168
(77), 167 (27), 166 (25), 165 (40), 163 (11), 162 (18), 161 (18), 160 (41), 159 (17), 152 (12), 149 (15), 143 (14),
137 (12), 132 (11), 131 (53), 129 (10), 119 (19), 118(26), 117 (33), 116 (32), 115 (32), 111 (10), 108(10), 107
(58), 106 (17), 105 (100), 104 (11), 103 (48), 102 (35), 99 (30), 97 (11), 95 (15), 93 (17), 91 (26), 90 (74), 89 (55),
83 (14), 79 (25), 78 (20), 77 (55), 75 (11), 71 (17), 69 (16), 65 (38), 64 (71), 63 (27), 57 (25), 55 (15). HR-DIP-
‡
MS: 560.1065 (C29H21F5O4S ; calc. 560.1081).
Benzyl 2-Benzyl-3-phenyl-2-(pyridin-2-ylsulfonyl)propanoate (12e). Yield 60 mg (64%). Rf 0.26. IR: 1735,
1318, 1266, 1189, 1155. 1H-NMR: 8.43 (d, J ˆ 4.3, 1 arom. H); 7.57 7.05 (m, 18arom. H); 5.19 ( s, CH2O); 3.65,
3.55 (2d, J ˆ 14.0, 2 CH2C). 13C-NMR: 167.58(C ˆO); 157.23, 134.44, 134.31 (arom. C); 148.93, 137.36, 131.09,
128.83, 128.48, 128.45, 127.87, 126.95, 126.62, 124.07 (arom. CH); 76.85 (CS); 68.04 (CH2O); 38.67 (2 CH2C).
‡
DIP-MS: 471 (0.2, M ), 407 (12), 316 (19), 298 (16), 219 (18), 192 (13), 191 (18), 178 (14), 159 (24), 115 (40),
‡
103 (10), 91 (100), 79 (42), 78(46), 77 (23), 65 (20), 52 (14). HR-DIP-MS: 472.1534 (C 28H26NO4S ; calc.
472.1582).
Benzyl 2-Benzyl-3-phenyl-2-(pyrimidin-2-ylsulfonyl)propanoate (12f). Yield 55 mg (58%). Rf 0.28. IR:
1735, 1322, 1263, 1190, 1125. 1H-NMR: 8.32 (d, J ˆ 4.9, 2 arom. H); 7.37 7.03 (m, 16 arom. H); 5.21 (s, CH2O);
3.70, 3.55 (2d, J ˆ 14.0, 2 CH2C). 13C-NMR: 167.04 (CˆO); 157.34, 131.38, 128.82, 128.45, 128.32, 127.87, 127.03,
122.65 (ArCH); 134.65, 133.82, 128.58, 128.53 (arom. C); 74.95 (CS); 67.75 (CH2O); 38.46 (2 CH2C). DIP-MS:
‡
391 (0.06, [M À pymSO2] ), 408(38), 329 (26), 299 (16), 273 (12), 237 (35), 222 (19), 221 (29), 200 (12), 219
(44), 209 (20), 195 (14), 194 (100), 193 (59), 192 (18), 191 (18), 186 (14), 183 (30), 181 (11), 180 (22), 179 (19),
178(15), 177 (31), 169 (55), 161 (50), 159 (46), 157 (15), 145 (21), 131 (18), 126 (12), 117 (23), 116 (10), 115
‡
(47), 92 (83), 91 (75), 81 (24), 80 (29), 77 (10), 65 (13), 64 (13), 51 (15). HR-DIP-MS: 472.1430 (C27H24N2O4S ;
calc. 472.1456).

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4299
Isopropyl 2-Benzyl-2-[(3,4-dichlorophenyl)sulfonyl]-3-phenylpropanoate (12g). Yield 29 mg (30%).
1
Rf 0.38. IR: 1725, 1372, 1271, 1162, 1145. H-NMR: 7.84 (s, 1 arom. H); 7.62, 7.52 (2d, J ˆ 8.6, 2 arom. H); 7.22
(m, 15 arom. H); 5.05 4.99 (m, Me2CH); 3.43 (m, 2 CH2C); 1.19 (d, J ˆ 6.1, Me2CH). 13C-NMR: 167.22
(CˆO); 138.80, 137.82, 134.23, 132.96 (arom. C); 132.79, 130.97, 130.20, 129.94, 128.05, 127.35 (arom. CH); 78.62
‡
(CS); 71.31 (CHO); 39.26 (2 CH2C); 21.46 (Me2CH). DIP-MS: 491 (4, [M ‡ 1] ), 431 (20), 283 (15), 282 (81),
280 (33), 241 (13), 240 (42), 239 (48), 237 (24), 223 (17), 222 (53), 221 (15), 220 (33), 219 (39), 209 (11), 205
(16), 196 (11), 195 (58), 194 (34), 191 (42), 190 (20), 189 (37), 181 (54), 180 (12), 179 (96), 178 (39), 167 (25),
166 (23), 165 (64), 163 (12), 162 (88), 161 (27), 160 (100), 159 (45), 152 (20), 149 (26), 148 (47), 147 (66), 146
(56), 145 (76), 143 (12), 133 (95), 132 (37), 131 (63), 130 (12), 119 (30), 118(46), 117 (41), 116 (28), 115 (14),
111 (16), 110 (16), 109 (26), 107 (87), 105 (95), 103 (91), 102 (34), 92 (23), 91 (62), 90 (13), 89 (20), 79 (24), 78
‡
(33), 77 (42), 75 (12), 74 (16), 65 (68), 64 (12), 63 (13), 51 (12). HR-DIP-MS: 490.0730 (C25H24Cl2O4S ; calc.
490.0772).
Benzyl 2-Benzyl-2-{[3,5-bis(trifluoromethyl)phenyl]sulfonyl}-3-phenylpropanoate (12h). Yield 70 mg
1
(58%). Rf 0.60. IR: 1724, 1356, 1279, 1189, 1143. H-NMR: 8.16 (s, 2 arom. H); 7.99 (s, 1 arom. H); 7.38 7.05
(m, 15 arom. H); 5.14 (s, CH2O); 3.50, 3.42 (2d, J ˆ 14.6, 2 CH2C). 13C-NMR: 167.32 (CˆO); 141.32, 133.54,
131.73 (arom. C); 131.97 (q, J(C,F) ˆ 35.4, 2 CCF3); 130.97, 130.93, 128.92, 128.69, 128.63, 128.14, 127.56, 127.08
(arom. CH); 122.29 (q, J(C,F) ˆ 271.7, 2 CF3); 79.18(CS); 68.28(CH 2O); 39.47 (2 CH2C). DIP-MS: 606 (0.2,
‡
M ), 330 (23), 329 (96), 328(40), 316 (16), 312 (12), 311 (60), 283 (14), 261 (10), 251 (18), 239 (11), 238(85),
237 (49), 222 (22), 221 (88), 220 (69), 219 (29), 214 (16), 213 (33), 205 (16), 195 (18), 194 (41), 193 (94), 192
(94), 191 (77), 181 (30), 180 (10), 179 (34), 178 (70), 167 (17), 165 (24), 163 (11), 161 (88), 160 (24), 159 (91),
145 (11), 143 (13), 131 (66), 125 (12), 117 (31), 116 (41), 115 (98), 107 (15), 105 (20), 104 (10), 103 (40), 92
‡
(100), 91 (42), 90 (13), 89 (15), 79 (11), 77 (27), 65 (65), 57 (22). HR-DIP-MS: 499.0793 (C24H17F6O3S , [M À
‡
OBn] ; calc. 499.0803).
Isopropyl 2-Benzyl-2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-3-phenylpropanoate (12i). Yield 79 mg
1
(71%). Rf 0.57. IR: 1724, 1356, 1279, 1189, 1143. H-NMR: 8.22 (s, 2 arom. H); 8.04 (s, 1 arom. H); 7.37 7.21
(m, 10 arom. H); 5.07 5.01 (m, Me2CH); 3.52, 3.44 (2d, J ˆ 14.4, 2 CH2C); 1.18( d, J ˆ 6.1, Me2CH). 13C-NMR:
167.17 (CˆO); 141.48, 136.52 (arom. C); 132.16 (q, J(C,F) ˆ 30.5, 2 CCF3); 131.10, 131.02, 130.94, 128.47, 128.14,
127.61 (arom. CH); 122.39 (q, J(C,F) ˆ 271.50, 2 CF3); 79.04 (CS); 71.64 (Me2CH); 39.52 (2 CH2C); 21.32
‡
(Me2CH). DIP-MS: 558(0.24, M ), 242 (100), 240 (11), 142 (73), 79 (17). HR-DIP-MS: 558.1300
‡
(C27H24F6O4S ; calc. 558.1299).
Isopropyl 2-Benzyl-2-[(4-methylphenyl)sulfonyl]-3-phenylpropanoate (12j)/Isopropyl 2-[(4-Methylphe-
nyl)sulfonyl]-3-phenylpropanoate. Yield 44 mg (12j/monoalkylated product 1 :1). Rf 0.58. IR: 1738, 1338,
1281, 1140, 1118. 1H-NMR: 7.80, 7.74 (2d, J ˆ 8.5, 4 arom. H); 7.34, 7.29 (2d, J ˆ 8.5, 4 arom. H); 7.25 7.12
(m, 15 arom. H); 5.00 4.91, 4.85 4.76 (2m, 2 H, Me2CH); 4.14 (dd, J ˆ 11.1, 3.3, 1 H, CHS); 3.51 3.43
(m, 4 H, CH2C); 3.42 3.37, 3.24 3.16 (2m, 2 H, CH2CH), 1.13, 0.99, 0.92 (3d, J ˆ 6.1, 12 H, 2 Me2CH).
13C-NMR: 167.53, 164.88 (CˆO); 145.42, 144.85, 135.54, 134.89, 134.58, 130.96, 130.91, 129.66, 129.40, 129.03,
128.86, 128.63, 127.84, 127.14, 126.89 (arom. C, arom. CH); 77.74 (CS); 72.13 (CHS); 70.79, 69.90 (Me2CH);
‡
38.44 (2 CH2C); 32.63 (2 CH2CH); 21.66, 21.60, 21.35, 21.23, 21.15 (2 Me2CH). DIP-MS (12j): 346 (0.4, M ), 287
(60), 192 (29), 191 (28), 190 (13), 150 (100), 149 (20), 148 (49), 147 (32), 145 (33), 132 (24), 131 (62), 107 (56),
‡
104 (35), 103 (48), 92 (26), 91 (26), 77 (33), 65 (92). DIP-MS (monoalkylated product): 436 (0.5, M ), 91 (100).
‡
‡
HR-DIP-MS: 346.1234 (C19H22O4S ; calc. 346.1239); 436.1706 (C26H28O4S ; calc. 436.1708).
Benzyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-2-methylpropanoate (13a). Yield 53 mg (58%).
Rf 0.33 (hexane/AcOEt 3 :1). IR: 1744, 1313, 1278, 1138, 1122. 1H-NMR: 8.25 (s, 2 arom. H); 8.11
(s, 1 arom. H); 7.37 724 (m, 5 arom. H); 5.12 (s, CH2O); 1.68( s, 2 Me). 13C-NMR: 168.16 (CˆO); 138.70,
134.36 (arom. C); 132.47 (q, J(C,F) ˆ 35.4, 2 CCF3); 130.86, 130.81, 128.66, 127.89, 127.53 (arom. CH); 122.33
‡
(q, J(C,F) ˆ 271.7, 2 CF3); 69.83 (CS); 68.18 (CH2O); 20.02 (2 Me). DIP-MS: 454 (0.5, M ), 176 (29), 107 (65),
‡
‡
91 (100), 70 (15). HR-DIP-MS: 347.0188 (C12H9F6O3S ; [M À OBn] ; calc. 347.0176).
Benzyl 2-Allyl-2-{[3,5-bis(trifluoromethyl)phenyl]sulfonyl}pent-4-enoate (13b). Yield 75 mg (74%).
Rf 0.33 (hexane/AcOEt 3 :1). IR: 3083, 1740, 1642, 1359, 1280, 1153, 1140. 1H-NMR: 8.26 (s, 2 arom. H);
8.11 (s, 1 arom. H); 7.36 7.27 (m, 5 arom. H); 5.83 5.73 (m, 2 CHˆ); 5.19 5.13 (m, 2 CH2ˆ); 5.13 (s, CH2O);
2.93 (dd, J ˆ 14.6, 6.7, 1 CH2C); 2.81 (dd, J ˆ 14.6, 7.3, 1 CH2C). 13C-NMR: 166.82 (CˆO); 139.37, 134.08
(arom. C); 132.43 (q, J(C,F) ˆ 34.2, 2 CCF3); 130.91, 130.20, 128.80, 128.68, 127.59 (arom. CH); 128.21
(2 CHˆ); 122.67 (q, J(C,F) ˆ 271.4, 2 CF3); 120.95 (2 CH2ˆ); 79.04 (CS); 68.35 (CH2O); 35.04 (2 CH2C). DIP-
‡
MS: 506 (4, M ), 228(15), 213 (23), 183 (12), 130 (19), 104 (11), 93 (17), 92 (100), 91 (11), 79 (23), 77 (26), 65
‡
(36), 53 (11). HR-DIP-MS: 506.1018(C 23H20F6O4S ; calc. 506.0986).

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Isopropyl 2-Allyl-2-{[3,5-bis(trifluoromethyl)phenyl]sulfonyl}pent-4-enoate (13c). Yield 74 mg (81%).
1
Rf 0.47 (hexane/AcOEt 3 :1). IR: 3086, 1728, 1639, 1357, 1281, 1184, 1146. H-NMR: 8.33 (s, 2 arom. H); 8.17
(s, 1 arom. H); 5.90 5.76 (m, 2 CHˆ); 5.23 5.17 (m, 2 CH2ˆ); 5.05 4.96 (m, Me2CH); 2.89 (dd, J ˆ 14.6, 6.7,
1 CH2C); 2.79 (dd, J ˆ 14.6, 7.3, 1 CH2C); 1.25 (d, J ˆ 6.1, Me2CH). 13C-NMR: 166.38(C ˆO); 139.54 (arom. C);
132.39 (q, J(C,F) ˆ 35.0, 2 CCF3); 131.04, 127.64, 127.61 (arom. CH); 130.43 (2 CHˆ); 122.67 (q, J(C,F) ˆ 271.4,
‡
2 CF3); 120.73 (2 CH2ˆ); 75.75 (CS); 71.24 (Me2CH); 35.18(2 CH2C); 21.32 (Me2CH). DIP-MS: 458(1, M ),
217 (10), 191 (10), 178(12), 177 (11), 176 (40), 174 (16), 173 (53), 170 (33), 167 (10), 163 (15), 149 (24), 125
(19), 123 (47), 121 (13), 105 (13), 99 (10), 98 (19), 97 (48), 95 (24), 85 (15), 83 (46), 70 (23), 69 (34), 67 (19), 57
‡
(100). HR-DIP-MS: 458.0916 (C19H20F6O4S ; calc. 458.0986).
Benzyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-2-(prop-2-ynyl)pent-4-ynoate (13d). Yield 67 mg
(67%). Rf 0.38 (hexane/AcOEt 3 :1). IR: 3292, 2105, 1739, 1370, 1280, 1186, 1147. 1H-NMR: 8.34 (s, 2 arom. H);
8.14 (s, 1 arom. H); 7.38 7.35 ( m, 5 arom. H); 5.21 (s, CH2O); 3.22 (dd, J ˆ 17.1, 2.4, 1 CH2C); 3.08( dd, J ˆ 17.1,
3.1, 1 CH2C); 2.08( t, J ˆ 2.4, 2 CHꢀC). 13C-NMR: 165.30 (CˆO); 138.42, 133.94 (arom. C); 132.77
(q, J(C,F) ˆ 34.2, 2 CCF3); 130.97, 130.92, 128.81, 128.61, 128.32 (arom. CH); 122.23 (q, J(C,F) ˆ 271.7,
2 CF3); 76.26 (2 CꢀCH); 73.84 (2 CHꢀC); 73.27 (CS); 69.09 (CH2O); 21.68(2 CH2C). DIP-MS: 502 (2,
‡
M ), 226 (15), 225 (100), 224 (89), 207 (11), 195 (28), 185 (30), 179 (45), 166 (15), 165 (17), 133 (10), 131 (31),
120 (92), 119 (18), 118 (54), 117 (14), 115 (20), 107 (76), 105 (15), 93 (17), 92 (38), 91 (35), 90 (58), 89 (38), 79
‡
(23), 65 (21). HR-DIP-MS: 502.0674 (C23H16F6O4S ; calc. 502.0673).
4-Isopropyl 2,6-Dimethyl 4-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}hepta-1,6-diene-2,4,6-tricarboxylate
(13e). Yield 67 mg (58%). Rf 0.40 (hexane/AcOEt 3 :1). IR: 3087, 1736, 1628, 1358, 1281, 1188, 1147. 1H-NMR:
8.42 (s, 2 arom. H); 8.17 (s, 1 arom. H); 6.34 (s, 1 CH2ˆC); 5.76 (s, 1 CH2ˆC); 5.10 5.05 (m, Me2CH); 3.75
(s, 2 MeO); 3.26, 3.11 (2d, J ˆ 15.3, 2 CH2C); 1.22 (d, J ˆ 6.1, Me2CH). 13C-NMR: 167.09, 166.89 (CˆO); 139.87,
134.35, 134.31 (arom. C, CˆCH2); 132.40 (q, J(C,F) ˆ 34.2, 2 CCF3); 131.53, 131.48, 127.73, 127.69, 127.59
(arom. CH); 129.42 (2 CH2ˆ); 122.30 (q, J(C,F) ˆ 271.4, 2 CF3); 76.68(CS); 71.82 (Me 2CH); 52.22 (2 MeO);
‡
32.49 (2 CH2C); 21.21 (Me2CH). DIP-MS: 531 (12, [M À OiPr] ), 500 (13), 493 (23), 469 (45), 465 (45), 436
(11), 298(14), 297 (28), 261 (25), 255 (37), 238(14), 237 (97), 261 (25), 255 (37), 224 (11), 223 (98), 222 (55),
213 (51), 209 (11), 206 (33), 205 (97), 205 (97), 195 (32), 194 (23), 192 (26), 191 (97), 179 (15), 178(15), 177
(86), 164 (15), 163 (67), 152 (12), 151 (18), 149 (34), 147 (18), 146 (22), 145 (15), 139 (13), 137 (13), 135 (42),
134 (11), 125 (10), 121 (19), 119 (41), 118(14), 107 (19), 105 (13), 92 (13), 91 (100), 79 (25), 77 (23), 69 (15), 65
‡
(28), 59 (79), 55 (13), 53 (12). HR-DIP-MS: 574.1102 (C23H24F6O8S ; calc. 574.1096).
Isopropyl (4E)-2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-5-phenyl-2-[(2E)-3-phenylprop-2-enyl]pent-
4-enoate (13f). Yield 59 mg (48%). Rf 0.44. IR: 3060, 1739, 1644, 1370, 1280, 1189, 1147. 1H-NMR: 8.36
(s, 2 arom. H); 8.16 (s, 1 arom. H); 7.31 7.24 (m, 10 arom. H); 6.50 (d, J ˆ 15.9, 2 PhCHˆ); 6.21 (dt, J ˆ 15.9,
7.32, 2 CH2CHˆ); 5.08 5.02 ( m, Me2CH); 3.10 (dd, J ˆ 14.6, 6.71, 1 CH2CHˆ); 3.00 (dd, J ˆ 14.6, 7.3,
1 CH2CHˆ); 1.26 (d, J ˆ 6.7, Me2CH). 13C-NMR: 166.49 (CˆO); 139.63, 136.54 (arom. C); 135.61, 131.02,
128.63, 126.27 (arom. CH); 132.52 (q, J(C,F) ˆ 34.2, 2 CCF3); 122.39 (q, J(C,F) ˆ 271.7, 2 CF3); 127.84, 121.75
‡
(2 CHˆCH); 76.38(CS); 71.34 (Me 2CH); 34.83 (2 CH2CHˆ); 21.46 (Me2CH). DIP-MS: 551 (2, [M À OiPr] ),
548 (10), 332 (17), 291 (23), 290 (43), 289 (86), 273 (20), 272 (20), 271 (41), 245 (51), 244 (21), 243 (43), 241
(26), 229 (13), 228 (18), 213 (26), 206 (87), 205 (37), 204 (15), 200 (18), 199 (63), 198 (18), 187 (56), 186 (37),
181 (24), 180 (100), 179 (10), 170 (14), 169 (90), 168 (10), 167 (78), 165 (18), 156 (14), 155 (87), 154 (13), 153
(28), 143 (18), 142 (48), 141 (60), 129 (73), 128 (67), 127 (22), 118 (46), 117 (37), 116 (30), 115 (44), 105 (19),
‡
104 (51), 103 (13), 92 (27), 86 (12), 77 (19). HR-DIP-MS: 610.1631 (C31H28F6O4S ; calc. 610.1613).
Isopropyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-5-methyl-2-(3-methylbut-2-enyl)hex-4-enoate
(13g). Yield 80 mg (78%). Rf 0.53 (hexane/AcOEt 8 :1). IR: 3080, 1736, 1625, 1358, 1270, 1178, 1140.
1H-NMR: 8.33 (s, 2 arom. H); 8.14 (s, 1 arom. H); 5.13 5.11 (m, 2 CHˆ); 5.06 4.97 (m, Me2CH); 2.77 (d, J ˆ
6.7, 2 CH2C); 1.70, 1.58(2 s, 2 Me2Cˆ); 1.24 (d, J ˆ 6.1, Me2CH). 13C-NMR: 167.05 (CˆO); 140.23 (arom. C);
136.39 (Me2Cˆ); 132.23 (q, J(C,F) ˆ 35.4, 2 CCF3); 130.86, 130.81, 127.33 (arom. CH); 122.45 (q, J(C,F) ˆ
271.7, 2 CF3); 116.34 (2 CHˆ); 76.64 (CS); 70.84 (Me2CH); 29.89 (2 CH2C); 25.97, 21.21 (2 Me2Cˆ); 17.96
‡
(Me2CH). DIP-MS: 514 (0.6, M ), 238 (13), 237 (100), 236 (82), 213 (20), 196 (19), 195 (86), 194 (86), 193 (82),
181 (16), 179 (59), 177 (29), 163 (10), 161 (19), 153 (12), 152 (12), 151 (62), 150 (18), 149 (87), 147 (13), 140
(24), 139 (39), 138(46), 137 (35), 133 (21), 127 (39), 126 (28), 125 (27), 124 (12), 123 (35), 121 (19), 119 (13),
111 (33), 109 (53), 108 (15), 107 (62), 105 (21), 95 (37), 94 (16), 93 (83), 91 (30), 81 (29), 80 (13), 79 (47), 77
‡
(28), 70 (14), 69 (22), 67 (22), 56 (12), 55 (12), 53 (18). HR-DIP-MS: 514.1650 (C23H28F6O4S ; calc. 514.1613).
Benzyl 1-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}cyclopentanecarboxylate (13h). Yield 70 mg (73%).
Rf 0.29 (hexane/AcOEt 3 :1). IR: 1742, 1310, 1278, 1174, 1143. 1H-NMR: 8.26 (s, 2 arom. H); 8.08
(s, 1 arom. H); 7.34 7.20 (m, 5 arom. H); 5.10 (s, CH2O); 2.52 2.34 (m, 2 CH2C); 1.98 1.86, 1.75 1.62 (2 m,

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2 CH2CH2C). 13C-NMR: 168.23 (CˆO); 140.26, 134.33 (arom. C); 132.42 (q, J(C,F) ˆ 35.4, 2 CCF3); 130.31,
130.26, 128.64, 127.84, 127.33, 127.29 (arom. CH); 122.34 (q, J(C,F) ˆ 271.7, 2 CF3); 79.68(CS); 68.23 (CH 2O);
‡
32.60 (2 CH2C); 25.31 (2 CH2CH2C). DIP-MS: 480 (0.9, M ), 349 (26), 261 (35), 213 (33), 204 (11), 203 (100),
202 (93), 157 (39), 113 (17), 108(14), 107 (53), 97 (78), 95 (74), 92 (57), 91 (18), 90 (13), 89 (11), 79 (15), 77
‡
(15), 69 (41), 68 (38), 67 (39), 65 (43), 50 (10). HR-DIP-MS: 480.0829 (C21H18F6O4S ; calc. 480.0830).
Benzyl 1-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}cyclopent-3-ene-1-carboxylate (13i). Yield 88 mg
(92%). Rf 0.38 (hexane/AcOEt 3 :1). IR: 3093, 1732, 1626, 1362, 1281, 1182, 1143. 1H-NMR: 8.31
(s, 2 arom. H); 8.02 (s, 1 arom. H); 7.34 7.10 (m, 5 arom. H); 5.58 5.41 ( m, CHˆCH); 5.07 (s, CH2O); 2.39
(dd, J ˆ 7.3, 5.50, 1 CH2C); 2.13 (dd, J ˆ 7.3, 6.1, 1 CH2C). 13C-NMR: 164.58(C ˆO); 143.01, 133.94 (arom. C);
132.39 (q, J(C,F) ˆ 34.1, 2 CCF3); 130.05, 128.87, 128.76, 128.63, 128.18 (arom. CH); 122.31 (q, J(C,F) ˆ 271.7,
‡
2 CF3); 121.43 (CHˆCH); 79.04 (CS); 68.35 (CH2O); 35.04 (2 CH2C). DIP-MS: 478(4, M ), 395 (10), 391
(12), 382 (11), 355 (16), 277 (32), 272 (19), 261 (25), 228 (11), 227 (13), 224 (17), 214 (23), 213 (100), 194 (32),
176 (11), 159 (13), 149 (24), 148(10), 145 (14), 143 (26), 141 (11), 138(13), 132 (15), 131 (12), 123 (10), 119
(18), 111 (16), 102 (10), 99 (18), 98 (19), 97 (17), 96 (18), 92 (18), 91 (81), 90 (17), 89 (14), 85 (19), 83 (34), 81
‡
(17), 77 (48), 75 (18), 71 (17), 70 (12), 69 (29), 65 (20), 57 (36). HR-DIP-MS: 387.0125 (C 14H9F6O4S , [M À
‡
Bn] ; calc. 387.0168).
Benzyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-2,3-dihydro-1H-indene-2-carboxylate (13j). Yield
60 mg (57%). Rf 0.35 (hexane/AcOEt 3 :1). IR: 1732, 1353, 1281, 1180, 1140. 1H-NMR: 8.20 (s, 2 arom. H);
8.02 (s, 1 arom. H); 7.38 7.07 ( m, 9 arom. H); 5.16 (s, CH2O); 3.83, 3.72 (2d, J ˆ 17.1, 2 CH2C). 13C-NMR:
167.24 (CˆO); 139.47, 137.92, 134.29 (arom. C); 132.43 (q, J(C,F) ˆ 34.2, 2 CCF3); 130.14, 130.09, 128.63, 127.81,
127.73, 124.18(arom. CH); 122.89 ( q, J(C,F) ˆ 271.8, 2 CF3); 79.49 (CS); 68.67 (CH2O); 38.65 (2 CH2C). DIP-
‡
MS: 528(0.7, M ), 261 (12), 250 (14), 213 (12), 149 (24), 143 (100), 139 (15), 116 (50), 105 (12), 104 (11), 97
‡
(11), 91 (75), 83 (12), 71 (20), 70 (14), 69 (13), 57 (37). HR-DIP-MS: 251.1065 (C17H15O2 , [M À
‡
(CF3)2C6H3SO2] ; calc. 251.1072).
Isopropyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-2,3-dihydro-1H-indene-2-carboxylate (13k). Yield
58mg (60%). Rf 0.43 (hexane/AcOEt 8 :1). IR: 1732, 1359, 1284, 1182, 1144. 1H-NMR: 8.27 (s, 2 arom. H); 8.08
(s, 1 arom. H); 7.14 7.07 (m, 4 arom. H); 5.04 4.98( m, Me2CH); 3.80, 3.70 (2d, J ˆ 17.1, 2 CH2C); 1.24 (d, J ˆ
6.1, Me2CH). 13C-NMR: 166.72 (CˆO); 139.63, 138.03 (arom. C); 132.92 (q, J(C,F) ˆ 35.4, 2 CCF3); 130.18,
130.13, 127.61, 124.08(arom. CH); 122.39 ( q, J(C,F) ˆ 271.7, 2 CF3); 79.44 (CS); 71.53 (CHO); 38.65 (2 CH2C);
‡
21.23 (Me2CH). DIP-MS: 480 (0.2, M ), 421 (34), 401 (23), 261 (29), 213 (16), 204 (23), 203 (88), 202 (81), 195
(10), 163 (18), 162 (86), 161 (75), 160 (45), 144 (50), 143 (47), 117 (100), 116 (35), 115 (83), 114 (13), 91 (12),
‡
‡
89 (20). HR-DIP-MS: 203.1080 (C13H15O2 , [M À (CF3)2C6H3SO2] ; calc. 203.1072).
6-Isopropyl 1-Methyl (2E)-5-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}hex-2-enedioate (14a). Yield 40 mg
(42%). Rf 0.60. IR: 3100, 1731, 1660, 1357, 1282, 1191, 1147. 1H-NMR: 8.35 (s, 2 arom. H); 8.21 (s, 1 arom. H);
6.79 (m, ˆCHCH2); 5.96 (d, J ˆ 15.3, ˆCHCO); 5.01 4.93 (m, Me2CH); 4.10 (dd, J ˆ 10.4, 4.3, CHS); 3.73
(s, MeO); 3.17 2.83 (m, CHCH2); 1.18, 1.23 (2d, J ˆ 6.1, Me2CH). 13C-NMR: 165.62, 165.59 (CˆO); 141.91
(CHˆCH2); 138.63 (arom. C); 132.62 (q, J ˆ 35.3, 2 CCF3); 130.89, 128.13, 126.41 (arom. CH); 122.34
(q, J(C,F) ˆ 271.3, 2 CF3); 124.14 (COCHˆ); 72.16 (Me2CH); 70.77 (CHS); 51.70 (MeO); 33.62 (CH2CH);
‡
21.26, 13.56 (Me2CH). DIP-MS: 445 (2, [M À OMe] ), 434 (41), 417 (11), 403 (11), 385 (13), 277 (10), 261 (13),
213 (73), 199 (10), 194 (15), 167 (17), 158(18), 157 (99), 140 (12), 139 (100), 116 (15), 115 (91), 113 (21), 111
(87), 109 (19), 108 (24), 107 (42), 99 (11), 97 (95), 83 (13), 81 (62), 80 (15), 79 (10), 71 (11), 69 (17), 68 (11), 59
‡
(34), 55 (35), 53 (53), 51 (10). HR-EI-MS: 476.0735 (C18H18F6O6S ; calc. 476.0728).
1-Isopropyl 5-Methyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-4-methylenepentanedioate (14b). Yield
39 mg (41%). Rf 0.40 (hexane/AcOEt 8 :1). IR: 3077, 1730, 1629, 1356, 1281, 1181, 1144. 1H-NMR: 8.36
(s, 2 arom. H); 7.64 (s, 1 arom. H); 5.98, 5.24 (2s, ˆCH2); 4.80 4.69 (m, Me2CHO); 4.57 (dd, J ˆ 11.0, 4.0,
CHS); 3.17 (s, MeO); 3.14 3.13 (m, 1 H, CHCH2); 2.88 2.80 (m, 1 H, CHCH2); 0.81 (d, J ˆ 6.1, Me2CH).
13C-NMR: 166.02, 164.10 (CˆO); 140.21 (arom. C); 133.95 (CˆCH2); 133.01 (q, J(C,F) ˆ 35.3, 2 CCF3); 129.82,
127.90, 127.85, 127.82 (arom. CH); 122.28 (q, J(C,F) ˆ 271.3, 2 CF3); 124.10 (CˆCH2); 71.06 (CHO); 69.01
‡
(CHS); 52.28(MeO); 29.85 ( CH2Cˆ); 21.45, 21.22 (Me2CH). DIP-MS: 476 (1, M ), 385 (24), 277 (11), 213
(27), 199 (11), 194 (18), 163 (16), 157 (72), 144 (14), 139 (18), 125 (100), 112 (16), 98 (21), 97 (84), 82 (17), 81
‡
(24), 59 (23), 55 (23), 53 (88), 51 (16). HR-DIP-MS: 476.0733 (C18H18F6O6S ; calc. 476.0728).
8. Alkylation of 9i with Michael Acceptors: General Procedure. Method A: To a soln. of sulfonylacetate 9i
(76 mg, 0.2 mmol), DBU (6.1 ml, 0.04 mmol), and LiBr (11 mg, 0.12 mmol) in THF (3 ml), the corresponding
electrophile (0.44 mmol) was added. The mixture was heated at 608 for 1 d. After quenching with sat. NH4Cl
soln., the mixture was extracted with AcOEt (2 Â 5 ml) the combined org. phase dried (Na2SO4) and
evaporated, and the crude products purified by FC (hexane, AcOEt).

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Helvetica Chimica Acta Vol. 85 (2002)
Method B: Sulfonylacetate 9i (76 mg, 0.2 mmol), Si(OEt)4 (547 ml, 2.4 mmol), CsF (37 mg, 0.24 mmol),
and the corresponding Michael acceptor (0.44 mmol) were stirred and heated at 608 for 1 d. AcOEt (5 ml) was
then added, the mixture washed with H2O (3 Â 5 ml), the org. phase dried (Na2SO4) and evaporated, and the
crude product purified by FC (hexane/AcOEt).
1,5-Diethyl 3-Isopropyl 3-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}pentane-1,3,5-tricarboxylate (13l).
Yield, see Table 3. Rf 0.23. IR: 1739, 1359, 1281, 1191, 1140. 1H-NMR: 8.35 (s, 2 arom. H); 8.18 (s, 1 arom. H);
5.07 4.97 (m, Me2CH); 4.15 (q, J ˆ 7.3, 2 MeCH2O); 2.70 2.17 (m, 4 CH2); 1.27 (m, Me2CH, 2 MeCH2O).
13C-NMR: 171.67, 166.32 (CˆO); 139.27 (arom. C); 132.56 (q, J(C,F) ˆ 34.2, 2 CCF3); 131.04, 127.64, 127.61
(arom. CH); 122.35 (q, J(C,F) ˆ 271.4, 2 CF3); 75.33 (CS); 71.63 (Me2CH); 60.94 (2 CH2O); 29.07, 26.49
‡
(4 CH2); 21.29 (Me2CH); 14.08(2 MeCH2O). DIP-MS: 519 (25, [M À OiPr] ) 420 (11), 419 (45), 392 (19), 391
(81), 373 (100), 372 (15), 351 (23), 331 (62), 213 (18), 201 (51), 195 (28), 194 (14), 167 (26), 159 (21), 144 (18),
143 (15), 142 (22), 141 (25), 140 (10), 139 (33), 131 (64), 115 (15), 114 (54), 113 (66), 101 (16), 88 (30), 87 (14),
‡
86 (29), 85 (27), 73 (15), 57 (13), 55 (33). HR-DIP-MS: 578.1416 (C23H28F6O8S ; calc. 578.1409).
1,5-Di(tert-butyl) 3-Isopropyl 3-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}pentane-1,3,5-tricarboxylate
(13m). Yield see Table 3. Rf 0.30. IR: 1730, 1364, 1281, 1150, 1103. 1H-NMR: 8.34 (s, 2 arom. H); 8.18
(s, 1 arom. H); 5.07 4.98( m, Me2CH); 2.61 2.19 (m, 4 CH2); 1.44 (s, 2 Me3C); 1.26 (d, J ˆ 6.1, Me2CH).
13C-NMR: 170.94, 166.42 (CˆO); 139.37 (arom. C); 132.91 (q, J(C,F) ˆ 35.1, 2 CCF3); 131.09, 127.80, 127.76
(arom. CH); 122.30 (q, J(C,F) ˆ 271.4, 2 CF3); 81.38 (CS); 75.48 (2 Me3C); 71.05 (Me2CH); 30.14 (2 CH2CO);
‡
22.23 (2 CH2C); 27.99 (2 Me3C); 21.29 (Me2CH). DIP-MS: 634 (0.3, [M À OiPr] ), 562 (18), 525 (23), 524 (100),
508(14), 507 (43), 506 (67), 465 (50), 464 (92), 463 (31), 451 (13), 449 (14), 447 (72), 446 (64), 445 (55), 444
(79), 443 (70), 420 (14), 419 (68), 418(46), 417 (19), 416 (12), 408(32), 391 (12), 390 (73), 360 (12), 359 (88),
346 (16), 331 (19), 302 (20), 279 (24), 262 (12), 261 (79), 247 (14), 246 (78), 245 (39), 228 (40), 227 (66), 214
(25), 213 (70), 204 (22), 203 (88), 195 (20), 194 (30), 188 (10), 187 (78), 186 (94), 185 (50), 184 (10), 169 (30),
168(70), 167 (31), 166 (16), 163 (10), 159 (10), 158(20), 157 (89), 145 (26), 144 (14), 143 (27), 141 (54), 140
(69), 139 (71), 131 (10), 130 (38), 129 (38), 127 (73), 126 (10), 125 (69), 123 (13), 122 (14), 121 (11), 114 (11),
113 (73), 112 (54), 111 (53), 101 (14), 99 (40), 98(14), 95 (45), 83 (15), 71 (26), 67 (17), 59 (23), 58(55), 56
‡
(46), 55 (45). HR-DIP-MS: 634.2037 (C27H36F6O8S ; calc. 634.2035).
Isopropyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-5-oxo-2-(3-oxobutyl)hexanoate (13n). Yield 60 mg
(58%). Rf 0.46. IR: 1739, 1713, 1352, 1280, 1141, 1130. 1H-NMR: 8.27 (s, 2 arom. H); 8.19 (s, 1 arom. H); 5.12
5.06 (m, Me2CH); 2.61 2.56 (m, 2 CH2CO); 2.44 2.04 (m with s at 2.27, 2 CH2C, 2 MeCO); 1.23 (d, J ˆ 6.1,
Me2CH). 13C-NMR: 213.19, 166.11 (CˆO); 138.25 (arom. C); 132.56 (q, J(C,F) ˆ 34.2, 2 CCF3); 130.76, 127.84,
127.79 (arom. CH); 122.28( q, J(C,F) ˆ 271.4, 2 CF3); 77.21 (CS); 73.57 (Me2CH); 34.48(2 CH2CO); 28.23
‡
(2 MeCO); 25.40 (2 CH2C); 21.36 (Me2CH). DIP-MS: 503 (2, [M À Me] ), 241 (47), 240 (17), 182 (29), 181
(100), 180 (49), 165 (14), 163 (33), 153 (10), 139 (95), 138 (27), 137 (96), 123 (83), 121 (63), 113 (18), 111 (26),
‡
109 (12), 96 (11), 95 (33), 93 (42), 85 (13), 77 (11), 71 (31), 58 (28). HR-DIP-MS: 518.1192 (C21H24F6O6S ; calc.
518.1198).
Isopropyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-4-carbamoylbutanoate (14c).Yield 42 mg (47%).
Rf 0.37. IR: 3393, 1730, 1729, 1667, 1366, 1278, 1134, 1100. 1H-NMR: 8.36 (s, 2 arom. H); 8.19 (s, 1 arom. H); 5.62
(br. s, NH2); 5.04 4.92 (m, Me2CH); 4.31 (dd, J ˆ 8.5, 4.3, CHS); 2.56 2.28 (m, 2 CH2); 1.10 (d, J ˆ 6.1, Me
2CH). 13C-NMR: 172.76 (CONH2); 164.46 (CˆO); 140.45 (arom. C); 132.98( q, J ˆ 34.2, 2 CCF3); 129.70,
127.87 (arom. CH); 122.21 (q, J(C,F) ˆ 271.3, 2 CF3); 71.11 (Me2CH); 69.22 (CHS); 31.52 (CH2CO); 22.05
‡
(CH2CH); 21.39, 21.15 (Me2CH). DIP-MS: 449 (0.6, M ), 391 (17), 390 (100), 373 (27), 368(27), 350 (12), 336
(11), 331 (47), 318 (14), 271 (32), 261 (18), 213 (69), 194 (17), 172 (80), 130 (85), 113 (24), 112 (60), 86 (10), 85
‡
(41), 84 (23), 73 (10), 72 (45), 69 (18), 59 (47), 55 (26). HR-DIP-MS: 172.0987 (C8H14NO3 , [M À
‡
(CF3)2C6H3SO2] ; calc. 172.0973).
9. Synthesis of Aconitates 18. To a soln. of the corresponding sulfonylacetate 9 (0.2 mmol), K2CO3 (174 mg,
1.2 mmol), and Bu4NBr (7 mg, 0.02 mmol) in MeCN (3 ml) was added ethyl bromoacetate (50 ml, 0.44 mmol).
The mixture was stirred at r.t. for the time indicated in Table 4. The reaction was then quenched with sat. NH4Cl
soln., the mixture extracted with AcOEt (2 Â 3 ml), the combined org. phase dried (Na2SO4) and evaporated,
and the crude aconitate 18 purified by FC (hexane/AcOEt).
2-Benzyl 1,3-Diethyl (1E)-Prop-1-ene-1,2,3-tricarboxylate (18a). Yields, see Table 4. Rf 0.60. IR: 3074, 1732,
1656, 1362, 1280, 1142, 1134. 1H-NMR (500 MHz): 7.37 (s, 5 arom. H); 6.97 (s, CHˆC); 5.24 (s, PhCH2O);
4.28 4.07 ( m, 2 MeCH2O); 3.97 (s, CH2Cˆ); 1.32 1.18( m, 2 MeCH2O). 13C-NMR (125 MHz): 168.95, 165.38,
165.20 (CˆO); 139.79 (CˆCH); 132.14 (arom. C); 131.94, 128.95, 128.61, 128.56, 128.43, 128.24, 123.77 (CˆCH,
arom. CH); 68.86 (PhCH2O); 61.39, 60.09 (2 MeCH2O); 33.48( CH2Cˆ); 19.72 (Me2CH); 13.98, 13.64

Helvetica Chimica Acta Vol. 85 (2002)
4303
‡
(2 MeCH2O). EI-MS: 276 (0.22, [M À OEt] ), 214 (11), 185 (10), 139 (18), 90 (100). HR-EI-MS: 275.0906
‡
‡
(C15H15O5 , [M À OEt] ; calc. 275.0919).
1,3-Diethyl 2-Isopropyl (1E)-Prop-1-ene-1,2,3-tricarboxylate (18b). Yields, see Table 4. Rf 0.57. IR: 3075,
1
1730, 1656, 1362, 1279, 1145, 1136. H-NMR (500 MHz): 6.92 (s, CHˆC); 5.15 5.07 (m, Me2CH); 4.28 4.09
(m, 2 MeCH2O); 3.95 (s, CH2Cˆ); 1.33 1.23 (m, 2 MeCH2O). 13C-NMR (125 MHz): 169.88, 165.41, 165.35
(CˆO); 140.39 (CˆCH); 128.74 (CˆCH); 69.56 (Me2CH); 60.92, 60.89 (MeCH2O); 33.08( CH2Cˆ); 21.58
‡
(Me2CH); 14.06, 14.02 (2 MeCH2O). EI-MS: 272 (0.31, M ), 211 (17), 184 (57), 183 (36), 166 (12), 156 (18),
‡
155 (21), 139 (24), 138(64), 137 (26), 111 (100), 110 (11), 83 (24). HR-EI-MS: 227.0906 (C 11H15O5 , [M À
‡
OEt] ; calc. 227.0919).
2-Benzyl 1,3-Diethyl 2-(Pyridin-2-ylsulfonyl)propane-1,2,3-tricarboxylate (17). Yield 46 mg (50%). Rf 0.18.
1
IR: 1735, 1730, 1358, 1280, 1140, 1131. H-NMR: 8.66 (d, J ˆ 4.3, 1 arom. H); 7.90 7.84 (m, 2 arom. H); 7.36
7.23 (m, 6 arom. H); 5.09 (m, Me2CH); 4.12 (q, J ˆ 6.7, 2 MeCH2O); 3.62 3.55 (m, 2 CH2C); 1.25 (t, J ˆ 6.7,
2 MeCH2O). 13C-NMR: 169.21, 165.88 (CˆO); 153.86, 134.39 (arom. C); 150.09, 137.83, 128.37, 128.26, 127.95,
125.51 (arom. CH); 71.56 (CS); 68.39 (Me2CH); 61.07 (2 MeCH2O); 33.67 (CH2C); 13.90 (MeCH2). DIP-MS:
‡
272 (0.69, M ), 398(18), 249 (10), 233 (62), 210 (10), 206 (14), 201 (14), 195 (13), 193 (31), 192 (39), 182 (21),
181 (17), 180 (11), 179 (21), 178 (52), 177 (12), 169 (94), 167 (82), 166 (10), 165 (16), 145 (12), 141 (82), 142
(23), 141 (100), 140 (42), 139 (27), 136 (15), 129 (13), 127 (24), 126 (23), 124 (13), 117 (18), 116 (13), 115 (25),
114 (25), 113 (82), 112 (29), 111 (14), 108 (20), 107 (31), 106 (18), 105 (14), 104 (10), 103 (12), 95 (31), 93 (12),
92 (91), 91 (55), 90 (18), 86 (19), 85 (39), 80 (56), 79 (79), 78 (82), 77 (33), 69 (15), 68 (27), 67 (18), 65 (93), 64
‡
(14), 63 (23), 52 (60), 51 (79). HR-EI-MS: 463.1289 (C22H25NO8S ; calc. 463.1301).
10. Cycloisomerization Reactions: General Procedure. Dry HCl was bubbled through a soln. of the
corresponding 1,6-diene (0.2 mmol) and palladium acetate (5 mol-%) in CHCl3 (3 ml) for ca. 15 min. Then the
mixture was stirred under reflux for 16 h. The resulting brown soln. was evaporated, the residue dissolved in
AcOEt, the mixture filtered through Celite to remove the catalyst, the eluate evaporated, and the residue
purified by FC (hexane/AcOEt): 15 or 16.
rel-(1R,4S)-Isopropyl 1-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-3,4-dimethylcyclopent-2-ene-1-carbox-
ylate (15). Yield 66 mg (72%). Rf 0.41 (hexane/AcOEt 8.1). IR: 3079, 1738, 1628, 1361, 1280, 1181, 1143.
1H-NMR: 8.31 (s, 2 arom. H); 8.15 (s, 1 arom. H); 5.18 5.14 ( m, CHˆC); 5.06 4.94 (m, Me2CH); 3.04 2.96,
2.39 2.33 (2m, CH2C); 2.82 2.78 (m, MeCH); 1.78( s, MeCˆ); 1.78 1.13 ( m, MeCH, Me2CH). 13C-NMR
(125 MHz): 166.78(C ˆO); 156.66 (CˆCH); 140.32 (arom. C); 132.51 (q, J(C,F) ˆ 34.2, 2 CCF3); 130.62, 127.23
(arom. CH); 122.40 (q, J(C,F) ˆ 271.7, 2 CF3); 119.23 (CHˆ); 85.77 (CS); 70.92 (Me2CH); 42.81 (CHCH2);
‡
36.03 (CH2); 21.32 (Me2CH); 18.56 (MeCHCˆ); 14.93 (MeCHCˆ). DIP-MS: 458(0.2, M ), 394 (37), 393
(100), 392 (11), 352 (15), 351 (95), 350 (15), 333 (17), 332 (10), 331 (77), 311 (10), 307 (38), 306 (12), 305 (66),
292 (10), 291 (16), 241 (10), 227 (58), 208 (17), 107 (71), 79 (61), 78 (10), 77 (19), 59 (11). HR-DIP-MS:
‡
i
‡
371.05789 (C15H13F6O2S , [M À CO2 Pr] ; calc. 371.0540).
rel-(1R,4R)-Isopropyl 1-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-3,4-diisopropylcyclopent-2-ene-1-car-
boxylate (16). Yield 70 mg (68%). Rf 0.23 (hexane/AcOEt 8 :1). IR: 3076, 1722, 1628, 1360, 1280, 1183, 1144.
1H-NMR: 8.33 (s, 2 arom. H); 8.14 (s, 1 arom. H); 5.13 5.11 (m, CHˆ); 5.09 4.97 (m, Me2CHO); 2.78 2.75
(m, CH2, CHCˆ, CHCHMe); 1.70, 1.58(2 s, 2 Me2CH); 1.24 (d, J ˆ 6.1, 1 Me2CH). 13C-NMR (125 MHz): 167.06
(CˆO); 140.21 (arom. C); 136.39 (CˆCH); 132.53 (q, J(C,F) ˆ 34.18, 2 CCF3); 130.86, 130.81, 127.39, 127.34,
127.29 (arom. CH); 122.45 (q, J(C,F) ˆ 271.7, 2 CF3); 116.32 (CHˆ); 70.84 (CS); 70.84 (Me2CHO); 39.38
‡
(ˆCCHCH2); 29.90 (CH2); 25.97, 21.32, 17.97 (Me2CHCˆ, Me2CHCH, Me2CHO). DIP-MS: 514 (2, M ), 261
(10), 237 (54), 236 (91), 213 (36), 196 (14), 195 (100), 194 (97), 193 (92), 192 (16), 181 (12), 179 (49), 177 (39),
176 (15), 167 (13), 163 (13), 161 (26), 153 (27), 152 (20), 151 (57), 150 (15), 149 (72), 147 (18), 140 (19), 139
(97), 138(34), 137 (36), 135 (15), 133 (60), 127 (29), 126 (28), 125 (39), 124 (16), 123 (43), 121 (38), 119 (17),
111 (40), 109 (63), 108 (19), 107 (80), 105 (30), 97 (15), 96 (11), 95 (70), 94 (20), 93 (85), 91 (49), 87 (12), 85
(13), 83 (15), 81 (42), 80 (17), 79 (66), 77 (38), 71 (45), 70 (20), 69 (56), 68 (11), 67 (43), 65 (11), 59 (78), 57
‡
‡
(22), 56 (22), 55 (57), 53 (27). HR-DIP-MS: 237.1829 (C15H25O2 , [M À (CF3)2C6H3SO2] ; calc. 237.1855).
11. Diels-Alder Cycloadditions: Typical Procedure. Paraformaldehyde (12 mg, 2 mmol), copper(II) acetate
(2 mg, 0.01 mmol), AcOH (45 ml, 0.4 mmol), the corresponding 1,3-diene (0.4 mmol) and the (arylsulfonyl)-
acetate (0.2 mmol) were placed in the sealed tube. The tube was shaken and then heated at 1008 for the time
indicated in Scheme 6. The solvent was then evaporated and the obtained crude mixture purified by FC (hexane/
AcOEt): pure compounds 19 21.
Benzyl 1-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}-3,4-dimethylcyclohex-3-ene-1-carboxylate (19). Yield
86 mg (83%). Rf 0.42 (hexane/AcOEt 8 :1). IR: 3084, 1731, 1632, 1360, 1280, 1140, 1104. 1H-NMR: 8.20
(s, 2 arom. H); 8.11 (s, 1 arom. H); 5.15, 5.06 (2d, J ˆ 12.2, PhCH2O); 2.75 2.58( m, 1 CH2Cˆ); 2.33 2.29

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Helvetica Chimica Acta Vol. 85 (2002)
(m, 1 CH2C); 2.27 2.07 (m, CH2CH2Cˆ); 1.60, 1.49 (2s, 2 MeCˆ). 13C-NMR (125 MHz): 166.90 (CˆO);
138.53, 134.53 (arom. C); 132.53 (q, J(C,F) ˆ 34.2, 2 CCF3); 130.53, 130.49, 128.54, 127.85, 127.56 (arom. CH);
125.23, 121.93 (CˆC); 122.28( q, J(C,F) ˆ 271.4, 2 CF3); 73.29 (CS); 67.99 (PhCH2O); 32.45, 28.62, 25.48 (CH2);
‡
19.35, 18.34 (MeCˆ). DIP-MS: 520 (0.7, M ), 243 (69), 242 (78), 152 (39), 151 (47), 150 (41), 136 (10), 1035
(77), 133 (100), 121 (12), 108 (17), 107 (68), 92 (47), 91 (55), 83 (12), 69 (10), 65 (37), 55 (18). HR-DIP-MS:
‡
‡
385.0697 (C16H15F6O2S , [M À CO2Bn] ; calc. 385.0710).
(2-endo/2-exo)-Isopropyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}bicyclo[2.2.1]hept-5-ene-2-carboxyl-
ate (20). Yield 68mg (73%). Rf 0.37 (hexane/AcOEt 8:1). IR: 1741, 1634, 1350, 1246, 1140, 1122. 1H-NMR
(500 MHz): 8.30 (s, 2 arom. H, endo); 8.28 (s, 2 arom. H, exo); 8.16 (s, 1 arom. H, endo); 8.14 (s, 1 arom. H,
exo); 6.49 (dd, J ˆ 5.5, 3.1, HÀC(5), exo); 6.39 (dd, J ˆ 5.5, 3.1, HÀC(5), endo); 6.21 (dd, J ˆ 5.2, 3.1, HÀC(6)
exo); 5.93 (dd, J ˆ 5.2, 3.1, HÀC(6), endo); 4.89 4.79 (m, 2 Me2CH, exo ‡ endo); 3.56 (br. s, HÀC(1), exo);
3.37 (br. s, HÀC(1), endo); 3.12 (br. s, 2 HÀC(4), exo ‡ endo); 2.81 (dd, J ˆ 12.9, 4.0, HexoÀC(3), exo); 2.68
(dd, J ˆ 12.9, 3.7, HexoÀC(3), endo); 2.29 (m, 2 HsynÀC(7), endo ‡ exo); 2.18( dd, J ˆ 12.9, 2.8, HendoÀC(3),
endo); 2.11 (dd, J ˆ 12.9, 2.8, HendoÀC(3), exo); 1.61 1.54 (m, HantiÀC(7), exo ‡ endo); 1.26 1.13
(m, 2 Me2CH, exo ‡ endo). 13C-NMR (125 MHz): 167.90 (CˆO, exo); 166.83 (CˆO, endo); 141.60 (arom. C,
exo); 140.83 (arom. C, endo); 142.30, 140.71, 133.86, 131.26, 130.10 (m), 129.75 (m), 127.46 (m), 127.36 (m)
(2 CHˆCH, arom. CH, exo ‡ endo); 132.60 (q, J(C,F) ˆ 35.4, 2 CCF3, exo ‡ endo); 122.40 (q, J(C,F) ˆ 271.4,
2 CF3, exo ‡ endo); 81.40 (CS, exo); 80.98 (CS, endo); 71.22 (Me2CH, exo); 70.81 (Me2CH, endo); 51.59 (CHC,
exo); 50.26 (CHC, endo); 49.29 (CHCH2CH, exo); 47.14 (CHCH2CH, exo); 43.00 (CHCH2, exo); 42.42
(CHCH2, endo); 33.94 (CH2C, exo); 33.12 (CH2C, endo); 21.28, 21.21, 21.15, 21.08 (2 Me2CH, exo ‡ endo). DIP-
‡
MS: 468(0.4, M ), 454 (24), 433 (17), 408 (21), 402 (18), 389 (13), 388 (64), 386 (13), 330 (22), 288 (10), 286
(14), 271 (13), 270 (100), 220 (45), 200 (18), 156 (17), 129 (41), 127 (24), 108 (13). HR-DIP-MS: 468.0848
‡
(C20H28F6O4S ; calc. 468.0830).
(2-endo/2-exo)-Isopropyl 2-{[3,5-Bis(trifluoromethyl)phenyl]sulfonyl}bicyclo[2.2.2]oct-5-ene-2-carboxyl-
ate (21). Yield 40 mg (42%). Rf 0.37 (hexane/AcOEt 8 :1). IR: 3057, 1732, 1626, 1358, 1279, 1183, 1146.
1H-NMR (500 MHz): 8.31 8.13 (m, 6 arom. H, endo ‡ exo); 6.47 (t, J ˆ 7.3, HÀC(5), exo); 6.36 (t, J ˆ 7.3,
HÀC(5), endo); 6.23 (t, J ˆ 7.3, HÀC(6), exo); 6.10 (t, J ˆ 7.3, HÀC(6), endo); 5.04 4.96 (m, Me2CH, exo);
4.78 4.70 ( m, Me2CH, endo); 3.45 (br. s, HÀC(1), endo); 3.10 2.65 (m, 4 H, exo ‡ endo); 2.60 2.30 (m, 5 H,
exo ‡ endo); 1.90 1.75 (m, HantiÀC(8), endo); 1.50 1.01 (m, 18 H, exo ‡ endo). 13C-NMR (125 MHz): 167.65
(CˆO, exo); 167.38(C ˆO, endo); 140.85, 140.66 (arom. C, exo ‡ endo); 142.45, 137.29, 136.13, 131.13, 130.57,
129.84, 128.68, 127.36 (2 CHˆCH, arom. CH, exo ‡ endo); 132.65 (q, J(C,F) ˆ 34.8, 2 CCF3,exo ‡ endo); 122.28
(q, J(C,F) ˆ 271.8, 2 CF3, exo ‡ endo); 78.57 (CS, exo); 78.17 (CS, endo); 71.31 (Me2CH, exo); 71.01 (Me2CH,
endo); 35.25 (CHC, exo); 34.74 (CHC, endo); 30.83 (CH2C, endo); 30.50 (CH2C, exo); 29.68( CHCH2, exo);
29.62 (CHCH2, endo); 24.24, 20.05 (CHCH2CH2CH, endo); 23.38, 22.21 (CHCH2CH2CH, exo); 21.55, 21.38,
‡
21.30, 21.20 (2 Me2CH, exo ‡ endo). DIP-MS: 470 (3, M ), 277 (12), 261 (23), 194 (10), 193 (100), 152 (48), 151
(12), 135 (14), 133 (52), 124 (12), 123 (17), 115 (15), 107 (10), 106 (28), 105 (19), 91 (25), 80 (41), 79 (65), 77
‡
(28), 73 (33). HR-DIP-MS: 470.0975 (C20H20F6O4S ; calc. 470.0986).
12. Reduction of the Sulfonyl Group with Zinc: Typical Procedure. To a soln. of sulfonylpropanoate 12i
(0.2 mmol, 137 mg) in THF (1 ml), was added activated Zn (78mg, 1.2 mmol) and sat. aq. NH 4Cl soln. (3 ml).
The mixture was stirred vigorously and heated at 808 for 2 d. The mixture was diluted with AcOEt and filtered
through Celite. The filtrate was washed with a NaHCO3 soln. and then with brine. The org. phase was dried
(Na2SO4) and evaporated and the crude product purified by FC (hexane/AcOEt): 39 mg (70%) of isopropyl 2-
benzyl-3-phenylpropanoate (22). Rf 0.55 (hexane/AcOEt 8:1). IR: 1727, 1355, 1279, 1175, 1142. 1H-NMR:
7.28 7.16 ( m, 10 arom. H); 6.97 (s, CHˆC); 4.86 4.78 (m, Me2CH); 2.97 2.94 (m, 2 PhCH2); 2.88 2.79
(m, CHCO); 0.95 (d, J ˆ 6.1, Me2CH). 13C-NMR: 174.39 (CˆO); 139.11 (arom. C); 128.92, 128.29, 126.30
‡
(arom. CH); 67.39 (CHO); 49.71 (CHCO); 38.39 (2 PhCH2); 21.52 (Me2CH). DIP-MS: 282 (2, M ), 190 (31),
‡
148(72), 147 (11), 130 (37), 116 (13), 91 (22), 90 (100), 64 (10). HR-DIP-MS: 282.1638(C 19H22O2 ; calc.
282.1620).
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Received June 6, 2002