Synthesis of acylphosphine sulfides by rhodium-catalyzed reaction of acid fluorides and diphosphine disulfides

Article abstract of DOI:10.1016/j.tetlet.2010.07.038

A rhodium complex catalyzed the reaction of acid fluorides and tetraethyldiphosphine disulfide giving acylphosphine sulfides. Aromatic acid fluorides with electron donating p-groups reacted smoothly giving the products in high yields. Aliphatic acid fluorides with secondary and tertiary a-carbons were also converted to alkanoylphosphine sulfides, whereas the reaction of a substrate with an α-methylene carbon was accompanied by enol ester formation.

Full text of DOI:10.1016/j.tetlet.2010.07.038

Tetrahedron Letters 51 (2010) 4957–4958
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Tetrahedron Letters
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Synthesis of acylphosphine sulfides by rhodium-catalyzed reaction of acid
fluorides and diphosphine disulfides
Mieko Arisawa a, Toru Yamada 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:
A rhodium complex catalyzed the reaction of acid fluorides and tetraethyldiphosphine disulfide giving
Received 19 May 2010
Revised 3 July 2010
Accepted 8 July 2010
Available online 11 July 2010
acylphosphine sulfides. Aromatic acid fluorides with electron donating p-groups reacted smoothly giving
the products in high yields. Aliphatic acid fluorides with secondary and tertiary
a-carbons were also con-
verted to alkanoylphosphine sulfides, whereas the reaction of a substrate with an
was accompanied by enol ester formation.
a
-methylene carbon
Ó 2010 Published by Elsevier Ltd.
Acylphosphorus compounds are phosphorus analogs of amides
and esters, and their synthesis have attracted much interest:1 The
Arbuzov reaction of acid chlorides with trialkyl phosphites was of-
ten used to obtain acylphosphonates;2 acylphosphines were ob-
tained by the reaction of phosphines and phosphine oxides with
acid chlorides in the presence of bases;3 and silylphosphines were
employed for this transformation without the base.4 These synthe-
ses provided acylphosphonates, acylphosphines, or oxides. In con-
lized the benzoylphosphine sulfides towards hydrolysis, and the p-
methoxybenzoylphosphine sulfide obtained from p-methoxyben-
zoyl fluoride could be purified by rapid silica gel chromatography
without decomposition. In addition, use of tetraethyldiphosphine
disulfide 7 in place of 2 further improved the stability of the product.
Using these substrates, the catalyst loading could be reduced to
1 mol %. p-Methoxybenzoyl fluoride was reacted with 7 (1 equiv)
in the presence of RhH(PPh3)4 (1 mol %) and (Ph2PCH2CH2)2PPh
(2 mol %) in refluxing THF for 3 h, and p-methoxybenzoyldiethyl-
phosphine sulfide was obtained in 97% yield (Table 1, entry 1). The
formation of Et2PSF was indicated by 19F NMR d –96.3 (J =
1017 Hz) and 31P NMR d 133.4 (J = 1013 Hz). The effect of the phos-
phine ligand was critical, and no reaction occurred in its absence.
trast, only
a scattered synthesis of acylphosphine sulfides
appeared, which generally used a sulfuration reaction of acylphos-
phines.5 Described in this work is a versatile method for the syn-
thesis of acylphosphine sulfides from acid fluorides and
diphosphine disulfides, which was catalyzed by a rhodium com-
plex (Scheme 1). Our previous work showed a high reactivity of
the organofluorine compounds under rhodium catalysis,6 and this
method was applied here to the reaction of acid fluorides.7,8
When an equimolar mixture of benzoyl fluoride 1 and tetrame-
thyldiphosphine disulfide 2 were reacted at room temperature in
THF for 6 h in the presence of RhH(PPh3)4 (20 mol %) and 1,2-
bis(diphethylphosphino)ethane (dppe, 40 mol %), benzoyldimeth-
ylphosphine sulfide 3 was obtained in 12% yield by 1H NMR analysis
of the crude products (Scheme 2). Bis(dimethylthiophosphinyl)-
phenylmethanol 4 (23%) and its benzoate ester 5 (22%) were isolated
along with benzoic acid 6 (36%). The byproducts 4, 5, and 6 were
formed by hydrolysis of 3 followed by the addition of HPSMe2 to 3.
No reaction occurred in the absence of the rhodium complex or
dppe.
O
C
S
O
C
S
S
Rh cat
+
R
F
Et2P PEt2
R
PEt2
Scheme 1.
RhH(PPh3)4 (20 mol%)
dppe (40 mol%)
O S
O
S
S
+
PhC PMe2
Me2P PMe2
PhCF
THF, r.t., 6 h
2
1
3 12%
HO S
PhCOO S
In order to suppress the formation of the byproducts, the sub-
strate structure was examined. It turned out that the introduction
of an electron-donating p-substituent on the benzoyl moiety stabi-
PhC PMe2
PhC PMe2
PMe2
+
PhCO2H
+
+
PMe2
S
6 36%
4 23%
S
5 22%
* Corresponding author.
E-mail address: yama@mail.pharm.tohoku.ac.jp (M. Yamaguchi).
Scheme 2.
0040-4039/$ - see front matter Ó 2010 Published by Elsevier Ltd.
doi:10.1016/j.tetlet.2010.07.038

4958
M. Arisawa et al. / Tetrahedron Letters 51 (2010) 4957–4958
Table 1
NOE experiments. The enol ester 10 should be formed from 9 by
Rhodium-catalyzed reaction of acid fluoride and 7
the reaction with 8, which was confirmed by the following exper-
iment. The reaction of 8 and 9 in the presence of RhH(PPh3)4
(2 mol %) and (Ph2PCH2CH2)2PPh (4 mol %) in refluxing THF for
4 h gave 10 in 13% yield. This reaction was also rhodium-catalyzed,
RhH(PPh3)4 (1 mol%)
O S
O
S
(Ph2PCH2CH2)2PPh (2 mol%)
S
+
RC PEt2
RCF
Et2P PEt2
THF, refl., 3 h
which indicated the involvement of ketone
rhodium complex.9 Such a reactivity of the rhodium complex to-
wards
-phenylthio ketones was recently reported.10
a-activation by the
7
Entry
R
Yield (%)
a
In summary, a rhodium-catalyzed method for the synthesis of
acylphosphine sulfides was developed using acid fluorides and
diphosphine disulfide. The method provided a series of aromatic
and aliphatic acylphosphine sulfides, and the properties and reac-
tivities of these novel organophosphorus compounds now can be
studied in a systematic way.
1
2
3
4
5
6
7
8
p-MeOC6H4
p-MeC6H4
3,5-(MeO)2C6H5
2,4,6-Me3C6H2
p-Me2NC6H4
Ph
97
79 (88)a
76
53, 73b
77, 99b
63 (80)a
18 (52)a
93
p-ClC6H4
n-Pr2CH
9
10
11
PhMeCH
1-Methylcyclohexyl
1-Adamantyl
88
85
94
Typical experimental procedures
In a two-necked flask equipped with a reflux condenser was
a
In parentheses are crude yields obtained by 1H NMR.
RhH(PPh3)4 (2 mol %), (Ph2PCH2CH2)2PPh (4 mol %).
b
placed p-methoxybenzoyl fluoride (77.1 mg, 0.5 mmol),
7
(121.2 mg, 0.5 mmol), RhH(PPh3)4 (5.8 mg, 1.0 mol %), and bis(2-
diphenylphosphinoethyl)-phenylphosphine (5.3 mg, 2.0 mol %) in
tetrahydrofuran (1 mL) under an argon atmosphere, and the solu-
tion was stirred under reflux for 4 h. Then, the solvent was re-
moved under reduced pressure, and the residue was purified by
flash column chromatography on silica gel within 10–15 min giv-
ing diethyl(4-methoxybenzoyl)phosphine sulfide (124.6 mg, 97%).
RhH(PPh3)4 (1 mol%)
O
S
S
(Ph2PCH2CH2)2PPh (2 mol%)
+
F
n-C10H21CH2C
Et2P PEt2
THF, refl., 3 h
7
8
O S
S
Acknowledgments
n-C10H21CH2CO2
n-C10H21
+
n-C10H21CH2C PEt2
PEt2
This work was supported by the Grant-in-Aid for Scientific Re-
search (No. 21229001), GCOE program, and WPI Initiative from
JSPS. M.A. expresses her thanks to the Grant-in-Aid for Scientific
Research from MEXT (No. 22689001) and also to the Naito
Foundation.
9 33%
10 29%
Scheme 3.
Supplementary data
Bidentate ligands with the phosphino groups separated by two car-
bon atoms such as 1,2-bis(diethylphosphino)ethane (depe), 41%;
1,2-bis(diphenylphosphino)ethane (dppe), 85%; 1,2-bis(diphenyl-
phosphino)ethylene (dppv), 54%; and 1,2-bis(diphenylphos-
phino)benzene (dppBz), 78% exhibited catalytic activity. Among
these, the tridentate phosphine (Ph2PCH2CH2)2PPh gave a higher
yield of the product. Other ligands such as (p-MeOC6H4)3P, (p-ClC6
H4)3P, 1,2-bis(diphenylphosphino)methane (dppm), 1,2-bis
(diphenylphosphino)propane (dppp), and 1,2-bis(diphenylphos-
phino)ferrocene (dppf) were not effective at all. It was also noted
that essentially no reaction occurred under the same rhodium-cata-
lyzed conditions using p-methoxybenzoyl chloride.
The reaction was applied to several aromatic acid fluorides pos-
sessing electron-donating groups, and aroylphosphine sulfides
were obtained in high yields (entries 1–5). Benzoyl fluoride and
p-chlorobenzyl fluoride also gave the products in good yields as
indicated by crude 1H NMR analysis (entries 6 and 7). They, how-
ever, decomposed during isolation, which resulted in lower iso-
lated yields. The reaction could be applied to aliphatic acid
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tetlet.2010.07.038.
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phine sulfides were obtained in high yields (entries 8–11).
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a
a different reactivity. When undecanoyl fluoride 8 was reacted
with 7 in the presence of RhH(PPh3)4 (1 mol %), (Ph2PCH2CH2)2PPh
(2 mol %) in refluxing THF for 4 h, undecanoyldiethylphosphine
sulfide 9 was obtained in 33% yield, which was accompanied by
(E)-(1-undecanoyloxy-1-undecenyl)diethylphosphine sulfide 10
in 29% yield (Scheme 3). The stereochemistry at the olefin moiety
was determined by 1H(vinyl)–31P coupling constant 10.4 Hz and
9.
A
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