Synthesis of hydrazinoheterocycles from Morita-Baylis-Hillman adducts of nitroalkenes with azodicarboxylates

Article abstract of DOI:10.1039/c5ob02656c

Conjugated nitroalkenes and nitrodienes undergo smooth α-hydrazination with azodicarboxylates through an imidazole catalyzed carbon-heteroatom bond formation under Morita-Baylis-Hillman conditions. The resulting hydrazinonitroalkenes take part in 1,3-dipo

Full text of DOI:10.1039/c5ob02656c

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Pandey, N. Ayyagari, C. Dey, R. Kale and I. N. Namboothiri, Org. Biomol. Chem., 2016, DOI:
10.1039/C5OB02656C.
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DOI: 10.1039/C5OB02656C
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ARTICLE
Synthesis of hydrazinoheterocycles from Morita-Baylis-Hillman
adducts of nitroalkenes with azodicarboxylates
Received 00th January 20xx,
Accepted 00th January 20xx
Vaijinath Mane, Jyoti Pandey, Narasihmam Ayyagari, Chandan Dey, Raju Kale and Irishi N. N.
Namboothiri*
DOI: 10.1039/x0xx00000x
Conjugated nitroalkenes and nitrodienes undergo smooth α-hydrazination with azodicarboxylates through an imidazole
catalyzed carbon-heteroatom bond formation under Morita-Baylis-Hillman conditions. The resulting hydrazinonitroalkenes
take part in 1,3-dipolar cycloaddition with azide under mild conditions to give hydrazinotriazoles. A [3+2] annulation with
phenols and naphthols involving Michael addition and cyclization as the key steps lead to arenodihydrofurans bearing a
key hydrazinodicarboxylate moiety. Both regioisomers of naphthodihydrofurans could be synthesized by our methodology
by employing the appropriate naphthol.
www.rsc.org/
biological18 perspective. Natural products Bicunningines,19
Conocarpan20 and Megapodiol21 as well as synthetic compounds
possessing an arenodihydrofuran skeleton exhibit potent biological
properties (Figure 1).22 In spite of the above, there is no general and
convenient approach for the synthesis of arenodihydrofurans and,
Introduction
Functionalization of electron deficient alkenes at the α-position,
normally under amine or phosphine catalysed conditions, popularly
known as the Morita-Baylis-Hillman (MBH) reaction, is an efficient
methodology for the synthesis of multi-functional molecules.1
Although various electron deficient alkenes such as α,β-unsaturated
carbonyl compounds, nitriles, sulfones and phosphonates have
been employed as substrates in the MBH reaction1 and its
vinylogous version, the Rauhut-Currier (RC) reaction,2 for over four
decades, α,β-unsaturated nitro compounds emerged as potential
substrates only in the last decade.3-5 In recent years, the
applications of MBH and RC adducts of nitroalkenes have been
extensively investigated in the synthesis of complex molecules,6-9
including several carbocycles7 and heterocycles.8-9 However, there
are only handful of examples for the synthesis of MBH adducts via
carbon-heteroatom bond formation.4-5,10 To our knowledge, such
MBH adducts have not been exploited for the synthesis of complex
molecules, especially heterocycles.
to our knowledge, such skeletons bearing
a
key
hydrazinodicarboxylate moiety remains unreported hitherto.
From another perspective, 1,2,3-triazoles are versatile
heterocycles, easily synthesized by azide-alkyne cycloaddition
(Huisgen 1,3-dipolar cycloaddition/click reaction)11 or via other
miscellaneous methods including condensation of azide with an
active methylene compound (Dimroth triazole synthesis).12 1,2,3-
Triazoles are extensively employed as biological agents13 and co-
ordinating ligands.14 However, synthesis of 1,2,3-triazoles bearing a
hydrazine moiety did not receive sufficient attention,15 and, to our
knowledge, 1,2,3-triazoles bearing a hydrazinodicarboxylate moiety
remains unreported in the literature.
Arenodihydrofurans belong to an important class of heterocycles
that has been extensively investigated from both synthetic16-17 and
Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076,
India
Electronic Supplementary Information (ESI) available: X-ray data tables and copies
of NMR spectra. CCDC reference numbers CCDC 1444163-1444164. For ESI and
Figure 1
crystallographic
data
in
CIF
or
other
electronic
format
See
DOI: 10.1039/x0xx00000x
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Earlier, we reported our preliminary results on the synthesis of α- Table 1 MBH reaction of nitroalkenes and nitrodienes 1 with
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DOI: 10.1039/C5OB02656C
hydrazinonitroalkenes via MBH reaction of nitroalkenes with various azodicarboxylates 2a
azodicarboxylates in the presence of stoichiometric amounts
imidazole or DMAP.4 Later on, this reaction has been carried out
under the co-catalytic influence of DMAP and a thiazolium derived
NHC.5 This is a full version of our preliminary communication which
describes not only further scope of the reaction but applications of
the hydrazinonitroalkenes in the synthesis of heterocycles such as
triazoles
and
arenodihydrofurans
bearing
a
key
hydrazinodicarboxylate moiety.
Results and discussion
For the first time, we reported the MBH reaction of nitroalkenes 1
with heteroatom centered electrophiles such as azodicarboxylates 2
which afforded α-hydrazinonitroalkenes 3 (Scheme 1).4 The reaction
was carried out under two different conditions, namely, in the
presence of imidazole in THF and DMAP in CH3CN at room
temperature under N2. The imidazole catalyzed reactions were
superior to the DMAP catalyzed reactions in terms of product yield
although the reaction times were comparable.
aYields after purification by silica gel column chromatography.
Scheme 1 Our previous report on the MBH reaction of nitroalkenes
1 with azodicarboxylates 24
1
Since the H NMR and, to some extent, the 13C NMR spectra of the
MBH adducts 3 recorded at room temperature consisted of broad
signals, we recorded the 1H NMR spectra of a selected compound at
different temperatures (233-328 K).4 This led to sharp multiple
signals at low temperatures and relatively sharp averaged signals at
high temperatures. This phenomenon was attributed to the
anisotropy of the carbonyl group which in turn was a result of the
restricted
rotation
about
the
C-N
bond
of
the
hydrazinodicarboxylate moiety due to its partial double bond
character. However, the spectral pattern was quite complex due to
the two isopropyl groups. Therefore, in order to further simplify the
observed spectral pattern, a selected MBH adduct 3a has been
prepared using dimethyl azodicarboxylate 2 (E = CO2Me) as the
electrophile under imidazole catalyzed conditions (Table 1).
The 1H NMR spectrum of 3a recorded at room temperature
showed single but broad signals for the olefinic proton and the
aromatic protons. However, two separate signals, one almost at the
base line, were observed for the methyl protons. Subsequently,
1
variable temperature H NMR spectra of 3a were recorded in the
range -50 to +50 oC (223-323 K) with a gap of 10 oC (Figure 2). As the
o
temperature was lowered (10 to -50 C), gradual broadening of the
signals followed by their multiplication was observed indicating
slower rotation about the C-N bond resulting in several rotamers.
On the other hand, upon increasing the temperature, relatively
sharp averaged signals were observed for all the protons due to
faster rotation about the C-N bond.
Figure 2 Variable temperature 1H NMR spectra of 3a recorded at
different temperatures in the range -50 to +50 oC (223-323 K)
The scope of nitroalkenes was successfully extended by
synthesizing diisopropyl hydrazinodicarboxylates of nitrodienes 3b-
2 | J. Name., 2012, 00, 1-3
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3d, aliphatic nitroalkenes 3e and those with other dialkyl The above optimized conditions were employed for the
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hydrazinodicarboxylates 3f in good to excellent yields (Table 1). For cycloaddition of other selected MBH adducts 3f and 3h-l with
DOI: 10.1039/C5OB02656C
instance, while a nitrodiene bearing an electron donating ortho- sodium azide (Table 3). It is discernible from Table 3 that there is no
substituted aryl group afforded the product 3c in excellent yield appreciable substituent effect in this reaction as substrates bearing
(92%), the yield was 75% with the phenyl derivative 3b and was both electron withdrawing and electron donating aryl groups afford
much lower (61%) with an electron withdrawing ortho-substituted the
aryl group 3d. The product 3e was isolated in high yield (81%) when
a representative β-alkyl nitroalkene 1e was subjected to α-
hydrazination. The structure, including double bond geometry of
3e, was unambiguously established by single crystal X-ray analysis.
Further, the reaction of 4-methoxynitrostyrene 1f with di-tert-butyl
azodicarboxylate 2 (E = CO2tBu) led to the product 3f in 65% yield,
much lower compared to the yields obtained with DIAD.4
Subsequently, we decided to investigate the possible applications
of hydrazinonitroalkenes 3 as potential substrates for the synthesis
of heterocycles possessing a key hydrazinodicarboxylate moiety.
This is based on the presumption that elimination of nitro group
would be more facile when compared to hydrazinodicarboxylate
moiety.
Table 3 Substrate scope for the synthesis of triazoles 4
Entry 3, Ar, R
4
Time (h) % Yield a
1
2
3
4
5
6
7
3g, 4-ClC6H4, iPr
3h, 4-FC6H4, iPr
3i, 2-NO2C6H4, iPr
3j, 4-OMeC6H4, iPr
3k, (3,4-OMe)2C6H3, iPr
3l, 2-Thienyl, iPr
4a
4b
4c
4d
4e
4f
3
72
68
64
65
62
60
70
At the outset, the MBH adduct 3g was selected as the model
substrate for the 1,3-dipolar cycloaddition with sodium azide for
the synthesis of hydrazinotriazoles (Table 2). When inorganic bases
such as K2CO3 and Cs2CO3 were employed for the reaction in DMF
at room temperature, the product 4a was isolated in 50% yield in 4-
5 h (entries 1-2). However, a mild amine base such as imidazole and
3.5
2.5
20
22
18
22
3f, 4-OMeC6H4, tBu
4g
a
quaternary ammonium salt such as tetrabutylammonium
aAfter purification by silica gel column chromatography
hydrogen sulfate (TBAHS) turned out to be better mediators for this
reaction. While the product 4a was isolated in 60% yield in the
presence of imidazole (entry 3), the yield was much higher (72%) in
the presence of TBAHS (entry 4). However, the TBAHS mediated
reaction in other solvents such as THF and dioxane gave only
complex mixtures (entries 5-6). Other quaternary ammonium salts
products in 60-72% yield (entries 1-7). While increase in
deactivation of the aryl group from Cl (3g) to F (3h) to NO2 (3i)
appears to lower the yield marginally (72%, 68% and 64%,
respectively, for 4a, 4b and 4c, entries 1-3), no such trend is
observed in the case of substrates bearing electron rich aryl groups
(entries 4-7). Thus the MBH adducts bearing aryl groups with single
and multiple electron donating substituents 3j and 3k and the one
bearing a heteroaryl group 3l furnish the corresponding products
4d, 4e and 4f, respectively, in comparable yields (60-65%, entries 4-
6). Finally, the effect of R group in the hydrazinodicarboxylate
moiety was investigated by replacing iso-propyl with tert-butyl (3f)
which led to the formation of product 4g in 70% yield (entry 7).
such
as
tetrabutylammonium
bromide
(TBAB)
and
tetrabutylammonium iodide (TBAI) were unsuitable for our reaction
(entries 7-8).
Table 2 Optimization of the reaction conditions for the 1,3-dipolar
cycloaddition of sodium azide with MBH adducts 3
Having demonstrated the application of MBH adducts 3 in the
synthesis of hydrazinotriazoles 4, we pursued other targets, namely,
hydrazinodihydrofurans 6, 8 and 10 which appeared accessible from
MBH adducts 3 and various arenols 5, 7 and 9 via a cascade
intermolecular Friedel-Crafts reaction-intramolecular cyclization. At
the outset, β-naphthol 5 and MBH adduct 3m were chosen as
model substrates for the synthesis of hydrazinonaphthofuran 6a
(Table 4). Initially, when inorganic bases such as K2CO3 and Cs2CO3
were screened for this reaction in THF at room temperature, the
product 6a was isolated in 68% and 89% yields, respectively (entries
1-2). While Et3N was ineffective for this reaction (entry 3), other
amine bases such as DMAP, DBU and DABCO afforded the product
6a only in low to moderate yield (31-54%, entries 4-6). In view of
the modest performance of amine bases in our reaction, we turned
back to Cs2CO3 and also subjected the reaction mixture to
Entry
Base
Solvent
DMF
DMF
DMF
DMF
THF
1,4-dioxane
DMF
Time (h)
% Yield a
50
1
2
3
4
5
6
7
8
K2CO3
Cs2CO3
Imidazole
TBAHS
TBAHS
TBAHS
TBAB
5
4
4
3
3
3
4
4
50
60
72
b
-
-
b
40
b
TBAI
DMF
-
aAfter purification by silica gel column chromatography. bComplex
mixture
o
microwave irradiation at 100 C. We were pleased to observe the
completion of the reaction in 10 min to afford the product 6a in
91% yield (entry 7). Further screening of solvents such as CH3CN,
1,4-dioxan and CHCl3 (entries 8-10) confirmed that the best solvent
was CH3CN (93% yield, entry 8).
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reaction of various aryl and heteroaryl MBH adduVcitesw A3rticwleitOhnliαne-
naphthol 7.
DOI: 10.1039/C5OB02656C
Table 4 Optimization of the reaction conditions for the [3+2]
annulation of β-naphthol 5 with hydrazinonitroalkene 3ma
Table 5 Synthesis of dihydronaphthofurans 6 via cascade reaction of
β-naphthol 5 with hydrazinonitroalkenes 3
Entry
Base
Solvent
THF
THF
THF
THF
THF
THF
THF
Time
24 h
18 h
24 h
48 h
48 h
32 h
10 min
10 min
12 min
10 min
% Yielda
68
1
2
3
4
5
6
7
8
9
10
K2CO3
Cs2CO3
Et3N
DMAP
DBU
DABCO
Cs2CO3
Cs2CO3
Cs2CO3
Cs2CO3
89
Entry
1
2
3
4
5
6
7
8
3, Ar
3m, C6H5
R
6
% Yielda
93
76
73
71
53
86
92
77
63
81
71
88
79
b
-
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
Et
6a
6b
6c
6d
6e
6f
6g
6h
6i
45
54
3n, 4-MeC6H4
3j, 4-OMeC6H4
3k, 3,4-(OMe)2C6H3
3h, 4-FC6H4
3o, 1-naphthyl
3l, 2-Thienyl
3p, 2-furyl
3b, C6H5CH=CH
3q, 4-OMeC6H4
3r, 4-ClC6H4
3s, 2-Thienyl
3t, 4-OMeC6H4
31
91c
93c
83d
77d
CH3CN
1,4-dioxan
CHCl3
aAfter silica gel column chromatography; bNo reaction; cThe
reaction was carried out under microwave at 100 oC.
9
10
11
12
13
6j
6k
6l
Et
Et
t-Bu
6m
The above optimized conditions were subsequently employed to
investigate the scope of the MBH adduct 3 in the synthesis of
hydrazinodihydrofurans 6 (Table 5). Thus MBH adducts 3 bearing
various aromatic groups at the β-position were employed for
reaction with β-naphthol 5 under the optimized conditions. While
the MBH adduct 3m, bearing parent phenyl, furnished the product
6a in excellent yield (93%, entry 1), the yields of
hydrazinodihydrofurans 6b-d, derived from other MBH adducts 3n,
3j and 3k, bearing electron rich aryl groups, were also good (71-
76%). However, in the case of 3h, bearing an electron deficient aryl
group, lower yield of the product 6e (53%) was encountered (entry
5). Hydrazinonitroalkenes possessing other groups β to nitro group
such as a fused aromatic ring (3o) and heteroaryl groups, thienyl
and furyl (3l and 3p), were also excellent substrates which provided
the products 6f-h in 77-92% yield (entries 6-8). A nitrodiene derived
MBH adduct 3b also delivered the desired product 6i in satisfactory
yield (63%, entry 9). Besides diisopropylhydrazinodicarboxylates of
nitroalkenes 3b-p (entries 1-9), diethyl- 3q-s and di-t-butyl 3t
derivatives were also amenable for our reaction affording the
products 6j-m in good to excellent yield (71-88%, entries 10-13).
aAfter silica gel column chromatography.
Table 6 Synthesis of dihydronaphthofurans 8 by cascade reaction of α-
naphthol 7 with hydrazinonitroalkenes 3
Entry
3, Ar
R
8
% Yielda
52b
34
1
2
3
4
5
6
3m, C6H5
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
Et
8a
8b
8c
8d
8e
8f
3j, 4-OMeC6H4
3k, 3,4-(OMe)2C6H3
3l, 2-Thienyl
3p, 2-furyl
36
50c
40
After successful execution of our methodology for the synthesis of
hydrazinonaphtho[2,1-b]furans 6 from β-naphthol 5, we shifted our
focus to the synthesis of regioisomers of 6, viz.
hydrazinonaphtho[1,2-b]furans 8 (Table 6). This required only the
replacement of β-naphthol 5 with α-naphthol 7. Selected MBH
adducts 3 were treated with α-naphthol 7 under the optimized
conditions. It may be noted that though the reactions were
3q, 4-OMeC6H4
46
aAfter silica column chromatography; bThe yields were 52% and 50%
when the reactions were carried out at 70 oC and 40 oC,
c
o
respectively; The reaction was carried out at 40 C; the yield was
41% when the reaction was carried out at 100 oC.
complete in 10 min, the yields of naphthofurans
8 were
considerably lower (34-52%) due to decomposition. Attempts to
improve the yield by microwave irradiation at lower temperature
were either not successful (entry 1) or met with only marginal
success (entry 4). But, nevertheless, we were pleased to note that
hydrazinonaphthofurans 8a-f were easily accessible via cascade
Further scope of our methodology was investigated using
substituted β-naphthols and phenols 9 (Table 7). For instance, 6-
bromo-2-naphthol 9a reacted well with MBH adduct 3m and
afforded dihydronaphthofuran 10a in excellent yield (87%). 3-
4 | J. Name., 2012, 00, 1-3
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Amido-2-naphthol 9b also took part in the cascade Friedel-Crafts amine catalyst such as imidazole to afford hydrazinodicarboxylates
reaction-cyclization with MBH adduct 3m, despite the decreased of nitroalkenes which exhibit dynamic pheDnOomI: 1e0n.1o0n3V9oi/enCw5NAOrMtBic0lRe2O6tin5ml6inCee
nucleophilicity of naphthol due to the presence of the amido group, scale. These compounds have been utilized for the first time for the
and delivered the desired product 10b in 86% yield. While synthesis of various heterocycles such as triazoles and arenofurans
substituted phenol 9c performed reasonably well by providing possessing
a key hydrazinodicarboxylate moiety by taking
dihydrobenzofuran 10c in 49% yield, parent phenol 9d and advantage of the relative ease of elimination of nitro group when
phloroglucinol 9e provided only complex mixtures under our compared to the hydrazinodicarboxylate moiety.
experimental conditions.
Scheme
dihydroarenofurans
2
Proposed mechanism for the formation of
Table 7 Scope of naphthols and phenols 9 for the synthesis of
dihydrofurans 10a
Experimental Section
General. The melting points recorded are uncorrected. NMR
1
1
1
spectra (1H, H decoupled 13C, 19F, 13C-APT, H-1H COSY and H-1H
NOESY) were recorded with TMS as the internal standard. The
coupling constants (J values) are given in Hz. High resolution mass
spectra were recorded under ESI Q-TOF conditions. X-ray data were
aYields after silica gel column chromatography.
collected on
a
diffractometer equipped with graphite
monochromated Mo K radiation. The structure was solved by
direct methods SHELXS-97 and refined by full-matrix least squares
against F2 using SHELXL-97 software. Complete characterization
data including NMR spectra for compounds 3g-l were reported
earlier.4
The relative stereochemistry of the aryl group and the
1
hydrazinodicarboxylate moiety was assigned to be trans from H-
1H-NOESY experiment with a representative compound 6c. This is
based on the absence of any NOE interaction between the aromatic
protons of 4-methoxyphenyl and the isopropyl protons of
hydrazinodicarboxylate. Later single crystal analysis of
a
General procedure for the synthesis of MBH Adducts 3. To a
stirred solution of nitroalkene 1 (1 mmol) in THF (2 ml), under N2
and protected from light, was added imidazole (68 mg, 1 mmol)
followed by diazo compound 2 (1.5 mmol) and the reaction mixture
was stirred at room temperature. After the completion of the
reaction (monitored by TLC), THF was removed in vacuo, the
residue was treated with water (10 ml) and acidified with 5N HCl
(10 ml). The aqueous layer was extracted with ethyl acetate (3  10
ml), the combined organic layers were washed with brine (20 ml),
dried over anhydrous Na2SO4 and concentrated in vacuo. The crude
residue was purified by silica gel column chromatography (10-20%
EtOAc/pet ether, gradient elution).
representative compound 6b confirmed this assignment (>90o
dihedral angle for ArC-C-C-N).
The proposed mechanism, taking β-naphthol
5 as the
representative arenol, envisages Cs2CO3 mediated addition of 5 to
MBH adduct 3 in a Michael fashion leading to the formation of
intermediate I which forms an acyliminium type intermediate II
with the loss of nitro group. Enolization of II and intramolecular 5-
exo-trig cyclization gives rise to product 6.
Conclusions
α-Hydrazination of a variety of nitroalkenes and nitrodienes using
azodicarboxylates proceeds in the presence of a mild nucleophilic
(E)-Dimethyl
1-(2-(furan-2-yl)-1-nitrovinyl)hydrazine-1,2-
o
dicarboxylate (3a). Yellow solid; Yield 242 mg, 85%; mp 145 C; IR
(KBr, cm-1) 3451 (m), 3299 (s), 1748 (vs), 1657 (s), 1522 (s), 1464 (s),
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1303 (vs); 1H NMR (CDCl3, 400 MHz) δ 3.75 (s, 6H), 6.66 (unresolved Di-tert-butyl (E)-1-(2-(4-methoxyphenyl)-1-nitrovinyl)hydrazine-
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m, 1H), 7.14 (br s, 1H), 7.73 (unresolved m, 2H), 8.00 (s, 1H); 13C 1,2-dicarboxylate (3f). Yellow solid; Yield 380 mg, 93%; mp 140-
DOI: 10.1039/C5OB02656C
NMR (CDCl3, 100 MHz) δ 53.1, 54.7, 114.0, 120.5, 122.2, 139.3, 142oC; IR (KBr, cm-1) 3366 (s), 1744 (vs), 1648 (m), 1605 (s), 1488
145.6, 148.2, 154.7, 156.0; m/z (QTOF ES+, Ar) 308 (MNa+, 100); (vs), 1394 (m), 1369 (m); 1H NMR (CDCl3, 500 MHz) δ 1.28, 1.47,
HRMS (QTOF ES+, Ar) calcd for C10H11N3O7Na (MNa+) 308.0489, 1.48, 1.51 (s, 18H), 3.87 (s, 3H), 6.80 (br s, 1H), 6.99 (d, J = 8.0 Hz,
found 308.0495.
2H), 7.92 (s, 1H), 8.12 (br unresolved d, 2H); 13C NMR (CDCl3, 125
MHz) δ 27.8, 28.0, 28.2, 28.3, 55.6, 81.9, 84.2, 114.7, 122.3, 131.6,
135.0, 142.2, 153.2, 154.9, 163.1; HRMS (ES+) calcd for
C19H27N3O7Na (MNa+) 432.1741, found 432.1746.
Diisopropyl 1-((1E,3E)-1-nitro-4-phenylbuta-1,3-dienyl)hydrazine-
1,2-dicarboxylate (3b). Yellow crystalline solid; Yield 283 mg, 75%;
o
mp 88-90 C; IR (KBr, cm-1) 3460 (m), 3276 (m), 1750 (s), 1716 (s),
1634 (m), 1526 (m), 1375 (m), 1320 (s); 1H NMR (CDCl3, 400 MHz) δ General procedure for the synthesis of triazoles 4 from MBH
1.18-1.31 (br unresolved, 12H), 5.03 (septet, J = 5.8 Hz, 2H), 6.95- adducts 3 and sodium azide. To a stirred solution of MBH adduct 3
7.00 (br unresolved, 1H), 7.19-7.23 (br unresolved, 1H), 7.39-7.40 (1.0 mmol) in dry DMF (2 mL) was added NaN3 (130 mg, 2.0 mmol)
(m, 3H), 7.60 (br unresolved, 3H), 7.81 (d, J = 11.0 Hz, 1H); 13C NMR followed by tetrabutylammonium hydrogen sulfate (TBAHS, 339
(CDCl3, 100 MHz) δ 21.6, 21.8, 70.3, 72.5, 121.2, 128.2, 128.9, 130.4, mg, 1.0 mmol) and the reaction mixture was stirred at room
134.5, 135.4, 142.9, 146.8, 153.9, 155.6; m/z (QTOF ES+, Ar) 400 temperature. After completion of the reaction (monitored by TLC),
(MNa+, 100), 203 (8), 142 (8), 115 (8); HRMS (QTOF ES+, Ar) calcd for saturated aqueous NaHCO3 was added and the reaction mixture
C18H23N3O6Na (MNa+) 400.1485, found 400.1473.
was extracted with diethyl ether (3 × 10 mL). The organic layer was
washed with brine (10 mL), dried over Na2SO4 and concentrated in
vacuo. The crude product was purified by silica gel column
chromatography using 35% EtOAc: pet ether (gradient elution).
Diisopropyl
1-((1E,3E)-4-(2-methoxyphenyl)-1-nitrobuta-1,3-
dienyl)hydrazine-1,2-dicarboxylate (3c). Yellow crystalline solid;
Yield 374 mg, 92%; mp 128-130 oC; IR (KBr, cm-1) 3484 (m), 3267
(m), 1770 (s), 1751 (s), 1716 (s), 1525 (m), 1376 (m); 1H NMR (CDCl3, Diisopropyl 1-(4-(4-chlorophenyl)-1H-1,2,3-triazol-5-yl)hydrazine-
400 MHz) δ 1.17 (d, J = 5.8 Hz, 6H), 1.25-1.30 (br unresolved, 6H), 1,2-dicarboxylate (4a). White foam; Yield 275 mg, 72%; IR (KBr, cm-
3.91 (s, 3H), 5.02 (septet, J = 6.2 Hz, 2H), 6.90-7.01 (m, 3H), 7.34- 1) 3246 (br vs), 1739 (br vs), 1406 (m); H NMR (CDCl3, 300 MHz, 50
1
7.38 (unresolved m, 1H), 7.63-7.69 (unresolved m, 2H), 7.84 (d, J = oC) δ 0.99 (6H, broad unresolved d), 1.23 (d, J = 6.2 Hz, 6H), 4.87
10.9 Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ 21.8, 22.0, 55.6, 70.4, (septet, J = 6.2 Hz, 1H), 5.00 (septet, J 6.2 Hz, 1H), 7.39 (d, J = 8.4
72.5, 111.2, 121.0, 121.4, 124.6, 128.3, 132.0, 135.9, 142.2, 142.4, Hz, 2H), 7.87 (br s, 1H), 7.94 (d, J = 8.4 Hz, 2H); 13C NMR (CDCl3, 75
154.2, 155.7, 158.2; m/z (QTOF ES+, Ar) 430 (MNa+, 100), 362 (6), MHz, 50 C) δ 21.6, 22.0, 70.7, 72.2, 128.0, 128.8, 129.0, 135.0,
º
173 (2); HRMS (QTOF ES+, Ar) calcd for C19H25N3O7Na (MNa+) 154.1, 156.0; MS (ES+, Ar) m/z (rel intensity) 384 (35, [MH+2]+), 382
430.1590, found 430.1593.
(100, MH+), 340 (12), 296 (10); HRMS cal for C16H21N5O4Cl (MH+)
382.1282, found 382.1278.
Diisopropyl 1-((1E,3E)-1-nitro-4-(2-nitrophenyl)buta-1,3-
dienyl)hydrazine-1,2-dicarboxylate (3d). Pale yellow crystalline Diisopropyl 1-(4-(4-fluorophenyl)-1H-1,2,3-triazol-5-yl)hydrazine-
o
solid; Yield 257 mg, 61%; mp 157-159 C; IR (KBr, cm-1) 3467 (m), 1,2-dicarboxylate (4b). White solid; Yield 248 mg, 68%; mp 121-
o
1
3289 (m), 1745 (s), 1715 (vs), 1538 (m), 1518 (m), 1495 (m), 1310 123 C; IR (KBr, cm-1) 3281 (br m), 1724 (vs); H NMR (CDCl3, 500
(m); 1H NMR (CDCl3, 400 MHz) δ 1.28-1.32 (br unresolved, 12H), MHz, 55 oC) δ 1.01 (partially resolved d, J = 4.0 Hz, 6H), 1.25 (d, J =
5.03 (septet, J = 5.9 Hz, 2H), 6.95-7.05 (br unresolved, 1H), 7.51- 6.2 Hz, 6H), 4.88 (septet, J = 6.2 Hz, 1H), 5.03 (d, J = 6.2 Hz, 1H), 7.14
7.55 (unresolved, 1H), 7.66-7.70 (m, 3H), 7.82-7.89 (br unresolved (t, J = 8.8 Hz, 2H), 7.90 (s, 1H), 8.01 (dd, J = 8.8, 5.5 Hz, 2H); 13C NMR
o
m, 2H), 8.02 (d, J = 7.6 Hz, 1H); 13C NMR (CDCl3, 100 MHz) δ 21.7, (CDCl3, 125 MHz, 55 C) δ 21.6, 22.0, 70.6, 72.2, 115.8 (d, JC-F = 22.5
21.9, 70.6, 72.8, 124.9, 125.7, 129.0, 130.2, 130.9, 133.2, 133.6, Hz), 125.6, 129.5 (d, JC-F = 8.0 Hz), 139.3, 142.7, 154.2, 156.0, 163.3
140.1, 144.4, 148.2, 153.8, 155.7; m/z (QTOF ES+, Ar) 445 (MNa+, (d, JC-F = 247.4 Hz); 19F -112.2; MS (ES+, Ar) m/z (rel intensity) 405
100), 399 (13), 313 (45), 248 (22), 227 (59), 121 (19), 77 (25); HRMS ([M+1]K+, 98), 389 (]M+1]Na+, 65), 388 (MNa+, 100), 367 ([M+2]+,
(QTOF ES+, Ar) calcd for C18H22N4O8Na (MNa+) 445.1335, found 97); HRMS (ES+) calcd for C16H20N5O4FNa (MNa+) 388.1392, found
445.1314.
388.1390.
(E)-Diisopropyl
(2-cyclohexyl-1-nitrovinyl)hydrazine-1,2- Diisopropyl 1-(4-(2-nitrophenyl)-1H-1,2,3-triazol-5-yl)hydrazine-
dicarboxylate (3e).5 Pale yellow solid; Yield 289 mg, 81%; mp 81-83 1,2-dicarboxylate (4c). Brown foam; Yield 64%; IR (KBr, cm-1) 3349
oC (lit5 92-94 oC); IR (KBr, cm-1) 3286 (s), 1754 (s), 1721 (vs), 1540 (s), (br vs), 1734 (m), 1717 (m), 1533 (s), 1377 (m); 1H NMR (CD3OD, 300
1504 (m), 1376 (m); 1H NMR (CDCl3, 400 MHz) δ 1.20-1.29 (m, 17H), MHz, 50 oC) δ 0.97-1.07 (br unresolved, 6H), 1.21 (d, J = 6.2 Hz, 6H),
1.66-1.77 (m, 6H), 2.90-3.00 (unresolved m, 1H), 5.00 (septet, J = 4.80 (septet, J = 6.2 Hz, 1H), 4.86 (septet, J = 6.2 Hz, 1H), 7.64 (td, J
8.2 Hz, 2H), 6.83 (br s, 1H), 7.08 (d, J = 11.0 Hz, 1H); 13C NMR (CDCl3, =7.5, 1.3 Hz, 1H), 7.72 (td, J = 7.5, 1.3 Hz, 1H), 7.82-7.93 (br
100 MHz) δ 21.7, 22.0, 24.8, 25.7, 30.7, 31.4, 36.9, 70.3, 72.5, 142.4, unresolved, 1H), 8.01 (br d, J = 7.5 Hz, 1H); 13C NMR (CD3OD, 75
144.1, 154.2, 155.4; m/z (QTOF ES+, Ar) 380 (MNa+, 100), 358 (34), MHz, 50 oC) δ 21.9, 22.3, 71.1, 72.9, 125.6, 131.2, 133.3, 133.9,
311 (34), 225 (19), 183 (48); HRMS (QTOF ES+, Ar) calcd for 150.3, 155.3, 157.9; MS (ES+, Ar) m/z (rel intensity) 415 (MNa+,
C16H27N3O6Na (MNa+) 380.1798, found 380.1791; Selected X-Ray 100); HRMS cal for C16H20N6O6Na 415.1337, found 415.1337.
data: C16H27N3O6, M = 357.41, Triclinic, space group P -1, a = 9.777
Diisopropyl
1-(4-(4-methoxyphenyl)-1H-1,2,3-triazol-5-
(5) Å, b = 10.159 (5) Å, c = 10.306 (5) Å, α = 102.265(7)°, β
=
yl)hydrazine-1,2-dicarboxylate (4d). White foam; Yield 245 mg,
65%; IR (KBr, cm-1) 3263 (br vs), 1739 (m), 1716 (m), 1516 (m), 1386
(m); 1H NMR (CDCl3, 300 MHz, 50 oC) δ 0.95-1.05 (broad unresolved
d, 6H), 1.22 (d, J = 6.2 Hz, 6H), 3.81 (s, 3H), 4.82-4.90 (br unresolved
septet, 1H), 4.99 (septet, J = 6.3 Hz, 1H), 6.95 (d, J 8.7 Hz, 2H), 7.95
(d, J = 8.7 Hz, 2H); 13C NMR (CDCl3, 75 MHz, 50 oC) δ 21.7, 22.1,
55.5, 70.5, 72.0, 114.4, 121.8, 128.9, 139.2, 142.3, 154.4, 156.1,
3
3
100.480 (6)°, γ = 90.508 (8)°, V = 982.4 (8) Å , Dc = 1.208 Mg/m , Z
-1
= 2, F(000) = 384, λ = 0.71070 Å, µ = 0.093 mm , total/unique
reflections = 17915/5352 [R(int) = 0.0759], T = 293(2) K, θ range =
3.03 to 29.30°, Final R [I>2 σ (I)]: R1 = 0.0497, wR2 = 0.1054; R (all
data): R1 = 0.0876, wR2 = 0.1212.
6 | J. Name., 2012, 00, 1-3
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Organic & Biomolecular Chemistry
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Journal Name
ARTICLE
160.4; MS (ES+, Ar) m/z (rel intensity) 378 (100, MH+), 336 (8), 292 119.9, 123.3, 123.4, 126.9, 128.1, 128.9, 129.8, 130.0,Vi1ew30Ar.t2ic,le1O3n0l.in5e,
(7); HRMS cald for C17H24N5O5 (MH+) 378.1777, found 378.1780.
Diisopropyl 1-(4-(3,4-dimethoxyphenyl)-1H-1,2,3-triazol-5-
137.0, 138.2, 154.7, 156.7; HRMS (ES+) calcd for C H O N Na
27 30 5 2
DOI: 10.1039/C5OB02656C
(MNa+) 485.2047, found 485.2051; Selected X-ray data: C27H30N2O5,
M = 462.53, Triclinic, space group P -1, a = 11.116(3)Å, b =
11.260(3)Å, c = 11.711(3)Å, = 63.523(15)°,  = 71.584(17)°,  =
yl)hydrazine-1,2-dicarboxylate (4e). White solid; Yield 255 mg,
62%; mp 107-109 oC; IR (KBr, cm-1) 3276 (w), 1732 (s); 1H NMR
3
o
3
69.128(17)°, V = 1204.2(6) Å , Dc = 1.276 Mg/m , Z = 2, F(000) =
(CDCl3, 400 MHz, 55 C) δ 0.97 (partially resolved d, J = 3.3 Hz, 6H),
-1
1.21 (d, J = 6.2 Hz, 6H), 3.88 (s, 3H), 3.93 (s, 3H), 4.85 (septet, J = 6.2
Hz, 1H), 4.98 (septet, J = 6.2 Hz, 1H), 6.91 (d, J = 8.4 Hz, 1H), 7.53
(dd, J = 8.1, 1.5 Hz, 1H), 7.75 (br s, 1H), 8.08 (s, 1H); 13C NMR (CDCl3,
492, λ = 0.71075 Å, µ = 0.088 mm , total/unique reflections =
12275/4222 [R(int) = 0.0404], T = 150 K, θ range = 3.064 to 25.000°,
Final R [I>2 σ (I)]: R1 = 0.0421, wR2 = 0.0969; R (all data): R1 =
0.0527, wR2 = 0.1031.
o
100 MHz, 55 C) δ 21.5, 21.9, 56.0, 56.3, 70.2, 71.8, 110.6, 111.3,
111.7, 120.1, 121.9, 142.1, 149.5, 149.8, 154.3, 155.8; MS (ES+, Ar)
m/z (rel intensity) 430 (MNa+, 100), 408 MH+, 62); HRMS (ES+) calcd
for C18H25N5NaO6 (MNa+) 430.1697, found 430.1702.
Diisopropyl
1-trans-(1-(4-methoxyphenyl)-1,2-
dihydronaphtho[2,1-b]furan-2-yl)hydazine-1,2-dicarboxylate (6c).
White solid; Yield 131 mg, 73%; mp 81-82 oC; IR (KBr, cm-1) 3306 (br
s), 1728 (vs); 1H NMR (CDCl3, 400 MHz) δ 1.10-1.29 (br poorly
resolved d, 12H), 3.74 (s, 3H), 4.91-5.03 (m, 2H), 5.08 (br unresolved
d, 1H), 6.45-6.50 (br unresolved d, 1H), 6.56 (br s, 1H), 6.80 (d, J =
8.7 Hz, 2H), 7.15 (d, J = 9.2 Hz, 1H), 7.19 (d, J = 8.7 Hz, 2H), 7.22-7.30
(m, 3H), 7.73 (d, J = 9.2 Hz, 1H), 7.76-7.80 (m, 1H); 13C NMR (CDCl3,
125 MHz) δ 21.7, 21.9, 49.6, 55.3, 70.3, 71.5, 97.7, 111.6, 114.4,
119.9, 123.2, 123.3, 126.8, 128.9, 129.0, 129.3, 129.9, 130.1, 130.4,
133.3, 154.7, 156.6, 158.9; HRMS (ES+) calcd for C27H30O6N2K (MK+)
517.1735, found 517.1738.
Diisopropyl
1-(4-(thiophen-2-yl)-1H-1,2,3-triazol-5-yl)hydrazine-
1,2-dicarboxylate (4f). Brown foam; Yield 212 mg, 60%; IR (KBr, cm-
1) 3518 (br m), 3230 (br m), 1720 (vs), 1377 (s); H NMR (CD3OD,
300 MHz, 50 C) δ 1.02-1.18 (br unresolved d, 6H), 1.23 (d, J = 6.2
1
o
Hz, 6H), 4.80-4.90 (unresolved septet, 1H), 4.94 (septet, J 6.2 Hz,
1H), 7.11 (dd, J = 4.5, 3.6 Hz, 1H), 7.46 (d, 4.5 Hz, 1H), 7.55-7.65 (br
unresolved, 1H); 13C NMR (CD3OD, 75 MHz, 50 oC) δ 22.0, 22.3, 71.1,
72.9, 127.5, 128.1, 128.7, 131.6, 143.0, 155.8, 158.0; MS (ES+, Ar)
m/z (rel intensity) 354 (100, MH+), 312 (15), 268 (12); HRMS cal for
C14H20N5O4S (M+) 354.1236, found 354.1231.
Diisopropyl
1-trans-(1-(3,4-dimethoxyphenyl)-1,2-
dihydronaphtho[2,1-b]furan-2-yl)hydrazine-1,2-dicarboxylate (6d).
White solid; Yield 145 mg, 71%; mp 91-92 oC; IR (KBr, cm-1) 3312 (br,
m), 1728 (s); 1H NMR (CDCl3, 400 MHz) δ 1.11-1.27 (br poorly
resolved d, 12H), 3.74 (s, 3H), 3.81 (s, 3H), 4.95-5.00 (m, 2H), 5.05-
5.15 (br unresolved d, 1H), 6.45-6.50 (br unresolved d, 1H), 6.67 (br
s, 1H), 6.76, 6.80 (ABq, J = 10.0 Hz, 2H), 6.87 (s, 1H), 7.14 (d, J = 8.3
Hz, 1H), 7.24-7.30 (m, 2H), 7.31-7.35 (m, 1H), 7.73 (d, J = 8.3 Hz,
Di-tert-butyl
1-(1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)hydrazine-1,2-dicarboxylate (4g). White solid; Yield
282 mg, 70 %; mp 193-195 oC; IR (KBr, cm-1) 3284 (br w), 1728 (s);
1H NMR (CDCl3, 500 MHz, 55 oC) δ 1.26 (s, 9H), 1.49 (s, 9H), 3.49 (br
s, 1H), 3.85 (s, 3H), 6.97 (d, J = 7.6 Hz, 2H), 7.11 (s, 1H), 7.88 (d, 7.6
Hz, 2H); 13C NMR (CDCl3, 125 MHz, 55 C) δ 27.9, 28.4, 55.4, 82.0,
o
83.3, 114.4, 122.2, 128.8, 153.2, 155.2, 160.3; MS (ES+, Ar) m/z (rel
intensity) 444 (MK+, 50), 428 (MNa+, 100), 406 (MH+, 12), 372 (10);
HRMS (ES+) calcd for C19H27N5O5Na (MNa+) 428.1904, found
428.1902.
1
1H), 7.78 (d, J = 7.4 Hz, 1H), Confirmed by H-1H COSY experiment;
13C NMR (CDCl3, 125 MHz) δ 21.6, 21.9, 50.0, 55.8, 55.8, 69.9, 70.1,
71.4, 97.5, 111.2, 111.5, 111.5, 119.6, 120.2, 123.2, 123.2, 126.7,
128.8, 129.8, 130.1, 130.4, 133.6, 148.2, 149.3, 154.6, 156.5; HRMS
(ES+) calcd for C28H32N2O7Na (MNa+, 100) 531.2102, found
531.2100.
General procedure for the tandem Michael/Friedel-Crafts reaction
of arenols 5, 7 and 9 with hydrazinonitroalkenes 3. A solution of
arenol 5, 7 or 9 (0.4 mmol), hydrazinonitroalkene 3 (0.48 mmol, 1.2
equiv) and Cs2CO3 (156 mg, 0.48 mmol, 1.2 equiv) in CH3CN (2 ml)
Diisopropyl 1-trans-(1-(4-fluorophenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)hydrazine-1,2-dicarboxylate (6e). White solid; Yield 99
was irradiated with microwave radiation at 100 oC for
̴10 min
1
mg, 53%; mp 80-83 oC; IR (KBr, cm-1) 3302 (br s), 1732 (vs); H NMR
(monitored by TLC). The reaction mixture was concentrated in
vacuo and the crude residue was purified by silica gel column
chromatography by eluting with ethyl acetate/pet ether (10-15%,
gradient elution).
(CDCl3, 500 MHz) δ 1.13-1.26 (br poorly resolved d, 12H), 4.95-5.01
(m, 2H), 5.10-5.15 (br unresolved d, 1H), 6.40-6.45 (br unresolved d,
1H), 6.60 (br s, 1H), 6.99 (t, J = 8.3 Hz, 2H), 7.17 (d, J = 8.8 Hz, 1H),
7.22-7.30 (m, 5H), 7.78 (d, J = 8.8 Hz, 1H), 7.80-7.83 (m, 1H); 13C
NMR (CDCl3, 125 MHz) δ 21.8, 22.0, 22.1, 49.8, 70.5, 71.7, 97.5,
111.7, 115.9 (d, JC-F = 21.3 Hz), 119.4, 123.2, 123.4, 127.0, 129.0,
129.9 (d, JC-F = 7.5 Hz), 130.0, 130.3, 130.5, 136.9, 154.6, 156.7,
162.3 (d, JC-F = 243.8 Hz); 19F NMR (CDCl3, 470 MHz) -115.4 (major), -
115.1 (minor); HRMS (ES+) calcd for C26H27O5N2FNa (MNa+, 100)
489.1796, found 489.1797.
Diisopropyl 1-trans-(1-phenyl-1,2-dihydronaphtho[2,1-b]furan-2-
yl)hydrazine-1,2-dicarboxylate (6a). White solid; Yield 178 mg,
93%; mp 81-83 oC; IR (KBr, cm-1) 3310 (br m), 1726 (s); 1H NMR
(CDCl3, 500 MHz) δ 1.15-1.38 (br poorly resolved d, 12H), 4.98-5.05
(m, 2H), 5.05-5.15 (br unresolved d, 1H), 6.35-6.40 (br unresolved d,
1H), 6.65 (br s, 1H), 7.21 (d, J = 8.8 Hz, 1H), 7.27-7.33 (m, 8H), 7.80
(d, J = 8.8 Hz, 1H), 7.83-7.85 (m, 1H); 13C NMR (CDCl3, 125 MHz) δ
21.8, 22.0, 50.5, 70.4, 71.6, 97.6, 111.6, 119.7, 123.3, 126.9, 127.4,
128.3, 128.9, 129.1, 130.0, 130.3, 130.4, 141.3, 154.6, 156.7; HRMS
(ES+) calcd for C26H28N2O5Na (MNa+) 471.1890, found 471.1890.
Diisopropyl 1-trans-(1-(naphthalen-1-yl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)hydrazine-1,2-dicarboxylate (6f). White solid; Yield
171 mg, 86%; mp 162-163 oC; IR (KBr, cm-1) 3304 (br s), 1728 (vs); 1H
NMR (CDCl3, 400 MHz) δ 1.00-1.50 (br poorly resolved d, 12H), 4.98-
5.17 (m, 2H), 5.75-6.00 (br unresolved d, 1H), 6.20-6.51 (br
unresolved d, 1H), 6.74 (br s, 1H), 7.19-7.31 (m, 6H), 7.59-7.96 (m,
6H), 8.60-8.90 (br unresolved m, 1H); 13C NMR (CDCl3, 125 MHz) δ
21.6, 22.0, 46.7, 70.3, 71.7, 97.6, 111.6, 119.4, 123.4, 123.7, 124.6,
125.2, 125.5, 125.7, 126.0, 126.5, 127.0, 128.0, 128.9, 130.0, 130.3,
130.6, 132.1, 134.4, 136.8, 154.3, 157.3; HRMS (ES+) calcd for
C30H30O5N2Na (MNa+, 100) 521.2047, found 521.2046.
Diisopropyl 1-trans-(1-(p-tolyl)-1,2-dihydronaphtho[2,1-b]furan-2-
yl)hydrazine-1,2-dicarboxylate (6b). White solid; Yield 140 mg,
76%; mp 141-143 C; IR (KBr, cm-1) 3307 (br m), 1728 (vs); H NMR
(CDCl3, 500 MHz) δ 1.15-1.46 (br poorly resolved d, 12H), 2.34 (s,
3H), 4.97-5.04 (m, 2H), 5.10-5.15 (br unresolved d, 1H), 6.35-6.40
(br unresolved d, 1H), 6.65 (br s, 1H), 7.11-7.23 (m, 5H), 7.28-7.34
(m, 3H), 7.79 (d, J = 8.8 Hz, 1H), 7.82-7.85 (m, 1H); 13C NMR (CDCl3,
125 MHz) δ 21.3, 21.8, 22.0, 50.0, 50.4, 70.4, 71.5, 97.7, 111.7,
o
1
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
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Organic & Biomolecular Chemistry
Page 8 of 11
ARTICLE
Journal Name
Diisopropyl
1-trans-(1-(thiophen-2-yl)-1,2-dihydronaphtho[2,1- 156.7; HRMS (ES+) calcd for C24H23ClO5N2Na (MNa+, 100) 477.1188,
View Article Online
b]furan-2-yl)hydrazine-1,2-dicarboxylate (6g). White solid; Yield found 477.1188.
DOI: 10.1039/C5OB02656C
167 mg, 92%; mp 105-107 oC; IR (KBr, cm-1) 3304 (br s), 1729 (vs); 1H
Diethyl
1-trans-(1-(thiophen-2-yl)-1,2-dihydronaphtho[2,1-
NMR (CDCl3, 500 MHz) δ 1.03-1.40 (br unresolved d, 12H), 4.85-5.05
b]furan-2-yl)hydrazine-1,2-dicarboxylate (6l). White solid; Yield
150 mg, 88%; mp 76-78 C; IR (KBr, cm-1) 3303 (br m), 1731 (vs); H
NMR (CDCl3, 500 MHz) δ 1.17-1.32 (br m, 6H), 4.21-4.28 (br m, 4H),
5.48 (br unresolved d, 1H), 6.60 (br s, 1H), 6.65-6.75 (br unresolved
d, 1H), 6.98-7.05 (br unresolved m, 2H), 7.19 (d, J = 8.7 Hz, 1H),
7.22-7.26 (br unresolved m, 1H), 7.30-7.38 (m, 2H), 7.46-7.52 (br
unresolved m, 1H), 7.80 (d, J = 8.7 Hz, 1H), 7.84 (d, J = 7.9 Hz, 1H);
13C NMR (CDCl3, 125 MHz) δ 14.4 (× 2), 45.9, 62.5, 63.6, 97.6, 111.6,
119.3, 123.1, 123.4, 125.3, 126.1, 127.1, 127.2, 128.9, 130.0, 130.3,
130.7, 144.3, 155.1, 156.3, 156.7; HRMS (ES+) calcd for
o
1
(m, 2H), 5.35-5.45 (br poorly resolved d, 1H), 6.20-6.40 (br
unresolved d, 1H), 6.39 (br s, 1H), 6.92 (dd, J = 5.0, 3.5 Hz, 1H), 6.96-
7.03 (unresolved m, 1H), 7.14 (d, J = 8.8 Hz, 1H), 7.16-7.20 (br
unresolved m, 2H), 7.25-7.33 (m, 3H), 7.43 (d, J = 7.9 Hz, 1H), 7.75
(d, J = 8.8 Hz, 1H), 7.79 (d, J = 7.9 Hz, 1H); 13C NMR (CDCl3, 125
MHz) δ 21.7, 21.9, 22.0, 22.0, 45.8, 70.4, 71.6, 73.1, 97.4, 111.7,
119.4, 123.1, 123.4, 125.2, 126.1, 127.1, 127.2, 128.5, 128.9, 130.0,
130.4, 130.7, 144.4, 154.6, 156.4; HRMS (ES+) calcd for
C24H26N2O5SNa (MNa+, 100) 477.1455, found 477.1453.
Diisopropyl
1-trans-(1-(furan-2-yl)-1,2-dihydronaphtho[2,1- C22H22O5N2SNa (MNa+) 449.1142, found 449.1141.
b]furan-2-yl)hydrazine-1,2-dicarboxylate (6h). White solid; Yield
Di-tert-butyl
1-trans-(1-(4-methoxyphenyl)-1,2-
135 mg, 77%; mp 66-67 C; IR (KBr, cm-1) 3306 (br m), 1732 (s); H
NMR (CDCl3, 400 MHz) δ 1.09-1.36 (br poorly resolved d, 12H), 4.90-
4.98 (br unresolved m, 1H), 5.02 (septet, J = 6.2 Hz, 1H), 5.19-5.25
(br m, 1H), 6.10-6.20 (br unresolved d, 1H), 6.25-6.35 (br
unresolved m, 2H), 6.60-6.90 (br unresolved m, 1H), 7.15 (d, J = 8.8
Hz, 1H), 7.27-7.31 (m, 1H), 7.34-7.39 (m, 2H), 7.49 (d, J = 8.0 Hz,
1H), 7.76 (d, J = 8.8 Hz, 1H), 7.80 (d, J = 8.0 Hz, 1H); 13C NMR (CDCl3,
125 MHz) δ 21.7, 22.0, 44.9, 70.4, 71.6, 94.4, 108.0, 110.6, 111.7,
117.5, 122.7, 123.4, 127.1, 128.9, 129.9, 130.4, 130.5, 142.6, 153.0,
154.5, 156.3; HRMS (ES+) calcd for C24H26N2O6Na (MNa+, 100)
461.1683, found 461.1679.
o
1
dihydronaphtho[2,1-b]furan-2-yl)hydrazine-1,2-dicarboxylate
(6m). White solid; Yield 160 mg, 79%; mp 97-99oC; IR (KBr, cm-1)
1
3323 (br w), 1726 (vs); H NMR (CDCl3, 500 MHz) δ 1.41, 1.49 (s,
18H), 3.77 (s, 3H), 5.05-5.60 (br unresolved d, 1H), 6.33 (br
unresolved d, 1H), 6.62 (br s, 1H), 6.83 (d, J = 8.6Hz, 2H), 7.15-7.25
(m, 3H), 7.27-7.32 (m, 3H), 7.76 (d, J = 8.6 Hz, 1H), 7.78-7.82 (m,
1H); 13C NMR (CDCl3, 125 MHz) δ 28.2, 28.2, 49.6, 55.3, 81.6, 82.9,
97.4, 111.7, 114.4, 120.0, 123.2, 123.3, 126.8, 128.9, 129.3, 129.9,
130.1, 130.5, 133.5, 153.9, 155.6, 156.7, 158.8; HRMS (ES+) calcd for
C29H34N2O6K (MK+) 545.2048, found 545.2042.
Diisopropyl 1-trans-(3-phenyl-2,3-dihydronaphtho[1,2-b]furan-2-
yl)hydrazine-1,2-dicarboxylate (8a). White solid; Yield 93 mg, 52%;
mp 174-175 oC; IR (KBr, cm-1) 1725 (vs); 1H NMR (CDCl3, 400 MHz) δ
1.20-1.50 (br poorly resolved d, 12H), 4.90-5.10 (partially resolved
m, 3H), 6.43-6.49 (br unresolved d, 1H), 6.80 (br s, 1H), 7.19 (d, J =
8.2 Hz, 1H), 7.28-7.36 (m, 5H), 7.44 (d, J = 8.2 Hz, 1H), 7.48-7.52 (m,
2H), 7.84-7.86 (m, 1H), 8.00-8.05 (m, 1H); 13C NMR (CDCl3, 100 MHz)
δ 21.9, 22.0, 51.4, 70.3, 71.6, 97.4, 120.2, 121.2, 121.7, 122.1,
122.8, 125.7, 126.2, 127.5, 128.1, 128.4, 129.0, 134.4, 141.5, 154.2,
154.7, 156.4; HRMS (ES+) calcd for C26H28N2O5Na (MNa+) 471.1890,
found 471.1890.
(E)-Diisopropyl 1-trans-(1-styryl-1,2-dihydronaphtho[2,1-b]furan-
2-yl)hydrazine-1,2-dicarboxylate (6i). White solid; Yield 120 mg,
63%; mp 71-74 oC; IR (KBr, cm-1) 3306 (br s), 1725 (vs); 1H NMR
(CDCl3, 500 MHz) δ 1.09-1.28 (br poorly resolved d, 12H), 4.75 (br
unresolved m, 1H), 4.91 (br unresolved m, 1H), 5.02 (septet, J = 6.1
Hz, 1H), 6.42 (dd, J = 15.8, 8.6 Hz, 2H), 6.75 (d, J = 15.8 Hz, 1H), 7.12
(d, J = 8.8 Hz, 1H), 7.18-7.24 (m, 1H), 7.25-7.33 (m, 3H), 7.34-7.41
(m, 3H), 7.66-7.76 (m, 1H), 7.72 (d, J = 8.8 Hz, 1H), 7.78 (d, J = 8.2
Hz, 1H); 13C NMR (CDCl3, 125 MHz) δ 21.7, 22.0, 22.0, 48.3, 70.2,
71.6, 95.7, 111.6, 119.2, 122.9, 123.3, 123.5, 126.6, 127.0, 127.7,
128.6, 128.9, 129.8, 130.1, 130.7, 133.2, 136.8, 154.7, 156.1, 156.3;
HRMS (ES+) calcd for C28H30N2O5Na (MNa+) 497.2047, found
497.2060.
Diisopropyl
1-trans-(3-(4-methoxyphenyl)-2,3-
dihydronaphtho[1,2-b]furan-2-yl)hydrazine-1,2-dicarboxylate (8b).
o
White solid; Yield 65 mg, 34%; mp 142-143 C; IR (KBr, cm-1) 3301
(br m), 1728 (vs); 1H NMR (CDCl3, 400 MHz) δ 1.15-1.35 (br
unresolved d, 12H), 3.79 (s, 3H), 4.89-4.90 (br poorly resolved d,
1H), 4.95-5.05 (m, 2H), 6.39-6.40 (br unresolved d, 1H), 6.65 (br s,
1H), 6.85 (d, J = 8.6 Hz, 2H), 7.15 (d, J = 8.3 Hz, 1H), 7.20-7.26 (m,
2H), 7.42 (d, J = 8.3 MHz, 1H), 7.45-7.50 (m, 2H), 7.82-7.84 (m, 1H),
7.98-8.00 (m, 1H); 13C NMR (CDCl3, 125 MHz) δ 21.9, 22.1, 50.6,
55.4, 70.3, 71.6, 97.9, 114.4, 120.2, 121.2, 121.7, 122.4, 122.8,
125.7, 126.2, 128.1, 129.5, 133.6, 134.4, 154.1, 154.8, 156.5, 159.0;
HRMS (ES+) calcd for C27H30N2O6Na (MNa+) 501.1996, found
501.1992.
Diethyl
1-trans-(1-(4-methoxyphenyl)-1,2-dihydronaphtho[2,1-
b]furan-2-yl)hydrazine-1,2-dicarboxylate (6j). White solid; Yield
o
1
146 mg, 81%; mp 83-84 C; IR (KBr, cm-1) 3307 (br m), 1732 (vs); H
NMR (CDCl3, 500 MHz) δ 1.19-1.32 (br poorly resolved t, 6H), 3.80
(s, 3H), 4.10-4.18 (unresolved m, 1H), 4.26 (q, J = 6.7 Hz, 3H), 5.07-
5.13 (br unresolved d, 1H), 6.52-6.57 (br unresolved d, 1H), 6.86 (d,
J = 8.5 Hz, 2H), 7.19 (d, J = 8.8 Hz, 1H), 7.22 (br d, J = 8.5 Hz, 2H),
7.27-7.30 (m, 3H), 7.78 (d, J = 8.8 Hz, 1H), 7.81-7.85 (m, 1H); 13C
NMR (CDCl3, 125 MHz) δ 14.5, 49.8, 55.4, 62.5, 63.6, 98.7, 111.6,
114.5, 119.9, 123.4, 126.9, 128.9, 129.3, 130.0, 130.3, 130.4, 133.3,
155.2, 156.5, 159.0; HRMS (ES+) calcd for C25H2O6N2Na (MNa+)
473.1683, found 473.1680.
Diisopropyl
1-trans-(3-(3,4-dimethoxyphenyl)-2,3-
dihydronaphtho[1,2-b]furan-2-yl)hydrazine-1,2-dicarboxylate (8c).
o
White solid; Yield 73 mg, 36%; mp 131-132 C; IR (KBr, cm-1) 3308
Diethyl
1-trans-(1-(4-chlorophenyl)-1,2-dihydronaphtho[2,1-
1
b]furan-2-yl)hydrazine-1,2-dicarboxylate (6k). White solid; Yield
(br m), 1728 (vs); H NMR (CDCl3, 500 MHz) δ 1.22-1.31 (br poorly
o
1
130 mg, 71%; mp 82-84 C; IR (KBr, cm-1) 3305 (br m), 1732 (vs); H
NMR (CDCl3, 400 MHz) δ 1.17 (t, J = 6.9 Hz, 3H), 1.24 (t, J = 6.5 Hz,
3H), 4.08-4.28 (m, 4H), 5.11 (d, J = 4.1 Hz, 1H), 6.50 (bs, 1H), 6.55-
6.60 (br unresolved d, 1H), 7.15 (d, J = 8.8 Hz, 1H), 7.19-7.30 (m,
7H), 7.76 (d, J = 8.8 Hz, 1H), 7.79-7.81 (m, 1H); 13C NMR (CDCl3, 125
MHz) δ 14.4, 14.4, 50.0, 62.6, 63.7, 97.8, 111.6, 119.0, 123.2, 123.5,
127.1, 129.0, 129.3, 129.7, 130.0, 130.2, 130.6, 133.4, 139.6, 155.1,
resolved d, 12H), 3.83 (s, 3H), 3.89 (s, 3H), 4.90-4.95 (br unresolved
d, 1H), 4.96-5.06 (m, 2H), 6.43-6.73 (br unresolved, 2H), 6.78-6.88
(m, 3H), 7.17 (d, J = 8.1 Hz, 1H), 7.41 (d, J = 8.2 Hz, 1H), 7.44-7.48
(m, 2H), 7.79-7.84 (m, 1H), 7.95-8.01 (m, 1H); 13C NMR (CDCl3, 125
MHz) δ 21.8, 21.9, 22.0, 50.9, 56.0, 70.1, 71.5, 97.5, 111.5, 120.1,
120.4, 121.2, 121.7, 122.0, 122.8, 125.6, 126.2, 128.1, 133.8, 134.3,
8 | J. Name., 2012, 00, 1-3
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Organic & Biomolecular Chemistry
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Journal Name
ARTICLE
148.4, 149.4, 154.0, 154.8, 156.6; HRMS (ES+) calcd for 98.3, 116.9, 120.1, 120.8, 122.6, 123.9, 124.1, 126.0,Vi1ew27A.r0tic,le1O27nl.in7e,
C28H32N2O7Na (MNa+) 531.2102, found 531.2107.
128.1, 128.7, 129.2, 129.5, 129.7, 130.3, 13D1O.4I,: 1103.210.43,9/1C356O.7B,01246506.4C,
152.6, 155.0, 157.2, 162.2; H NMR (CDCl3, 500 MHz, 323K) δ 1.15-
1
Diisopropyl
1-trans-(3-(thiophen-2-yl)-2,3-dihydronaphtho[1,2-
1.31 (br poorly resolved d, 12H), 2.27 (s, 3H), 4.85-5.00 (br
unresolved, 1H), 5.04 (heptet, J = 6.3 Hz, 1H), 5.15-5.20 (br
unresolved d, 1H), 6.77-6.84 (br unresolved, 1H), 6.93-6.99 (br,
unresolved 1H), 7.00-7.03 (br unresolved, 1H), 7.13-7.20 (br m, 2H),
7.21-7.32 (m, 8H), 7.50-7.80 (br unresolved, 1H), 8.35 (d, J = 8.0 Hz,
1H), 8.45-8.55 (br unresolved, 1H), 9.48-9.56 (br unresolved, 1H); 1H
NMR (DMSO-d6, 500 MHz, 333K) δ 1.00-1.25 (br unresolved, 6H),
1.23 (d, J = 6.3 Hz, 6H), 2.36 (s, 3H), 4.50-4.53 (br unresolved, 1H),
4.90 (heptet, J = 6.3 Hz, 2H), 5.10-5.20 (br unresolved, 1H), 6.65-
6.75 (br unresolved, 1H), 7.09 (t, J = 7.4 Hz, 1H), 7.23-7.34 (m, 6H),
7.37 (t, J = 7.3 Hz, 3H), 7.42-7.47 (br unresolved, 1H), 8.10 (d, J = 8.2
Hz, 1H), 8.24 (br d, J = 6.1 Hz, 1H), 8.60 (s, 1H), 9.45-9.60 (br
unresolved, 1H); 13C NMR (DMSO-d6, 125 MHz, 333K) δ 17.2, 21.3,
49.0, 68.5, 70.5, 97.9, 118.0, 121.4, 122.0, 123.9, 124.0, 126.0,
127.3, 128.5, 128.8, 128.9, 129.9, 130.1, 130.6, 131.6, 136.6, 140.3,
152.3, 161.2; HRMS (ES+) calcd for C34H35N3O6Na (MNa+) 604.2418,
found 604.2425.
b]furan-2-yl)hydrazine-1,2-dicarboxylate (8d). White solid; Yield 89
mg, 50%; mp 137-139 C; IR (KBr, cm-1) 3303 (br m), 1732 (vs); H
NMR (CDCl3, 400 MHz) δ 1.18-1.29 (br poorly resolved d, 12H), 4.93-
5.10 (br unresolved m, 2H), 5.21-5.27 (br unresolved d, 1H), 6.35-
6.45 (br unresolved, 1H), 6.97-6.99 (dd, J = 4.8, 3.6 Hz, 1H), 7.04-
7.08 (br unresolved m, 1H), 7.22-7.24 (br unresolved m, 1H), 7.30
(d, J = 8.3 Hz, 1H), 7.45 (d, J = 8.3 Hz, 1H), 7.47-7.49 (m, 2H), 7.80-
7.85 (m, 2H), 7.97-8.00 (m, 1H); 13C NMR (CDCl3, 125 MHz) δ 21.9,
22.1, 46.7, 70.4, 71.8, 97.2, 120.2, 121.3, 121.6, 121.8, 122.6, 125.1,
125.8, 126.2, 126.4, 127.3, 128.2, 134.6, 144.4, 153.8, 154.7, 156.4;
HRMS (ES+) calcd for C24H26N2O5SNa (MNa+) 477.1455, found
477.1453.
o
1
Diisopropyl
1-trans-(3-(furan-2-yl)-2,3-dihydronaphtho[1,2-
b]furan-2-yl)hydrazine-1,2-dicarboxylate (8e). White solid; Yield 72
1
mg, 40%; mp 119-120 oC; IR (KBr, cm-1) 3386 (br w), 1728 (s); H
NMR (CDCl3, 400 MHz) δ 1.15-1.29 (br poorly resolved d, 12H), 4.88-
4.98 (br unresolved d, 1H), 5.00-5.08 (br unresolved m, 2H), 6.10-
6.23 (br unresolved, 1H), 6.30-6.34 (br unresolved, 1H), 6.40-6.46
(br unresolved, 1H), 6.70-7.00 (br unresolved, 1H), 7.27 (d, J = 8.3
Hz, 1H), 7.37-7.38 (unresolved m, 1H), 7.39 (d, J = 8.3 Hz, 1H), 7.42-
7.47 (m, 2H), 7.79-7.7.83 (m, 1H), 7.96-7.80 (br poorly resolved m,
1H); 13C NMR (CDCl3, 100 MHz) δ 21.8, 22.0, 45.5, 70.3, 71.6, 94.3,
107.3, 110.5, 119.7, 120.2, 121.2, 121.7, 122.3, 125.7, 126.3, 128.1,
134.5, 142.7, 153.4, 153.9, 154.6, 156.3; HRMS (ES+) calcd for
C24H26N2O6Na (MNa+) 461.1683, found 461.1684.
Diisopropyl
1-trans-(5-(benzyloxy)-6-methoxy-3-phenyl-2,3-
dihydrobenzofuran-2-yl) hydrazine-1,2-dicarboxylate (10c). White
solid; Yield 104 mg, 49%; mp 122-123 oC; IR (KBr, cm-1) 3307 (br m),
1727 (vs); 1H NMR (CDCl3, 500 MHz) δ 1.20-1.40 (br poorly resolved
d, 12H), 3.89 (s, 3H), 4.65-4.75 (br unresolved, 1H), 4.95-5.05 (br
unresolved, 2H), 5.01 (s, 2H), 6.20-6.50 (br unresolved, 2H), 6.53 (s,
1H), 6.64 (s, 1H), 7.16-7.27 (br poorly resolved multiplet, 2H), 7.28-
7.36 (m, 6H), 7.38-7.41 (m, 2H); 13C NMR (CDCl3, 125 MHz) δ 22.0,
22.1, 22.1, 50.6, 56.3, 70.3, 71.6, 72.6, 95.0, 113.3, 118.7, 127.4,
127.8, 127.9, 128.2, 128.5, 128.9, 137.4, 141.2, 142.9, 151.2, 153.7,
154.7, 156.4; HRMS (ES+) calcd for C30H34N2O7Na (MNa+) 557.2258,
found 557.2258.
Diethyl
1-trans-(3-(4-methoxyphenyl)-2,3-dihydronaphtho[1,2-
b]furan-2-yl)hydrazine-1,2-dicarboxylate (8f). White solid; Yield 83
mg, 46%; mp 95-97 oC; IR (KBr, cm-1) 3301 (br m), 1732 (vs); 1H NMR
(CDCl3, 400 MHz) δ 1.22-1.28 (br poorly resolved q, 6H), 3.79 (s, 3H),
4.15-4.28 (m, 4H), 4.88-4.93 (br unresolved d, 1H), 6.53-6.58 (br
unresolved d, 1H), 6.70 (br s, 1H), 6.86 (d, J = 8.6 MHz, 2H), 7.15 (d,
J = 8.2 Hz, 1H), 7.21 (br d, J = 8.6 Hz, 2H), 7.43 (d, J = 8.2 Hz, 1H),
7.46-7.50 (m, 2H), 7.82-7.84 (m, 1H), 7.98-8.02 (m, 1H); 13C NMR
(CDCl3, 125 MHz) δ 14.5 (× 2), 50.7, 55.4, 62.5, 63.6, 98.0, 114.4,
120.1, 121.3, 121.7, 122.3, 122.8, 125.8, 126.2, 128.1, 129.5, 133.5,
134.4, 154.0, 155.3, 156.8, 159.1; HRMS (ES+) calcd for
C25H26N2O6Na (MNa+) 473.1683, found 473.1681.
Acknowledgements
INNN thanks SERB, DST India for financial assistance. VM and
NA thank CSIR India and UGC India, respectively, for a senior
research fellowship. JP thanks DST India and RK thanks IIT
Bombay for a postdoctoral research associateship. The authors
thank Dr. Mamta Dadwal for performing preliminary studies in
this project.
Diisopropyl 1-trans-(7-bromo-1-phenyl-1,2-dihydronaphtho[2,1-
b]furan-2-yl)hydrazine-1,2-dicarboxylate (10a). White solid; Yield
o
183 mg, 87%; mp 218-219 C; IR (KBr, cm-1) 3358 (br s), 1741 (s),
Notes and references
1736 (s); 1H NMR (CDCl3, 500 MHz) δ 1.09-1.30 (br poorly resolved
d, 12H), 4.70-5.20 (br unresolved, 3H), 6.50-6.80 (br unresolved,
1H), 7.16-7.50 (m, 7H), 7.50-7.90 (br unresolved, 3H), 8.40-8.60 (br
m, 1H), 9.60-9.77 (br m, 1H); 13C NMR (CDCl3, 125 MHz) δ 21.9,
22.1, 49.5, 70.5, 71.9, 99.0, 121.2, 122.8, 124.3, 127.9, 128.0, 128.8,
129.3, 129.6, 130.1, 131.6, 132.9, 140.3, 152.5, 154.9, 157.0, 162.5;
HRMS (ES+) calcd for C26H27BrO5N2Na (MNa+) 549.0996, found
549.0998.
1
(a) K. Morita, Z. Suzuki and H. Hirose, Bull. Chem. Soc. Jpn.,
1968, 41, 2815; (b) A. B. Baylis and M. E. D. Hillman, Ger.
Offen. 2155113, 1972; Chem. Abstr., 1972, 77, 34174q; M. E.
D. Hillman, A. B. Baylis, U. S. Patent 1973, US3743669;
Selected recent reviews: (c) Y. Wei and M. Shi, Chem. Rev.,
2013, 113, 6659; (d) D. Basavaiah and B. C. Sahu,
Chimia, 2013, 67, 8; (e) Guillena, D. J. Ramon and M. Yus,
Catalysis, 2012, 24, 223; (f)
D.
Basavaiah
and
G.
Veeraraghavaiah, Chem. Soc. Rev., 2012, 41, 68; (g) V. Singh
and S. Batra, Tetrahedron, 2008, 64, 4511; (h) V. Declerck, J.
Martinez and F. Lamaty, Chem. Rev. 2009, 109, 1.
(a) M. M. Rauhut and H. Currier, U. S. Patent 1963, 3074999;
Chem. Abstr. 1963, 58, 11224a. Review: (b) C. E. Aroyan, A.
Dermenci and S. J. Miller, Tetrahedron, 2009, 65, 4069.
Review: (a) K. Kaur and I. N. N. Namboothiri, Chimia, 2012,
66, 913; Articles: (b) N. Rastogi, I. N. N. Namboothiri and M.
Cojocaru, Tetrahedron. Lett., 2004, 45, 4745; (c) R. Mohan,
N. Rastogi, I. N. N. Namboothiri, S. M. Mobin and D. Panda,
Diisopropyl
dihydronaphtho
1-trans-(1-phenyl-4-(o-tolylcarbamoyl)-1,2-
[2,1-b]furan-2-yl)hydrazine-1,2-dicarboxylate
(10b). White solid; Yield 200 mg, 86%; mp 217-218 oC; IR (KBr, cm-1)
3376 (br s), 3230 (br m), 1728 (vs), 1669 (s); 1H NMR (CDCl3, 500
MHz, 294K) δ 1.15-1.50 (br poorly resolved d, 12H), 2.27 (br s, 3H),
4.50-4.70 (br unresolved, 1H), 5.00-5.15 (br unresolved septet, 2H),
5.15-5.20 (br unresolved d, 1H), 6.70-7.40 (br unresolved, 13H),
8.10-8.90 (br unresolved, 2H), 9.50-9.65 (br unresolved, 1H); 13C
NMR (CDCl3, 125 MHz, 297K) δ 18.2, 22.1 (× 2), 49.3, 70.1, 71.4,
2
3
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 9
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Page 10 of 11
ARTICLE
Journal Name
Bioorg. Med. Chem., 2006, 14, 8073; (d) I. Deb, M. Dadwal, S.
M. Mobin and I. N. N. Namboothiri, Org. Lett., 2006, , 1201;
(e) M. Dadwal, R. Mohan, D. Panda, S. M. Mobin and I. N. N.
Namboothiri, Chem. Commun., 2006, 338; (f) N. Rastogi, R.
Mohan, D. Panda, S. M. Mobin and I. N. N. Namboothiri, Org.
Chen, N. Shao, H. Zhu, B. Zhang and H. Zou, VTieewtArartihcleedOrnolinne,
8
2013, 69, 10558; (f) Oxa- and aza-triquinanes: J. An, L.-Q. Lu,
DOI: 10.1039/C5OB02656C
Q.-Q. Yang, T. Wang and W.-J. Xiao, Org. Lett., 2013, 15, 542;
(g) Tetrahydropyridines: M. Yaqub, C.-Y. Yu, Y.-M. Jia and Z.-
T. Huang, Synlett, 2008, 1357; Imidazoles: (h) T. Kumar, D.
Verma, R. F. S. Menna-Barreto, W. O. Valenca, E. N. da Silva
Júnior and I. N. N. Namboothiri, Org. Biomol. Chem.,
2015, 13, 1996; (i) E. Gopi, T. Kumar, R. F. S. Menna-Barreto,
W. O. Valenca, E. N. da Silva Junior and I. N. N. Namboothiri,
Org. Biomol. Chem. 2015, 13, 9862; (j) Different heterocyclic
scaffolds: H. Zhu, N. Shao, T. Chen and H. Zou, Chem.
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Tetrahedron: Asymmetry, 2010, 21, 891; (k) P. Shanbhag, P.
R. Nareddy, M. Dadwal, S. M. Mobin and I. N. N.
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Kumar, T. Kumar, S. M. Mobin and I. N. N. Namboothiri, J.
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Wang, Y.-F. Chen, L.-F. Niu and P.-F. Xu, Org. Lett., 2009, 11,
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9
Furans from 1, 3-dicarbonyl compounds: (a) D. K. Nair, S. M.
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3349; (b) W.-Y. Huang, Y.-C. Chen and K. Chen, Chem. Asian
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and I. N. N. Namboothiri, RSC Advances 2015, , 69990;
,
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5
Arenofurans from arenols: (d) T. Kumar, S. M. Mobin and I.
N. N. Namboothiri, Tetrahedron, 2013, 69, 4964; (e) S.
Anwar, W.-Y. Huang, C.-H. Chen, Y.-S. Cheng and K. Chen,
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4
5
M. Dadwal, S. M. Mobin and I. N. N. Namboothiri, Org.
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X.-Y. Chen, F. Xia and S. Ye, Org. Biomol. Chem. 2013, 11, 5722. 10 For DABCO catalyzed reactions of azodicarboxylates with (a)
6 Selected articles: (a) V. Barbier, F. Couty and O. R. P. David,
Eur. J. Org. Chem., 2015, 3679; (b) B. Han, X. Xie, W. Huang,
X. Li, L. Yang and C. Peng, Adv. Synth. Catal., 2014, 356, 3676;
(c) J.-Q. Zhang, J.-J. Liu, C.-L. Gu, D. Wang and L. Liu, Eur. J.
Org. Chem., 2014, 5885; (d) N. Lu, H. Wang and Y. Wang,
Bull. Kor. Chem. Soc., 2013, 34, 3591; (e) X.-Y. Chen, F. Xia
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11 Selected Reviews: (a) K. C. Majumdar and K. Ray,
Synthesis, 2011, 23, 3767; (b) A. Lauria, R. Delisi, F. Mingoia,
A. Terenzi, A. Martorana, G. Barone and A. M. Almerico, Eur.
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X. Yu, Y. Wang, G. Wu, H. Song, Z. Zhou and C. Tang,
Tetrahedron: Asymmetry, 2010, 21, 2988; (k) Y. Wang, S. Zhu
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Yadav, Tetrahedron, 2012, 68, 2459; (m) Z.-W. Guo, J.-W. Xie,
C. Chen and W.-D. Zhu, Org. Biomol. Chem., 2012, 10, 8471;
(n) G. Talavera, E. M. Reyes, J. L. Vicario and L. Carrillo,
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Lan, N. S. Dange, G.-H. Lee and J.-H. Liao, Eur. J. Org. Chem.,
2013, 2472; (p) J. An, L.-Q. Lu, Q.-Q. Yang, T. Wang and W.-J.
Xiao, Org. Lett., 2013, 15, 542; (q) M. Yaqub, C. Y. Yu, Y. M.
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12 Selected Reviews: (a) J.-P. Wan, D. Hu, Y, Liu and S. Sheng,
ChemCatChem, 2015, 7, 901; (b) Y. Jiang and C. Kuang, Mini-
Rev. Med. Chem., 2013, 13, 713; (c) M. D. Hill, Name
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13 Selected Reviews: (a) Antitubercular: R. S.Keri, S. A. Patil, S.
Budagumpi and B. M. Nagaraja, Chem. Biol. Drug
Des., 2015, 86, 410; (b) Anticancer: M. A. Dar, S. Shrivastava
and P. F. Iqbal, World J. Pharm. Res., 2015, 4, 1949; (c)
Peptidomimetic: I. E. Valverde and T. L. Mindt,
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14 Selected Reviews: (a) P. I. P.
Elliott, Organomet.
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9
, 1357; (r) N. Lu, L. Meng,
, 1113; (s) M.
1
Bakthadoss, N. Sivakumar, A. Devaraj and D. S. Sharada,
Synthesis, 2011, 13, 2196.
17 Synthesis of dihydroarenofurans, selected articles: (a) I. C.
Chipoline, V. F. Ferreira and F. de. C. da Silva, Curr. Org.
Synth., 2015, 12, 565; (b) M. Sadeghpour, A. Olyaei, J.
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C. Jarava-Barrera, F. Esteban, C. Navarro-Ranninger, A. Parra
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Xu, J. An, X, Jia, X. Wang and C. Wang, J. Org.
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(a) Terphenyls: E. Gopi and I. N. N. Namboothiri, J. Org.
Chem., 2014, 79, 7468; (b) Cyclopentenes: L. F. Yeh, S. Anwar
and K. Chen, Tetrahedron, 2012, 68, 7317; Bicyclic skeletons:
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(a) Imidazopyridines: D. K. Nair, S. M. Mobin and I. N. N.
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Org. Lett., 2012, 14
,
4580; (b)
Pyranonaphthaquinones: D. K. Nair, R. F. S. Menna‐Barreto,
E. N. da Silva Júnior, S. M. Mobin and I. N. N. Namboothiri,
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Y.-J. Ke and K. Chen, Asian J. Org. Chem., 2013, 2, 330; (e) T.
10 | J. Name., 2012, 00, 1-3
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Organic & Biomolecular Chemistry
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Journal Name
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View Article Online
DOI: 10.1039/C5OB02656C
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