Microwave-assisted efficient oxidative coupling of 2-naphthols in the solid state

Article abstract of DOI:10.1081/SCC-120013000

Microwave-assisted oxidative coupling of 2-naphthols at solid state gave the corresponding coupling products in high yields, which provides a simple, rapid and efficient approach to the preparation of binaphthols.

Full text of DOI:10.1081/SCC-120013000

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MICROWAVE-ASSISTED EFFICIENT OXIDATIVE COUPLING
OF 2-NAPHTHOLS IN THE SOLID STATE
Shun-Jun Ji a , Jianmei Lu a , Xinlin Zhu a , Jin Yang a , Jian-Ping Lang a & Lin Wu a
a Department of Chemistry, Suzhou University, 1 Shizi St. Suzhou, Jiangsu, 215006, China
Version of record first published: 16 Aug 2006.
To cite this article: Shun-Jun Ji, Jianmei Lu, Xinlin Zhu, Jin Yang, Jian-Ping Lang & Lin Wu (2002): MICROWAVE-ASSISTED
EFFICIENT OXIDATIVE COUPLING OF 2-NAPHTHOLS IN THE SOLID STATE, Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic Chemistry, 32:19, 3069-3074
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SYNTHETIC COMMUNICATIONS
Vol. 32, No. 19, pp. 3069–3074, 2002
MICROWAVE-ASSISTED EFFICIENT
OXIDATIVE COUPLING OF
2-NAPHTHOLS IN THE SOLID STATE
*
Shun-Jun Ji, Jianmei Lu, Xinlin Zhu, Jin Yang,
Jian-Ping Lang, and Lin Wu
Department of Chemistry, Suzhou University,
1 Shizi St. Suzhou, Jiangsu 215006, China
ABSTRACT
Microwave-assisted oxidative coupling of 2-naphthols at solid
state gave the corresponding coupling products in high yields,
which provides a simple, rapid and efficient approach to the
preparation of binaphthols.
Optically active 1,10-binaphthalene-2,20-diol and its derivatives have
been of synthetic interest associated with wide applicability of the enantio-
mers in chirality induction,[1] since a convenient and economic way for
obtaining the enantiomers is the resolution of the racemic 1,10-binaphtha-
lene-2,20-diol.[2] There have been some known methods for the oxidative
coupling of 2-naphthols to give 1,10-binaphthalene-2,20-diol using FeCl3,[3]
K3Fe(CN)6,[4] Mn(acac)3,[5] CuCl(OH),[6] CuSO4(Al2O3)[7] and Cu(II)–
amine complexes[8–10] as coupling reagents. In most cases, however, the
oxidative couplings of 2-naphthol are usually carried out by treatment of
*Corresponding author. Fax: þ86 (512) 7242919; E-mail: shunjun@suda.edu.cn
3069
DOI: 10.1081/SCC-120013000
Copyright & 2002 by Marcel Dekker, Inc.
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3070
JI ET AL.
naphthol in solution with stoichiometric amount of metal salts such as
FeCl3 or manganese tris(acetyl acetonate), which reaction times are longer
(9–120 h),[11] or by the use of a Cu(II)–amine complex combined with
AgCl.[12] Recently, molecular oxygen as the oxidant in the presence of a
catalytic amount (10%) of VO(acac)2 in solution have been investigated.[11]
The coupling reaction of aerated powder mixtures of 2-naphthols and FeCl3
under ultrasound irradiation at 50ꢀC has been reported by Toda et al.[3a]
and Villemin’s group has reported the oxidative coupling of 2-naphthol
using an excess amount of FeCl3 under microwave irradiation.[3b]
However, the effect of a variety of amount FeCl3Á6H2O for oxidative coup-
ling of 2-naphthols under microwave intermittent irradiation in the solid
state have not yet been reported.
Since the appearance of first article on the use of microwave energy in
chemical synthesis,[13] the approach has now developed into a useful tech-
nique for a variety of applications in organic synthesis.[14–17] Especially, the
solvent-free reactions can be conducted on the solid supports, which has
been intensively investigated.[16,17] During the course of our studies, we have
investigated microwave-assisted copolymerization, reduction, and synthesis
[18]
of one-dimensional polymericcomplex in solid state.
We herein wish to
report a simple, rapid and efficient method for oxidative coupling reaction
of 2-naphthols in the solid state in the presence of coupling agents
(i.e., FeCl3) under microwave irradiation to give 1,10-binaphthalene-
2,20-diol in high yields.
In a typical procedure, a mixture of 2-naphthols (0.72 g, 5 mmol) and
FeCl3Á6H2O (1.35 g, 5 mmol) was finely powdered by grinding in an agate
mortar. The mixture was transferred to an Erlenmeyer flask and placed in a
commercial microwave oven operating at 2450 MHz frequency while adopt-
ing intermission irradiation. The reaction process was monitored by TLC
with pre-coated plates of silica gel in a one-minute time slot. After specify
the usual workup, decomposition the reaction mixture with dilute HCl and
purified by column chromatography (hexane–EtOAc ¼ 4 : 1) to afford the
coupling product 2a in 97% yield. Similar treatment of other naphthol
derivatives gave the corresponding binaphthols in 80–97% yields and the
results are summarized in Table 1.
The use of 2 equiv. of FeCl3Á6H2O (Table 1, Entry 3) did not increase
the yield of coupling product 2a. Further increasing the reaction time had no
significant effect on the yield and resulted in minor amount of decomposi-
tion (Table 1, Entry 2). The coupling reaction of 3-(methoxycarbonyl)-
2-naphthol 1f was very sluggish. It gave 80% yield of 2f after 20 min
irradiation and 13% of 1f was recovered (Table 1, Entry 8).
In order to choose the ideal reaction condition, 2-naphthol (1a) was
chosen as model compound. Oxidizing reagent, irradiation time, and

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OXIDATIVE COUPLING OF 2-NAPHTHOLS
3071
Table 1. Microwave Assisted Oxidative Coupling of 2-Naphtholsa
Naphthol
Entry
Substrate
R1
R2
R3
Time/min
Product/%b
1
2
3
4
5
6
7
8
1a
1a
1a
1b
1c
1d
1e
1f
H
H
H
H
H
H
H
H
Br
H
H
H
H
H
H
H
5
10
5c
8
4
4
2a
2a
2a
2b
2c
2d
2e
2f
(97)
(93)
(95)
(89)
(93)
(90)
(89)
(80)
H
OCH3
OH
H
H
Me
CO2Me
7
20
H
aAll the reactions were performed on 5 mmol scale at ambient pressure; bCompounds
2a–f were identified according to data reported in Ref. [7,10]; c2 equiv. of
FeCl3ꢀ6H2O was employed.
irradiation power were found to be important factor which influence the
coupling reaction. These results are summarized in Table 2. On the basis of
these results, it was found that the coupling reaction also proceeds in the
presence of a catalytic amount of FeCl3Á6H2O. For example, irradiation
with microwave to a mixture of finely powdered 1a and a 0.2 molar
amount of FeCl3Á6H2O for 20 min gave 2a in 90% yield and 31% yield
under a nitrogen atmosphere (Table 2, Entries 4,5). This result shows that
oxidation of Fe2þ to Fe3þ under the air occurs easily for open system and
intermission irradiation. In the case of same irradiation time and same
amounts of oxidant reagent (Table 2, Entries 6,7 and Table 1, Entry 1), it
seems that the effect of microwave energy for the present coupling reaction is
evident.
The results obtained by the microwave-assisted solid-state process are
rather different compared to those attained by the traditional thermal method
in the solid and in solution, of which the yields were lower (Table 2,
Entries 12–14). It appears that, aside from the thermal effect, the microwave
energy may also have other non-thermal effect. In case of CuCl2Á2H2O,
K3Fe(CN)6 and (NH4)2Ce(NO3)6, the oxidative coupling reaction also

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3072
JI ET AL.
Table 2. Oxidative Coupling of 2-Naphthol at Different Statea
Entry
Reagent (mmol)
Method
Time/min
Product/%d
1
2
3
4
5
6
7
8
9
10
11
12
13
14
FeCl3Á6H2O (1.0)
FeCl3Á6H2O (1.0)
FeCl3Á6H2O (0.5)
FeCl3Á6H2O (0.2)
FeCl3Á6H2O (0.2)
FeCl3Á6H2O (1.0)
FeCl3Á6H2O (1.0)
Mn(OAc)3 (1.0)
CuCl2Á2H2O (1.0)
K3Fe(CN)6 (1.0)
(NH4)2Ce(NO3)6 (1.0)
FeCl3Á6H2O (2.0)
FeCl3Á6H2O (2.0)
FeCl3Á6H2O (2.0)
700 W
700 W
700 W
700 W
700 W
100 W
450 W
700 W
700 W
700 W
700 W
Á/35ꢀCb
Á/35ꢀCb
Refluxc
1
3
11
20
20
5
45
69
95
90
31e
24
68
90
81
85
85
64
68
60
5
5
10
10
10
60
180
180
aAll the reactions were performed on 5 mmol scale at ambient pressure; bThe mixture
was put in a test tube and kept at 35ꢁC; The reaction was performed in ethanol–
c
d
water (1 : 1); Isolated yield; Carried out under nitrogen.
e
proceeded smoothly to give binaphthols in high yields, (Table 2, Entries
8–11). Especially, the successive coupling reaction is very interesting by
using the (NH4)2Ce(NO3)6 as oxidative coupling reagent.
In conclusion, we have developed an improved oxidative coupling of
naphthol by microwave-assisted solid-state process, which provides an effi-
cient, simple and rapid methods for the synthesis of 1,10-binaphthalene-
2,20-diol. The study of non-thermal effect of microwave energy and the
application of cerium compounds for microwave reaction are now in
progress in our laboratory.
ACKNOWLEDGMENT
The project was supported by National Science Foundation of China
(No. 20172039).
REFERENCES
1. Trost, B.M. Pure Appl. Chem. 1992, 64, 315; Kagan, H.B.; Riant, O.
Chem. Rev. 1992, 92, 1007; Mikami, K.; Shimizu, M. Chem. Rev. 1992,

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OXIDATIVE COUPLING OF 2-NAPHTHOLS
3073
92, 1021; Noyori, R.; Takaya, H. Acc. Chem. Res. 1990, 23, 345;
Noyori, R. Asymmetric Catalysis in Organic Synthesis; Wiley Sons:
New York, 1994.
2. Brunel, J.-M.; Buono, G. J. Org. Chem. 1993, 58, 7313; Pu, L. Chem.
Rev. 1998, 98, 2405; Sridhar, M.; Vadivel, S.K.; Bhalerao, U.T.
Tetrahedron Lett. 1997, 38, 5695; Wang, Y.; Sun, J.; Ding, K.
Tetrahedron 2000, 56, 4447.
3. (a) Pummerer, R.; Rieche, A.; Prell, E. Ber. 1926, 59, 2159; Toda, F.;
Tanaka, K.; Iwata, S. J. Org. Chem. 1989, 54, 3007; Ding, K.; Wang,
Y.; Zhang, L.; Wu, Y.; Matsuura, T. Tetrahedron 1996, 52, 1005;
Bao, J.; Wulff, W.D.; Dominy, J.B.; Fumo, M.J.; Grant, E.B.; Rob,
A.C.; Whitcomb, M.C.; Yeung, S.-M.; Ostrander, R.L.; Rheingold,
A.L. J. Am. Chem. Soc. 1996, 118, 3392; Rasmussen, M.O.;
Axelsson, O.; Tanner, D. Synth. Commun. 1997, 27, 4027; Li, T.-S.;
Duan, H.-Y.; Li, B.-Z.; Tewari, B.B.; Li, S.-H. J. Chem. Soc. Perkin
Trans. 1 1999, 291; (b) Villemin, D.; Sauvaget, F. Synlett. 1994, 435.
4. Feringa, B.; Wynberg, H. J. Org. Chem. 1981, 46, 2547.
5. Yamamoto, K.; Fukushima, H.; Okamoto, Y.; Hatada, K.; Nakazaki,
M. J. Chem. Soc. Chem. Commun. 1984, 1111; Dewar, M.J.S.;
Nakaya, T. J. Am. Chem. Soc. 1968, 90, 7134.
6. Noji, M.; Nakajima, M.; Koga, K. Tetrahedron Lett. 1994, 35, 7983;
Nakajima, M.; Miyoshi, I.; Kanayama, K.; Hashimoto, S.-I.; Noji, M.;
Koga, Kenji. J. Org. Chem. 1999, 64, 2264.
7. Sakamoto, T.; Yonehara, H.; Pac, C. J. Org. Chem. 1994, 59, 6859.
8. Feringa, B.; Wynberg, H. Tetrahedron Lett. 1977, 18, 4447.
9. Feringa, B.; Wynberg, H. Bioorg. Chem. 1978, 7, 397; Brussee, J.;
Jansen, A.C.A. Tetrahedron Lett. 1983, 24, 3161.
10. Nakajima, M.; Hashimoto, S.; Noji, M.; Koga, K. Chem. Pharm. Bull.
1998, 46, 1814; Brussee, J.; Groenedijk, J.L.G.; te Koppele, J.M.;
Jansen, A.C.A. Tetrahedron 1985, 41, 3313.
11. Hwang, D.-R.; Chen, C.-P.; Uang, B.-J. J. Chem. Soc. Chem.
Commun. 1999, 1207.
12. Smrcina, M.; Polakova, J.; Vyskocil, S.; Kocovsky, P. J. Org. Chem.
1993, 58, 4534.
13. Gedye, R.; Smith, F.; Westaway, K.; Ali, H.; Baldisera, L.; Laberge, L.;
Rousell, J. Tetrahedron Lett. 1986, 27, 279.
14. Abramovich, R.A. Org. Prep. Proced. Int. 1991, 23, 683; Whittaker,
A.G.; Hicks, R.J. Microwave Power Electromagnet Energy 1995, 30,
27; Varma, R.S. Microwave-Assisted Reaction Under Solvent-Free
‘Dry’ Conditions. In Microwaves:Theory and Application in Material
Processing IV, Clark, D.E., Sutton, W.H., Lewis, D.A., Eds.;
American Ceramic Society, Ceramic Transactions 1997, 80, 357.

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3074
JI ET AL.
15. Majetich, G.; Defrauw, J. Tetrahedron Lett. 1987, 28, 6553.
16. Oussaid, A.; Thach, L.N.; Loupy, A. Tetrahedron Lett. 1997, 38, 2451.
17. Varma, R.S.; Chatterjee, A.K.; Varma, M. Tetrahedron Lett. 1993, 34,
3207; Varma, R.S.; Saini, R.K. Tetrahedron Lett. 1997, 38, 2623;
Varma, R.S.; Meshram, H.M. Tetrahedron Lett. 1997, 38, 5427,
7973; Varma, R.S.; Dahiya, R.; Saini, R.K. Tetrahedron Lett. 1997,
38, 8819; Varma, R.S.; Dahiya, R. Synth. Commun. 1998, 28, 4087;
Varma, R.S.; Saini, R.K. Tetrahedron Lett. 1997, 38, 4337.
18. Lu, J.; Zhu, X.; Ji, S.-J.; Zhu, J.; Chen, Z. J. Appl. Polym. Sci. 1998, 68,
1563; Lu, J.; Ji, S.-J.; Zhu, X.; Chen, Z. Chin. J. Synth. Chem. (in Eng.)
2000, 8, 87; Lang, J.-P.; Liu, J.; Chen, M.-Q.; Lu, J.; Bian, G.-Q.; Xin,
X.-Q. J. Chem. Soc. Chem. Commun. 1994, 2665.
Received in Japan June 25, 2001