Efficient and mild synthesis of functionalized 2,3-dihydrofuran derivatives via domino reaction in water

Article abstract of DOI:10.1016/j.tetlet.2011.02.093

An efficient and mild method for the synthesis of functionalized tricyclic 2,3-dihydrofurans, bicyclic 2,3-dihydrofurans, and other tetrasubstituted 2,3-dihydrofurans by domino reaction of 1,3-dicarbonyl compounds and α-bromonitroalkenes with a large subs

Full text of DOI:10.1016/j.tetlet.2011.02.093

Tetrahedron Letters 52 (2011) 2379–2382
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Tetrahedron Letters
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Efficient and mild synthesis of functionalized 2,3-dihydrofuran derivatives
via domino reaction in water
⇑
Jian-Wu Xie , Ping Li, Ting Wang, Fei-Ting Zhou
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials Department of Chemistry and Life Science, Zhejiang Normal University, Jinhua 321004, China
a r t i c l e i n f o
a b s t r a c t
Article history:
An efficient and mild method for the synthesis of functionalized tricyclic 2,3-dihydrofurans, bicyclic 2,3-
dihydrofurans, and other tetrasubstituted 2,3-dihydrofurans by domino reaction of 1,3-dicarbonyl com-
Received 28 December 2010
Revised 16 February 2011
Accepted 22 February 2011
Available online 4 March 2011
pounds and
trans isomers) in moderate to excellent yield (up to 96%) has been reported.
Ó 2011 Elsevier Ltd. All rights reserved.
a-bromonitroalkenes with a large substrate scope and excellent diastereoselectivity (only
The dihydrofuran derivatives are an important class of hetero-
cycles, widely present in numerous natural products and biologi-
cally active derivatives.1 Owing to their importance, different
approaches toward the synthesis of dihydrofuran derivatives have
been reported on the basis of [4+1] annulation of sulfur ylide with
intramolecular nucleophilic displacement of C affords the
multisubstituted dihydrofuran derivatives 3.
In an initial study, we investigated the domino reaction
between 4-hydroxylcoumarin 1a and -bromonitroalkene 2a in a
a
series of organic solvents and bases. A few representative results
are shown in Table 1. To our delight, the domino reaction pro-
ceeded smoothly to provide the desired product 3aa when the
reaction was carried out in the presence of bases (120 mol %) in
THF at room temperature for 48 h (Table 1, entries 1–4). Good yield
was obtained when the domino reactions were catalyzed by NaOAc
(86% yield, entry 3). Various bases such as triethylamine, DABCO,
were also screened and similar results were achieved (entries
1–2). Lower yield was isolated when the reaction was catalyzed
with a more strong base NaOH (31% yield, entry 4). Subsequently
we investigated the effects of solvents with NaOAc. Good yields
were obtained in DCM and ethanol (entries 6 and 7). Organic sol-
vents can cause significant air pollution, land contamination and
water pollution in many synthetic organic processes, and the
development of efficient synthetic methodologies for organic
a
-ylidene-b-diketones2, and by the reaction of
benzothiazole or
a-ketosulfides with
a
-keto polyfluoroalkane sulfones with alde-
hydes.3,4 Moreover, dihydrofurans have also been obtained by
cyclization5,6 and ring enlargement reaction.7,8 Among the meth-
ods, the most frequently used synthetic methods for the construc-
tion of dihydrofurans are the reactions of 1,3-dicarbonyl
compounds with appropriate olefins.9,10 Very recently, one-pot
synthesis of substituted dihydrofurans from Lewis base-catalyzed
three-component condensation was reported by Shi’s group.11
However, these approaches have some drawbacks from the view-
point of atom economy or environmental concern. In the course
of our investigations on the use of a-bromonitroalkenes in organic
synthesis, the a-bromonitroalkenes are characterized by high and
versatile reactivity.12 Especially, the bromo or nitro group could
behave as a better leaving group in the reaction. Therefore, many
heterocyclic compounds have been constructed from the
a-bro-
monitroalkenes.12,13 Recently, our group14 and Rueping’s group15
have reported a novel domino reaction of 1,3-dicarbonyl com-
NO2
O
O
X
NO2
Br
pounds and
a-bromonitroalkenes to afford chiral tricyclic 2,3-
Ar
Base
Ar
+
dihydrofurans, bicyclic 2,3-dihydrofurans, and tetrasubstituted
2,3-dihydrofurans in high yields and enantioselectivities. Encour-
aged by the good results, we envisaged that domino reaction
X
O
O
R1
2
3
R1
1
NO2
intramolecular
nucleophilic
displacement
would be possible between the
dicarbonyl compounds 1, as outlined in Scheme 1. First, the reac-
tion of -bromonitroalkenes 1 with 1,3-dicarbonyl compounds 2
a-bromonitroalkenes with 1,3-
Michael Additon
Br
Ar
O2N
O
O2N
O
a
Br
Br
O
Ar
gives the Michael addition product A. Then, the enolate anion C
was formed under the basic conditions. Finally, the subsequent
NO2
Base
Ar
Ar
O
Br
X
A
O
X
B
O
X
R1
R1
R1
C
⇑
Corresponding author. Fax: +86 579 82282610.
E-mail address: xiejw@zjnu.cn (J.-W. Xie).
Scheme 1. The novel method for the synthesis of benzopyran derivatives.
0040-4039/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2011.02.093

2380
J.-W. Xie et al. / Tetrahedron Letters 52 (2011) 2379–2382
Table 2
Table 1
Synthesis of tricyclic 2,3-dihydrofurans 3a
Screening studies of the domino reaction of 4-hydroxyl- coumarin 1a and
a
-
bromonitroalkene 2aa
NO2
Ar
O
OH
120 mol% NaOAc
20 mol% TBAB
NO2
NO2
O
OH
O
Ar
H3CO
+
+
H2O, rt, 72h
Br
NO2 120% mol base
X
X
O
R
R
O
solvent, rt, 48h
OCH3
Br
2
3
1
O
O
O
2a
1a
3aa
Entry
1
Ar
(2)
3
Yieldb (%)
Entry
Solvent
Base
Yieldb (%)
1
2
3
4
5
6
7
8
1a
1b
1c
1d
1e
1a
1a
1a
1a
1b
1b
p-MeO-C6H4
p-MeO-C6H4
p-MeO-C6H4
p-MeO-C6H4
p-MeO-C6H4
p-Me-C6H4
Ph
p-Cl-C6H4
p-Br-C6H4
p-Cl-C6H4
2-Furanyl
(2a)
(2a)
(2a)
(2a)
(2a)
(2b)
(2c)
(2d)
(2e)
(2d)
(2f)
3aa
3ba
3ca
3da
3ea
3ab
3ac
3ad
3ae
3bd
3bf
93 (91)
95 (82)
93 (88)
88 (86)
90(81)
87(90)
90 (78)
96 (89)
83 (77)
96 (90)
88 (80)
1
2
THF
THF
THF
THF
DCM
Ethanol
H2O
Et3N
84
83
86
31
72
87
80
93
DABCO
NaOAc
NaOH
NaOAc
NaOAc
NaOAc
NaOAc
3c
4c
5c
6c
7c
8c,d
H2O
9
10
11
a
Unless noted otherwise, reactions were performed with 0.20 mmol of 1a,
0.22 mmol of 2a, 120 mol % of catalyst in 2.0 mL solvent for 48 h.
b
a
Isolated yield.
20 mol % TBAB was added.
72 h.
Unless noted otherwise, reactions were performed with 0.20 mmol of 1,
0.30 mmol of 2a, 120 mol % of NaOAc, 20 mol %TBAB in 2.0 mL H2O for 72 h.
Isolated yield.
c
d
b
reactions, in the absence of organic solvents, is an important chal-
lenge toward reducing the amount of waste.16,17 An ideal organic
reaction would proceed in an environmentally benign solvent, such
as water.18,19 We were pleased to find that the domino reaction
proceeded smoothly to provide the desired product 3aa with good
yield using water as solvent (entry 7). we got excellent yield (93%
yield) in water catalyzed by NaOAc, while the reaction time should
be extended (entry 8).
OH
NO2
O
O
O
120 mol% NaOAc
20 mol% TBAB
H2O, rt, 72h
1a
+
Cl
Cl
NO2
Br
O
3ad
O
Consequently, an array of 4-hydroxylcoumarin derivatives
2d
(Fig. 1) were explored in the reactions with a variety of
a-bro-
monitroalkenes to establish the general utility of this new method-
ology. The reactions were generally conducted in water with
120 mol % of NaOAc in water at room temperature. As summarized
in Table 2, the electronic characteristics of 4-hydroxylcoumarin
derivatives seemed to have limited effects on the yield. Good to
excellent yields were obtained for a diversity of 4-hydroxylcoum-
arin derivatives 1a–1d bearing electron-withdrawing or donating
groups (entries 1–5).20 In addition, 4-hydorxythiocoumarin 2e
exhibited good reactivity. High yields were also obtained in the
reactions of 4-hydroxylcoumarin and electron-withdrawing sub-
Before reaction
After 72h
Figure 2. Photo of the reactions of 1a with 2d (Table 2, entry 8).
Table 3
Synthesis of bicyclic 2,3-dihydrofurans 3a
NO2
Ar
O
O
120 mol% NaOAc
20 mol% TBAB
NO2
+
Ar
H2O, 70°C, 3h
R
R
Br
O
O
R
stituent or electron-denoting substituent on aryl ring of
monitroalkenes substrates 2b–2e (entries 6–9). It turned out that
the substituents on the phenyl group of -bromonitroalkenes
a-bro-
R
2
3
1
a
Entry
1
Ar
(2)
3
Yieldb (%)
had little influence on the domino reactions. Gratifyingly, raising
the temperature to 70 °C, good to excellent yields were obtained,
while the reaction time reduced to 3 h (Table 2, entries 1–9, yield
in bracket). It is worthy of note that white precipitate was formed
when the reactions were carried out at room temperature for 72 h
1
2
3
4
5
6
1f
1f
1f
1f
1f
1g
p-MeO-C6H4
p-Me-C6H4
Ph
p-Cl-C6H4
p-Br-C6H4
p-MeO-C6H4
(2a)
(2b)
(2c)
(2d)
(2e)
(2a)
3fa
3fb
3fc
3fd
3fe
76c
70
80
83
79
74
3ga
(Fig. 2, e.g., the reaction of
a-bromonitroalkenes 1a with 2d) and
a
tricyclic 2,3-dihydrofurans were easily isolated by filtration, then
washed with ethanol or recrystallized from ethanol to give the
pure tricyclic 2,3-dihydrofurans.
Unless noted otherwise, reactions were performed with 0.20 mmol of 1,
0.30 mmol of 2a, 120 mol % of NaOAc, 20 mol %TBAB in 2.0 mL H2O at 70 °C for 3 h.
b
Isolated yield.
Having succeeded in synthesizing tricyclic 2,3-dihydrofurans,
we turned our attention to the possible synthesis of bicyclic 2,3-
dihydrofurans using 1,3-cyclohexanediones ( Fig. 1) as nucleo-
philes. Unfortunately, very poor results were observed when the
domino reaction of 1f–2a was carried out at room temperature.
To our delight, the yields were dramatically increased when the
reactions were carried out at 70 °C after 3 h (Table 3). Table 3
OH
S
O
O
OH
O
1a R = H
1b R = 6-Me
1c R = 5,7-(Me)2
1d R = 6-F
O
O
O
O
R
shows that
a-bromonitroalkenes with electron-withdrawing or
1f
1e
1g
donating substituents provided the bicyclic 2,3-dihydrofurans
Figure 1. The structures of cyclic 1,3-dicarbonyl compounds.
3fa–3fe in good yields (70–83%, entries 1–5). For the reaction of

J.-W. Xie et al. / Tetrahedron Letters 52 (2011) 2379–2382
2381
O
References and notes
R
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+
O
O
120 mol% NaOAc
20 mol% TBAB
NO2
O
R
H2O, 70
°C, 3h
Br
2a
O2N
product 3 yield%
1h-1i
O
R
CH3 3ha
OEt 3ia
65
53
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S. J. Am. Chem. Soc. 2001, 123, 12095.
Figure 3. Molecular structure of 3fa.
a
-bromonitroalkene 1a, good yield was also achieved with 5,5-di-
methyl-1,3-cyclohexanedione (entry 6). The reactions of acyclic
1,3-dicarbonyl compounds 1h–1i with 2a also found to be success-
ful, and tetrasubstituted 2,3-dihydrofurans 3ha–3ia were obtained
with moderate yield (Scheme 2).
The stereochemistries of the products 3 are assigned on the ba-
sis of specific coupling constants (J) and HPLC in comparison with
the literature data,21 then the stereochemistries of 3 were estab-
lished unambiguously by X-ray analysis of 3fa (Fig. 3). It confirms
the trans configuration as illustrated by the ORTEP diagram de-
picted in Figure 3.22
11. Zhong, C.; Liao, T.; Tuguldur, O.; Shi, X. Org. Lett. 2010, 12, 2064.
12. Xie, J.-W.; Wang, Z.; Yang, W.-J.; Kong, L.-C.; Xu, D.-C. Org. Biomol. Chem. 2009,
7, 4352.
In conclusion, an efficient method for the synthesis of function-
alized 2,3-dihydrofurans by domino reaction of 1,3-dicarbonyl
compounds with a-bromonitroalkenes has been investigated. The
13. Muruganantham, R.; Mobin, S. M.; Namboothiri, I. N. N. Org. Lett. 2007, 9, 1125;
Ayyagari, N.; Jose, D.; Mobin, S. M.; Namboothiri, I. N. N. Tetrahedron Lett. 2011,
52, 258.
14. Fan, L.-P.; Li, P.; Li, X.-S.; Xu, D.-C.; Ge, M.-M.; Zhu, W.-D.; Xie, J.-W. J. Org. Chem.
2010, 75, 8716.
domino reaction can proceed smoothly in an environmentally be-
nign solvent–water and provides pure functionalized tricyclic
2,3-dihydrofurans, bicyclic 2,3-dihydrofurans, and tetrasubstituted
2,3-dihydrofurans with excellent diastereoselectivity (only trans
isomers) in moderate to excellent yield. The reaction’s scope
proved to be quite broad. Notably, pure tricyclic 2,3-dihydrofurans
were easily obtained in a simple procedures. This novel methodol-
ogy should be of great interest for natural product synthesis and
pharmaceutical synthesis for the mild reaction conditions.
15. Rueping, M.; Parra, A.; Uria, U.; Besseliévre, F.; Merino, E. Org. Lett. 2010, 12,
5680.
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17. Clean Solvents: Alternative Media for Chemical Reactions and Processing, ACS
Symposium Series 819, Abraham, M. A. and Moens, L. ed., Washington, D.C.,
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18. (a)For general references see: Organic Synthesis in Water; Grieco, P. A., Ed.;
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Blackwell Publishing Ltd.: Oxford, UK, 2007; (c) Hailes, H. C. Org. Process Res.
Dev. 2007, 11, 114.
Acknowledgments
19. For recent reviews on other environmentally benign solvents see: (a) Rayner, C.
M. Org. Process Res. Dev. 2007, 11, 121; (b) Oakes, R. S.; Clifford, A. A.; Rayner, C.
M. J. Chem. Soc., Perkin Trans. 1 2001, 9, 917; (c) Habermann, J.; Ponzi, S.; Ley, S.
V. Mini-Rev. Org. Chem. 2005, 2, 125; (d) Sheldon, R. Chem. Commun. 2001,
2399.
We are grateful for the financial support from the National Nat-
ural Science Foundation of China (20902083) and the Natural Sci-
ence Foundation of Zhejiang Province, China (Y4090082).
20. Typical experimental procedure for the domino reaction of 1,3-dicarbonyl
compounds with
(0.2 mmol, 1 equiv),
a
-bromonitroalkenes 2. Method A: 4-hydroxylcoumarin 1a
-bromonitroalkene 2a (0.30 mmol, 1.5 equiv), NaOAc
a
(20 mg, 0.24 mmol) and TBAB (12 mg, 0.024 mol) were stirred at room
temperature in H2O (2 mL) for 72 h, then extracted with ethyl acetate and
dried with Na2SO4, the solvent was removed and flash chromatography on
silica gel (10% ethyl acetate/petroleum ether) or recrystallized from ethanol
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tetlet.2011.02.093.
gave 3aa as
a white solid. Method B: 4-hydroxylcoumarin 1a (0.2 mmol,

2382
1 equiv),
J.-W. Xie et al. / Tetrahedron Letters 52 (2011) 2379–2382
a
-bromonitroalkene 2a (0.30 mmol, 1.5 equiv), NaOAc (20 mg,
[Compound 4ca 6.17 (d, J = 1.8 Hz, 1H), 4.86 (d, J = 1.2 Hz, 1H); (J. Org. Chem.
2010, 75, 8716]. Diastereoselectivity (3ca) was also determined by HPLC
analysis on chiral Chiralpak columns and the HPLC data was identical to that
reported in the literature (4ca, J. Org. Chem. 2010, 75, 8716).
0.24 mmol) and TBAB (12 mg, 0.024 mol) were stirred at 70 °C in H2O (2 mL)
for 3 h, then extracted with ethyl acetate and dried with Na2SO4, the solvent
was removed and flash chromatography on silica gel (10% ethyl acetate/
petroleum ether) gave 3aa as a white solid. 1H NMR (400 MHz, CDCl3) d (ppm)
7.88–7.86 (d, J = 7.79 Hz, 1H), 7.70 (m, 1H), 7.47–7.43 (dd, J = 10.72, 8.49 Hz,
2H), 7.20–7.18 (d, J = 8.60 Hz, 2H), 6.92–6.90 (d, J = 8.68 Hz, 2H), 6.21 (d,
J = 2.16 Hz, 1H), 4.90 (d, J = 1.77 Hz, 1H), 3.79 (s, 3H), 2.48 (s, 3H); 13C NMR
(100 MHz, CDCl3) d (ppm) 165.4, 160.5, 157.9, 155.5, 133.8, 128.3, 128.3, 127.5,
124.8, 123.1, 117.3, 114.9, 114.9, 111.6, 111.2, 105.1, 55.4, 53.1. IR (KBr) cmÀ1
3075, 2998, 2892, 1753, 1446, 688; ESI-HRMS: calcd for C18H13NO6 + Na
362.06382, found 362.06375.
22. Crystal data for 3fa C5H15NO5 (289.28), Monoclinic, space group C2/c,
a = 22.0833(10), b = 7.0950(3), c = 20.9180(10) Å, U = 2856.5(2) Å3, Z = 8,
specimen 0.653 Â 0.263 Â 0.248 mm3, T = 296(2) K, SIEMENS P4 diffractometer,
absorption coefficient 0.102 mmÀ1, reflections collected 21781, independent
reflections 3315 [R(int) = 0.0258], refinement by Full-matrix least-squares on F2,
data/restraints/parameters 3315/0/190, goodness-of-fit on F2 = 1.039, final R
indices [I >2r(I)] R1 = 0.0431, wR2 = 0.1166, R indices (all data) R1 = 0.0561,
wR2 = 0.1283, largest diff. peak and hole 0.219 and À0.249 e ÅÀ3
.
21. For example, compound 3ca [6.16 (d, J = 1.82 Hz, 1H), 4.85 (d, J = 1.22 Hz, 1H)]
exhibited coupling constants (J) data identical to that reported in the literature