1
1
Table 1 (continued )
Entry Aryl halide
nowadays is an important issue in research. Importantly,
in all our reactions, the catalyst removal is a much easier task
as both the copper salt and ligand come out from organic
phase to water along with all other inorganic components
during water work-up. In general, a fairly pure product is
obtained just by water work-up of the reaction mixture. In
summary, we have developed an efficient and environmentally
b
t/h
Product
Yield (%)
1
2
2
9
24
80
0
20
54
2
friendly catalyst system (D-glucose/Cu(OAc) ) for the conversion
of aryl halides to corresponding phenols with an easy way of
catalyst removal. This new catalytic system provides high
selectivity towards phenol formation in the presence of many
competitive nucleophiles. This is the first report of direct usage
of readily available D-glucose as a ligand in transition metal-
catalyzed organic reactions. The D-glucose is one of the
cheapest ligands among reports available in literature and
contains multiple chiral centers. This could open up a new
scope for enantiopure synthesis of various important optically
active phenols, as well as kinetic resolution of optically active
aryl halides in one of the cheapest and environmentally
friendly ways. The application of this water soluble D-glucose
as a ligand for other organic reactions, detailed mechanistic
study and kinetic resolution of racemic aryl halides for
synthesis of enantiopure phenols are under progress.
c
30
1
24
d
d
22
24/80
99/80
a
ArX (0.5 mmol), Cu(Oac)
2
ÁH
2
O (0.025 mmol), D-glucose (0.025
O.
Isolated yield. Reaction performed in 10 mmol scale. Reaction
mmol) and KOH (2–4 mmol) were reacted in 2 mL DMSO/H
b
2
c
d
performed without catalyst.
Then the investigation was initiated to know the efficiency
of the L1-Cu(OAc)
2
catalyzed phenol formation reaction
towards several aryl halides and the results are summarized
in Table 1. Various aryl iodides and bromides were converted
to corresponding phenols under the optimized reaction
conditions. Aryl iodides containing both electron-donating
This work was supported by the DST (Project No.: SR/S1/
OC-06/2008) New Delhi, India. K. G. T. thanks CSIR India
for the research fellowship.
(
entries 2–6, and 13) and electron-withdrawing groups (entries
–12) provided good to excellent yields. Performances of aryl
8
Notes and references
bromides with an electron-donating group in the ortho
position are quite satisfactory (entries 14 and 18) and many
aryl bromides with electron-withdrawing groups provided
excellent yields of the corresponding phenol (entries 15–17).
In the presence of an electron-withdrawing nitro group, chloro
benzenes also provided excellent yields for the phenol
formation (entry 22) but with a weak electron-withdrawing
benzoyl group, chlorobenzene provided less yield (entry 21).
The conventional nucleophilic substitution reactions were
performed with bromo- and chlorobenzenes containing
electron-withdrawing nitro groups without a copper catalyst
and these reactions took much more time than the copper-
catalyzed reactions (entries 17 and 22). Many dihalobenzenes
were also converted to corresponding dihydroxybenzenes with
moderate to excellent yields (entries 18–20). It was found that
1
2
(a) P. P. Deshpande and S. J. Danlshefsky, Nature, 1997, 387, 164;
(b) K. Tatsuta and S. Hosokawa, Sci. Technol. Adv. Mater., 2006,
7
, 397; (c) A. David, Isr. J. Chem., 2010, 50, 204; (d) Y. Huang,
S. Hu, S. Zuo, Z. Xu and C. Han, J. Mater. Chem., 2009, 19, 7759.
(a) M. Arisawa, S. Utsumi, M. Nakajima, N. G. Ramesh,
H. Tohma and Y. Kita, Chem. Commun., 1999, 469;
(b) M. Dieguez, C. Claver and O. Pamies, Eur. J. Org. Chem.,
2
007, 4621; (c) A. Monopoli, V. Calo, F. Ciminale, P. Cotugno,
C. Angelici, N. Cioffi and A. Nacci, J. Org. Chem., 2010, 75, 3908.
A. B. Naidu, E. A. Jaseer and G. Sekar, J. Org. Chem., 2009, 74, 3675.
3
4 (a) P. Muthupandi, S. K. Alamsetti and G. Sekar, Chem. Commun.,
2009, 3288; (b) S. K. Alamsetti and G. Sekar, Chem. Comm., 2010,
7
235.
5
6
7
(a) T. George, R. Mabon, G. Sweeny, J. B. Sweeney and
A. J. Tavassoli, J. Chem. Soc., Perkin Trans. 1, 2000, 2529,
references therein; (b) R. Bal, M. Tada, T. Sasaki and
Y. Iwasawa, Angew. Chem., Int. Ed., 2006, 45, 448.
(a) K. W. Anderson, T. Ikawa, R. E. Tundel and S. L. Buchwald,
J. Am. Chem. Soc., 2006, 128, 10694; (b) T. Schulz, C. Torborg,
1
-bromo-2-iodobenzene provided a very good yield of the
B. Scha
M. Beller, Angew. Chem., Int. Ed., 2009, 48, 918.
(a) C. M. Kormos and N. E. Leadbeater, Tetrahedron, 2006, 62,
728; (b) A. Tlili, N. Xia, F. Monnier and M. Taillefer, Angew.
¨ ¨
ffner, J. Huang, A. Zapf, R. Kadyrov, A. Borner and
corresponding dihydroxy product but when 1,2-diiodobenzene
was the substrate the yield reduced drastically (entries 18 and
4
2
0), which may be because of higher steric bulk with the iodo
Chem., Int. Ed., 2009, 48, 8725; (c) D. Zhao, N. Wu, S. Zhang,
P. Xi, X. Su, J. Lan and J. You, Angew. Chem., Int. Ed., 2009, 48,
group compared to the bromo group. When two iodo groups
are apart in 1,3-diiodobenzene, an excellent yield of corres-
ponding dihydroxy product is obtained (entry 19). The other
sterically hindered ortho-substituted aryl halides also yielded
the corresponding phenols in moderate to good yields (entries
8
729; (d) D. Yang and H. Fu, Chem.–Eur. J., 2010, 16, 2366;
e) L. Jing, J. Wei, L. Zhou, Z. Huang, Z. Li and X. Zhou, Chem.
(
Commun., 2010, 46, 4767.
8
9
(a) The optimization table for various copper salts, solvent mixtures,
catalyst loading, bases and temperature is available in electronic
supplementary information (Table 1w); (b) The results are summarized
in Table 2w of the electronic supplementary information.
V. Declerck and J. Martinez, F. Lamaty Synlett, 2006, 3029.
4
and 5). Even nucleophilic and base sensitive groups like
hydroxy, ketone and acid sensitive cyano groups containing
aryl halides survived well during the course of the reaction.
The phenol formation reactions of simple iodobenzene and
p-chlorobenzophenone were carried out in large scale (10 mmol)
and they provided similar yields compared to small scale
reactions (entries 1 and 21). Catalyst removal and reuse
10 (a) J. Xie, X. Zhu, M. Huang, F. Meng, W. Chen and Y. Wan, Eur.
J. Org. Chem., 2010, 3219.
1
1 (a) S. Munirasu, A. Deshpande and D. Baskaran, Macromol.
Rapid Commun., 2008, 29, 1538; (b) continuous removal of the
catalyst from polyphenylene ethers, L. M. Phynes, US Patent
4654418, 1987.
6
694 Chem. Commun., 2011, 47, 6692–6694
This journal is c The Royal Society of Chemistry 2011