Equilibrium shift in the rhodium-catalyzed acyl transfer reactions

Article abstract of DOI:10.1016/j.tet.2011.07.031

Rhodium/phosphine complexes catalyze equilibrium acyl transfer reactions between acid fluorides, aryl esters, acylphosphine sulfides, and thioesters. The use of appropriate co-substrates to accept heteroatom groups shifted the equilibrium to desired products. Acylphosphine sulfides and aryl esters were converted to acid fluorides using benzoylpentafluorobenzene as the fluoride donor, and the fluorination reaction of thioesters employed (4-tolylthio) pentafluorobenzene. Acid fluorides were converted into acylphosphine sulfides and thioesters using diphosphine disulfides and disulfides/triphenylphosphine, respectively. Aryl esters were obtained from acid fluorides and phenols in the presence of triphenylsilane. Aryl esters, acylphosphine sulfides, and thioesters were also interconverted in the presence of rhodium complexes. These rhodium-catalyzed acyl transfer reactions proceeded under neutral conditions without using acid or base. The involvement of acyl rhodium intermediates in these reactions was suggested by the carbothiolation reaction of thioesters and alkynes.

Full text of DOI:10.1016/j.tet.2011.07.031

Tetrahedron 67 (2011) 7846e7859
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Equilibrium shift in the rhodium-catalyzed acyl transfer reactions
,
a
a
a
a
Mieko Arisawa a , Yui Igarashi , Haruki Kobayashi , Toru Yamada , Kentaro Bando ,
*
Takuya Ichikawa a, Masahiko Yamaguchi a
,b,
*
a Department of Organic Chemistry, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
b WPI Research Center, Advanced Institute for Materials Research, Tohoku University, Aoba, Sendai 980-8577, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 17 June 2011
Received in revised form 12 July 2011
Accepted 12 July 2011
Available online 24 July 2011
Rhodium/phosphine complexes catalyze equilibrium acyl transfer reactions between acid fluorides, aryl
esters, acylphosphine sulfides, and thioesters. The use of appropriate co-substrates to accept heteroatom
groups shifted the equilibrium to desired products. Acylphosphine sulfides and aryl esters were con-
verted to acid fluorides using benzoylpentafluorobenzene as the fluoride donor, and the fluorination
reaction of thioesters employed (4-tolylthio)pentafluorobenzene. Acid fluorides were converted into
acylphosphine sulfides and thioesters using diphosphine disulfides and disulfides/triphenylphosphine,
respectively. Aryl esters were obtained from acid fluorides and phenols in the presence of triphenylsi-
lane. Aryl esters, acylphosphine sulfides, and thioesters were also interconverted in the presence of
rhodium complexes. These rhodium-catalyzed acyl transfer reactions proceeded under neutral condi-
tions without using acid or base. The involvement of acyl rhodium intermediates in these reactions was
suggested by the carbothiolation reaction of thioesters and alkynes.
Keywords:
Equilibrium
Acyl transfer
Rhodium catalyst
Co-substrate
Co-product
Ó 2011 Published by Elsevier Ltd.
1. Introduction
acid or base. For example, acyl transfer reactions involving sulfur,
phosphorous, and fluoride atoms are of interest.
Acyl transfer reactions, which exchange acyl groups between
heteroatoms, such as oxygen, nitrogen, and halogens, are important
in chemistry and biology.1 Ester formation from alcohols and car-
boxylic acids catalyzed by acid, for example, has been particularly
well examined. Transesterification is another acyl transfer reaction
for obtaining esters, and ester alkoxy groups are exchanged with
alcohols under acid or base catalysis. Because the reactions are
equilibria, techniques are required to obtain products in high yields.
A shift of equilibrium is often achieved using excess alcohol, and
alternatively azeotropic removal of water is also effective. To avoid
relatively complex procedures to shift the equilibrium, reactive
acylating reagents, such as acyl halides or acid anhydrides may be
treated with alcohols in the presence of bases. The base traps acids
formed and/or activates acylating reagents. Acyl transfer reactions
have been conducted in the presence of acid or base catalysts with
various devices to shift equilibrium.
Catalyzed equilibrium reactions have an advantage of facile re-
action control by catalysts and low activation energies. In addition,
various products can be obtained by simply shifting the equilibria.
For example, in an equilibrium reaction between S1/S2 and P1/P2,
any S1, S2, P1, or P2 can be the product, depending on the conditions
(Fig. 1(a)). The efficiency in such reactions is affected by the relative
thermodynamic stabilities of substrates S1/S2 and products P1/P2. If
their stabilities are comparable, an equilibrium state provides
a mixture of four compounds, and techniques to shift the equilib-
rium are required to obtain the desired products in high yields. Le
Chatelier’s principle may be applied to control equilibrium, and
pressure, temperature, or concentration may be varied for this
purpose. This method, however, has relatively limited applicability
from a synthetic point of view. The use of an excessive substrate can
also shift equilibrium, but that is not always convenient. We con-
sidered it attractive to control the relative thermodynamic stability
using co-substrates and co-products. When an appropriate co-
substrate S3 was used in the S1/S2 and P1/P2 reaction in place of
S2, the equilibrium could be shifted to P1 with the formation of P3
provided that the relative thermodynamic stability of the P1/P3
system was higher than that of the S1/S3 system (Fig. 1(b)). An
advantage of this method is that various combinations of S3 and P3
can be used to optimize the reaction giving P1. It was considered
interesting to apply this methodology to catalyze acyl transfer
reactions.
The development of novel catalysts for the acyl transfer reaction
is interesting, particularly when catalysts other than acid or base
are used. Such reactions can proceed under mild conditions, and
can exhibit different reactivity and selectivity from method using
* Corresponding authors. E-mail addresses: arisawa@m.tohoku.ac.jp (M. Arisawa),
yama@mail.pharm.tohoku.ac.jp (M. Yamaguchi).
0040-4020/$ e see front matter Ó 2011 Published by Elsevier Ltd.
doi:10.1016/j.tet.2011.07.031

M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
7847
noteworthy that these acyl transfer reactions proceed without us-
ing acid or base.
2. Results and discussion
2.1. Interconversion of aryl esters and acid fluorides
The acyl transfer reaction between esters and acid fluorides was
catalyzed by a rhodium catalyst. When an equimolar mixture of 4-
cyanophenyl 4-methoxybenzoate 1 and benzoyl fluoride 2 was
treated with RhH(PPh3)4 (5 mol %) and cis-bis(diphenylphosphino)
ethene (dppv, 10 mol %) in refluxing chlorobenzene for 3 h, a mix-
ture of 4-methoxybenzoyl fluoride 3 (41%) and 4-cyanophenyl
benzoate 4 (46%) was obtained with the recovery of 1 (43%) and
2 (37%, 1H NMR yield) (Scheme 2). No reaction occurred in the
absence of the rhodium complex.
O
C
O
C
MeO
O
CN
MeO
F
Fig. 1. Equilibrium control by co-substrate and co-product.
RhH(PPh3)4 (5 mol%)
dppv (10 mol%)
1
3 41%
+
+
O
C
O
C
PhCl, refl., 2 h
F
O
CN
During our studies on the transition-metal-catalyzed synthesis
of organoheteroatom compounds, we developed several acyl
transfer reactions: Rhodium-catalyzed alkylthio exchange reaction
of thioesters with disulfide;2 synthesis of acylphosphine sulfides
from acid fluorides and diphosphine disulfides;3 and conversion of
thioesters to acylphosphine sulfides by treatment with diphos-
phine disulfides.4 We also found that the rhodium-catalyzed re-
action of acid fluorides and thioesters was at equilibrium,5 and that
the equilibrium could be shifted in the presence of co-substrates:
thioesters were synthesized from acid fluorides in the presence of
triphenylphosphine; acid fluorides were synthesized from thio-
esters in the presence of hexafluorobenzene. The equilibrium was
shifted by the conversion of the co-substrates to the thermody-
namically stable co-products. The conversion of triphenylphos-
phine to triphenylphosphine difluoride promoted the formation of
thioesters, and that of hexafluorobenzene to aryl sulfides promoted
the formation of acid fluorides. Described in this study is an ex-
tension of this methodology to acyl transfer reactions between
thioesters, acylphosphine sulfides, aryl esters, and acid fluorides,
and each equilibrium (Scheme 1(a)) may be shifted to a desired
product by employing an appropriate heteroatom acceptor as a co-
substrate (Scheme 1(b)). Equilibrium shift in this paper means the
predominant formation of product P1 based on equilibrium in
Scheme 1(a). Acyl transfers catalyzed by transition metal com-
plexes were not known prior to this study, in which all the reactions
were catalyzed by rhodium/phosphine complexes. It is also
4 46%
recovered 1 43%
recovered 2 37%
2
O
O
O
C
O
Rh cat.
+
+
R
C
OAr
R' C F
R
F
R' C OAr
Scheme 2.
The results indicated that the acid fluoride and the aryl ester
were at equilibrium. It was expected that acid fluorides could be
obtained effectively from aryl esters by developing a technique to
shift the equilibrium. Benzoylpentafluorobenzene 5 was an effi-
cient co-substrate for this purpose with the formation of 1-
benzoyl-4-(4-cyanophenoxy)-2,3,5,6-tetrafluorobenzene 6 as the
co-product.
When 1 and 5 (1 equiv) were reacted in refluxing chlorobenzene
for 3 h in the presence of RhH(PPh3)4 (5 mol %) and dppv (10 mol %),
3 and 6 were obtained in 92% and 96% yields, respectively (Table 1,
entry 1). No reaction occurred in the absence of the rhodium
complex or dppv. The reaction could be applied to several 4-
cyanophenyl esters derived from aromatic and aliphatic acids in
high yields (entries 2e8). 4-Tolyl 4-methoxybenzoate, however,
gave a trace amount of 3. The substantial effect of the p-substituent
Table 1
Synthesis of acid fluorides from aryl esters
RhH(PPh3)4 (5 mol%)
dppv (10 mol%)
PhCl, refl., 3 h
F
F
O
RC
O
O
Ph C
+
F
+
F
RC OAr
F
F
F
O
F
F
(a) Equilibrium reaction
OAr
Ar = p-CNC6H4-
5
Ph C
O
O
O
O
Rh cat.
F
R1C XR2
R1C YR4
R3C XR2
R3C YR4
+
+
6
S1
S2
P1
P2
Entry
R
Yield of acid fluoride/%
X, Y = F, O, S, P
(b) Equilibrium shift using co-substrate S3 and co-product P3
1
2
3
4
5
6
7
8
4-MeOC6H4 (1)
3,5-(MeO)2C6H3
4-ClC6H4
n-C11H23
(n-Pr)2CH
4-(t-Butyl)cyclohexyl
1-Adamantyl
1-Methylcyclohexyl
92
93
73
94
90
88
92
88
O
O
Rh cat.
R1C XR2
R1C YR4
Z
XR2
P3
YR4
S3
+
+
Z
S1
P1
Scheme 1.

7848
M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
Table 3
at the phenoxy moiety may be related to the efficiency of the COeO
bond cleavage. Acid fluorides were generally synthesized from
carboxylic acids by treatment with reactive fluorinating reagents,
such as DAST or cyanuric fluoride.6,7 This transition-metal-
catalyzed synthesis of acid fluorides from aryl esters uses a stable
fluorinating reagent.
Rhodium-catalyzed reaction of acid fluorides and phenols
RhH(PPh3)4 (1 mol%)
O
O
dppe (2 mol%)
+
RC
F
+
HF
RC OAr
ArOH
N2 bubbling
PhCl, refl., 3 h
The ability to transfer fluoride to 4-cyanophenyl dodecanoate 7
was examined using pentafluorobenzenes with different sub-
stituents (Table 2). When (diphenylamino)pentafluorobenzene or
(butylthio)pentafluorobenzene was reacted, dodecanoyl acid fluo-
ride 8 was obtained in low yields (entries 1 and 2). Inefficiency of
hexafluorobenzene was unexpected (entry 4), which might be be-
cause of catalyst deactivation. In the case of (4-tolylthio)penta-
fluorobenzene, the yield increased to 62%, which was accompanied
by 1-(4-cyanophenoxy)-4-(4-tolylthio)-2,3,5,6-tetrafluorobenzene
in 62% yield (entry 3). Acetylpentafluorobenzene, benzoylpenta-
fluorobenzene 5, and cyanopentafluorobenzene gave 8 in 66%, 89%,
and 95% yields, respectively (entries 5e7). The results indicated
a higher fluoride transfer ability of pentafluorobenzene derivatives
with an electron-withdrawing group. In these reactions, the co-
products derived from the pentafluorobenzenes were
4-cyanophenoxy derivatives. Thus, the rhodium-catalyzed conver-
sion of aryl esters to acid fluorides was conducted using 5 as a co-
substrate giving 6 as a co-product. It is also worth noting that this
reaction can be regarded as a method to synthesize polyfluorinated
diaryl ethers by the substitution of aromatic fluorides. This is an
advantage of the equilibrium shift method, in that various com-
pounds may be obtained from a single reaction.
Entry
R
Ar
Yield of ester/%
1
2
3
4
5
6
7
8
9
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
2-Tol
4-Tol
4-MeOC6H4
4-PhC6H4
92
96
99
99
96
89
89, 99%ee
89
80
82
4-NO2C6H4
(S)-p-C6H4CH2CH(NHBoc)CO2Me
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-ClC6H4
4-MeOC6H4
n-C9H19
10
Alcohols efficiently reacted as well as phenols (Table 4). When
1-octanol was reacted with benzoyl fluoride 2 (1 equiv) in the
presence
of
RhH(PPh3)4
(2.5
mol
%)
and
1,2-
bis(diphenylphosphino)ethane (dppe, 5 mol %), octyl benzoate
was obtained in 85% yield (entry 1). No reaction occurred in the
absence of the rhodium complex and dppe. High temperature and
nitrogen bubbling were again required for this reaction, and the
yield of octyl benzoate decreased to 13% when the reaction was
run at room temperature and to 15% without nitrogen bubbling.
The synthesis of esters from acid fluorides and alcohols in the
presence of a stoichiometric amount of base were reported.6b,8 The
rhodium method provides esters in high yields without using
base.
Table 2
Effect of pentafluorobenzenes on the acid fluorides synthesis from aryl ester 7
RhH(PPh3)4 (5 mol%)
dppv (10 mol%)
PhCl, refl., 2 h
F
F
O
C
7
O
C
+
F
+
F
n-C11H23
OAr
R
n-C11H23
8
F
F
F
F
F
Table 4
Ar = p-CNC6H4-
R
Rhodium-catalyzed reaction of acid fluorides and alcohols
OAr
RhH(PPh3)4 (2.5 mol%)
F
O
O
dppe (5 mol%)
+
RC
F
+
R'OH
RC OR'
HF
N2 bubbling
Entry
R
Yield of 8/%
PhCl, refl., 4 h
1
2
3
4
5
6
7
8
Ph2N
n-C4H9S
4-TolS
F
MeCO
PhCO
CN
15
31
62
8
66
Entry
R
R0
Yield of ester/%
1
2
3
4
Ph
Ph
n-C11H23
n-C8H17
PhCH2
PhCO2(CH2)2
PhCO2(CH2)2
85
87
62
71
89, 94a
95
1-Methylcyclohexyl
4-Fluoronitrobenzene
42a
a
Reaction time: 3 h.
The reaction shown in Tables 3 and 4 used the removal of
The reverse reaction, synthesis of aryl esters from acid fluorides,
hydrogen fluoride to shift the equilibrium between acid fluoride
and aryl esters. The co-substrate method of removing hydrogen
fluoride was also examined, and triphenylsilane was found to
promote the aryl esterification at considerably lower tempera-
tures. The reaction of benzoyl fluoride 2, 4-methoxyphenol
(1 equiv), and triphenylsilane in the presence of RhH(PPh3)4
(1 mol %) and dppe (2 mol %) in chlorobenzene at room temper-
ature for 3 h gave 4-methoxyphenyl benzoate (96%) along with
triphenylsilyl fluoride (87%) (Scheme 3). Using the silane, the re-
action temperature could be markedly reduced from chloroben-
zene reflux at 132 ꢀC to room temperature. This equilibrium shift
method employed triphenylsilane as a co-substrate giving tri-
phenylsilyl fluoride as a co-product. This reaction is a novel es-
terification using acid fluorides, which are generally less reactive
than acid chlorides.
was examined. The reaction of benzoyl fluoride 2 and phenol
(1 equiv) in the presence of RhH(PPh3)4 (1 mol %) and dppe
(2 mol %) in refluxing chlorobenzene under nitrogen bubbling for
3 h gave phenyl benzoate in 92% yield (Table 3, entry 1). The rho-
dium complex and dppe were both essential for the reaction, and
no reaction occurred in the absence of either substance. High
temperatures were required, and the yield decreased to 43% in
refluxing THF. Without nitrogen bubbling, the yield dropped to 31%
in refluxing chlorobenzene even with the addition of 2 mol %
RhH(PPh3)4 and 4 mol % dppe. The removal of hydrogen fluoride
probably shifted the equilibrium to form aryl esters. The evolution
of acid was indicated by pH test paper at the top of the refluxing
condenser. The reaction was applied to aromatic and an aliphatic
acid fluorides (entry 10). The reaction of protected tyrosine pro-
ceeded without racemization (entry 7).

M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
7849
RhH(PPh3)4 (1 mol%)
RhH(PPh3)4 (0.1 mol%)
dppe (0.2 mol%)
O
O
C
dppe (2 mol%)
PhCl, r.t., 3 h
O
(4-TolS)2
+
PPh3
(0.5 eq.) (0.5 eq.)
+
+
PhC F +
2
MeO
OH Ph3SiH
F
F
THF, refl., 5 h
O
2
+
Ph3PF2
PhC S(4-Tol)
+
+
C
O
OMe
Ph3SiF
87%
88%
96%
Scheme 5.
RhH(PPh3)4 (2.5 mol%)
dppe (5 mol%)
PhCl, r.t., 3 h
O
C
+
n-C H17OH Ph3SiH
+
8
The use of hexafluorobenzene as a co-substrate promoted the
formation of acid fluorides from thioesters.5 The reaction of S-(4-
tolyl) 4-methoxybenzothioate 11 and hexafluorobenzene
(2 equiv) in the presence of RhH(PPh3)4 (2.5 mol %) and dppe
2
O
C
O-n-C8H17
81%
Ph3SiF
68%
(5 mol %) in refluxing chlorobenzene for
3 h gave 4-
Scheme 3.
methoxybenzoyl fluoride and 1,4-di(4-tolylthio)-2,3,5,6-
tetrafluorobenzene 12 in 94% and 99% yields, respectively
(Scheme 6).
Rhodium/phosphine complexes catalyzed the equilibrium acyl
transfer reaction between acid fluorides and aryl esters. In the
presence of acceptors for phenoxy or fluoride, the equilibrium
could be shifted to either product. The formation of acid fluorides
from aryl esters was promoted by the addition of benzoylpenta-
fluorobenzene 5 with the formation of aryl ethers; that of aryl
esters from acid fluorides was promoted by the addition of tri-
phenylsilane with the formation of triphenylsilyl fluoride or by the
removal of hydrogen fluoride.
RhH(PPh3)4 (2.5 mol%)
dppe (5 mol%)
O
C
+
MeO
S(4-Tol)
C6F6
2 eq.
PhCl, refl., 3 h
11
F
F
F
O
C
+
F
4-TolS
S(4-Tol)
MeO
F
3 94%
12 99%
2.2. Interconversion of acid fluorides and thioesters
Scheme 6.
Our previous work described the equilibrium acyl transfer
reaction between acid fluorides and thioesters (Scheme 4).5 When
S-(4-tolyl) 3,5-dimethoxybenzothioate 9 and 4-methoxybenzoyl
fluoride 3 were treated with RhH(PPh3)4 (5 mol %) and dppe
(10 mol %) in refluxing chlorobenzene for 3 h, a mixture of
3,5-dimethoxybenzoyl fluoride 10 (37%) and S-(4-tolyl)
4-methoxybenzothioate 11 (40%) was obtained with the recovery of
9 (55%) and 3 (35%). No reaction occurred in the absence of the
rhodium complex.
In this work, substituted pentafluorobenzenes were compared
in the fluorination of S-(4-tolyl) 3,5-dimethoxybenzothioate 9
(Table 5). When (4-tolylthio)pentafluorobenzene was reacted with
9 (1 equiv) in the presence of RhH(PPh3)4 (2.5 mol %) and dppe
(5 mol %), 3,5-dimethoxybenzoyl fluoride 10 was obtained in 86%
yield along with 1,4-bis(4-tolylthio)-2,3,5,6-tetrafluorobenzene 12
in 92% yield (entry 3). No reaction occurred in the absence of the
rhodium complex and dppe ligand. In the case of hexa-
fluorobenzene, 10 was obtained in 79% yield along with 12 in 79%
yield (based on the 4-tolylthio group) (entry 4). The yield of 10
decreased with pentafluorobenzenes possessing either electron
donating groups, such as diphenylamino and butylthio groups, or
electron-withdrawing groups, such as acetyl, benzoyl, and cyano
groups (entries 1e2 and 5e7). In these reactions, 9 was recovered
quantitatively. 4-Substituted pentafluorobenzenes were obtained
as co-products derived from the 4-tolylthio group, and no other
regioisomers were isolated. (4-Tolylthio)pentafluorobenzene 13
MeO
O
C
MeO
MeO
O
C
F
S
Me
RhH(PPh3)4 (5 mol%)
dppe (10 mol%)
MeO
10 37%
9
+
+
PhCl, refl., 3 h
O
C
O
C
3
MeO
F
MeO
S
Me
11 40%
recovered 9 55%
recovered 3 35%
O
O
C
O
C
O
Table 5
Rh cat.
Effect of pentafluorobenzenes on acid fluoride synthesis from thioester
+
+
R C SAr
R'
F
R
F
R' C SAr
MeO
MeO
O
C
O
C
Scheme 4.
S(4-Tol)
F 10
RhH(PPh3)4 (2.5 mol%)
dppe (5 mol%)
PhCl, refl., 2 h
9
MeO
MeO
F
F
F
F
+
F
R
+ R
S(4-Tol)
The use of triphenylphosphine as a co-substrate promoted the
formation of thioesters from acid fluorides (Scheme 5).5 For ex-
ample, benzoyl fluoride 2, di(4-tolyl) disulfide (0.5 equiv), and tri-
phenylphosphine (0.5 equiv) were reacted in refluxing THF for 3 h
in the presence of RhH(PPh3)4 (0.1 mol %) and dppe (0.2 mol %), and
S-(4-tolyl) benzothioate was obtained in 88% yield. The formation
of triphenylphosphine difluoride was confirmed by NMR. The
equilibrium was shifted to thioesters by the addition of triphenyl-
phosphine, which trapped fluoride to form triphenylphosphine
difluoride.
F
F
F
F
Entry
R
Yield of 10/%
1
2
3
4
5
6
7
Ph2N
43
48
86
79
20
49
32
n-C4H9S
4-TolS (13)
F
MeCO
PhCO
CN

7850
M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
and hexafluorobenzene, which gave 12 as a co-product, showed
a greater p-tolylthio acceptor ability.
chlorobenzene for 4 h, 4-(dimethylamino)benzoyl fluoride 15 (20%)
and diethyl(4-methoxybenzoyl)phosphine sulfide 16 (18%) were
obtained with recovery of 14 (73%) and 3 (68%) (Scheme 8).
Different substituted pentafluorobenzenes were used for the
formation of acid fluorides from aryl esters and thioesters
(Scheme 7). The formation of acid fluorides from thioesters was
promoted by the conversion of (4-tolylthio)pentafluorobenzene 13
or hexafluorobenzene to aryl sulfides; the formation of acid fluorides
from aryl esters was promoted by the conversion of benzoylpenta-
fluorobenzene 5 to aryl ethers; both reactions provided aryl ethers
and sulfides in the p-orientation. Previously, we observed that the
rhodium-catalyzed arylthiolation reactions of polyfluorobenzenes
tended to form 1,4-difluoro derivatives (p-difluoride rule).9 The re-
sults obtained in these studies may be explained by the minimization
of the dipole moment in the product: in the formation of acid fluo-
rides from thioesters, two 4-tolylthio groups at the 1,4-position in the
co-product minimized the dipole moment in the product. In the re-
actions using hexafluorobenzene, (4-tolylthio)pentafluorobenzene
13 was not detected, which indicated a very rapid second 4-
tolylthiolation reaction compared with the first reaction. Because
similar 4-tolylthiolation was involved, 13 and hexafluorobenzene
showed a similar reactivity. In the formation of acid fluorides from
aryl esters, the 4-cyanophenoxy moiety probably balanced well with
the benzoyl moiety in 6. The rhodium complex probably recognized
O
C
O S
PEt2
Me2N
F
Me2N
MeO
C
RhH(PPh3)4 (2 mol%)
dppe (4 mol%)
15 20%
14
+
+
O
C
3
O S
PhCl, refl., 4 h
F
MeO
C
PEt2
16 18%
recovered 14 73%
recovered 3 68%
O
C F
O S
O S
O
C
Rh cat.
+
+
F
R'
R
R
C
PEt2
R' C PEt2
Scheme 8.
We previously reported the synthesis of acylphosphine sulfides
from acid fluorides and diphosphine sulfide with concomitant
formation of fluorophosphine sulfide.3 For example, when 4-
methoxybenzoyl fluoride 3 and tetraethyldiphosphine disulfide
17 (1 equiv) were treated with RhH(PPh3)4 (1 mol %) and bis(2-
diphenylphosphinoethyl)phenylphosphine (2 mol %) in refluxing
THF for 4 h, diethyl(4-methoxybenzoyl)phosphine sulfide 16 was
obtained in 97% yield (Scheme 9). The formation of fluo-
rodiethylphosphine sulfide 18 was confirmed by NMR analysis. The
equilibrium between acid fluorides and acylphosphine sulfides was
shifted to the latter using 17 as a co-substrate with the formation of
18 as a co-product.
the bias in the
p-electron distribution on the aromatic nucleus and
reacted with a fluorine atom in the direction to minimize the bias.
F
F
F
F
F
F
O
O
RC
Rh cat.
Rh cat.
F
4-TolS
RC SAr +
4-TolS
SAr
OAr
+
+
F
F
F
F
13
F
F
F
F
O
O
RC
O
Ph C
O
Ph C
+
F
RC OAr
RhH(PPh3)4 (1 mol%)
S
O
C
S
(Ph2PCH2CH2)2PPh (2 mol%)
F
F
F
F
+ Et P PEt2
MeO
F
2
5
THF, refl., 3 h
O S
co-substrate
co-product
CN
3
17
S
Et2P
+
F
minimum dipole moment
MeO
C
PEt2
F
F
F
F
F
16 97%
18
4-TolS
S(4-Tol)
X
O
Scheme 9.
F
F
F
The reverse reaction, synthesis of acid fluorides from acyl-
phosphine sulfides, was examined using another co-substrate.
When 14 and benzoylhexafluorobenzene 5 (2 equiv) were reacted
in the presence of RhH(PPh3)4 (5 mol %) and 1,2-
bis(diethylphosphino)ethane (depe, 10 mol %) in refluxing chloro-
benzene for 4 h, acid fluoride 15 was obtained in 87% yield along
with 18 in 58% yield (Scheme 10). No reaction occurred in the ab-
sence of the rhodium complex. In this reaction, the expected co-
product, (4-benzoylphenyl)diethylphosphine sulfide 19 was not
obtained, and 18 was formed instead. The mechanism of this re-
action is now under investigation.
12
6
X = MeCO
= PhCO
= CN
Scheme 7.
RhH(PPh3)4-dppe catalyzed the equilibrium acyl transfer re-
action between acid fluorides and thioesters, and the use of a co-
substrate shifted the equilibrium to either product. The reaction
of acid fluorides and disulfides in the presence of triphenylphos-
phine gave thioesters accompanied by triphenylphosphine
difluoride. The same complex catalyzed the reaction of aryl thio-
esters and (4-tolylthio)pentafluorobenzene 13 giving acid fluorides
accompanied by 1,4-di(p-tolylthio)-2,3,5,6-tetrafluorobenzenes 12.
RhH(PPh3)4 (5 mol%)
depe (10 mol%)
F
F
F
O S
C PEt2 +
O
Ph C
Me2N
F
PhCl, refl., 4 h
F
2.3. Interconversion of acylphosphine sulfides and acid
fluorides
14
5
F
F
F
O
S
S
O
+
Et2P F
PEt2
Ph C
The equilibrium in rhodium-catalyzed interconversions be-
tween acid fluorides and acylphosphine sulfides was examined.
When equimolar amounts of diethyl(4-dimethylaminobenzoyl)
phosphine sulfide 14 and 4-methoxybenzoyl fluoride 3 were
treated with RhH(PPh3)4 (2 mol %) and dppe (4 mol %) in refluxing
Me2N
C F
15 87%
Scheme 10.
F
19
18 58%

M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
7851
adamantanecarbonyl)phosphine sulfide 21 (32%) were obtained
with recovery of 14 (50%) and 20 (54%) (Scheme 11).
We have shown that acid fluorides undergo equilibrium acyl
transfer reactions with aryl esters, thioesters, and acylphosphine
sulfides under rhodium-catalyzed conditions. In addition, acid
fluorides were converted efficiently into acylphosphine sulfides,
thioesters, and aryl esters by using appropriate co-substrates
(Fig. 2). The formation of acylphosphine sulfides was promoted
by the conversion of tetraethylphosphine disulfide 17 as a co-
substrate to diethylphosphine fluoride 18 as a co-product; the
formation of thioesters was promoted by the conversion of tri-
phenylphosphine as a co-substrate to triphenylphosphine difluor-
ide as a co-product; and the formation of aryl esters was promoted
by the conversion of triphenylsilane as a co-substrate to triphe-
nylsilyl fluoride as a co-product or by the removal of hydrogen
fluoride. Acid fluorides can be versatile reagents for the acyl
transfer reaction between heteroatoms.
O S
O S
PEt2 21 32%
+
Me2N
C
PEt2
Ad
C
RhH(PPh3)4 (5 mol%)
depe (10 mol%)
14
+
PhCl, refl., 3 h
O
O
C
Ad
C
S
OMe
Me2N
S
OMe
22 36%
20
recovered 14 50%
recovered 20 54%
O S
PEt2
O S
+
R' C PEt2
O
C
O
C
Rh cat.
Scheme 11.
+
R'
SAr
R
SAr
R
C
We previously reported the synthesis of acylphosphine sulfides
from For example, when S-(4-tolyl) 4-
thioesters.4
methoxybenzothioate 11 and tetraethyldiphosphine disulfide 17
(1 equiv) were reacted in refluxing chlorobenzene in the presence
of RhH(PPh3)4 (5 mol %) and depe (10 mol %), (4-methoxybenzoyl)
diethylphosphine sulfide 23 was obtained in 55% yield along with
4-tolyl diethyldithiophosphinate 24 in 51% yield (Scheme 12). No
reaction occurred in the absence of the rhodium complex. The
equilibrium was shifted to acylphosphine sulfide using 17 as a co-
substrate with the formation of 24 as a co-product.
RhH(PPh3)4 (5 mol%)
O
C S
S
S
depe (10 mol%)
PhCl, refl., 6 h
+
Me
MeO
Et2P PEt2
17
11
O
S
S
+
MeO
C PEt2
Et2P
S
Me
23 55%
Scheme 12.
24 51%
Fig. 2. Equilibrium control between acid fluorides and acylphosphine sulfides, thio-
esters, or aryl esters using appropriate heteroatom acceptors.
Then the reverse reaction, synthesis of thioesters from acyl-
phosphine sulfides, was examined. The reaction of diethyl{4-
(dimethylamino)benzoyl}phosphine sulfide 14 and diphenyl
disulfide (1 equiv) in the presence of RhH(PPh3)4 (2 mol %) and
dppe (4 mol %) in refluxing THF gave S-phenyl 4-(dimethylamino)
benzothioate in 99% yield along with phenyl dieth-
yldithiophosphinate in 91% yield (Table 6, entry 1). No reaction
occurred in the absence of the rhodium complex and dppe ligand.
The reaction could be applied to aromatic and aliphatic acylphos-
phine sulfides. The equilibrium between acylphosphine sulfides
and thioesters was shifted to thioester by converting disulfides as
co-substrates to thiophosphinates as co-products.
The reverse reactions to form acid fluorides from acylphosphine
sulfides, aryl esters, and thioesters were conducted using appro-
priately substituted pentafluorobenzenes as co-substrates (Fig. 2).
The formation of acid fluorides from acylphosphine sulfides was
promoted by the conversion of 4-benzoylpentafluorobenzene as
a co-substrate to diethylphosphine fluoride as a co-product; the
formation of acid fluorides from aryl esters was promoted by the
conversion of benzoylpentafluorobenzene as a co-substrate to aryl
ethers as a co-product; and the formation of acid fluorides from
thioesters was promoted by the conversion of (4-tolylthio)penta-
fluorobenzene as a co-substrate to aryl sulfides as a co-product.
Thus, the equilibrium was shifted between acid fluorides and
acylphosphine sulfides, thioesters, or aryl esters by using appro-
priate heteroatom acceptors.
Table 6
Rhodium-catalyzed reaction of acylphosphine sulfides and disulfides
RhH(PPh3)4 (2 mol%)
O S
R C PEt2
O
2.4. Interconversion of acylphosphine sulfides and thioesters
S
dppe (4 mol%)
THF, refl., 3 h
+
+
SR' SR'
R C SR'
Et2P SR'
At this stage, it was of interest to learn whether the rhodium-
catalyzed method could be used for the interconversion between
aryl esters, acylphosphine sulfides, and thioesters. It was confirmed
that the equilibrium between acylphosphine sulfides and thioesters
was catalyzed by the rhodium complex. When diethyl{4-(dime-
thylamino)benzoyl}phosphine sulfide 14 and S-(4-methoxy) ada-
mantanoate 20 were treated with RhH(PPh3)4 (5 mol %) and
depe (10 mol %) in refluxing chlorobenzene for 3 h, S-(4-methoxy)
25
26
Entry
R
R0
Yield of 25/%
Yield of 26/%
1
2
3
4
5
6
4-Me2NC6H4
4-Me2NC6H4
4-Me2NC6H4
4-Me2NC6H4
4-Me2NC6H4
n-C11H23
Ph
99
93
97
83
99
90
91
88
90
78
99
82
4-MeOC6H4
4-Tol
4-ClC6H4
n-C8H17
Ph
4-dimethylaminobenzoate
22
(36%)
and
diethyl(1-

7852
M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
2.5. Interconversion of acylphosphine sulfide and aryl esters
The reverse reaction, synthesis of aryl esters from acylphos-
phine sulfides, was examined. In the presence of the RhH(PPh3)4
(5 mol %) and dppe (10 mol %), 14 was converted to 4-cyanophenyl
The equilibrium between acylphosphine sulfides and aryl esters
was examined. When 14 and 4-cyanophenyl 2-propylpentanoate
27 were reacted in refluxing chlorobenzene for 2 h in the pres-
ence of RhH(PPh3)4 (5 mol %) and depe (10 mol %), 4-cyanophenyl
4-(dimethylamino)benzoate 28 (40%) and diethyl(2-propylpenta-
noyl)phosphine sulfide 29 (42%) were obtained with recovery of 14
(52%) and 27 (46%) (Scheme 13). No reaction occurred in the ab-
sence of the rhodium complex.
4-dimethylaminobenzoate
(95%)
by
reaction
with
4-
methoxyphenol in refluxing THF for 4 h (Scheme 15). The use of
the rhodium complex was essential for this reaction.
RhH(PPh3)4 (5 mol%)
O S
dppe (10 mol%)
+
PEt2
Me2N
C
MeO
OH
THF, refl., 4 h
14
O
C
S
O
O S
+
Me2N
O
Et2P
H
OMe
Me2N
C O
CN
Me2N
C
14
PEt2
RhH(PPh3)4 (5 mol%)
depe (10 mol%)
95%
33 86%
28 40%
+
O
+
Scheme 15.
PhCl, refl., 2 h
CN
O S
PEt2
29 42%
C
O
C
The rhodium catalyst equilibrated the acyl transfer reaction be-
tween acylphosphine sulfides and aryl esters, and the use of co-
substrates shifted the reaction toward the production of either prod-
uct. The use of diphosphine disulfide promoted the formation of acyl-
phosphine sulfides, and the use of phenol promoted that of aryl esters.
27
recovered 14 52%
recovered 27 46%
O S
PEt2
O S
R' C PEt2
O
C
O
Rh cat.
+
+
R'
OAr
R C OAr
R
C
2.6. Interconversion of aryl esters and thioesters
Scheme 13.
Using tetraethyldiphosphine disulfide 17 as a co-substrate, aryl
esters were efficiently converted to acylphosphine sulfides. In the
presence of RhH(PPh3)4 (5 mol %) and depe (10 mol %), 27 and 17
(1 equiv) were reacted in refluxing chlorobenzene for 3 h, and
diethyl(2-propylpentanoyl)phosphine sulfide 29 was obtained in
60% yield along with 4-cyanophenyl diethylphosphinothioate 30 in
58% yield (Scheme 14(a)). No reaction occurred in the absence of
the rhodium complex. The reaction was applied to O-(4-
cyanophenyl) 3,5-dimethoxybenzoate 31, and diethyl(3,5-
dimethoxybenzoyl)phosphine sulfide 32 was obtained in 59%
yield (Scheme 14(b)). The equilibrium was shifted to acylphosphine
sulfides using 17 as a co-substrate with the formation of phosphi-
nothioate 30 as a co-product. The results may be consistent with
the PeO bond being stronger than the PeP bond. Acylphosphine
sulfides can now be synthesized from aryl esters as well as acid
fluorides.3 A few syntheses of acylphosphine sulfides appear in the
literature, all of which use the sulfuration reaction of acylphos-
phines.10 The rhodium-catalyzed method shown in this study is
versatile for the synthesis of acylphosphine sulfides.
The rhodium-catalyzed equilibrium between aryl esters and
thioesters was examined. When 4-cyanophenyl dodecanoate 7 and
S-(4-tolyl) 4-methoxybenzoate 11 were reacted in refluxing chlo-
robenzene in the presence of RhH(PPh3)4 (5 mol %) and depe
(10 mol %), S-(4-tolyl) dodecanthioate 34 (49%) and 4-cyanophenyl
4-methoxybenzoate 1 (49%) were obtained with recovery of 7 (50%)
and 11 (49%) (Scheme 16).
O
C
O
C
n-C11H23
O
CN
n-C11H23
S
Me
34 49%
RhH(PPh3)4 (5 mol%)
dppe (10 mol%)
7
+
+
PhCl, refl., 3 h
O
C
O
C
MeO
S
+
Me
MeO
O
CN
11
1 49%
recovered 7 50%
recovered 11 49%
O
O
O
C
O
Rh cat.
+
R C SAr'
R'
SAr'
R
C
OAr
R' C OAr
(a) Reaction of aliphatic ester with 17.
Scheme 16.
RhH(PPh3)4 (5 mol%)
O
C
S
S
depe (10 mol%)
PhCl, refl., 3 h
+
O
CN
Et2P PEt2
The transesterification of thioesters and alcohols has been
studied in macrolactonation using acid or base promoters.11 We
describe herein the rhodium-catalyzed conversion of thioesters to
aryl esters without using acid or base. S-(4-Tolyl) 4-
methoxybenzoate 11 and 4-cyanophenol (1 equiv) were reacted
in the presence of RhH(PPh3)4 (10 mol %) and dppe (20 mol %)
under an air atmosphere, and 4-cyanophenyl 4-methoxybenzoate 1
was obtained in 69% yields along with di(4-tolyl) disulfide 35 in 59%
yield (Scheme 17(a)). 4-Toluenethiol 36 was not detected in this
reaction. Thiol 36 could be oxidized to 35 under rhodium catalysis
conditions,12 which might have shifted the equilibrium to aryl es-
ters by removing 36 from the system. In accordance with this, when
the reaction was conducted under an argon atmosphere, yield of 1
decreased to 36% and thiol 36 and disulfide 35 were obtained in 21%
and 22% yields (1H NMR), respectively. No reaction occurred in the
absence of the rhodium complex. In the case of 4-chlorophenol, 4-
chlorophenyl 4-methoxybenzoate was obtained in 71% yield
27
17
S
O S
PEt2
+
C
Et2P
O
CN
29 60%
30 58%
(b) Reaction of aromatic ester with 17.
RhH(PPh3)4 (5 mol%)
depe (10 mol%)
MeO
S
S
Et2P PEt2
O
C
+
CN
O
PhCl, refl., 3 h
MeO
31
17
MeO
S
S
PEt2
O
C
+
Et2P
O
CN
MeO
32 59%
30 53%
Scheme 14.

M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
7853
shifted the equilibrium to desired products (Fig. 3). Aryl esters
were synthesized from acylphosphine sulfides, thioesters, and acid
fluorides by reaction with phenols (reactions B, F, and D), in which
the formation of diethylphosphine sulfide, disulfides, and triphe-
nylsilyl fluoride, or removal of hydrogen fluoride, respectively,
shifted the equilibrium to aryl ethers. Aryl esters were converted
to these compounds using oxygen acceptors as co-substrates.
Acylphosphine sulfides were formed using the conversion of tet-
raethylphosphine disulfide to O-aryl diethylphosphinothioates
(reaction A); thioesters, by the conversion of S-aryl dieth-
ylphosphinothioate to O-aryl diethylphosphinothioates (reaction
E); and acid fluorides, by the conversion of benzoylpenta-
fluorobenzene to aryl ethers (reaction C). The synthesis of acid
fluorides from acylphosphine sulfides or thioesters was conducted
using substituted pentafluorobenzenes as co-substrates. Acid
fluorides were formed from acylphosphine sulfides using the
conversion of 4-benzoylpentafluorobenzene to diethylphosphine
fluoride (reaction H); acid fluorides were formed from thioesters
using the conversion of 4-tolylpentafluorobenzene to aryl sulfides
(reaction J). The reverse conversions of acid fluorides into acyl-
phosphine sulfides and thioesters were conducted in the presence
of fluoride acceptors as co-substrates. Acylphosphine sulfides were
formed using the conversion of tetraethyldiphosphine disulfide to
diethylphosphine fluoride (reaction G); thioesters were formed
using the conversion of triphenylphosphine to triphenylphosphine
difluoride (reaction I). The equilibrium reaction between acyl-
phosphine sulfides and thioesters was shifted using disulfides for
the formation of thioesters (reaction K), and tetraethyldiphos-
phine disulfides for the formation of acylphosphine sulfides (re-
action L). These are novel rhodium-catalyzed acyl transfer
reactions via equilibrium shifts using appropriate co-substrates.
(a) Reaction of 11 with 4-cyanophenol.
RhH(PPh3)4 (10 mol%)
dppe (20 mol%)
O
+
MeO
C
S(4-Tol)
MeO
NC
OH
PhCl, refl., 9 h
11
O
C
+
+
O
CN
(4-TolS)2
4-TolSH
35
1
36
21%a)
59%
under Ar
under Air
22%a)
n.d.
36%
69%
a) Crude 1H-NMR Yield.
(b) Reaction of phenols.
RhH(PPh3)4 (5 mol%)
dppe (10 mol%)
O
O
C
+
C S(4-Tol)
ArOH
MeO
MeO
OAr
PhCl, refl., 9 h, Air
11
a)
a)
4-CNC H
69%
71%
77%
Ar =
6
4
4-ClC6H4
4-Tol
4-MeOC6H4 67%
PhCH2
47%
a) RhH(PPh3)4 (10 mol%) and dppe (20 mol%) were used.
Scheme 17.
(Scheme 17(b)). 4-Cresol and 4-methoxyphenol also reacted in the
presence of RhH(PPh3)4 (5 mol %) and dppe (10 mol %). Aryl esters
were formed efficiently from thioesters and phenols.
The reverse reaction, synthesis of thioesters from aryl esters,
was examined. When 4-cyanophenyl 3,5-dimethoxybenzoate was
reacted with phenyl dimethyldithiophosphinate (1 equiv) in the
presence of RhH(PPh3)4 (2.5 mol %) and dppe (5 mol %) in refluxing
cholorobenzene for 3 h, S-phenyl 3,5-dimethoxybenzoate was
obtained in 89% yield along with O-(4-cyanophenyl) dimethyl-
phosphinothioate 38 in 86% yield (Table 7, entry 1). The equilibrium
between aryl esters and thioesters was shifted to thioesters using
dithiophosphinate as a co-substrate with the formation of phos-
phinothioate as a co-product. The observation may be consistent
with the energy of the PeO bond being higher than that of the PeS
bond.
Table 7
Rhodium-catalyzed reaction of aryl esters and dithiophosphinate
RhH(PPh3)4 (2.5 mol%)
dppe (5 mol%)
PhCl, refl., 3 h
O
C
S
+
CN
R
O
Me2P SAr
O
C
S
Me2P
+
SAr
R
O
CN
37
38
Entry
R
Ar
Yield of 37/%
Yield of 38/%
1
2
3
4
3,5-(MeO)2C6H4
3,5-(MeO)2C6H4
4-MeOC6H4
Ph
89
87
83
84
86
83
82
83
4-Tol
4-Tol
4-Tol
(n-C3H7)2CH
Fig. 3. Equilibrium control of rhodium-catalyzed acyl transfer reactions.
2.7. Mechanistic considerations
A rhodium complex catalyzed the equilibrium acyl transfer re-
action between aryl esters and thioesters. In the presence of phenol
and dithiophosphinate as co-substrates, the equilibrium could be
shifted to aryl esters and thioesters, respectively.
Rhodium catalysts equilibrated acyl transfer reactions between
acid fluorides, acylphosphine sulfides, thioesters, and aryl esters,
and the use of appropriate heteroatom acceptors as co-substrates
A possible mechanism of these acyl transfer reactions is as fol-
lows (Fig. 4). Oxidative addition of an acyl compound to a low
valent rhodium complex provides a C(O)eRheXR intermediate,
which undergoes an exchange reaction with another acyl com-
pound C0(O)eYR0 forming a new C(O)eRheYR0 complex. Then, the

7854
M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
3. Conclusion
In summary, the rhodium-catalyzed method can be used for acyl
transfer equilibrium between acid fluorides, acylphosphine sul-
fides, thioesters, and aryl esters. Appropriate co-substrates changed
the relative thermodynamic stabilities of substrates and products,
and efficiently provided desired products. This method using the
combination of a transition metal catalyst and heteroatom accep-
tors can be generally used to shift equilibria.
4. Experimental section
4.1. General
1H, 13C, 19F, 31P NMR spectra were recorded on a Varian Mercury
Fig. 4. Possible mechanism of acyl transfer reaction.
(400 MHz) or a JEOL JNM-ECA 600 (600 MHz). Tetramethylsilane (
0.00) was used as internal standard for 1H NMR. 13C NMR was
referenced to the residual solvent (CDCl3, 77.0). Trifluoroacetic
acid ( ꢁ6.0) were used as ex-
ꢁ79.0) and triphenylphosphine (
d
product is liberated by reductive elimination with the regeneration
of the rhodium catalyst.
d
d
d
The carbothiolation reaction13 of thioesters and 1-alkynes pro-
ceeded under rhodium catalysis, which is consistent with the for-
mation of RCOeRheXR0 complex under the stated conditions.
When an equimolar mixture of S-butyl 4-cyanobenzothioate and 1-
decyne in DMSO was heated at 100 ꢀC for 12 h in the presence of
RhH(PPh3)4 (10 mol %) and Et2PhP (30 mol %), (E)-3-butylthio-1-(4-
cyanophenyl)-2-undecen-1-one 39 was obtained in 57% yield (E/
Z¼77/23) as a mixture of stereoisomers (Table 8, entry 2). No re-
action occurred in the absence of the rhodium complex and Et2PhP
ligand. The solvent was not limited to DMSO, and using THF solvent
39 was obtained in 20% yield (E/Z¼60/40) in the presence of
RhH(PPh3)4 (5 mol %) and Et2PhP (10 mol %) (entry 3). When the p-
substituent was changed to chloride or hydrogen, the yield of the
carbothiolated products decreased (entries 4 and 5). The reaction of
S-alkyl thioesters also gave products in moderate yields. An ali-
phatic thioester and S-aryl ester gave the product in low yields. It is
likely that the rhodium complex oxidatively added to the COeS
bond of thioesters to form COeRheS species, which underwent
carbothiolation with an alkyne. A metal-catalyzed carbothiolation
reaction of aryl thioesters and 1-alkynes was reported by Kambe.14
Alkyl thioesters, however, were less reactive, and trifluoroacetyl
thioesters were used instead. The rhodium-catalyzed method
exhibited different reactivity. In many of the acyl transfer reactions
described, the oxidative addition of the rhodium complex to the
eCOeX compounds probably occurred.
ternal standard. IR spectra were measured on a JASCO FT/IR-410
spectrophotometer. Melting points were determined with
a Yanaco micro melting point apparatus without correction. High-
and low-resolution mass spectra were measured on a JEOL JMS-DX-
303, a JEOL JMS-700, or a JMS-T100GC spectrometer. KANTO
CHEMICAL Co., Inc. silica gel 60 (40e50 mm) was employed for flash
column chromatography.
4.2. Equilibrium reaction of aryl ester and acid fluoride
(Scheme 2)
In a two-necked flask equipped with a reflux condenser were
placed 4-cyanophenyl 4-methoxybenzoate 1 (0.25 mmol, 63.3 mg),
benzoyl fluoride 2 (0.25 mmol, 27
mL), RhH(PPh3)4 (5 mol %,
14.4 mg), and cis-1,2-bis(diphenylphosphino)ethene (10 mol %,
9.9 mg) in chlorobenzene (1 mL) under an argon atmosphere, and
the solution was stirred under reflux for 2 h. The solvent was re-
moved under reduced pressure, and the residue was purified by
flash column chromatography on silica gel giving 4-
methoxybenzoyl fluoride 3 (15.7 mg, 41%) and 4-cyanophenyl
benzoate 4 (25.7 mg, 46%) as well as recovered 1 (27.3 mg, 43%)
and 2 (37% by 1H NMR yield). Compound 3: colorless oil. 1H NMR
(400 MHz, CDCl3)
d
3.90 (3H, s), 6.99 (2H, dd, J¼8.8, 1.2 Hz), 8.00
(2H, d, J¼8.8 Hz). 13C NMR (100 MHz, CDCl3)
d 55.6, 114.4, 116.8 (d,
J¼61.4 Hz), 133.8 (d, J¼3.8 Hz), 157.3 (d, J¼337.2 Hz), 165.2. 19F NMR
(377 MHz, CDCl3)
d 13.0. IR (neat) v 1799, 1607, 1513, 1254, 1171,
1021, 1001 cmꢁ1. MS (EI) m/z 154 (Mþ, 100%), 126 (MþꢁCO, 30%).
HRMS calcd for C8H7O2F: 154.0430. Found: 154.0412. Compound 4:
colorless solid. Mp 91.5e92.5 ꢀC (hexane). Lit.15 91.0e91.5 ꢀC
Table 8
Carbothiolation reaction of thioesters and a 1-alkyne
RhH(PPh3)4 (5 mol%)
Et2PhP (15 mol%)
DMSO, 100 °C, 12 h
O
C
(benzene). 1H NMR (400 MHz, CDCl3)
d
7.38 (2H, d, J¼8.8 Hz), 7.54
+
X
SR
n-C8H17
H
(2H, t, J¼7.6 Hz), 7.68 (1H, t, J¼7.6 Hz), 7.75 (2H, d, J¼8.8 Hz), 8.20
(2H, d, J¼8.0 Hz). 13C NMR (100 MHz, CDCl3)
d 109.8, 118.2, 122.9,
O
X
128.6, 128.7, 130.2, 133.7, 134.1, 154.2, 164.3. IR (KBr) v 3049, 2229,
1735, 1502, 1269, 1217, 1065 cmꢁ1. MS (EI) m/z 223 (Mþ, 22%), 105
(MþꢁC7H4NO, 100%). HRMS calcd for C14H9O2N: 223.0633. Found:
223.0632.
RS
n-C8H17
Entry
R
X
Yield/%
1
2
3
4
5
6
7
8
9c
n-C4H9
n-C4H9
n-C4H9
n-C4H9
n-C4H9
Me
PhCH2
4-Tol
n-C8H17
CN (39)
CN (39)
CN (39)
Cl
H
CN
49 (E/Z¼73/27)
4.3. Typical procedures for the synthesis of acid fluoride,
synthesis of p-methoxybenzoyl fluoride 3 (Table 1)
57 (E/Z¼77/23)a
20 (E/Z¼60/40)b
37 (E/Z¼82/18)a
28 (E/Z¼79/21)a
55 (E/Z¼69/31)a
58 (E/Z¼72/28)a
3 (Z major)
In a two-necked flask equipped with a reflux condenser were
placed 1 (0.25 mmol, 63.3 mg), benzoylpentafluorobenzene 5
(0.25 mmol, 68 mg), RhH(PPh3)4 (5 mol %, 14.4 mg), and cis-1,2-
bis(diphenylphosphino)ethene (10 mol %, 9.9 mg) in chloroben-
zene (1 mL) under an argon atmosphere, and the solution was
stirred under reflux for 3 h. The solvent was removed under re-
duced pressure, and the residue was purified by flash column
CN
CN
16 (E only)
a
RhH(PPh3)4 (10 mol %) and Et2PhP (30 mol %) were used.
THF refl.
b
c
S-Octyl octanoate was used.

M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
7855
chromatography on silica gel giving 4-methoxybenzoyl fluoride 3
(35.3 mg, 92%) and 1-benzoyl-4-(4-cyanophenoxy)-2,3,5,6-
tetrafluorobenzene 6 (88.8 mg, 96%). Compound 6: colorless
solid. Mp 100.5e101.5 ꢀC (hexane/diethyl ether¼2/1). 1H NMR
(petroleum ether). Lit.15 87e88 ꢀC (benzene). 1H NMR (400 MHz,
CDCl3)
3.83 (3H, s), 6.94 (2H, tt, J¼1.2, 9.2 Hz), 7.13 (2H, dd, J¼1.2,
d
9.2 Hz), 7.51 (2H, tt, J¼1.6, 8.0 Hz), 7.63 (1H, tt, J¼1.6, 7.2 Hz), 8.20
(2H, dt, J¼8.8, 5.2 Hz) 13C NMR (100 MHz, CDCl3)
d 55.6, 114.5,122.4,
(400 MHz, CDCl3)
d
7.13 (2H, d, J¼8.8 Hz), 7.56 (2H, t, J¼8.0 Hz), 7.70
128.5, 129.6, 130.1, 133.5, 144.4, 157.3, 165.5. IR (KBr) v 2935, 1729,
1594, 1508, 1454, 1195, 1029, 869, 754, 713 cmꢁ1. MS (EI) m/z 228
(Mþ, 43%), 105 (MþꢁC7H7O2, 100%). HRMS calcd for C14H12O3:
228.0396. Found: 228.0768. Triphenylsilyl fluoride colorless solid.
Mp 64.0e65.0 ꢀC (hexane). Lit.16 64 ꢀC. 1H NMR (400 MHz, CDCl3)
(2H, d, J¼8.8 Hz), 7.71 (1H, t, J¼8.0 Hz), 7.90 (2H, d, J¼8.0 Hz). 13C
NMR (100 MHz, CDCl3)
d
107.9, 115.8 (t, J¼20.8 Hz), 116.3, 118.1,
129.1, 129.7, 133.7 (t, J¼12.7 Hz), 134.4, 135.1, 135.8, 141.2 (dm,
J¼253.0 Hz), 144.0 (dddd, J¼252.0, 12.7, 8.2, 4.5 Hz), 159.4, 185.4. 19F
NMR (377 MHz, CDCl3)
d
ꢁ151.7 (2F, dd, J¼21.4, 8.3 Hz), ꢁ139.4 (2F,
d
7.41 (6H, t, J¼7.6 Hz), 7.48 (3H, t, J¼7.6 Hz), 7.65 (6H, dd, J¼7.6,
dd, J¼21.4, 8.3 Hz). IR (KBr) v 3076, 2229, 1682, 1493, 1236 cmꢁ1. MS
(EI) m/z 371 (Mþ, 100%), 105 (MþꢁC13H4F4NO, 65%). HRMS calcd for
C20H9O2F4N: 371.0569. Found: 371.0565.
1.6 Hz). 13C NMR (100 MHz, CDCl3)
d
128.1, 130.8, 132.5 (d,
J¼16.7 Hz), 135.0 (d, J¼2.3 Hz). IR (KBr) v 3051, 3025, 1429, 1124,
841 cmꢁ1. MS (EI) m/z 278 (Mþ, 100%), 201 (MþꢁC6H5, 41%). HRMS
calcd for C18H15SiF: 278.0948. Found: 278.0927.
4.4. Synthesis of acid fluoride from p-cyanophenyl
dodecanoate 7 and benzoylpentafluorobenzene 5 (Table 2)
4.7. Equilibrium reaction of thioester and acid fluoride
(Scheme 4)
In a two-necked flask equipped with a reflux condenser were
placed
7 (0.25 mmol, 75.3 mg), 5 (0.25 mmol, 68.0 mg),
In a two-necked flask equipped with a reflux condenser were
RhH(PPh3)4 (5 mol %, 14.4 mg), and cis-1,2-bis(diphenylphosphino)
ethene (10 mol %, 9.9 mg) in chlorobenzene (1 mL) under an argon
atmosphere, and the solution was stirred under reflux for 2 h. The
solvent was removed under reduced pressure, and the residue was
purified by flash column chromatography on silica gel giving
dodecanoyl fluoride 8 (44.8 mg, 89%) and 6 (78.0 mg, 84%).
placed S-(4-tolyl) 3,5-dimethoxybenzothioate
9 (0.25 mmol,
72 mg), 4-methoxybenzoyl fluoride 3 (0.25 mmol, 38.5 mg),
RhH(PPh3)4 (5 mol %, 14.4 mg), and 1,2-bis(diphenylphosphino)
ethane (10 mol %, 10.0 mg) in chlorobenzene (1 mL) under an argon
atmosphere, and the solution was stirred under reflux for 3 h. The
solvent was removed under reduced pressure, and the residue was
purified by flash column chromatography on silica gel giving 3,5-
dimethoxybenzoyl fluoride 10 (17.2 mg, 37%) and S-(4-tolyl) 4-
methoxybenzothioate 11 (25.8 mg, 40%) as well as recovered 9
(39.7 mg, 55%) and 3 (13.6 mg, 35%). Compound 10: colorless solid.
Compound 8: colorless oil. 1H NMR (400 MHz, CDCl3)
d 0.88 (3H, t,
J¼7.6 Hz), 1.26e1.38 (16H, m), 1.68 (2H, quint, J¼7.2 Hz), 2.50 (2H,
t, J¼7.2 Hz). 13C NMR (100 MHz, CDCl3)
d 14.1, 22.7, 23.9 (d,
J¼1.5 Hz), 28.7, 29.1, 29.2, 29.3, 29.5, 29.6, 31.9, 32.1 (d, J¼48.5 Hz),
163.6 (d, J¼358.4 Hz). 19F NMR (377 MHz, CDCl3)
d 42.4. IR (neat) v
Mp 57.5e58.0 ꢀC (hexane). 1H NMR (400 MHz, CDCl3)
d 3.85 (6H, s),
2926, 2856, 1844, 1088 cmꢁ1. MS (EI) m/z 202 (Mþ, 0.5%), 100
(MþꢁC7H16, 100%). HRMS calcd for C12H23FO: 202.3088. Found:
202.1733.
6.76 (1H, t, J¼2.4 Hz), 7.17 (2H, d, J¼2.8 Hz). 13C NMR (100 MHz,
CDCl3)
d
55.7, 108.0, 108.8 (d, J¼3.8 Hz), 126.5 (d, J¼60.6 Hz), 157.2
(d, J¼341.8 Hz), 161.0. 19F NMR (377 MHz, CDCl3)
d 15.6. IR (neat) v
3099, 3066, 2947, 2844, 1805, 1606, 1593, 1468, 1429, 1356, 1306,
1209, 1200, 1186, 1161, 1065, 1022, 930, 876, 750, 688 cmꢁ1. MS (EI)
m/z 184 (Mþ, 100%), 154 (MþꢁCH2O, 13%). HRMS calcd for C9H9O3F:
184.0536. Found: 184.0540. Compound 11: colorless crystals. Mp
64.5e65.5 ꢀC (hexane/diethyl ether¼5/1). 1H NMR (400 MHz,
4.5. Typical procedures for the synthesis of esters, synthesis
of phenyl benzoate (Tables 3 and 4)
In a two-necked flask equipped with a reflux condenser were
placed 2 (0.5 mmol, 54 mL), phenol (0.5 mmol, 47.0 mg), RhH(PPh3)4
CDCl3)
d
2.40 (3H, s),
d
3.89 (3H, s), 6.96 (2H, d, J¼8.8 Hz), 7.26 (2H,
(1 mol %, 5.8 mg), and 1,2-bis(diphenylphosphino)ethane (2 mol %,
4.0 mg) in chlorobenzene (1 mL) under an argon atmosphere, and
the solution was stirred under reflux with nitrogen bubbling for 3 h.
The solvent was removed under reduced pressure, and the residue
was purified by flash column chromatography on silica gel giving
phenyl benzoate (45.4 mg, 92%) as colorless solid. Mp 69.5e70.0 ꢀC
(ethanol). Lit.15 69e70 ꢀC (benzene). 1H NMR (400 MHz, CDCl3)
d, J¼8.4 Hz), 7.39 (2H, d, J¼8.4 Hz), 8.01 (2H, d, J¼8.8 Hz). 13C NMR
(100 MHz, CDCl3) d 21.3, 55.5, 113.8, 124.0, 129.4, 129.6, 130.0, 135.1,
139.6, 163.9, 189.0. IR (KBr) v 1664, 1599, 1506, 1257, 1210,
1169 cmꢁ1. MS (EI) m/z 258 (Mþ, 2%), 135 (MþꢁMeC6H4S, 100%).
HRMS calcd for C15H14O2S: 258.0715. Found: 258.0699.
d
7.22 (2H, d, J¼8.0 Hz), 7.27 (1H, t, J¼8.0 Hz), 7.43 (2H, t, J¼8.0 Hz),
4.8. Synthesis of S-(4-tolyl) benzothioate (Scheme 5)
7.51 (2H, t, J¼8.0 Hz), 7.64 (1H, t, J¼8.0 Hz), 8.21 (2H, d, J¼8.0 Hz).
13C NMR (100 MHz, CDCl3)
d
121.7, 125.9, 128.5, 129.5, 129.6, 130.1,
In a two-necked flask equipped with a reflux condenser were
placed benzoyl fluoride 2 (620 mg, 5.0 mmol), bis(4-tolyl) disulfide
(615 mg, 2.5 mmol), RhH(PPh3)4 (5.8 mg, 0.1 mol %), 1,2-
bis(diphenylphosphino)ethane (4.0 mg, 0.2 mol %), and triphenyl-
phosphine (655 mg, 50 mol %) in tetrahydrofuran (2 mL) under an
argon atmosphere, and the solution was stirred under reflux for 5 h.
The solvent was removed under reduced pressure, and RhH(PPh3)4
was removed by short flash column chromatography on silica gel.
Then, the solvent was removed under reduced pressure, and the
residue was purified by flash column chromatography on silica gel
giving S-(4-tolyl) benzothioate (1.006 g, 88%). Colorless solid. Mp
76e78 ꢀC (hexane). Lit.17 73e73.5 ꢀC. 1H NMR (400 MHz, CDCl3)
133.6, 150.9, 165.2. IR (KBr) v 3058, 1731, 1266, 1199, 1064 cmꢁ1. MS
(EI) m/z 198 (Mþ, 20%), 105 (MþꢁC6H5O, 100%). HRMS calcd for
C13H10O2: 198.0681. Found: 198.0677.
4.6. The synthesis of esters from benzoyl fluoride 2 and 4-
methoxyphenol using triphenylsilane (Scheme 3)
In a two-necked flask equipped with a reflux condenser were
placed 2 (0.5 mmol, 54 mL), 4-methoxyphenol (0.5 mmol, 62 mg),
triphenylsilane (0.5 mmol, 130 mg), RhH(PPh3)4 (1 mol %, 5.8 mg),
and 1,2-bis(diphenylphosphino)ethane (2 mol %, 4.0 mg) in chlo-
robenzene (1 mL) under an argon atmosphere, and the solution was
stirred at room temperature for 3 h. The solvent was removed
under reduced pressure, and the residue was purified by flash
column chromatography on silica gel giving 4-methoxyphenyl
benzoate (109.1 mg, 96%) and triphenylsilyl fluoride (121.1 mg,
87%). 4-Methoxyphenyl benzoate colorless solid. Mp 89.0e90.0 ꢀC
d
2.41 (3H, s), 7.27 (2H, d, J¼7.2 Hz), 7.40 (2H, d, J¼6.8 Hz), 7.48 (2H,
t, J¼7.2 Hz), 7.60 (1H, t, J¼8.0 Hz), 8.03 (2H, d, J¼7.2 Hz). 13C NMR
(100 MHz, CDCl3) d 21.4, 123.7, 127.5, 128.7, 130.1, 133.6, 135.0, 136.7,
139.8, 190.6. IR (KBr) v 1669, 1205, 899 cmꢁ1. MS (EI) m/z 228 (Mþ,
12%), 105 (MþꢁC7H7S, 100%). HRMS calcd for C14H12OS: 228.0609.
Found: 228.0589.

7856
M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
4.9. Synthesis of 4-methoxybenzoyl fluoride using
hexafluorobenzene (Scheme 6)
1312, 1267, 1234, 1170, 1028, 920, 841, 769, 749, 581 cmꢁ1. MS (EI)
m/z 256 (Mþ, 6%), 135 (MþꢁMeOC6H4CO, 100%). HRMS calcd for
C12H17O2PS: 256.0687. Found: 256.0705.
In a two-necked flask equipped with a reflux condenser were
placed S-(4-tolyl) 4-methoxybenzothioate 11 (0.25 mmol, 64.5 mg),
4.12. The reaction of 4-methoxybenzoyl fluorides 3 and
tetraethyldiphosphine disulfide 17 (Scheme 9)
hexafluorobenzene (0.5 mmol, 57.7
mL), RhH(PPh3)4 (2.5 mol %,
7.2 mg), and 1,2-bis(diphenylphosphino)ethane (5 mol %, 5.0 mg) in
chlorobenzene (1 mL) under an argon atmosphere, and the solution
was stirred under reflux for 3 h. The solvent was removed under
reduced pressure, and the residue was purified by flash column
chromatography on silica gel giving 4-methoxybenzoyl fluoride 3
(36.3 mg, 94%) and 2,3,5,6-tetrafluoro-1,4-bis(4-tolylthio)benzene
12 (97.3 mg, 99%). Compound 12: mp 123e124 ꢀC (ethyl acetate).
In a two-necked flask equipped with a reflux condenser were
placed 4-methoxybenzoyl fluoride 3 (77.1 mg, 0.5 mmol), tetrae-
thyldiphosphine disulfide 17 (121.2 mg, 0.5 mmol), RhH(PPh3)4
(5.8 mg, 1.0 mol %), and bis(2-diphenylphosphinoethyl)phenyl-
phosphine (5.3 mg, 2.0 mol %) in tetrahydrofuran (1 mL) under an
argon atmosphere, and the solution was stirred under reflux for 4 h.
Then, the solvent was removed under reduced pressure, and the
residue was purified by flash column chromatography on silica gel
within 10e15 min giving the diethyl(4-methoxybenzoyl)phosphine
Lit.18 116e117 ꢀC. 1H NMR (400 MHz, CDCl3)
d 2.32 (6H, s), 7.11 (4H,
d, J¼8.4 Hz), 7.32 (4H, d, J¼8.0 Hz). 13C NMR (151 MHz, CDCl3)
d 21.1,
115.7 (m), 128.9, 130.1, 131.8, 138.5, 146.8 (m). 19F NMR (565 MHz,
CDCl3)
d
136.02. IR (KBr) v 2920, 1491, 1462, 1397, 1243, 957, 810,
sulfide 16 (124.6 mg, 97%). Diethylfluorophosphine sulfide 1819 1
NMR (400 MHz, CDCl3)
1.28 (6H, dt, J¼20.8, 7.6 Hz), 2.01e2.19 (4H,
m). 13C NMR (100 MHz, CDCl3)
15.9 Hz). 19F NMR (565 MHz, CDCl3)
NMR (162 MHz, CDCl3)
H
640, 620, 512, 488 cmꢁ1. MS (EI) m/z 394 (Mþ, 29%), 271
(MþꢁC7H7S, 14%). HRMS calcd for C20H14F4S2: 394.0473. Found:
394.0487.
d
d
6.3 (d, J¼4.6 Hz), 27.1 (dd, J¼67.4,
d
ꢁ96.3 (d, J¼1017.0 Hz). 31P
d
133.4 (d, J¼1012.7 Hz). IR (neat) v 2979,
4.10. Synthesis of 3,5-dimethoxybenzoyl fluoride 10 using
substituted pentafluorobenzene, reaction of 4-
tolylthiopentafluorobenzene (Table 5)
2943, 2912, 2883,1801,1606,1458,1404,1255,1171,1038,1018, 820,
783 cmꢁ1. MS (EI) m/z 140 (Mþ, 100%), 112 (MþꢁC2H4, 97%). HRMS
calcd for C4H10FPS: 140.0225. Found: 140.0211.
In a two-necked flask equipped with a reflux condenser were
4.13. The reaction of diethyl{4-(dimethylamino)benzoyl}
phosphine sulfide 14 and benzoylpentafluorobenzene 5
(Scheme 10)
placed S-(4-tolyl) 3,5-dimethoxybenzothioate
9 (0.25 mmol,
72 mg), (4-tolylthio)pentafluorobenzene 13 (0.25 mmol, 72.5 mg),
RhH(PPh3)4 (2.5 mol %, 7.2 mg), and 1,2-bis(diphenylphosphino)
ethane (5 mol %, 5.0 mg) in chlorobenzene (1 mL) under an argon
atmosphere, and the solution was stirred under reflux for 2 h. The
solvent was removed under reduced pressure, and the residue was
purified by flash column chromatography on silica gel giving 3,5-
dimethoxybenzoyl fluoride 10 (39.5 mg, 86%) and 1,4-bis(4-
tolylthio)-2,3,5,6-tetrafluoro benzene 12 (94.3 mg, 96%) as color-
less solid.
In a two-necked flask equipped with a reflux condenser were
placed 14 (0.25 mmol, 67.3 mg), 5 (0.5 mmol, 136 mg), RhH(PPh3)4
(5.0 mol %, 14.4 mg), and 1,2-bis(diethylphosphino)ethane
(10.0 mol %, 5.2 mg) in chlorobenzene (1 mL) under an argon at-
mosphere, and the solution was stirred under reflux for 4 h. The
solvent was removed under reduced pressure, and the residue was
purified by flash column chromatography on silica gel giving 4-
(dimethylamino)benzoyl fluoride 15 (36.3 mg, 87%) and diethyl-
fluorophosphine sulfide 18 (20.3 mg, 58%).
4.11. Equilibrium reaction of acylphosphine sulfide and acid
fluoride (Scheme 8)
4.14. Equilibrium reaction of acylphosphine sulfide
In a two-necked flask equipped with a reflux condenser were
placed diethyl{4-(dimethylamino)benzoyl}phosphine sulfide 14
(0.5 mmol, 134.5 mg), 4-methoxybenzoyl fluoride 3 (0.5 mmol,
77 mg), RhH(PPh3)4 (2 mol %, 11.5 mg), and 1,2-
bis(diphenylphosphino)ethane (4 mol %, 8.0 mg) in chloroben-
zene (1 mL) under an argon atmosphere, and the solution was
stirred under reflux for 4 h. The solvent was removed under re-
duced pressure, and the residue was purified by flash column
chromatography on silica gel giving 4-dimethylaminobenzoyl
fluoride 15 (16.6 mg, 20%) and diethyl(4-methoxybenzoyl)phos-
phine sulfide 16 (23 mg, 18%) as well as recovered 14 (97.8 mg, 73%)
and thioester (Scheme 11)
In a two-necked flask equipped with a reflux condenser were
placed diethyl{4-(dimethylamino)benzoyl}phosphine sulfide 14
(0.25 mmol, 67.3 mg), S-(4-methoxyphenyl) adamantanthioate 20
(0.25 mmol, 75.5 mg), RhH(PPh3)4 (5 mol %, 14.4 mg), and 1,2-
bis(diethylphosphino)ethane (10 mol %, 4.9 mg) in chlorobenzene
(1 mL) under an argon atmosphere, and the solution was stirred
under reflux for 3 h. The solvent was removed under reduced
pressure, and the residue was purified by flash column chroma-
tography on silica gel giving 1-(adamantanecarbonyl)dieth-
ylphosphine sulfide 21 (22.6 mg, 32%) and S-(4-methoxyphenyl) 4-
dimethylaminobenzothioate 22 (25.6 mg, 36%) as well as recovered
14 (33.5 mg, 50%) and 20 (40.7 mg, 54%). Compound 21: colorless
and
3 (52.4 mg, 68%). Compound 15: colorless solid. Mp
126.5e127.0 ꢀC (hexane/AcOEt¼2/1). 1H NMR (400 MHz, CDCl3)
d
3.09 (6H, s), 6.66 (2H, d, J¼8.0 Hz), 7.87 (2H, d, J¼8.8 Hz). 13C NMR
(100 MHz, CDCl3)
d
40.0, 110.3, 110.9 (d, J¼1.5 Hz), 133.4 (d,
solid. Mp 83.0e83.5 ꢀC (hexane). 1H NMR (400 MHz, CDCl3)
d 1.15
J¼3.7 Hz), 154.5, 158.2 (d, J¼332.6 Hz). 19F NMR (377 MHz, CDCl3)
(6H, dt, J¼19.6, 7.6 Hz), 1.75 (6H, t, J¼2.8 Hz), 1.76e1.89 (2H, m),
d
9.2. IR (neat) v 2921, 2832,2683, 1778, 1612, 1540,1488,1447, 1381,
2.05e2.18 (5H, m), 2.21 (6H, d, J¼3.6 Hz). 13C NMR (100 MHz, CDCl3)
1321, 1273, 1235, 1185, 1069, 1015, 982, 943, 821, 779, 754, 693, 585,
518, 499 cmꢁ1. MS (EI) m/z 167 (Mþ, 96), 166 (MþꢁH, 100). HRMS
calcd for C9H10OFN: 167.0746. Found: 167.0732. Compound 16: pale
d
6.4 (d, J¼3.8 Hz), 24.6 (d, J¼47.8 Hz), 27.7, 36.2, 36.8, 52.5 (d,
J¼37.9 Hz), 216.8 (d, J¼25.0 Hz). 31P NMR (162 MHz, CDCl3)
d 51.7. IR
(KBr) v 3326, 2971, 2919, 2885, 2852, 1674, 1454, 1148, 1046, 990,
925, 763, 743, 718, 674, 574 cmꢁ1. MS (EI) m/z 284 (Mþ, 6%), 135
(MþꢁC5H10OPS, 100). HRMS calcd for C15H25OPS: 284.1364. Found:
284.1358. Compound 22: colorless solid. Mp 207.0e208.0 ꢀC (ethyl
yellow oil 1H NMR (400 MHz, CDCl3)
d
1.21 (6H, dt, J¼18.8, 8.0 Hz),
1.99e2.32 (4H, m), 3.90 (3H, s), 6.96 (2H, d, J¼8.0 Hz), 8.59 (2H, d,
J¼8.4 Hz). 13C NMR (100 MHz, CDCl3)
d
6.4 (d, J¼4.5 Hz), 23.7 (d,
J¼48.5 Hz), 55.5, 113.9, 129.0 (d, J¼46.9 Hz), 132.7, 164.7, 198.5 (d,
acetate). 1H NMR (400 MHz, CDCl3)
d 3.07 (6H, s), 3.84 (3H, s), 6.66
J¼50.0 Hz). 31P NMR (162 MHz, CDCl3)
d
52.4. IR (neat) v 3071, 3005,
(2H, d, J¼9.2 Hz), 6.96 (2H, d, J¼8.8 Hz), 7.41 (2H, d, J¼9.2 Hz), 7.93
2972, 2936, 2909, 2877, 2840, 1638, 1596, 1573, 1508, 1457, 1422,
(2H, d, J¼9.2 Hz). 13C NMR (100 MHz, CDCl3)
d 40.0, 55.3,110.7,114.7,

M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
7857
118.9, 124.0, 129.6, 136.8, 153.8, 160.4, 188.5. IR (KBr) v 2905, 1605,
4.17. Equilibrium reaction of acylphosphine sulfide and aryl
ester (Scheme 13)
1591, 1242, 1172, 820 cmꢁ1. MS (EI) m/z 287 (Mþ, 4%), 148
(MþꢁSC7H7O, 100%). HRMS calcd for C16H17O2NS: 287.0980. Found:
287.0990.
In a two-necked flask equipped with a reflux condenser were
placed diethyl{4-(dimethylamino)benzoyl}phosphine sulfide 14
(0.25 mmol, 67.3 mg), 4-cyanophenyl 2-propylpentanoate 27
(0.25 mmol, 61.3 mg), RhH(PPh3)4 (5 mol %, 14.4 mg), and 1,2-
bis(diphenylphosphino)ethane (10 mol %, 10.0 mg) in chloroben-
zene (1 mL) under an argon atmosphere, and the solution was
stirred under reflux for 2 h. The solvent was removed under re-
duced pressure, and the residue was purified by flash column
chromatography on silica gel giving 4-cyanophenyl 4-(dimethyl-
amino)benzoate 28 (26.6 mg, 40%) and diethyl(2-propylpentanoyl)
phosphine sulfide 29 (26.0 mg, 42%) as well as recovered 14
(34.8 mg, 52%) and 27 (28.1 mg, 46%). Compound 28: colorless solid.
Mp 156.0e157.0 ꢀC (ethyl acetate). Lit.15 152e153 ꢀC (benzene). 1H
4.15. Reaction of S-(4-tolyl) 4-methoxybenzothioate 11 and
tetraethyldiphosphine disulfide 17 (Scheme 12)
In a two-necked flask equipped with a reflux condenser were
placed RhH(PPh3)4 (5.0 mol %, 14.4 mg), S-(4-tolyl) 4-metho-
xybenzothioate 11 (0.25 mmol, 64.5 mg), and tetraethyldiphos-
phine disulfide 17 (0.25 mmol, 60.5 mg) under an argon atmosphere.
Dry chlorobenzene (0.5 mL) and 1,2-bis(diethylphosphino)ethane
(10.0 mol%, 4.9 mg)were added, and thesolutionwasheated atreflux
for 6 h. The solvent was removed under reduced pressure, and the
residue was purified by flash column chromatography on silica gel
giving the diethyl(4-methoxybenzoyl)phosphine sulfide 23 (35.1 mg,
55%) as yellow solids and 4-tolyl diethyldithiophosphinate 24
(31.1 mg, 51%) as colorless oil. Compound 23: colorless oil. 1H NMR
NMR (400 MHz, CDCl3)
d
3.08 (6H, s), 6.68 (2H, d, J¼8.8 Hz), 7.32
(2H, d, J¼8.8 Hz), 7.69 (2H, d, J¼8.8 Hz), 8.01 (2H, d, J¼8.8 Hz). 13C
NMR (100 MHz, CDCl3) d 40.0, 109.0, 110.8, 114.6, 118.5, 123.1, 133.5,
(400 MHz, CDCl3)
d
1.21 (6H, dt, J¼20.0, 7.2 Hz), 2.00e2.32 (4H, m),
154.0, 154.8, 164.3. IR (neat) v 2914, 2823, 1718, 1599, 1163,
1049 cmꢁ1. MS (EI) m/z 266 (Mþ, 13%), 148 (MþꢁC7H4NO, 100%).
HRMS calcd for C16H24O2N2: 266.1055. Found: 266.1048. Com-
2.43 (3H, s), 7.29 (2H, d, J¼8.8 Hz), 8.44 (2H, d, J¼8.4 Hz). 13C NMR
(100 MHz, CDCl3)
d
6.4 (d, J¼4.5 Hz), 21.9, 23.7 (d, J¼48.5 Hz), 129.4,
130.1, 133.4 (d, J¼46.2 Hz), 146.0, 200.5 (d, J¼49.3 Hz). 31P NMR
pound 29: colorless oil. 1H NMR (400 MHz, CDCl3)
d 0.91 (6H, t,
(162 MHz, CDCl3)
d
52.5. IR (neat) v 3060, 3032, 2974, 2936, 2878,
J¼7.2 Hz), 1.15 (6H, dt, J¼19.6, 7.6 Hz), 1.21e1.46 (6H, m), 1.65e1.76
1784, 1704, 1645, 1602, 1572, 1456, 1408, 1379, 1223, 1209, 1178, 1119,
1032, 920, 825, 769, 726, 708, 635, 581 cmꢁ1. MS (EI) m/z 240 (Mþ,16),
136 (MeC6H4COeO,13),119 (MeC6H4CO,100), 91 (MeC6H4,16). HRMS
calcd for C12H17OPS: 240.0738. Found: 240.0740. Compound 24:
(2H, m), 1.80e2.10 (4H, m), 3.82 (1H, tt, J¼6.8, 6.0 Hz). 13C NMR
(100 MHz, CDCl3)
d
6.3 (d, J¼4.4 Hz), 14.1, 20.4, 22.8 (d, J¼46.8 Hz),
32.3, 48.5 (d, J¼38.7 Hz), 219.0 (d, J¼34.2 Hz). 31P NMR (162 MHz,
CDCl3)
d 51.7. IR (neat) v 3348, 2959, 2934, 2873, 1685, 1458, 1407,
colorless oil. 1H NMR (400 MHz, CDCl3)
d
1.30 (6H, dt, J¼21.2, 7.6 Hz),
1379, 1234, 1101, 1047, 1018, 1001, 775, 747, 730, 587 cmꢁ1. MS (EI)
m/z 248 (Mþ, 100%), 127 (MþꢁPr2CHCO, 52%). HRMS calcd for
C12H25OPS: 248.1364. Found: 248.1364.
1.92e2.07 (4H, m), 2.36 (3H, d, J¼2.0 Hz), 7.19 (2H, d, J¼8.0 Hz), 7.41
(2H, dd, J¼8.0, 2.0 Hz). 13C NMR (100 MHz, CDCl3)
6.8 (d, J¼5.2 Hz),
d
21.2, 27.5 (d, J¼49.9 Hz), 123.5 (d, J¼6.7 Hz), 130.1 (d, J¼2.2 Hz),136.0
(d, J¼3.7 Hz), 140.0 (d, J¼3.0 Hz). 31P NMR (162 MHz, CDCl3)
d
81.7. IR
4.18. Reaction of aryl esters and tetraethyldiphosphine
disulfide 17 (Scheme 17), synthesis of diethyl(2-
propylpentanoyl)phosphine sulfide 29
(neat) v 2971, 2933, 1491, 1452, 1018, 810, 769 cmꢁ1. MS (EI) m/z 244
(Mþ, 100%), 121 (MþꢁC7H7S, 80%). HRMS calcd for C11H17PS2:
244.0509. Found: 244.0502.
In a two-necked flask equipped with a reflux condenser were
placed 4-cyanophenyl 2-propylpentanoate 27 (0.25 mmol, 61.3 mg),
tetraethyldiphosphine disulfide 17 (0.25 mmol, 60.5 mg), RhH(PPh3)4
(5.0mol %,14.4mg), and1,2-bis(diethylphosphino)ethane (10.0mol %,
4.9 mg) in chlorobenzene (1 mL) under an argon atmosphere, and the
solution was stirred under reflux for 3 h. The solvent was removed
under reduced pressure, and the residue was purified by flash column
chromatography on silica gel giving diethyl(2-propylpentanoyl)
phosphine sulfide 29 (37 mg, 60%) and 4-cyanophenyl dieth-
ylphosphinothioate 30 (34.5 mg, 58%). Compound 30: colorless oil. 1H
4.16. The reaction of acylphosphine sulfides and disulfides
(Table 6), synthesis of S-phenyl 4-(dimethylamino)
benzothioate
In a two-necked flask equipped with a reflux condenser were
placed diethyl{4-(dimethylamino)benzoyl}phosphine sulfide 14
(0.25 mmol, 67.3 mg), diphenyl disulfide (0.25 mmol, 54.5 mg),
RhH(PPh3)4 (2.0 mol %, 5.8 mg), and 1,2-bis(diphenylphosphino)
ethane (4.0 mol %, 4.0 mg) in chlorobenzene (1 mL) under an argon
atmosphere, and the solution was stirred under reflux for 3 h. The
solvent was removed under reduced pressure, and the residue was
purified by flash column chromatography on silica gel giving S-
phenyl 4-(dimethylamino)benzothiate (63.4 mg, 99%) and phenyl
diethyldithiophosphinate (52.1 mg, 91%). S-Phenyl 4-(dimethyla-
mino)benzothioate colorless solid. Mp 196.5e197.5 ꢀC (ethyl ace-
NMR (400 MHz, CDCl3)
d
1.29 (6H, dt, J¼20.8, 7.6 Hz), 2.12e2.22 (4H,
m), 7.29 (2H, d, J¼8.8 Hz), 7.63 (2H, d, J¼8.8 Hz). 13C NMR (100 MHz,
CDCl3)
d
6.7 (d, J¼5.2 Hz), 27.4 (d, J¼69.2 Hz), 108.6, 118.3, 122.6 (d,
J¼4.5 Hz),133.7,154.3 (d, J¼9.0 Hz). 31P NMR (162 MHz, CDCl3)
d 111.3.
IR (neat) v 2977, 2881, 2227, 1601, 1500, 1225, 893, 789 cmꢁ1. MS (EI)
m/z 239 (Mþ, 100%), 121 (MþꢁC7H4NO, 82%). HRMS calcd for
C11H14ONPS: 239.0534. Found: 239.0521.
tate). 1H NMR (400 MHz, CDCl3)
d
3.07 (6H, s), 6.66 (2H, d, J¼9.2 Hz),
7.38e7.46 (3H, m), 7.48e7.54 (2H, m), 7.93 (2H, d, J¼9.2 Hz). 13C
NMR (100 MHz, CDCl3)
d
40.0, 110.7, 124.0, 128.3, 129.0, 129.0, 129.6,
4.19. Reaction of diethyl{4-(dimethylamino)benzoyl}
135.3, 153.9, 187.7. IR (KBr) v 2908, 1653, 1600, 1377, 1181, 897,
820 cmꢁ1. MS (EI) m/z 257 (Mþ, 5%), 148 (MþꢁSPh, 100%). HRMS
calcd for C15H15ONS: 257.0874. Found: 257.0872. Phenyl dieth-
phosphine sulfide 14 and 4-methoxyphenol (Scheme 15)
In a two-necked flask equipped with a reflux condenser were
placed 14 (0.25 mmol, 67.3 mg), 4-methoxyphenol (0.25 mmol,
31 mg), RhH(PPh3)4 (5.0 mol %, 14.4 mg), and 1,2-bis(dipheny-
lphosphino)ethane (10.0 mol %, 10.0 mg) in chlorobenzene (1 mL)
under an argon atmosphere, and the solution was stirred under
reflux for 4 h. The solvent was removed under reduced pressure, and
the residue was purified by flash column chromatography on silica
gel giving 4-methoxyphenyl 4-dimethylaminobenzoate (64.4 mg,
95%) and diethylphosphine sulfide 33 (26.2 mg, 86%). 4-
yldithiophosphinate colorless oil. 1H NMR (400 MHz, CDCl3)
d
1.30
(6H, dt, J¼21.6, 7.6 Hz), 1.92e2.11 (4H, m), 7.36e7.54 (3H, m),
7.52e7.56 (2H, m). 13C NMR (100 MHz, CDCl3)
6.9 (d, J¼5.2 Hz),
d
27.8 (d, J¼50.6 Hz), 127.2 (d, J¼6.7 Hz), 129.3 (d, J¼2.2 Hz), 129.7 (d,
J¼3.0 Hz), 136.2 (d, J¼3.7 Hz). 31P NMR (162 MHz, CDCl3)
d 81.5. IR
(neat) v 2972, 2933, 1472, 1023, 772, 749 cmꢁ1. MS (EI) m/z 230 (Mþ,
100%), 121 (MþꢁSPh, 95%). HRMS calcd for C10H15PS2: 230.0353.
Found: 230.0356.

7858
M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
Methoxyphenyl 4-dimethylaminobenzoate colorless solid. Mp
169.5e171.0 ꢀC (ethyl acetate/hexane¼2/1). Lit.15 173e173.5 ꢀC
70.8 mg), phenyl dimethyldithiophosphinate (0.25 mmol, 50.5 mg),
RhH(PPh3)4 (5 mol %, 14.4 mg), and 1,2-bis(diphenylphosphino)
ethane (10 mol %, 10.0 mg) in chlorobenzene (1 mL) under an air at
reflux for 3 h. The solvent was removed under reduced pressure,
and the residue was purified by flash column chromatography on
silica gel giving S-phenyl 3,5-dimethoxybenzothioate (61.1 mg,
89%) and O-(4-cyanophenyl) dimethylphosphinothioate 38
(45.5 mg, 86%). S-Phenyl 3,5-dimethoxybenzothioate colorless
solid. Mp 73.5e75.0 ꢀC (hexane/ethyl acetate¼4/1). 1H NMR
(benzene). 1H NMR (400 MHz, CDCl3)
d 3.07 (6H, s), 3.81 (3H, s), 6.69
(2H, d, J¼9.2 Hz), 6.92 (2H, d, J¼8.8 Hz), 7.11 (2H, d, J¼9.2 Hz), 8.05
(2H, d, J¼8.8 Hz). 13C NMR (100 MHz, CDCl3)
d 40.0, 55.6,110.7, 114.3,
116.0, 122.6, 131.9, 144.8, 153.6, 156.9, 165.8. IR (KBr) v 2906, 1712,
1188,1066 cmꢁ1. MS (EI) m/z 271 (Mþ,16%),148 (MþꢁC7H7O2,100%).
HRMS calcd for C16H17O3N: 271.1208. Found: 271.1205. Compound
33: colorless oil. 1H NMR (400 MHz, CDCl3)
d
1.27 (6H, dt, J¼21.2,
7.6 Hz), 1.88e2.06 (4H, m), 6.49 (1H, dm, J¼433.6 Hz). 13C NMR
(400 MHz, CDCl3)
d
3.83 (6H, s), 6.68 (1H, t, J¼2.4 Hz), 7.16 (2H, d,
(100 MHz, CDCl3)
d
6.9 (d, J¼4.6 Hz), 22.8 (d, J¼52.3 Hz). 31P NMR
J¼2.4 Hz), 7.43e7.46 (3H, m), 7.49e7.52 (2H, m). 13C NMR
(162 MHz, CDCl3)
d
31.9. IR (neat) v 2935, 2877,1456,1045, 901 cmꢁ1
.
(100 MHz, CDCl3) d 55.6, 105.1, 105.9, 127.3, 129.2, 129.5, 135.0,
MS (EI) m/z 122 (Mþ, 100%), 94 (Mþꢁ28, 60%). HRMS calcd for
138.4, 160.8, 190.0. IR (KBr) v 2939, 2837, 1680, 1593, 1159 cmꢁ1
.
C4H11PS: 122.0319. Found: 122.0306.
MS (EI) m/z 274 (Mþ, 15%), 165 (MþꢁC6H5S, 100%). HRMS calcd for
C15H14O3S: 274.0663. Found: 274.0650. Compound 38: colorless
solid. Mp 73.5e74.5 ꢀC (hexane/diethyl ether¼3/1). 1H NMR
4.20. Equilibrium reaction of thioester and aryl ester
(Scheme 16)
(400 MHz, CDCl3)
d
2.05 (6H, d, J¼13.2 Hz), 7.31 (2H, dd, J¼8.8,
1.2 Hz), 7.65 (2H, d, J¼8.8 Hz). 13C NMR (100 MHz, CDCl3)
d 24.1 (d,
J¼72.8 Hz), 108.9 (d, J¼1.5 Hz), 118.2, 122.6 (d, J¼4.5 Hz), 133.8,
153.9 (d, J¼9.1 Hz). IR (KBr) v 3101, 3066, 2983, 2235, 1602, 1500,
In a two-necked flask equipped with a reflux condenser were
placed 4-cyanophenyl dodecanoate 7 (0.25 mmol, 75.3 mg), S-(4-
tolyl) 4-methoxybenzothioate 11 (0.25 mmol, 64.5 mg),
RhH(PPh3)4 (5 mol %, 14.4 mg), and 1,2-bis(diphenylphosphino)
ethane (10 mol %, 10.0 mg) in chlorobenzene (1 mL) under an argon
atmosphere, and the solution was stirred under reflux for 3 h. The
solvent was removed under reduced pressure, and the residue was
purified by flash column chromatography on silica gel giving S-(4-
tolyl) dodecanethioate 34 (37.4 mg, 49%) and 4-cyanophenyl 4-
methoxybenzoate 1 (30.9 mg, 49%) as well as recovered 7
(37.6 mg, 50%) and 11 (31.4 mg, 49%). Compound 34:20 colorless oil.
1211, 742 cmꢁ1
.
MS (EI) m/z 211 (Mþ, 100%), 93 (Mþꢁ118
(C7H4NO), 61%). HRMS calcd for C9H10OSNP: 211.0221. Found:
211.0202.
4.23. Typical procedures for carbothiolation reaction of
thioesters (Table 8)
In a two-necked flask equipped with a reflux condenser were
placed RhH(PPh3)4 (5 mol %, 17.3 mg), diethylphenylphosphine
1H NMR (400 MHz, CDCl3)
d
0.88 (3H, t, J¼6.4 Hz), 1.26e1.33 (16H,
(15 mol %, 7.8
mL), S-butyl 4-cyanobenzothioate (0.30 mmol,
m), 1.70 (2H, quint, J¼7.2 Hz), 2.37 (3H, s), 2.63 (2H, t, J¼7.2 Hz), 7.22
65.7 mg), and 1-decyne (0.30 mmol, 41.5 mg) in dimethyl sulfoxide
(0.75 mL) under an argon atmosphere, and the solution was heated
at 100 ꢀC for 12 h. The mixture was purified by flash column
chromatography on silica gel giving (E)-3-n-butylthio-1-(4-
cyanophenyl)-2-undecen-1-one (E)-39 (38.3 mg, 36%) and (Z)-3-
n-butylthio-1-(4-cyanophenyl)-2-undecen-1-one (Z)-39 (14.2 mg,
13%). Compound (E)-39: yellow oil. 1H NMR (400 MHz, CDCl3)
(2H, d, J¼8.0 Hz), 7.29 (2H, d, J¼8.8 Hz). 13C NMR (100 MHz, CDCl3)
d
14.1, 21.3, 22.7, 25.6, 29.0, 29.2, 29.3, 29.4, 29.6, 31.9, 43.6, 77.2,
124.4, 130.0, 134.4, 139.5, 198.1. IR (neat) v 2925, 2854, 1710 cmꢁ1
.
MS (EI) m/z 306 (Mþ, 21%), 183 (MþꢁMeC6H4S, 98%), 124
(MeC6H4SH, 100%). HRMS calcd for C19H30OS: 306.2017. Found:
306.2010. Compound 1: colorless solid. Mp 114e115 ꢀC (hexane/
ethylacetate¼5/1). Lit.15 109e110 ꢀC (benzene). 1H NMR (400 MHz,
d
0.88 (3H, t, J¼7.0 Hz), 0.98 (3H, t, J¼7.4 Hz), 1.22e1.37 (8H, m), 1.42
CDCl3)
d
3.91 (3H, s), 7.00 (2H, dd, J¼6.8, 2.0 Hz), 7.36 (2H, dd, J¼6.8,
(2H, tt, J¼7.2, 7.2 Hz), 1.51 (2H, tq, J¼7.5, 7.5 Hz), 1.64 (2H, tt, J¼7.7,
7.7 Hz), 1.72 (2H, tt, J¼7.4, 7.4 Hz), 2.87 (4H, t, J¼7.2 Hz), 6.49 (1H, s),
7.75 (2H, d, J¼8.0 Hz), 7.96 (2H, d, J¼8.0 Hz). 13C NMR (100 MHz,
2.0 Hz), 7.74 (2H, dd, J¼6.8, 2.4 Hz), 8.14 (2H, dd, J¼6.8, 2.0 Hz). 13C
NMR (100 MHz, CDCl3) d 55.6, 109.5, 114.0, 118.4, 120.8, 123.0, 132.5,
133.7, 154.4, 164.0, 164.3 cmꢁ1. IR (KBr) v 3106, 2942, 2848, 2229,
1731, 1610, 1583, 1515, 1213, 1168. MS (EI) m/z 253 (Mþ, 2%), 135
(MþꢁMeOPh, 100%). HRMS calcd for C15H11NO3: 253.0739. Found:
253.0719.
CDCl3)
d 13.6, 14.1, 22.2, 22.6, 29.2, 29.3, 29.4, 29.7, 30.1, 31.6, 31.8,
35.6, 111.5, 115.0, 118.2, 128.3, 132.3, 143.7, 171.0, 184.9. IR (neat) v
2956, 2927, 2855, 1652, 1549, 1223, 1053, 819 cmꢁ1. MS (EI) m/z 357
(Mþ, 12%), 300 (MþꢁC4H9, 100%). HRMS calcd for C22H31NOS:
357.2126. Found: 315.2117. Compound (Z)-39: yellow oil. 1H NMR
4.21. Reaction of thioesters and phenols (Scheme 17),
synthesis of 4-cyanophenyl 4-methoxybenzoate 1
(400 MHz, CDCl3)
d
0.88 (3H, t, J¼7.0 Hz), 0.95 (3H, t, J¼7.4 Hz),
1.24e1.36 (8H, m), 1.41 (2H, tt, J¼7.3, 7.3 Hz), 1.49 (2H, tq, J¼7.4,
7.4 Hz), 1.65 (2H, tt, J¼7.9, 7.9 Hz), 1.67 (2H, tt, J¼7.5, 7.5 Hz), 2.61
(2H, t, J¼8.0 Hz), 2.90 (2H, t, J¼7.4 Hz), 6.92 (1H, s), 7.73 (2H, d,
J¼8.0 Hz), 8.00 (2H, dt, J¼1.8, 8.8 Hz). 13C NMR (75 MHz, CDCl3)
In a two-necked flask equipped with a reflux condenser were
placed S-(4-tolyl) methoxybenzothioate 11 (0.25 mmol, 64.5 mg),
4-cyanophenol (0.25 mmol, 29.8 mg), RhH(PPh3)4 (10 mol %,
28.8 mg), and 1,2-bis(diphenylphosphino)ethane (20 mol %,
20.0 mg) in chlorobenzene (1 mL) under an air at reflux for 9 h. The
solvent was removed under reduced pressure, and the residue was
purified by flash column chromatography on silica gel giving 4-
cyanophenyl 4-methoxybenzoate 1 (43.5 mg, 69%), and bis(4-
tolyl) disulfide (18.5 mg, 59%), as well as recovered 11 (15.3 mg,
24%) and 4-cyanophenol (5.9 mg, 20%).
d
13.6, 14.1, 22.1, 22.6, 29.16, 29.23, 29.3, 30.26, 30.33, 30.9, 31.8,
37.3, 115.0, 115.1, 118.3, 128.3, 132.3, 142.4, 170.1, 186.3. IR (neat) v
2927, 2855, 1633, 1526, 1238 cmꢁ1. MS (EI) m/z 357 (Mþ, 15%), 300
(MþꢁC4H9, 100%). HRMS calcd for C22H31NOS: 357.2126. Found:
315.2116.
Acknowledgements
4.22. Reaction of aryl esters and dithiophosphinate (Table 7),
synthesis of S-phenyl 3,5-dimethoxybenzoate
This work was supported by Grant-in-Aid for Scientific Research
(No. 21229001), the GCOE program, and the WPI Initiative from
JSPS. M.A. expresses her thanks for financial support from the
Grant-in-Aid for Scientific Research from MEXT (No. 22689001)
and also to the Asahi Glass Foundation.
In a two-necked flask equipped with a reflux condenser
were placed 4-cyanophenyl 3,5-dimethoxybenzoate (0.25 mmol,

M. Arisawa et al. / Tetrahedron 67 (2011) 7846e7859
7859
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12214.
Supplementary data
Supplementary data associated with this article can be found in
online version at doi:10.1016/j.tet.2011.07.031. These data include
MOL files and InChIKeys of the most important compounds described
in this article.
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