Direct synthesis of aryl ketones by palladium-catalyzed desulfinative addition of sodium sulfinates to nitriles

Article abstract of DOI:10.1002/chem.201101252

Mild yet direct: A convenient and efficient method for the synthesis of various aryl ketones by palladium-catalyzed desulfinative addition of aromatic sulfinic acid sodium salts to various nitriles is described (see scheme). Aromatic and aliphatic nitriles are successfully reacted with arenesulfinic acid sodium salts to form aryl ketones in good yields.

Full text of DOI:10.1002/chem.201101252

DOI: 10.1002/chem.201101252
Direct Synthesis of Aryl Ketones by Palladium-Catalyzed Desulfinative
Addition of Sodium Sulfinates to Nitriles
Jing Liu,[a] Xianya Zhou,[a] Honghua Rao,[b] Fuhong Xiao,[a] Chao-Jun Li,*[b] and
Guo-Jun Deng*[a]
Aryl ketones are fundamental intermediates in many
types of organic compound, for example, pharmaceuticals,
fragrances, and natural products.[1] Classical routes to syn-
thesize aryl ketones mainly rely on the Friedel–Crafts acyla-
tion of aromatic compounds in the presence of corrosive
AlCl3[2] and the oxidation of the corresponding secondary al-
cohols.[3] Transition-metal-catalyzed reactions provide many
opportunities for the synthesis of aryl ketones.[4] Among
them, hydroacylation is a useful synthetic method for pre-
steps to synthesize from arenes (via the halide and then re-
action with borate by using stoichiometric magnesium),[12]
although newer methods of direct boronic acid formation
[13]
À
from C H bonds have recently been explored. In 2010,
Larhed et al. developed a palladium-catalyzed decarboxyla-
tive addition of benzoic acids to nitriles, and various aryl ke-
tones can be synthesized with this method.[14] One of the
main advantages of this method is that the carboxylic acids
used for this transformation are comparably cheap and are
commercially available.[15] However, this method is mainly
suitable for ortho-functionalized electron-rich benzoic acids
and aliphatic nitriles.
À
paring aryl ketones from aldehydes and olefines through C
H bond activation and subsequent addition.[5]
Nitriles are normally very stable and widely commercially
available. The nucleophilic addition of organometallic re-
agents to nitriles is an old and well-known reaction for
ketone preparation. However, application of this addition
reaction has been limited by poor functional group toler-
ance.[6] In recent years, the transition-metal-catalyzed addi-
tion reaction has resulted in great progress in the synthesis
of aryl ketones from nitriles. One of the pioneering works
involving the use of nitriles as the starting materials for aryl
ketone synthesis was developed by Larock et al. by using
palladium as the catalyst. Arylboronic acids and even arene
Arenesulfonyl chlorides are active compounds and are
used as starting materials for preparing compounds contain-
ing a sulfonyl group.[16] They are also used as aryl sources
À
for C C bond-forming reactions through desulfinative
Heck-type reactions under harsh conditions (>1308C).[17]
Compared to the active and moisture sensitive arenesulfonyl
chloride, sulfinic acid sodium salts are comparably stable
and easy to handle. Thus, sulfinic acid sodium salts have the
À
potential to serve as the ideal aryl source for C C bond-
forming reactions through release of SO2. However, sulfinic
acids (or their sodium salts) are mainly used as sulfonylation
reagents[18] and rarely used as the aryl source in desulfina-
tive reactions.[19] Recently, we developed a palladium-cata-
lyzed desulfinative Heck-type reaction of aromatic sulfinic
acid sodium salts with various olefins under mild condi-
tions.[20] Herein, we report the direct synthesis of aryl ke-
tones by palladium-catalyzed desulfinative addition of aryl
sulfinic acid sodium salts to nitriles under mild conditions
(Scheme 1).
À
C H bonds were successfully added to nitriles to generate
various aryl ketones by the hydrolysis of the intermediate
ketimine in trifluoroacetic acid.[7] Later, Lu and Zhao,[8]
Miura et al.,[9] and others[10] developed various catalytic sys-
tems for aryl ketone synthesis from nitriles and arylboronic
acids, catalyzed by palladium or rhodium. Cheng et al. de-
veloped a nickel-catalyzed addition of arylboronic acids to
nitriles by using ZnCl2 as the Lewis acid, under mild condi-
tions.[11] However, arylboronic acids normally require several
We began our investigation by screening various palladi-
um salts for the desulfinative addition reaction between ben-
zonitrile (1a) and p-toluenesulfinic acid sodium salt (2a) in
the presence of trifluoroacetic acid, and the results are sum-
marized in Table 1. If benzonitrile was reacted with 2a
[a] J. Liu, X. Zhou, F. Xiao, Prof. Dr. G.-J. Deng
Key Laboratory of Environmental Friendly Chemistry and
Application of Ministry of Education
College of Chemistry, Xiangtan University
Xiangtan 411105 (China)
(2 equiv) in the presence of PdACHTUNRGTNEUNG(OAc)2 (5 mol%) and 1,10-
phenanthroline (1,10-phen; 10 mol%) in 1,4-dioxane/water
(3:2), the desired product was observed in 53% yield, as de-
Fax : (+86)731-58292477
E-mail: gjdeng@xtu.edu.cn
[b] Dr. H. Rao, Prof. Dr. C.-J. Li
Department of Chemistry, McGill University
Montreal, QC, H3 A2K6 (Canada)
Fax : (+1)514-398-3797
E-mail: cj.li@mcgill.ca
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201101252.
Scheme 1. General reaction scheme.
7996
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Chem. Eur. J. 2011, 17, 7996 – 7999

COMMUNICATION
Table 1. Optimization of the reaction conditions.[a]
nitriles 1b–g, and various asymmetric diaryl ketones were
obtained in moderate to good yields (Table 2, entries 2–7).
A series of functional groups, including methyl, methoxy,
fluoro, chloro, and acetyl, were tolerated under the opti-
mized reaction conditions. A moderate yield was obtained
when 2-methylbenzonitrile was reacted with 2a (Table 2,
entry 8). Aliphatic nitriles also worked well for this reaction.
Phenylacetonitrile and its substituted derivatives were
Catalyst
Ligand
Solvent
Yield
[%][b]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18[c]
19[d]
20[e]
Pd
Pd(O2CCF3)2
PdCl2
[Pd(acac)2]
[Pd2A(dba)3]
[Pd(cod)Cl2]
[Pd(NH3)4Cl2]
G
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
dipyridine
DMAP
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
1,4-dioxane
DMF
anisole
diglyme
THF
1,4-dioxane
1,4-dioxane
1,4-dioxane
53
54
41
42
58
52
40
70
91
60
2
trace
trace
3
45
56
67
71
63
47
Table 2. Desulfinative addition of 2a with various nitriles.[a]
G
Nitrile
Product
Yield
[%][b]
PdO
1
2
3
1a
1b
1c
3a 78
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
Pd(OH)2
DBU
PPh3
3b 72
3c 80
3d 81
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
1,10-phen
4
5
6
1d
1e
1 f
[a] Reaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), catalyst
(5 mol%), ligand (10 mol%), CF3CO2H (0.2 mL), solvent (0.3 mL), H2O
(0.2 mL), 1108C, 20 h, under air; acac=acetylacetone, dba=dibenzylide-
neacetone, cod=1,5-cyclooctadiene, DMAP=4-dimethylaminopyridine,
DBU= 1,8-diazabicycloACTHNUTRGNEUG[N 5.4.0]undec-7-ene. [b] GC yield based on 1a.
[c] 1,4-Dioxane/H2O=1:1. [d] At 908C. [e] No CF3CO2H was used.
3e 73
3 f 74
1
tected by GC-MS and H NMR methods (Table 1, entry 1).
Subsequently, various palladium salts were tested for this
desulfinative addition reaction and moderate yields were ob-
served (Table 1, entries 2–7). The reaction yield can be im-
proved to 70% if PdO was used (Table 1, entry 8). However,
the best yield was obtained with Pd(OH)2 as the catalyst,
for which the desired product was obtained in 91% yield
(Table 1, entry 9). Other ligands were also investigated for
this transformation but were less efficient (Table 1, en-
tries 10–13). The effect of solvents on this reaction was also
investigated. A low yield was obtained if the reaction was
carried out in DMF (Table 1, entry 14) although the reac-
tions in anisole, diglyme, and THF gave the desired product
in moderate yields (Table 1, entries 15–17). The ratio of 1,4-
dioxane to water also affected the reaction yield significant-
ly, decreasing it to 71% if the ratio of was changed to 1:1
(Table 1, entry 18). Decreasing the reaction temperature
also decreased the yield (Table 1, entry 19). Trifluoroacetic
acid played an important role in this addition reaction and
only 47% yield was achieved in its absence (Table 1,
entry 20).[21]
7
1g
3g 60
3h 51
8
9
1h
1i
3i
3j
82
10
11
12
13
1j
80 (78)[c]
1k
1l
3k 85
3l
83
1m
3m 82
3n 70
Next, the desulfinative addition of p-toluenesulfinic acid
sodium salt 2a to various nitriles was conducted under the
optimized conditions, and the results are summarized in
Table 2. The palladium-catalyzed desulfinative addition re-
action was successfully extended to various substituted aryl
14
1n
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G.-J. Deng, C.-J. Li et al.
Table 3. Desulfinative addition of 1b with various sodium sulfinates.[a]
Table 2. (Continued)
Nitrile
Sodium sulfinate
Product
Yield
[%][b]
Product
Yield
[%][b]
15[d]
1o
3o 42
1
2
2b
2c
3r
3s
76
65
16[d]
17[d]
1p
1q
3p 52
3q 65
3
2d
2e
2 f
3t
73
61
50
[a] Reaction conditions, unless otherwise noted:
1
(0.2 mmol), 2a
(0.4 mmol), Pd(OH)2 (5 mol%), 1,10-phen (10 mol%), CF3CO2H
(0.2 mL), 1,4-dioxane (0.3 mL), H2O (0.2 mL), 1108C, 20 h, under air.
[b] Isolated yield based on 1. [c] The yield in parenthesis was on a
5 mmol scale. [d] Pd(OH)2 (10 mol%) and 2,2’-bipyridine (10 mol%)
were used.
4
3u
3v
5[c]
smoothly reacted with 2a and gave the corresponding alkyl
aryl ketones in good yields (Table 2, entries 9–14). Pentane-
nitrile, octanenitrile, and decanonitrile were also reacted
with 2a, although under modified reaction conditions, and
gave the desired products in 42, 52, and 65% yield, respec-
tively (Table 2, entries 15–17).
6
7
2g
2h
3w
3x
35
53
Additionally, the results of the reaction between various
aryl sulfinic acid sodium salts and 4-methylbenzonitrile (1b)
are presented in Table 3. Benzenesulfinic acid sodium salt
(2b) was successfully reacted with 1b and gave the corre-
sponding product in 76% yield (Table 3, entry 1). Various
functional groups, including methoxy, tert-butyl, fluoro,
bromo, and trifluoromethyl, were tolerated, and the desired
products were obtained in moderate to good yields (Table 3,
entries 2–6). A more bulky substrate, 2-naphthylsulfinic acid
sodium salt (2h), also efficiently reacted with 1b and gave
the product in 53% yield (Table 3, entry 7).
[a] Reaction conditions, unless otherwise noted: 1b (0.2 mmol),
2
(0.4 mmol), Pd(OH)2 (5 mol%), 1,10-phen (10 mol%), CF3CO2H
(0.2 mL), 1,4-dioxane (0.3 mL), H2O (0.2 mL), 1108C, 20 h, under air.
[b] Isolated yield based on 1b. [c] Anisole was used instead of 1,4-diox-
ane.
A plausible mechanism to rationalize this transformation
is illustrated in Scheme 2. Similar to the PdII-catalyzed de-
carboxylative addition of benzoic acids to nitriles,[14] the pro-
posed mechanism involves the following six steps: 1) coordi-
nation of the arenesulfinic acid (or its sodium salt) to palla-
dium(II) to give complex I; 2) the desulfinative reaction of
the sulfinic acid to generate aryl–palladium complex II;
3) coordination of the nitrile group to form complex III;
4) 1,2-carbopalladation of the nitrile to generate ketimine
complex IV; 5) protonation of the ketimine by the acid to
give the free ketimine and a palladium(II) species; and
6) hydrolysis of the ketimine under acidic conditions to
afford the desired final aryl ketone.
In summary, we have developed a new Pd-catalyzed
method that allows the direct synthesis of aryl ketones from
aromatic sulfinic acid sodium salts and inexpensive nitrile
compounds. Ligands and solvents played an important role
in the reaction yield. A combination of Pd(OH)2 and 1,10-
phenanthroline in 1,4-dioxane/water (3:2) in air gave the de-
sired product in the best yield. Aromatic and aliphatic ni-
triles were successfully reacted with arenesulfinic acid
Scheme 2. Proposed mechanism.
sodium salts to form aryl ketones in moderate to good
yields. This procedure provides a rapid and convenient
method for the small-scale synthesis of aryl ketones.[22] Our
current efforts are focused on further mechanistic studies to
improve the catalytic efficiency and to overcome limitations
in substrate scope.
Experimental Section
Representative experimental procedure (3a, CAS: 134–84–9): A reaction
vessel (10 mL) was charged with a mixture of palladium hydroxide
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Chem. Eur. J. 2011, 17, 7996 – 7999

Synthesis of Aryl Ketones
COMMUNICATION
(1.4 mg, 0.01 mmol), 1,10-phenanthroline (3.6 mg, 0.02 mmol), sodium p-
toluenesulfinate (2a, 71.2 mg, 0.4 mmol), benzonitrile (1a, 20 mL,
0.2 mmol), and trifluoroacetic acid (0.2 mL) in 1,4-dioxane/water
(0.5 mL, 3:2). The reaction vessel was closed and the resulting solution
was stirred at 1108C for 20 h. After cooling to room temperature, the vol-
atiles were removed under vacuum and the residue was purified by
column chromatography (silica gel, petroleum ether/ethyl acetate, 50:1)
to give 3a as a white solid (30.5 mg, 78%).
rence, K. Kawamura, C. Incarvito, J. F. Hartwig, J. Am. Chem. Soc.
2006, 128, 13684; d) H. Chen, S. Schlecht, T. C. Semple, J. F. Hart-
wig, Science 2000, 287, 1995; e) J. Y. Cho, M. K. Tse, D. Holmes,
R. E. Maleczka, M. R. Smith, Science 2002, 295, 305; f) V. J. Olsson,
K. J. Szabꢄ, Angew. Chem. 2007, 119, 7015; Angew. Chem. Int. Ed.
2007, 46, 6891.
[14] J. Lindh, P. Sjçberg, M. Larhed, Angew. Chem. 2010, 122, 7899;
Angew. Chem. Int. Ed. 2010, 49, 7733.
[15] For a review on the use of carboxylic acids as substrates, see: L. J.
Goossen, N. Rodriguez, K. Goossen, Angew. Chem. 2008, 120, 3144;
Angew. Chem. Int. Ed. 2008, 47, 3100.
[16] a) P. Page, Organosulfur Chemistry: Stereochemical Aspects, Aca-
demic Press, San Diego, 1998; b) S. Dubbaka, P. Vogel, Angew.
Chem. 2005, 117, 7848; Angew. Chem. Int. Ed. 2005, 44, 7674;
c) N. S. Simpkins, Sulfones in Organic Synthesis, Pergamon Press,
Oxford, 1993.
Acknowledgements
This work was supported by the National Natural Science Foundation of
China (20902076), the “Academic Leader Program” of Xiangtan Univer-
sity and the “One Hundred Talent Project” of Hunan Province. We are
also grateful to the Canada Research Chair (Tier I) foundation (to C.-J.
Li).
À
[17] For desulfinative C C bond formation by using sulfonyl chlorides as
starting materials, see: a) A. Kasahara, T. Izumi, N. Kudou, H.
Azami, S. Yamamato, Chem. Ind. 1988, 51; b) A. Kasahara, T.
Izumi, K. Miyamoto, T. Sakai, Chem. Ind. 1989, 192; c) M. Miura,
H. Hashimoto, K. Itoh, M. Nomura, Tetrahedron Lett. 1989, 30, 975;
d) M. Miura, H. Hashimoto, K. Itoh, M. Nomura, J. Chem. Soc.
Perkin Trans. 1 1990, 2207; e) S. Reddy Dubbaka, P. Vogel, J. Am.
Chem. Soc. 2003, 125, 15292; f) S. Reddy Dubbaka, P. Vogel, Org.
Lett. 2003, 5, 95; g) S. Reddy Dubbaka, P. Steunenberg, P. Vogel,
Synlett 2004, 1235; h) S. Reddy Dubbaka, P. Vogel, Adv. Synth.
Catal. 2004, 346, 1793; i) S. R. Dubbaka, P. Vogel, Chem. Eur. J.
2005, 11, 2633; j) S. R. Dubbaka, D. B. Zhao, Z. F. Fei, C. M. R.
Volla, P. J. Dyson, P. Vogel, Synlett 2006, 3155; k) C. M. Rao Volla,
P. Vogel, Angew. Chem. 2008, 120, 1325; Angew. Chem. Int. Ed.
2008, 47, 1305; l) C. M. Rao Volla, S. R. Dubbaka, P. Vogel, Tetrahe-
dron 2009, 65, 504; m) C. M. Rao Volla, D. Markovic, S. R. Dubba-
ka, P. Vogel, Eur. J. Org. Chem. 2009, 6281.
Keywords: aryl ketones · desulfination · ketones · nitriles ·
palladium · sulfinic acids
[1] H. Surburg, J. Panten, Common Fragrance and Flavor Materials, 5th
ed., Wiley-VCH, Weinheim, 2006.
[2] G. Sartori, R. Maggi, Advances in Friedel–Crafts Acylation Reac-
tions, CRC Press, New York, 2010.
[3] a) G. Tojo, M. Fernꢁndez, Oxidation of Alcohols to Aldehydes and
Ketones, Springer, Berlin, 2006; b) J. E. Bꢂckvall, Modern Oxidation
Methods, Wiley-VCH, Weinheim, 2010; c) G. E. Dobereiner, R. H.
Crabtree, Chem. Rev. 2010, 110, 681.
[18] For recent examples of sulfonylation by using sodium sulfinates, see:
a) F. Sandrinelli, S. Perrio, P. Beslin, Org. Lett. 1999, 1, 1177; b) W.
Yang, C. Berthelette, Tetrahedron Lett. 2002, 43, 4537; c) S. Cacchi,
G. Fabrizi, A. Goggiamani, L. Parisi, R. Berning, J. Org. Chem.
2004, 69, 5608; d) W. Zhu, D. Ma, J. Org. Chem. 2005, 70, 2696;
e) C. Martin, F. Sandrinelli, C. Perrio, S. Perrio, M. Lasne, J. Org.
Chem. 2006, 71, 210; f) Z. Guan, W. Zuo, L. Zhao, Z. Ren, Y. M.
Liang, Synthesis 2007, 1465; g) J. Drabowicz, M. Kaiatkowska, P.
Kielbasinski, Synthesis 2008, 3563; h) B. Sreedhar, M. Reddy, P.
Reddy, Synlett 2008, 1949; i) H. Kim, A. Kasper, Y. Park, C.
Wooten, J. Hong, E. Moon, M. Dewhirst, Org. Lett. 2009, 11, 89;
[4] For selected recent examples, see: a) J. W. Ruan, O. Saidi, J. A. Iggo,
J. L. Xiao, J. Am. Chem. Soc. 2008, 130, 10510; b) A. Takemiya, J. F.
Hartwig, J. Am. Chem. Soc. 2006, 128, 14800; c) S. Ko, B. Kang, S.
Chang, Angew. Chem. 2005, 117, 459; Angew. Chem. Int. Ed. 2005,
44, 455; d) L. V. Desai, D. Ren, T. Rosner, Org. Lett. 2010, 12, 1032;
e) M. Pucheault, S. Darses, J. P. Genet, J. Am. Chem. Soc. 2004, 126,
15356; f) M. H. Savari, H. Sharghi, J. Org. Chem. 2004, 69, 6953;
g) H. Firouzabadi, N. Iranpoor, F. Nowrouzi, Tetrahedron 2004, 60,
10843; h) A. Bensari, N. T. Zaveri, Synthesis 2003, 267.
[5] For recent reviews on hydroacylation, see: a) M. C. Willis, Chem.
Rev. 2010, 110, 725, and references therein; b) D. C. Colby, R. G.
Bergman, J. A. Ellman, Chem. Rev. 2010, 110, 624; c) G. Fu in
Modern Rhodium-Catalyzed Organic Reactions (Ed.: P. Evans),
Wiley-VCH, Weinheim, 2005, pp. 79–91.
[6] For reviews, see: a) B. I. Roman, N. De Kimpe, C. V. Stevens, Chem.
Rev. 2010, 110, 5914; b) F. F. Fleming, Q. Z. Wang, Chem. Rev. 2003,
103, 2035.
[7] a) C. X. Zhou, R. C. Larock, J. Am. Chem. Soc. 2004, 126, 2302;
b) C. X. Zhou, R. C. Larock, J. Org. Chem. 2006, 71, 3551.
[8] a) B. W. Zhao, X. Y. Lu, Org. Lett. 2006, 8, 5987; b) B. W. Zhao,
X. Y. Lu, Tetrahedron Lett. 2006, 47, 6765.
´
j) A. Varela-ꢅlvavez, D. Markovic, P. Vogel, J. Sordo, J. Am. Chem.
Soc. 2009, 131, 9547; k) C. Liu, M. Li, D. Cheng, C. Yang, S. Tian,
Org. Lett. 2009, 11, 2543; l) M. Reddy, P. Reddy, B. Sreedhar, Adv.
Synth. Catal. 2010, 352, 1861; m) Y. Li, K. Cheng, X. Lu, J. Sun,
Adv. Synth. Catal. 2010, 352, 1876; n) M. Ueda, J. F. Hartwig, Org.
Lett. 2010, 12, 92; o) K. Maloney, J. Kuethe, K. Linn, Org. Lett.
2011, 13, 102.
[19] For early investigations on desulfinative reactions that use sulfinic
acid (salt), see: a) K. Garves, J. Org. Chem. 1970, 35, 3273; b) R.
Selke, W. Thiele, J. Prakt. Chem. 1971, 313, 875; c) E. Wenkert,
T. W. Ferreira, E. L. Michelotti, J. Chem. Soc. Chem. Commun.
1979, 637; d) for high efficiency biaryl synthesis by using sulfinic
acid sodium salts and aromatic bromides, see: K. Sato, T. Okoshi,
Patent, US5159082, 1992.
[20] X. Y. Zhou, J. Y. Luo, J. Liu, S. M. Peng, G. J. Deng, Org. Lett. 2011,
13, 1432.
[21] A similar yield was observed if the reaction was carried out under
an argon atmosphere and a much lower yield was obtained in
oxygen.
[9] K. Ueura, S. Miyamura, T. Satoh, M. Miura, J. Organomet. Chem.
2006, 691, 2821.
[10] a) H. Shimizu, M. Murakami, Chem. Commun. 2007, 2855; b) R. M.
Ceder, G. Muller, M. Ordinas, J. I. Ordinas, Dalton Trans. 2007, 83.
[11] Y. Wong, K. Parthasarathy, C. Cheng, Org. Lett. 2010, 12, 1736.
[12] a) D. G. Hall, Boronic Acids: Preparation, Applications in Organic
Synthesis and Medicine, Wiley-VCH, Weinheim, 2005; b) N.
Miyaura, A. Suzuki, Chem. Rev. 1995, 95, 2457; c) N. Miyaura, Top.
Curr. Chem. 2002, 219, 11.
À
[22] The price of 4-methylbenzenesulfinic acid sodium salt (2a, CAS:
824-79-3) is about 0.2 $ per gram, whereas the price of 4-methylben-
zeneboronic acid (CAS: 5720-05-8) is about 20 $ per gram (both
from Alfa Asear, 2011).
[13] For an excellent review on C H boronation, see: I. A. I. Mkhalid,
J. H. Barnard, T. B. Marder, J. M. Murphy, J. F. Hartwig, Chem. Rev.
2010, 110, 890; for selected recent examples, see: a) D. W. Robbins,
T. A. Boebel, J. F. Hartwig, J. Am. Chem. Soc. 2010, 132, 4068;
b) C. S. Wei, C. A. Jimꢃnez-Hyos, M. F. Videa, J. F. Hartwig, M. B.
Hall, J. Am. Chem. Soc. 2010, 132, 3078; c) J. M. Murphy, J. D. Law-
Received: April 23, 2011
Published online: May 30, 2011
Chem. Eur. J. 2011, 17, 7996 – 7999
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7999