Indium trichloride-catalyzed indium-mediated allylation of dihydropyrans and dihydrofurans in water

Article abstract of DOI:10.1055/s-2004-820030

A one-pot indium trichloride-catalyzed indium-mediated allylation of dihydropyrans and dihyfrofurans has been found to be feasible. This catalytic system afforded the allylated diols in moderate to high yields.

Full text of DOI:10.1055/s-2004-820030

LETTER
829
Indium Trichloride-Catalyzed Indium-Mediated Allylation of Dihydropyrans
and Dihydrofurans in Water
A
S
llylation of
D
o
ihydropyran
n
s
and Dihyd
g
rofurans in
W
ater Juan,a,b,c Zhi-Hao Hua, Shen Qi,* Shun-Jun Ji,a,b Teck-Peng Loh*a,b,c
b
a,b
a
b
c
College of Chemistry and Chemical Engineering, Suzhou University, Jiangsu 215006, P. R. China
Key Lab of Organic Synthesis of Jiangsu province, Suzhou University 215006, P. R. China
Department of Chemistry, 3 Science Drive 3, National University of Singapore, 117543, Singapore
Received 11 December 2003
Table 2 InCl -Catalyzed Indium-Mediated Allylation of Dihydro-
pyrans with Various Allylic Bromides
3
Abstract: A one-pot indium trichloride-catalyzed indium-mediated
allylation of dihydropyrans and dihyfrofurans has been found to be
feasible. This catalytic system afforded the allylated diols in mod-
erate to high yields.
R3
R3
OH
InCl3 (20 mol%)
R1
Br
+
HO
In
R1 R2
O
R2
Key words: InCl , allylation, aldehydes, polyols
3
H2O, 16 h, r.t
Entry
1
Allylic bromide
Yield (anti/syn)
Indium-mediated allylation continues to attract tremen-
dous attention among synthetic organic chemists because
of the mild reaction conditions. In our effort to develop a
Br
83%
1
2
3
4
68%
64%
58%
new strategy for the synthesis of polyols from functional-
Br
Br
2
ized lactols, we studied the one-pot acid catalyzed indi-
um-mediated allylation reaction of dihydropyrans and
dihydrofurans in aqueous media. In this paper, we report
that a one-pot indium trichloride-catalyzed indium-medi-
ated allylation of dihydropyrans and dihydrofurans in wa-
ter affords a wide variety of diols in moderate to high
yields.
2
CO Me
Br
5
6
78% (40:60)
52% (23:77)
Br
We envisaged that the reaction of indium trichloride, a
water-tolerant Lewis acid will catalyze the formation of
EtO2C
Br
lactol from commercially available dihydropyran in water
3
(
Table 1). Therefore, the progress of the formation of the
1
lactol in the reaction was monitored using H NMR when
commercially available 3,4-dihydropyran was subjected To our delight, the reactions with various allylic bromides
to indium trichloride (20 mol%) in water. Indeed when the proceeded smoothly in water to afford the corresponding
dihydropyran was subjected to indium trichloride in wa- 1,5-diols in moderate to very good yields. Moderate anti-
ter, the corresponding lactol was formed in quantitative selectivity was observed with bromocrotonate (entry 6). It
yield after 9 hours.
is important to note that no reaction was observed without
the addition of indium trichloride. The use of D O in this
reaction provides entry into the synthesis of deuteriated
alcohols, although the diasteroselectivities were low
2
With this result, we carry out a one-pot indium trichloride-
catalyzed indium-mediated allylation reaction of simple
dihydropyran in water. The results are shown in Table 2.
(
50:50).
Table 1 Relative Concentration of Dihydropyrans and Lactol in the Reaction Mixture
InCl3 (20 mol%)
O
2
H O , r.t.
O
OH
Time (hours)
Dihydropyran (%)
Lactol (%)
1
57
43
2
33
67
3
25
75
4
11
89
5
7
9
0
93
100
SYNLETT 2004, No. 5, pp 0829–0830
0
2.
0
4.
2
0
0
4
Advanced online publication: 04.03.2004
DOI: 10.1055/s-2004-820030; Art ID: U27703ST
Georg Thieme Verlag Stuttgart · New York
©

8
30
S. Juan et al.
LETTER
Next, the indium trichloride-catalyzed indium-mediated in this class of compounds. Efforts to extend this meth-
allylation of dihydrofurans were also carried out. The odology to more functionalized dihydropyrans for the
results are summarized in Table 3.
synthesis of polyols are in progress.4
Table 3 InCl -Catalyzed Indium-Mediated Allylation of Dihydro-
3
furans with Various Allylic Bromides
A Representative Procedure:
R3
R3
OH
In a 10 mL round bottom flask, 3,4-dihydro-2H-pyran (86 mg, 1
mmol) was dissolved in water (5 mL), then indium trichloride (44
mg, 0.2 mmol), indium (230 mg, 2 mmol) and allyl bromide (0.3
mL, 3 mmol) was added. The resultant mixture was stirred at r.t. for
InCl3 (20 mol%)
R1
Br
HO
+
In
R1 R2
O
R2
H2O, 16 h, r.t
1
6 h before extracting with EtOAc. The organic layers were com-
Entry
Allylic bromide
Yield (%, anti/syn)
bined, washed with brine, dried over anhyd MgSO , and concentrat-
4
ed using rotary evaporator. The corresponding product (119 mg)
was obtained after silica gel column chromatography in 83% yield.
Br
1
2
83
77
Br
Br
Acknowledgment
3
4
53
60
We thank the National Natural Science Foundation of China for
providing the research scholarship (No. 20172039) and the National
University of Singapore and the Ministry of Education (Singapore)
for providing the research funds.
CO2Me
Br
References
5
6
83 (40:60)
49 (24:76)
Br
(
1) Reviews of indium-mediated allylation reactions: (a) Li, C.
J.; Chan, T. H. Organic Reactions in Aqueous Media; John
Wiley and Sons: New York, 1997. (b) Li, C. J. Tetrahedron
EtO2C
Br
1996, 52, 5643. (c) Chan, T. H.; Isaac, M. B. Pure Appl.
Chem. 1996, 68, 919. (d) Paquette, L. A. In Green
Chemistry-Frontiers in Benign Chemical Syntheses and
Processes; Anastas, P. T.; Williamson, T. C., Eds.; Oxford
University Press: New York, 1998. (e) Li, C. J.; Chan, T. H.
Chem. Rev. 1993, 93, 2023.
As expected, the indium-catalyzed indium-mediated
allylation of dihydrofurans with various allylic bromides
proceeded smoothly to afford the corresponding 1,4-diols
in moderate to very good yields.
(
2) For selected papers on the use of indium complexes for
organic reactions in aqueous media: (a) Li, X. R.; Loh, T.-P.
Tetrahedron: Asymmetry 1996, 7, 1535. (b) Loh, T.-P.; Pei,
J.; Cao, G.-Q. Chem. Commun. 1996, 7, 1535. (c) Loh, T.-
P.; Pei, J.; Lin, M. Chem. Commun. 1996, 2315. (d) Loh,
T.-P.; Wei, L.-L. Tetrahedron Lett. 1998, 39, 323.
In conclusion, we have developed a new strategy for the
synthesis of polyols from dihydropyrans and dihydro-
furans. Lactol was generated in situ when dihydrofurans
or dihydropyrans were subjected to indium trichloride in
water. Using this one-pot method, a wide variety of 1,5-
diols and 1,4-diols can be easily prepared. The simplicity
of the reaction procedure coupled with the possibility of
obtaining a wide variety of polyols, this method will cer-
tainly attract the attention of organic chemists interested
(3) (a) Mikami, K.; Kishino, H.; Matsueda, H.; Loh, T.-P.
Synlett 1993, 497. (b) Tomooka, K.; Okinaga, T.; Suzuki,
K.; Tsuchihashi, G. Tetrahedron Lett. 1987, 6335.
(
4) Taken in part from the Master Thesis of Hua ZiHao,
National University of Singapore, 1999.
Synlett 2004, No. 5, 829–830 © Thieme Stuttgart · New York