One-pot synthesis of substituted Δ1-pyrrolines through the Michael addition of nitroalkanes to chalcones and subsequent reductive cyclization in aqueous media

Article abstract of DOI:10.1055/s-2006-950227

A facile and efficient one-pot synthesis of substituted Δ¹-pyrrolines in aqueous media has been developed. Upon treatment with aqueous sodium hydroxide in N,N-dimethylformamide, a range of chalcones underwent room temperature Michael addition r

Full text of DOI:10.1055/s-2006-950227

SPECIAL TOPIC
3301
One-Pot Synthesis of Substituted D1-Pyrrolines through the Michael Addition
of Nitroalkanes to Chalcones and Subsequent Reductive Cyclization in
Aqueous Media
O
ne-Pot Synthesisoof Substitute 1
n
d
D
-Pyrroli
g
nes in
A
que
o
j
us
M
e
i
Department of Chemistry, Northeast Normal University, Changchun 130024, P. R. of China
Fax +86(431)5098635; E-mail: dongdw663@nenu.edu.cn
Received 22 July 2006
obtained by catalytic hydrogenation with Pd/C is ob-
Abstract: A facile and efficient one-pot synthesis of substituted D1-
pyrrolines in aqueous media has been developed. Upon treatment
with aqueous sodium hydroxide in N,N-dimethylformamide, a
range of chalcones underwent room temperature Michael addition
served.16 It is assumed that, in the course of the reduction,
the nitro group in the adduct may first be transformed by
a Nef conversion into a carbonyl group, and the nitrogen
reactions with nitroalkanes. The resulting adducts were directly re- present in the final product could be provided by ammo-
duced in situ with Zn/HCl (aq) and subsequently underwent an in-
nium acetate.
tramolecular cyclization, affording the corresponding substituted
It should be mentioned that the above transformations
were carried out by a sequence of separate reaction steps,
each of which required its own conditions, reagents, sol-
vent, and catalyst. After each reaction was complete, the
solvent and the waste were removed and discarded, and
the intermediate product was separated and purified.
However, increasing environmental and economic pres-
sures are forcing the chemical community to search for
more efficient synthetic methods that use small, simple
components and environmentally benign solvents to gen-
erate complex structures in one pot, much the same as na-
ture does.17 These considerations, together with our
continuing interest in the synthetic utility of nitroal-
kanes,18 drove us to develop new methodologies for the
synthesis of important targets. We wish to report here the
one-pot synthesis of substituted D1-pyrrolines in aqueous
media.
D1-pyrrolines in high yields.
Key words: chalcones, cyclizations, Michael additions, hydroge-
nations, pyrrolines
Over the past few decades, the use of nitroalkanes as key
building blocks in organic synthesis has been steadily
growing. They are easily available, versatile, and stabi-
lized carbon nucleophiles that can react with common
electrophiles such as haloalkanes, aldehydes, and Michael
acceptors, leading to carbon–carbon bond formation.1,2
With regard to the Michael addition reactions of nitroal-
kanes, the adducts obtained still retain the nitro function
and, therefore, are capable of undergoing subsequent
transformation of the nitro group after the main addition
process. The nitro group can be removed from the mole-
cule by two distinct strategies: 1) replacement of the nitro
group with hydrogen through a nucleophilic addition-den-
itration process3–5 and 2) conversion of the nitro group
into a carbonyl group by the Nef reaction.6–8 Alternative-
ly, reduction of the nitro group to a primary amine can be
easily realized, thus modifying of the oxidation state of
the nitrogen atom.9–11 This latter process is often accom-
panied by a subsequent nucleophilic ring closure, when a
carbonyl or an ester function is present in the structure, to
directly afford pyrrolidines or pyrrolidinones.12–14 Most of
these reductions involve the use of catalytic hydrogena-
tion in the presence of Raney nickel or Pd/C, while in
some cases, complex hydrides and metals such as zinc or
iron are used. It has been demonstrated that the reducing
system employed plays an important role in the transfor-
mations. The reductive cyclization of g-nitroketones with
Zn/HCO2H–EtOH has been reported to consistently pro-
duce a mixture of pyrroline N-oxides and pyrrolines.15
When g-nitro diketone is treated with complex hydrides in
methanol, a different diastereomeric composition to that
The Michael addition reactions of nitroalkanes to elec-
tron-deficient alkenes have been extensively report-
ed.1a,b,19 It has been revealed that highly polar solvents
such as dimethyl sulfoxide, methanol, and water are able
to facilitate the addition of nitroalkanes even to less reac-
tive alkenes such as methylvinyl ketone under neutral
conditions.20 Of these solvents, water minimizes the for-
mation of undesired multiple adducts.
NO2
O
O
DMF–H2O
base, r.t.
MeNO2
+
1a
2a
3a
Scheme 1 Michael addition of nitromethane 2a to chalcone 1a.
In the present work, the reaction of chalcone 1a and ni-
tromethane 2a was investigated in the presence of various
bases, such as 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU), K2CO3, Et3N and NaOH in the aqueous medium.
Much to our delight, all the reactions proceeded smoothly
in a mixture of N,N-dimethylformamide (DMF) and water
at room temperature, affording the Michael adduct 4-ni-
SYNTHESIS 2006, No. 19, pp 3301–3304
x
x.
x
x
.
2
0
0
6
Advanced online publication: 04.09.2006
DOI: 10.1055/s-2006-950227; Art ID: C04406SS
© Georg Thieme Verlag Stuttgart · New York

3302
Y. Liang et al.
SPECIAL TOPIC
tro-1,3-diphenylbutan-1-one (3a), in good to high yields ly, the reduction of the nitro group in adduct 3a was
(Scheme 1). When the reaction was performed in the pres- followed by an intramolecular cyclization, generating the
ence of aqueous NaOH in DMF at room temperature, for substituted D1-pyrroline 4a in high yield, without isomer-
example, TLC indicated that the substrates were convert- ization to the D2-pyrroline22 or further hydrogenation to
ed into one main product within ten minutes. After work- the corresponding pyrrolidine.23 It is worth noting that,
up and purification by column chromatography of the unlike other reported reducing conditions,15,24 the pyrro-
resulting reaction mixture, the sole product 3a was ob- line N-oxide could not be detected in the present reaction
tained in 92% yield. However, it was observed that the system. The results indicate that the reaction media great-
same reaction proceeded sluggishly in ethanol–water and ly effects the reductive cyclization of the Michael adducts
no reaction occurred in tetrahydrofuran–water mixtures of nitroalkanes.
under the same conditions. A combination of DMF and
The success of the Michael addition reaction and the re-
aqueous NaOH proved to be the most suitable and effec-
ductive cyclization, promoted us to explore a possible
tive solvent/base pair among those examined, giving 3a in
one-pot transformation of nitroalkanes directly into sub-
good yield within a short reaction time. It is worth men-
tioning that similar reactions reported recently took sever-
stituted D1-pyrrolines in aqueous media. Thus, the reac-
tion of 1a with 2a was performed in DMF/NaOH at room
al hours for complete conversion at room temperature or
temperature and, after stirring for about ten minutes, the
mixture was then subjected to the above reductive cycliza-
under reflux conditions.21
tion conditions directly with Zn/HCl. The mixture was
NO2
O
kept at 80 °C under the reducing conditions for about 90
minutes, during which TLC monitoring indicated that 3a
had been completely consumed. Workup and column
chromatography of the resulting reaction mixture fur-
nished a white product characterized as 4a in 82% yield
(Table 1, entry 1).
N
Zn/HCl (aq)
DMF–H2O
4a
3a
Scheme 2 The reduction of the Michael adduct 3a.
To test the scope of the protocol, a series of chalcones 1b–
f and nitroalkanes 2a and 2b were also subjected to the
conditions described above. The reactions of 1b–f with 2a
proceeded smoothly, affording the corresponding substi-
tuted D1-pyrroline 4b–f in high yields (Table 1, entries 2–
8). In the same fashion, the reaction of chalcone 1a with
nitroethane 2b led to the corresponding substituted D1-
pyrroline 4g under the mild conditions, within 150 min-
utes, in good yield (Table 1, entry 7). It should be men-
tioned that the diastereomers of 4g were successfully
separated by column chromatography on silica gel (elu-
We then turned our attention to the reduction of the
Michael adduct. Thus, when 3a was reduced with Zn/HCl
(aq.) in DMF–H2O (1:1 by v/v) at 80 °C for about 90 min-
utes, workup and column chromatography of the resulting
reaction mixture gave only a single product in 85% yield.
Spectral and analytical data characterized this compound
as a mixture of racemic enantiomers of the D1-pyrroline
3,5-diphenyl-3,4-dihydro-2H-pyrrole (4a) (Scheme 2).
Unfortunately, these enantiomers could not separated us-
ing conventional chromatographic techniques. Apparent-
Table 1 One-Pot Synthesis of Substituted D1-Pyrrolines 4 in Aqueous Media from Nitroalkanes 1
O
N
R2
R3
R1
i) NaOH (aq), r.t.
R1
R2
+
R3CH2NO2
ii) Zn/HCl (aq), 80 °C
1
2
4
Entry
Substrates
Reaction Time (min)
Product
Yield (%)a
1
R1
Ph
Ph
R2
2
R3
H
i
ii
90
1
2
3
4
5
6
7b
1a
1b
1c
1d
1e
1f
Ph
2a
2a
2a
2a
2a
2a
2b
10
10
10
10
10
10
15
4a
4b
4c
4d
4e
4f
82
79
78
80
77
76
4-ClPh
H
90
90
4-ClPh
4-MePh
4-MeOPh
4-MeOPh
Ph
Ph
H
4-ClPh
Ph
H
90
H
90
4-ClPh
Ph
H
90
1a
CH3
150
4g-1
4g-2
38
35
a Isolated yields after silica gel chromatography of racemic enantiomers for 4a–g.
b 4g-1 and 4g-2 are diastereomers.
Synthesis 2006, No. 19, 3301–3304 © Thieme Stuttgart · New York

SPECIAL TOPIC
One-Pot Synthesis of Substituted D1-Pyrrolines in Aqueous Media
3303
1H NMR (CDCl3, 500 MHz): d = 3.06 (m, 1 H), 3.45 (m, 1 H), 3.68
(m, 1 H), 4.11 (m, 1 H), 4.52 (m, 1 H), 7.22 (m, 3 H), 7.31 (m, 2 H),
7.40 (d, J = 7.0 Hz, 2 H), 7.80 (d, J = 7.0 Hz, 2 H).
13C NMR (CDCl3, 125 MHz): d = 43.2, 44.2, 69.9, 126.8, 127.0,
129.02, 129.03, 129.2, 133.0, 136.9, 145.0, 171.6.
ent: petroleum ether–ethyl acetate, 50:1). The present pro-
tocol thus provides a facile and convenient route to five-
membered aza-heterocycles, D1-pyrrolines 4, which are
found in numerous natural products that possess impor-
tant bio- and pharmacological activities such as phero-
mones, alkaloids, steroids, hemes, and chlorophylls.25
This D1-pyrroline unit is also an important synthetic build-
ing block for a large variety of functionalized aza-hetero-
cycles, especially as the pro-chiral center, as part of a
cyclic imine, is amendable to further transformations.26
Anal. Calcd for C16H14ClN: C, 75.14; H, 5.52; N, 5.48. Found: C,
75.41; H, 5.40; N, 5.27.
3-(4-Chlorophenyl)-5-phenyl-3,4-dihydro-2H-pyrrole (4c)
White solid; mp 68–69 °C.
IR (KBr): 690, 820, 1462, 1498, 1548, 1647, 1694, 2926 cm–1.
In summary, a facile and efficient one-pot synthesis of
substituted D1-pyrrolines has been developed. The strate-
gy centers around Michael addition of nitroalkanes to
chalcones with subsequent reductive cyclization in aque-
ous media. The simplicity of execution, the mild condi-
tions, good yields, ready availability of substrates and a
broad range of synthetic utility of the products, especially
in relation to recent environmental concerns, makes the
protocol very attractive for academic research and practi-
cal applications. The scope and an asymmetric version of
the protocol are under investigation in our laboratory.
1H NMR (CDCl3, 500 MHz): d = 3.05 (m, 1 H), 3.48 (m, 1 H), 3.64
(m, 1 H), 4.07 (m, 1 H), 4.52 (m, 1 H), 7.14 (d, J = 8.5 Hz, 2 H),
7.27 (d, J = 8.5 Hz, 2 H), 7.44 (m, 3 H), 7.86 (d, J = 7.5 Hz, 2 H).
13C NMR (CDCl3, 125 MHz): d = 42.5, 44.3, 69.8, 127.9, 128.4,
128.8, 129.1, 130.9, 132.4, 134.3, 143.8, 172.5.
Anal. Calcd for C16H14ClN: C, 75.14; H, 5.52; N, 5.48. Found: C,
75.52; H, 5.38; N, 5.30.
5-(4-Chlorophenyl)-3-p-tolyl-3,4-dihydro-2H-pyrrole (4d)
White solid; mp 66–67 °C.
IR (KBr): 819, 1392, 1457, 1483, 1551, 1600, 1646, 2922 cm–1.
1H NMR (CDCl3, 500 MHz): d = 2.33 (s, 3 H), 3.03 (m, 1 H), 3.43
(m, 1 H), 3.64 (m, 1 H), 4.08 (m, 1 H), 4.50 (m, 1 H), 7.11 (m, 4 H),
7.40 (d, J = 8.5 Hz, 2 H), 7.80 (d, J = 8.5 Hz, 2 H).
13C NMR (CDCl3, 125 MHz): d = 21.2, 42.9, 44.2, 69.9, 126.9,
129.0, 129.2, 129.7, 133.1, 136.3, 136.8, 142.0, 171.6.
All reagents were purchased from commercial sources and used
without treatment, unless otherwise indicated. The products were
1
purified by column chromatography over silica gel. H NMR and
13C NMR spectra were recorded at 500 MHz and 125 MHz, respec-
tively, with TMS as internal standard at 25 °C on a Varian Inova-
500 spectrometer. IR spectra (KBr) were recorded on a Magna-560
FTIR spectrophotometer in the range of 400–4000 cm–1. Petroleum
ether (PE) used was the fraction boiling in the range 30–60 °C.
Anal. Calcd for C17H16ClN: C, 75.69; H, 5.98; N, 5.19. Found: C,
75.38; H, 6.10; N, 5.26. MS: m/z = 252.1 [M + H]+.
3-(4-Methoxyphenyl)-5-phenyl-3,4-dihydro-2H-pyrrole (4e)
Synthesis of Substituted D1-Pyrrolines 4; Typical Procedure
NaOH (1.0 M, 10 mL) was added to a stirred solution of 1a (2.08 g,
10 mmol) and 2a (0.61 g, 10 mmol) at r.t. in DMF (10 mL) and the
resulting mixture was stirred until the reaction was complete (~10
min as indicated by TLC) then granular Zn (3.27 g, 50 mmol) was
added. The mixture was stirred at 80 °C and conc HCl (20 mL) was
added very slowly. The mixture was stirred at 80 °C under the re-
ducing conditions for about 90 min, then allowed to come to r.t.,
neutralized with sat. aq NaHCO3 (30 mL) and extracted with
CH2Cl2 (3 × 20 mL). The combined organic layers were washed
with H2O (3 × 20 mL), dried over MgSO4, filtered and concentrated
in vacuo. The crude product was purified by silica gel chromatogra-
phy (PE–EtOAc, 50:1) to give the substituted D1-pyrroline 4a.
White solid; mp 55–56 °C.
IR (KBr): 762, 827, 1452, 1513, 1614, 1646, 2928 cm–1.
1H NMR (CDCl3, 500 MHz): d = 3.04 (m, 1 H), 3.45 (m, 1 H), 3.62
(m, 1 H), 3.78 (s, 3 H), 4.10 (m, 1 H), 4.51 (m, 1 H) 6.86 (d, J = 7.0
Hz, 2 H), 7.15 (d, J = 7.0 Hz, 2 H), 7.44 (d, J = 7.0 Hz, 3 H), 7.89
(d, J = 7.0 Hz, 2 H).
13C NMR (CDCl3, 125 MHz): d = 42.4, 44.3, 55.5, 70.0, 114.3,
127.9, 128.1, 128.4, 128.8, 128.9, 130.8, 134.6, 137.3, 158.4, 172.7.
Anal. Calcd for C17H17NO: C, 81.24; H, 6.82; N, 5.57. Found: C,
81.02; H, 6.70; N, 5.80.
5-(4-Chlorophenyl)-3-(4-methoxyphenyl)-3,4-dihydro-2H-
pyrrole (4f)
White solid; mp 65–67 °C.
IR (KBr): 676, 821, 1448, 1483, 1545, 1652, 1690 cm–1.
1H NMR (CDCl3, 500 MHz): d = 3.01 (m, 1 H), 3.42 (m, 1 H), 3.63
(m, 1 H), 3.78 (s, 3 H), 4.06 (m, 1 H), 4.49 (m, 1 H), 6.85 (d, J = 8.5
Hz, 2 H), 7.13 (d, J = 8.5 Hz, 2 H), 7.39 (d, J = 8.5 Hz, 2 H), 7.79
(d, J = 8.5 Hz, 2 H).
13C NMR (CDCl3, 125 MHz): d = 42.5, 44.3, 55.5, 69.9, 114.4,
129.0, 129.2, 129.4, 133.1, 136.8, 137.0, 158.4, 171.7.
3,5-Diphenyl-3,4-dihydro-2H-pyrrole (4a)
White solid; mp 56–57 °C.
IR (KBr): 696, 760, 1449, 1495, 1548, 1615, 1689, 2931 cm–1.
1H NMR (CDCl3, 500 MHz): d = 3.12 (m, 1 H), 3.48 (m, 1 H), 3.66
(m, 1 H), 4.13 (m, 1 H), 4.54 (m, 1 H), 7.24 (m, 3 H), 7.32 (m, 2 H),
7.45 (m, 3 H), 7.89 (d, J = 8.0 Hz, 2 H).
13C NMR (CDCl3, 125 MHz): d = 43.2, 44.3, 69.9, 126.7, 127.1,
127.9, 128.8, 129.0, 130.8, 134.5, 145.3, 172.7.
Anal. Calcd for C16H15N: C, 86.84; H, 6.83; N, 6.33. Found: C,
86.70; H, 6.90; N, 6.40.
Anal. Calcd for C17H16ClNO: C, 71.45; H, 5.64; N, 4.90. Found: C,
71.27; H, 5.45; N, 4.71.
5-(4-Chlorophenyl)-3-phenyl-3,4-dihydro-2H-pyrrole (4b)
White solid; mp 65.5–67.5 °C.
IR (KBr): 761, 828, 1400, 1456, 1558, 1593, 1620, 2923 cm–1.
2-Methyl-3,5-diphenyl-3,4-dihydro-2H-pyrrole (4g-1)
White solid; mp 79–80 °C.
IR (KBr): 698, 768, 1449, 1496, 1550, 1603, 1694, 2910 cm–1.
Synthesis 2006, No. 19, 3301–3304 © Thieme Stuttgart · New York

3304
Y. Liang et al.
SPECIAL TOPIC
(12) Ishibashi, H.; Okano, M.; Tamaki, H.; Maruyama, K.;
1H NMR (CDCl3, 500 MHz): d = 1.44 (d, J = 6.5 Hz, 3 H), 3.12 (m,
2 H), 3.56 (m, 1 H), 4.27 (m, 1 H), 7.23 (m, 3 H), 7.32 (m, 2 H),
7.42 (m, 3 H), 7.87 (m, 2 H).
Yakura, T.; Ikeda, M. J. Chem. Soc., Chem. Commun. 1990,
1436.
(13) (a) Nyerges, M.; Bitter, I.; Kádas, I.; Tóth, G.; Tőke, L.
Tetrahedron Lett. 1994, 35, 4413. (b) Nyerges, M.; Bitter,
I.; Kádas, I.; Tóth, G.; Tőke, L. Tetrahedron 1995, 51,
11489.
(14) (a) Mironiuk-Puchalska, E.; Kołaczkowska, E.; Sas, W.
Tetrahedron Lett. 2002, 43, 8351. (b) Domingos, J. L. O.;
Lima, E. C.; Dias, A. G.; Costa, P. R. R. Tetrahedron:
Asymmetry 2004, 15, 2313. (c) Felluga, F.; Gombac, V.;
Pitacco, G.; Valentin, E. Tetrahedron: Asymmetry 2004, 15;
3323.
13C NMR (CDCl3, 125 MHz): d = 21.5, 44.8, 52.1, 76.9, 126.8,
127.5, 127.9, 128.7, 129.0, 130.8, 134.6, 144.1, 170.8.
Anal. Calcd for C17H17N: C, 86.77; H, 7.28; N, 5.95. Found: C,
86.45; H, 7.18; N, 5.84.
2-Methyl-3,5-diphenyl-3,4-dihydro-2H-pyrrole (4g-2)
White solid; mp 81–82 °C.
IR (KBr): 695, 761, 1216, 1451, 1548, 1647, 1694 cm–1.
1H NMR (CDCl3, 500 MHz): d = 0.96 (d, J = 7.0 Hz, 3 H), 3.34 (m,
2 H), 3.74 (m, 1 H), 4.58 (m, 1 H), 7.15 (m, 2 H), 7.23 (m, 1 H),
7.29 (m, 2 H), 7.45 (m, 3 H), 7.91 (m, 2 H).
13C NMR (CDCl3, 125 MHz): d = 17.4, 41.3, 47.3, 71.4, 126.7,
127.9, 128.3, 128.5, 128.8, 130.8, 134.7, 141.5, 172.2.
(15) Cheruku, S. R.; Padmanilayam, M. P.; Vennerstrom, J. L.
Tetrahedron Lett. 2003, 44, 3701.
(16) Vavreka, M.; Janowitz, A.; Hesse, M. Tetrahedron Lett.
1991, 32, 5543.
(17) (a) Hall, N. Science 1994, 266, 32. (b) Tretze, L. F. Chem.
Rev. 1996, 96, 115. (c) Ballini, R.; Fiorini, D.; Gil, M. V.;
Palmieri, A.; Román, E.; Serrano, J. A. Tetrahedron Lett.
2003, 44, 2795.
Anal. Calcd for C17H17N: C, 86.77; H, 7.28; N, 5.95. Found: C,
86.46; H, 7.34; N, 5.80.
(18) Bi, X.; Dong, D.; Liu, Q.; Pan, W.; Zhao, L.; Li, B. J. Am.
Chem. Soc. 2005, 127, 4578.
Acknowledgment
(19) (a) Ballini, R.; Bosica, G. Tetrahedron Lett. 1996, 44, 8027.
(b) Kim, D. Y.; Huh, S. C. Tetrahedron 2001, 57, 8933.
(c) Zia-Ebrahimi, M.; Huffman, G. W. Synthesis 1996, 215.
(d) Kisanga, P. B.; Ilankumaran, P.; Fetterly, B. M.;
Verkade, J. G. J. Org. Chem. 2002, 67, 3555. (e) Mudaliar,
C. D.; Nivalkar, K. R.; Mashraqui, S. H. Org. Prep. Proced.
Int. 1997, 29, 584.
(20) (a) Lubineau, A.; Augé, J. Tetrahedron Lett. 1992, 33, 8073.
(b) Picquet, M.; Bruneau, C.; Dixneuf, P. H. Tetrahedron
1999, 55, 3937.
(21) (a) Ballini, R.; Marziali, P.; Mozzicafreddo, A. J. Org.
Chem. 1996, 61, 3209. (b) Mdoe, J. E. G.; Clark, J. H.;
Macquarrie, D. J. Synlett 1998, 625. (c) Ballini, R.; Fiorini,
D.; Gil, M. V.; Palmieri, A. Green Chem. 2003, 5, 475.
(d) Chetia, A.; Saikia, C. J.; Lekhok, K. C.; Boruah, R. C.
Tetrahedron Lett. 2004, 45, 2649.
(22) (a) Huisgen, R.; Gotthardt, H.; Bayer, H. O. Chem. Ber.
1970, 103, 2368. (b) Maryanoff, C. A.; Karash, C. B.;
Turchi, I. J. J. Org. Chem. 1989, 54, 3790. (c) Grigg, R.;
Lansdell, M. I.; Thornton-Pett, M. Tetrahedron 1999, 55,
2025. (d) Peddibhotla, S.; Tepe, J. J. J. Am. Chem. Soc.
2004, 126, 12776.
Financial support for this research by the NNSFC (20572013), the
Key Project of the Ministry of Education of China (105061) and the
Key Grant Project of the Ministry of Education of China (10412) is
greatly acknowledged.
References
(1) (a) Perlmutter, P. Conjugate Addition Reactions in Organic
Synthesis; Pergamon: Oxford, 1992. (b) Ballini, R.; Bosica,
G.; Fiorini, D.; Palmieri, A.; Petrini, M. Chem. Rev. 2005,
105, 933. (c) Galli, C.; Marotta, E.; Righi, P.; Rosini, G. J.
Org. Chem. 1995, 60, 6624. (d) Hanessian, S.; Pham, V.
Org. Lett. 2000, 2, 2975. (e) Ballini, R.; Bosica, G.; Fiorini,
D.; Gil, M. V.; Palmieri, A. Synthesis 2004, 605.
(2) (a) The Chemistry of Amino, Nitroso, Nitro and Related
Groups; Patai, S., Ed.; Wiley: Chichester, 1996. (b)Ono,N.
The Nitro Group in Organic Synthesis; Wiley-VCH: New
York, 2001. (c) Rosini, G.; Ballini, R. Synthesis 1988, 833.
(d) Adams, J. P. J. Chem. Soc., Perkin Trans. 1 2002, 2586.
(3) Nitro Compounds: Recent Advances in Synthesis and
Chemistry; Feuer, H.; Nielsen, A. T., Eds.; VCH: Weinheim,
1990.
(4) Rosini, G.; Ballini, R.; Zanotti, V. Synthesis 1983, 137.
(5) Gorman, A.; Killoran, J.; O’Shea, C.; Kenna, T.; Gallagher,
W. M.; O’Shea, D. F. J. Am. Chem. Soc. 2004, 126, 10619.
(6) Ballini, R.; Petrini, M. Tetrahedron 2004, 60, 1017.
(7) Taylor, E. C.; Liu, B. J. Org. Chem. 2003, 68, 9938.
(8) Pinnick, H. W. Org. React. 1990, 38, 655.
(23) Desai, M. C.; Lefkowitz, S. L. Bioorg. Med. Chem. Lett.
1993, 3, 2083.
(24) (a) Bapat, J. B.; Black, D. St.C.; Newland, G. Aust. J. Chem.
1974, 27, 1591. (b) Pfoertner, K. H.; Foricher, J. Helv.
Chim. Acta. 1980, 63, 658. (c) Aeppli, L.; Bernauer, K.;
Schneider, F.; Strub, K.; Oberhansli, W. E.; Pfoertner, K. H.
Helv. Chim. Acta. 1980, 63, 630. (d) Turner, M. J.;
Luckenbach, L. A.; Turner, E. L. Synth. Commun. 1986, 16,
1377.
(25) (a) Miltyk, W.; Palka, J. A. Comp. Biochem. Physiol. A
2000, 125, 265. (b) Stapon, A.; Li, R.; Townsend, C. A. J.
Am. Chem. Soc. 2003, 125, 8486.
(26) (a) Lombardo, M.; Fabbroni, S.; Trombini, C. J. Org. Chem.
2001, 66, 1264. (b) Shvekhgeimer, M.-G. A. Chem.
Heterocycl. Compd. 2003, 39, 405. (c) Goti, A.; Cicchi, S.;
Mannucci, V.; Cardona, F.; Guarna, F.; Merino, P.; Tejero,
T. Org. Lett. 2003, 5, 4235.
(9) Kan, T.; Fujimoto, T.; Ieda, S.; Asoh, Y.; Kitaoka, H.;
Fukuyama, T. Org. Lett. 2004, 6, 2729.
(10) Basavaiah, D.; Rao, J. S. Tetrahedron Lett. 2004, 45, 1621.
(11) Hagen, T. J.; Bergmanis, A. A.; Kramer, S. W.; Fok, K. F.;
Schmelzer, A. E.; Pitzele, B. S.; Swenton, L.; Jerome, G. M.;
Kornmeier, C. M.; Moore, W. M.; Branson, L. F.; Connor, J.
R.; Manning, P. T.; Currie, M. G.; Hallinan, E. A. J. Med.
Chem. 1998, 41, 3675.
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