Iron(III) chloride catalyzed synthesis of functionalized spiropyrimidines

Article abstract of DOI:10.1055/s-0033-1338533

Potentially bioactive pyrimidine-annulated spiroheterocyclic compounds are synthesized in good to excellent yields using readily available, cheap and environmentally friendly iron(III) chloride (FeCl₃) as the catalyst. The process is straightforward and provides a diverse range of spiropyrimidine derivatives via the 5-endo-dig mode of cyclization, starting from simple and easily available starting materials. Georg Thieme Verlag Stuttgart, New York.

Full text of DOI:10.1055/s-0033-1338533

3164▌
PAPER
paper
Iron(III) Chloride Catalyzed Synthesis of Functionalized Spiropyrimidines
Synthesis of Functionalized Spiropyrimidines
K. C. Majumdar,* Sudipta Ponra, Tapas Ghosh
Department of Chemistry, University of Kalyani, Kalyani 741235, West Bengal, India
Fax +91(33)25828282; E-mail: kcm@klyuniv.ac.in
Received: 31.05.2013; Accepted after revision: 22.08.2013
strating anticancer and anti-HIV properties.12
Abstract: Potentially bioactive pyrimidine-annulated spirohetero-
Spiropyrimidine13 derivatives possess desirable pharma-
cyclic compounds are synthesized in good to excellent yields using
cological properties due to the presence of both the spiro
framework and pyrimidine nucleus. Our earlier reported
readily available, cheap and environmentally friendly iron(III) chlo-
ride (FeCl3) as the catalyst. The process is straightforward and pro-
vides a diverse range of spiropyrimidine derivatives via the 5-endo- procedures for the synthesis of spiropyrimidines involved
either multistep14a or harsh reaction conditions.14b In con-
tinuation of our research on the development of easier
dig mode of cyclization, starting from simple and easily available
starting materials.
Key words: spiropyrimidines, iron(III) chloride, 5-endo-dig cycli-
zation, spiroheterocycles
methods for the synthesis of pharmacologically important
and potentially bioactive heterocyclic systems,15 we have
developed a simple and short protocol for the synthesis of
spiropyrimidine derivatives.
Heterocyclic compounds (natural and synthetic) play im-
portant roles in both drug discovery and chemical biology.
The spiro framework is an important subunit in many nat-
ural products including (–)-sibirine, nankakurine A (a
fused tetracyclic lycopodium alkaloid), β-vetivone, acore-
none B, halichlorine and (–)-cephalotaxine (Figure 1).1,2
Several spirocyclic compounds show, inter alia, anti-
inflammatory3 and herbicidal activity,4 whereas others are
known to act as aromatase inhibitors.5 Additionally, the
spirocyclic moiety has been incorporated into structures
during the synthesis of new ligands and catalysts, for ex-
ample, spirobisoxazolines, SPINOL, SPINOL-derived
phosphoric acids, etc.6–8 The selective construction of the
spiro fragment presents a challenge during the syntheses
of these types of alkaloids and various related products.9
Due to the often high cost and toxicity of palladium and
copper catalysts, the development of sustainable, environ-
mentally friendly and economic C–C and C–X bond-
forming protocols have attracted significant attention in
organic chemistry. Due to their ease of availability, low
price, sustainability and the fact that they are environmen-
tally benign, iron salts have received considerable atten-
tion as alternative and promising catalysts for many
organic transformations.16 Among various iron salts, fer-
ric chloride has been used as a Lewis acid to catalyze the
Friedel–Crafts reaction,17 the synthesis of esters and ace-
tals,18 the α-glycosidation of peracetylated sugars,19 and
the cyclization of 2-(trimethylsilylmethyl)pentadienal.20
Therefore, we considered it of interest to investigate
whether ferric chloride would catalyze the cyclization of
various aryl propargyl derivatives.
The substrates for the present investigation were accessed
by using our previously published procedure.14,21 As com-
pounds 1 gave substituted quinoline derivatives 2 via
iron(III) chloride (FeCl3) mediated cyclization,21 we en-
visaged that compound 3 would also undergo a similar
type of reaction to give cyclized product 4. However, in
practice, the anticipated reaction did not occur. This un-
successful attempt led us to investigate the similar reac-
tion of derivative 5 with iron(III) chloride (1 equiv, 24 h),
which afforded a mixture of products 6, 7 and 8. Once
again, we did not obtain the expected product, but inter-
estingly, compound 8 (obtained in a low 15% yield) was
found to possess a spirocyclic structure. This observation
inspired us to attempt the iron(III) chloride mediated reac-
tion of the analogous substrate 9a. This reaction yielded
the unusual product 10a, exclusively, in 74% yield; the
expected product 11 was not obtained (Scheme 1). The
structure of product 10a was confirmed from its spectral
and analytical data. The IR spectrum showed the presence
of a hydroxy group at 3272 cm–1, which was further con-
firmed by 1H NMR spectroscopy following deuterium ox-
ide (D2O) exchange. After establishing the exact structure
O
N
O
O
N
H
O
H
HO
OMe
Cl
HO
halichlorine
(–)-cephalotaxine
Figure 1 Some representative natural products containing a spiro
framework
The pyrimidine moiety is the active core of various nucle-
ic acids and plays important roles in the biological, phar-
maceutical and agrochemical sectors.10,11 The
introduction of functionality at the C-5 and C-6 positions
of uracil leads to biologically interesting molecules. A
number of 5-substituted uracil molecules such as (E)-5-
(2-bromovinyl)-20-deoxyuridine (BVDU), zidovudine
and stavudine are well-known therapeutic agents demon-
SYNTHESIS 2013, 45, 3164–3172
Advanced online publication: 24.09.2013
DOI: 10.1055/s-0033-1338533; Art ID: SS-2013-Z0379-OP
© Georg Thieme Verlag Stuttgart · New York
0
0
3
9
-
7
8
8
1
1
4
3
7
-
2
1
0
X

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Synthesis of Functionalized Spiropyrimidines
3165
Ts
N
N
FeCl3 (1 equiv)
DCE, reflux
(previous work21
)
R1
R1
2
1
R2
R2
Me
N
O
O
N
Me
N
Me
Me
O
N
N
FeCl3 (1 equiv)
DCE, reflux
(expected but not formed)
O
N
Me
Me
3
4
OMe
OMe
Ts
N
O
Ts
O
Ts
O
N
Ts
N
O
Me
O
NH
Me
N
Ph
Me
O
Me
O
N
N
N
FeCl3 (1 equiv)
N
+
+
O
DCE, reflux, 24 h
Ph
N
O
N
N
OH
Me
Me
Me
Me
Ph
O
7 (20%)
6 (60%)
5
8 (15%)
O
Me
N
O
Me
N
O
Me
O
Et
O
N
Et
N
O
Et
FeCl3 (1 equiv)
DCE, reflux
N
N
+
N
Ph
O
N
O
N
Et
OH
Ph
Et
Ph
Et
9a
10a (74%)
(unexpected but formed)
11
(expected but not formed)
Scheme 1
Table 1 Optimization of the Reaction Conditions
of the cyclized product, we screened several reaction pa-
rameters in order to optimize the conditions.
O
O
Me
N
Me
N
O
Et
O
We started our investigations with alkyne 9a as a model
substrate and the results are summarized in Table 1. When
compound 9a was treated with one equivalent of iron(III)
chloride, a 74% yield of the spirocyclic product 10a was
obtained. Increasing or decreasing the number of equiva-
lents of iron(III) chloride (from 0.2–2.0 equiv) did not ap-
preciably affect the yield of the final product 10a (Table
1, entries 1–4). The reaction time (at reflux temperature)
was also varied with the best yield of 10a being obtained
after refluxing for two hours (Table 1, entries 1 and 6–8).
The reaction did not proceed at room temperature (Table
1, entry 5). Next, the effect of the solvent (EtOH, CHCl3,
CH2Cl2, THF, MeCN) on the yield of the spiropyrimidine
derivative 10a was studied (Table 1, entries 9–13).
Among these solvents, acetonitrile was found to give
highest yield (94%) of the product (Table 1, entry 13). The
same reaction was also performed in the presence of other
catalysts [Fe(NO3)3, Fe2(SO4)3, FeCl3·6H2O, AgSbF6,
CuI, AlCl3, InCl3] under similar reaction conditions, but
with no improvement in the yield of the spiropyrimidine
(Table 1, entries 15–21). The optimized conditions were
as follows: iron(III) chloride (0.1 equiv), acetonitrile, re-
flux (open to air), with a reaction time of two hours.
N
Et
N
O
N
Ph
O
N
OH
Et
Ph
Et
9a
10a
Entry Catalyst (equiv) Solvent Temp Time (h) Yield (%)b
1
FeCl3 (1.0)
FeCl3 (2.0)
FeCl3 (0.5)
FeCl3 (0.2)
FeCl3 (0.1)
FeCl3 (0.1)
FeCl3 (0.1)
FeCl3 (0.1)
FeCl3 (0.1)
FeCl3 (0.1)
FeCl3 (0.1)
FeCl3 (0.1)
DCE
DCE
DCE
DCE
DCE
DCE
DCE
DCE
EtOH
CHCl3
reflux
reflux
reflux
reflux
r.t.
2
2
2
2
2
5
3
4
2
2
2
2
74
75
73
74
0
2
3
4
5
6
reflux
reflux
reflux
reflux
reflux
73
73
73
35
58
42
49
7
8
9
10
11
12
CH2Cl2 reflux
THF reflux
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, 3164–3172

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K. C. Majumdar et al.
PAPER
Table 1 Optimization of the Reaction Conditions (continued)
To test the scope and generality of this unusual reaction,
substrates 9b–f were subjected to the optimized reaction
conditions and the results are summarized in Table 2. The
reactions of alkynes 9b–d and 9f (X = NMe, NEt,
Y = CO) gave spirocycles 10b–d and 10f in 88–92%
yields. However, substrate 9e gave a slightly lower 82%
yield of the corresponding product 10e after three hours.
The reactions failed completely with substrates 3
(X = NMe, Y = CH2), 9g (X = NH, Y = CO) and 12
(X = O, Y = CO), and the starting materials were recov-
ered in each case. Substrates 13a–i (X = O, Y = CH2)
were treated under the optimized reaction conditions and,
pleasingly, the substituted spiropyrimidine derivatives
14a–i were obtained in 71–93% yields. In contrast, al-
kynes 13j (R = Me) and 13k (R = H) remained unreacted
(even after 4 h) under the optimized conditions. From the
results in Table 2, it is apparent that substrates which con-
tain electron-donating groups such as methoxy (OMe) and
ethoxy (OEt) on the aromatic substituent of the terminal
alkyne gave higher yields of the products in relatively
shorter reaction times, whereas the reaction failed com-
pletely when an aryl ring was not present on the terminal
alkyne.
O
O
Me
N
Me
N
O
N
Et
O
N
Et
N
O
N
Ph
O
OH
Et
Ph
Et
9a
10a
Entry Catalyst (equiv) Solvent Temp Time (h) Yield (%)b
13a
14
15
16
17
18
19
20
21
FeCl3 (0.1)
MeCN
MeCN
MeCN
MeCN
reflux
reflux
reflux
reflux
reflux
reflux
reflux
reflux
reflux
2
4
2
2
2
2
2
2
2
94
93
23
21
92
0
FeCl3 (0.1)
Fe(NO3)3 (0.1)
Fe2(SO4)3 (0.1)
FeCl3·6H2O (0.1) MeCN
AgSbF6 (0.1)
CuI (0.1)
MeCN
MeCN
MeCN
MeCN
34
21
41
AlCl3 (0.1)
InCl3 (0.1)
a Optimized reaction conditions.
b Yield of isolated product.
Table 2 Synthesis of Various Spiroheterocycles
O
O
Y
R1
O
X
X
R1
O
N
Y
R
N
FeCl3 (0.1 equiv)
MeCN, reflux
N
R2
R
N
OH
R2
Entry
1
Substrate
Time (h)
Product
Yield
94
O
O
Me
Me
N
O
Et
N
O
N
N
Et
N
N
9a
2
10a
O
N
Ph
O
O
N
OH
Et
Ph
Et
O
Et
N
Et
N
O
Et
O
Et
2
3
4
9b
9c
9d
2
2
2
10b
10c
10d
89
92
91
O
N
Ph
O
O
N
OH
Et
Ph
Me
Et
O
Me
N
O
Me
O
N
O
N
Me
O
N
N
Ph
O
N
OH
Me
Ph
Ph
Me
O
Et
N
Et
N
O
Me
O
O
N
Me
O
N
N
Ph
OH
N
Me
Me
Synthesis 2013, 45, 3164–3172
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Synthesis of Functionalized Spiropyrimidines
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Table 2 Synthesis of Various Spiroheterocycles (continued)
O
O
Y
R1
O
X
X
R1
O
N
Y
R
N
FeCl3 (0.1 equiv)
MeCN, reflux
N
R2
R
N
OH
R2
Entry
5
Substrate
Time (h)
Product
Yield
82
Et
N
Ph
HO
O
O
9e
3
10e
N
O
N
Et
O
N
Et
Et
Ph
O
O
Me
Me
O
Me
O
N
O
N
N
N
Me
O
N
6
9f
2
10f
88
N
Ph
N
OH
Et
Ph
Et
O
H
N
Me
O
O
7
8
9g
12
2
2
–
0
0
N
Me
Ph
O
O
Me
O
O
N
–
N
Me
Ph
O
Me
O
O
O
O
O
N
N
N
N
O
O
Me
N
N
N
N
N
9
13a
13b
13c
13d
2
14a
14b
14c
14d
93
92
91
91
Me
O
N
OH
OEt
Me
OEt
OMe
OMe
OEt
O
Me
O
O
O
Me
O
N
10
11
12
2
Me
N
OH
OMe
OMe
OEt
Me
O
Me
O
O
O
Me
O
N
2.5
Et
N
OH
Et
O
Me
O
O
O
Me
O
N
2.5
Et
N
OH
Et
© Georg Thieme Verlag Stuttgart · New York
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K. C. Majumdar et al.
PAPER
Table 2 Synthesis of Various Spiroheterocycles (continued)
O
O
Y
R1
O
X
X
R1
O
N
Y
R
N
FeCl3 (0.1 equiv)
MeCN, reflux
N
R2
R
N
OH
R2
Entry
Substrate
Time (h)
Product
Yield
O
Me
O
O
N
O
O
Me
O
N
N
13
13e
3
14e
86
Me
N
OH
Me
Me
Me
O
Et
O
N
O
O
Et
O
O
N
N
14
15
16
13f
13g
13h
3
14f
14g
14h
84
79
78
Et
N
OH
Me
Et
Me
O
N
Me
O
O
O
N
O
Me
O
N
3
Me
N
OH
Me
O
Et
O
O
O
N
O
Et
O
N
N
3.5
Et
N
OH
Et
O
Me
O
O
N
O
O
Me
O
N
N
17
13i
3.5
14i
71
Me
N
OH
Cl
Me
Cl
O
Me
O
O
O
N
N
18
19
13j
4
4
–
0
0
N
Et
Me
O
Me
O
13k
–
N
Me
The structures of these unusual products were confirmed J = 6.4 Hz, 1 H) ppm for the hydroxy group and the meth-
by spectroscopic studies and elemental analyses. The 1H ine hydrogen at C-10. On deuterium oxide exchange, the
NMR spectrum of compound 10a showed two character- doublet at δ = 7.24 disappeared and the doublet at δ = 4.93
istic doublets at δ = 4.93 (d, J = 6.0 Hz, 1 H) and 7.24 (d, collapsed into a one-proton singlet at δ = 4.91, which con-
Synthesis 2013, 45, 3164–3172
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Synthesis of Functionalized Spiropyrimidines
3169
firmed the presence of the hydroxy group at position C-10 lyzed 5-endo-dig intramolecular cyclization of easily
1
of the spiropyrimidine derivative. In the H NMR spec- available starting materials gives a diverse range of poten-
trum of compound 14a two characteristic doublets were tially bioactive spiropyrimidine derivatives in good to ex-
present at δ = 3.18 (d, J = 3.2 Hz, 1 H) and 4.77 (d, J = 3.2 cellent yields. This process utilizes simple starting
Hz, 1 H). On deuterium oxide exchange, the doublet at δ materials and a readily available, cheap and environmen-
= 3.18 disappeared and the doublet at δ = 4.77 appeared as tally benign catalyst.
a one-proton singlet at δ = 4.78. The IR spectrum of 14a
exhibited an absorption at 3428 cm–1 due to the hydroxy
Silica gel [Rankem (India), 60–120 mesh or 230–400 mesh] was
group. Additional support for the structures of the spiro-
pyrimidine derivatives came from matching the melting
points, mixed melting points, and the spectral data of the
newly synthesized compounds 14f–i with our earlier re-
ported compounds.14b During the preparation of this man-
uscript we became aware of the work of Yeh et al.22 in
which they reported the iron(III) chloride promoted cycli-
zation/chlorination of cyclic tosylamine-tethered 8-aryl-
2-en-7-yn-1-ols affording an azaspiro system. However,
these reactions resulted in halogenations and vinyl substi-
tution, which was not observed in our case.
used for chromatographic separation. Silica gel GF-254 [CDH (In-
dia)] was used for TLC. Petroleum ether (PE) refers to the fraction
boiling between 60–80 °C. Melting points were determined in open
capillaries using a metal bath apparatus [Sunbeam (India)] and are
uncorrected. IR spectra were run as KBr discs on a Perkin-Elmer
120-000A spectrometer. 1H and 13C NMR spectra were recorded on
a Bruker DPX-400 instrument as solutions in CDCl3 or DMSO-d6
with TMS as the internal standard. Mass spectra were recorded on
a Q-TOF Micro instrument. CHN analyses were obtained using a
Perkin Elmer 2400 series II CHN Analyzer.
Spiropyrimidines; General Procedure
To a stirred solution of FeCl3 (1 equiv) in MeCN (2 mL) was added
alkyne 9 or 13 (100 mg) at r.t., and the resulting mixture was stirred
at 80 °C under an air atmosphere for the appropriate amount of time
(see Table 2). After completion of the reaction as monitored by
TLC, the mixture was allowed to cool and extracted with CH2Cl2
(3 × 25 mL). The combined organic extract was washed with brine
(25 mL) and dried over Na2SO4. The solvent was removed by dis-
tillation and the resulting crude residue purified by filtration
through a pad of silica gel (60–120 mesh, PE–EtOAc) to give the
pure product 10 or 14.
A proposed reaction mechanism for the iron(III) chloride
catalyzed formation of the spiropyrimidine derivatives is
shown in Scheme 2. Initially, the alkyne moiety may be
activated by iron(III) chloride to generate the π-complex
A,21 which following intramolecular 5-endo-dig cycliza-
tion may produce the charged species B.14b The involve-
ment of a lone pair of electrons on one of the nitrogen
atoms of the pyrimidine ring may facilitate this mode of
cyclization by formation of the Mannich species B. Final-
ly, hydrolysis of the imino bond from the opposite side to
the R2 substituent (to avoid steric crowding) can afford the
spiropyrimidine derivatives. In order to determine the
source of the water for the hydrolysis step, we carried out
the reaction of substrate 9a using the optimized reaction
conditions, but in the presence of 4 Å molecular sieves un-
der a nitrogen atmosphere. On this occasion the reaction
failed completely, and thus we can conclude that the water
is derived from the solvent or from moisture in the atmo-
sphere.
5-{[3-(4-Methoxyphenyl)prop-2-yn-1-yl](methyl)amino}-1,3-
dimethylpyrimidine-2,4(1H,3H)-dione (3)
Yield: 139 mg (92%); gray solid; mp 98–100 °C.
IR (KBr): 2991, 2220, 1702, 1646 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.76 (s, 3 H), 3.38 (s, 3 H), 3.40
(s, 3 H), 3.80 (s, 3 H), 4.20 (s, 2 H), 6.74 (s, 1 H), 6.83 (d, J = 8.0
Hz, 2 H), 7.33 (d, J = 8.0 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 28.3, 37.1, 39.5, 44.0, 55.3, 82.4,
85.7, 113.9, 114.9, 125.4, 130.2, 133.1, 150.8, 159.6, 161.1.
MS (EI): m/z = 313.0 (100%) [M]+.
Anal. Calcd for C17H19N3O3: C, 65.16; H, 6.11; N, 13.41. Found: C,
65.33; H, 6.05; N, 13.34.
In conclusion, we have successfully developed a new,
straightforward, inexpensive and efficient methodology
for the regioselective synthesis of substituted pyrimidine-
annulated spiroheterocycles. This iron(III) chloride cata-
N-(1,3-Dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-
4-methyl-N-(3-phenylprop-2-yn-1-yl)benzenesulfonamide (5)
Yield: 112 mg (92%); light gray solid; mp 122–124 °C.
O
O
O
Y
X
R1
O
X
R1
O
X
R1
N
Y
5-endo-dig
FeCl3
N
Y
N
FeCl3
N
R2
Ar
N
R2
O
N
FeCl3
R2
Ar
Ar
H2O
FeCl3
B
A
– H
O
Y
X
R1
N
R
O
N
R2
OH
Scheme 2 A plausible mechanism for the iron(III) chloride mediated synthesis of the spiropyrimidine derivatives
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, 3164–3172

3170
K. C. Majumdar et al.
PAPER
IR (KBr): 3066, 1716, 1656, 1597 cm–1.
MS (ESI): m/z = 284.0 (36%) [M + H]+, 306.1 (100%) [M + Na]+.
1H NMR (400 MHz, CDCl3): δ = 2.43 (s, 3 H), 3.26 (s, 3 H), 3.43
(s, 3 H), 4.62 (s, 2 H), 7.26–7.37 (m, 7 H), 7.60 (s, 1 H), 7.73 (d,
J = 7.6 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 21.6, 28.2, 37.5, 39.6, 83.5, 85.4,
111.2, 122.2, 127.6, 128.3, 128.6, 129.5, 131.6, 135.8, 144.0, 146.5,
150.9, 160.2.
Anal. Calcd for C15H13N3O3: C, 63.60; H, 4.63; N, 14.83. Found: C,
63.49; H, 4.68; N, 14.77.
7,9-Diethyl-10-hydroxy-1-methyl-4-phenyl-1,7,9-triazaspi-
ro[4.5]dec-3-ene-2,6,8-trione (10a)
Yield: 99 mg (94%); colorless solid; mp 220–222 °C.
IR (KBr): 3272, 1717, 1678 cm–1.
1H NMR (400 MHz, DMSO-d6): δ = 0.72 (t, J = 7.2 Hz, 3 H), 1.15
(t, J = 7.2 Hz, 3 H), 2.81–2.85 (m, 1 H), 2.91 (s, 3 H), 2.92–3.05 (m,
1 H), 3.78 (q, J = 6.8 Hz, 2 H), 4.93 (d, J = 6.0 Hz, 1 H), 6.39 (s, 1
H), 7.14 (d, J = 6.4 Hz, 2 H), 7.24 (d, J = 6.4 Hz, 1 H), 7.36 (d,
J = 6.8 Hz, 3 H).
MS (ESI): m/z = 424.0 (10%) [M + H]+.
Anal. Calcd for C22H21N3O4S: C, 62.40; H, 5.00; N, 9.92. Found: C,
62.29; H, 5.04; N, 9.99.
N-(1,3-Dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-
4-methyl-N-(3-oxo-3-phenylpropyl)benzenesulfonamide (6)
Yield: 62.5 mg (60%); colorless solid; mp 88–90 °C.
IR (KBr): 3072, 1713, 1680, 1659, 1599 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.42 (s, 3 H), 3.21 (s, 3 H), 3.32
(t, J = 6.4 Hz, 2 H), 3.37 (s, 3 H), 3.95 (t, J = 6.4 Hz, 2 H), 7.28 (d,
J = 8.4 Hz, 2 H), 7.36 (s, 1 H), 7.47 (t, J = 7.6 Hz, 2 H), 7.59 (t,
J = 7.2 Hz, 1 H), 7.69 (d, J = 8.4 Hz, 2 H), 7.92 (d, J = 7.2 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 21.6, 28.2, 37.4, 38.8, 45.3,
112.5, 127.7, 128.0, 128.7, 129.5, 133.4, 135.7, 136.5, 143.9, 146.1,
150.9, 160.2, 198.2.
Following D2O exchange the signal at δ = 7.24 disappeared and the
resonance at δ = 4.93 was transformed into a singlet at δ = 4.91.
13C NMR (100 MHz, CDCl3): δ = 12.9, 13.3, 29.9, 37.6, 42.2, 74.8,
82.2, 125.9, 127.0, 128.8, 130.0, 131.9, 151.0, 158.2, 163.7, 172.7.
MS (EI): m/z = 343.0 (100%) [M]+.
Anal. Calcd for C18H21N3O4: C, 62.96; H, 6.16; N, 12.24. Found: C,
63.08; H, 6.12; N, 12.14.
1,7,9-Triethyl-10-hydroxy-4-phenyl-1,7,9-triazaspiro[4.5]dec-
3-ene-2,6,8-trione (10b)
Yield: 93.7 mg (89%); colorless solid; mp 226–228 °C.
MS (ESI): m/z = 464.2 (100%) [M + Na]+.
IR (KBr): 3281, 1720, 1672 cm–1.
Anal. Calcd for C22H23N3O5S: C, 59.85; H, 5.25; N, 9.52. Found: C,
60.09; H, 5.18; N, 9.61.
1H NMR (400 MHz, CDCl3): δ = 0.88 (t, J = 7.2 Hz, 3 H), 1.25–
1.33 (m, 6 H), 3.10 (q, J = 7.2 Hz, 2 H), 3.34 (q, J = 7.2 Hz, 1 H),
3.64 (q, J = 7.2 Hz, 1 H), 3.93–3.99 (m, 2 H), 4.85 (s, 2 H), 6.21 (s,
1 H), 7.10 (d, J = 7.6 Hz, 2 H), 7.34–7.39 (m, 3 H).
10-Hydroxy-7,9-dimethyl-4-phenyl-1-tosyl-1,7,9-triazaspi-
ro[4.5]dec-3-ene-6,8-dione (8)
Yield: 15.6 mg (15%); light gray solid; mp 168–170 °C.
IR (KBr): 3416, 2924, 1716, 1675 cm–1.
13C NMR (100 MHz, CDCl3): δ = 12.8, 13.3, 13.6, 37.6, 40.2, 42.1,
75.5, 81.8, 126.7, 126.9, 128.8, 129.9, 132.1, 151.1, 158.0, 164.4,
172.6.
1H NMR (400 MHz, CDCl3): δ = 2.44 (s, 3 H), 2.74 (s, 3 H), 3.20
(s, 3 H), 3.50 (dd, J = 4.0 Hz, 11.2 Hz, 1 H), 4.01 (t, J = 8.8 Hz, 1
H), 4.30 (t, J = 8.8 Hz, 1 H), 4.98 (d, J = 9.2 Hz, 1 H), 7.36 (d,
J = 8.4 Hz, 2 H), 7.48 (t, J = 8.0 Hz, 2 H), 7.62 (t, J = 8.4 Hz, 2 H),
7.85 (d, J = 7.8 Hz, 2 H), 8.01 (d, J = 8.4 Hz, 2 H).
MS (ESI): m/z = 380.0 (66%) [M + Na]+.
Anal. Calcd for C19H23N3O4: C, 63.85; H, 6.49; N, 11.76. Found: C,
63.64; H, 6.41; N, 11.82.
MS (ESI): m/z = 464.2 (100%) [M + Na]+.
10-Hydroxy-1,7,9-trimethyl-4-phenyl-1,7,9-triazaspi-
ro[4.5]dec-3-ene-2,6,8-trione (10c)
Yield: 97.6 mg (92%); colorless solid; mp 216–218 °C.
Anal. Calcd for C22H23N3O5S: C, 59.85; H, 5.25; N, 9.52. Found: C,
60.01; H, 5.29; N, 9.59.
IR (KBr): 3269, 1715, 1677 cm–1.
Compounds 9 were prepared according to an earlier published pro-
cedure; compounds 9a–e are known.14a
1H NMR (400 MHz, CDCl3): δ = 2.60 (s, 3 H), 3.08 (s, 3 H), 3.28
(s, 3 H), 4.75 (d, J = 5.2 Hz, 1 H), 5.33 (d, J = 5.6 Hz, 1 H), 6.19 (s,
1 H), 6.99 (d, J = 6.4 Hz, 2 H), 7.39 (d, J = 6.8 Hz, 3 H).
13C NMR (100 MHz, CDCl3): δ = 28.4, 29.9, 33.5, 75.2, 83.5,
126.2, 126.4, 128.7, 129.8, 132.1, 151.4, 158.3, 164.3, 172.2.
N-(1-Ethyl-3-methyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-
yl)-N-methyl-3-phenylpropiolamide (9f)
Yield: 160 mg (94%); colorless solid; mp 94–96 °C.
IR (KBr): 2214, 1656, 1651, 1593 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.23–1.38 (m, 3 H), 3.24 (s, 3 H),
3.42 (s, 3 H), 3.83–3.88 (m, 2 H), 7.33 (s, 3 H), 7.39–7.46 (m, 2 H),
7.48 (s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 14.5, 28.5, 35.1, 45.3, 82.0, 91.1,
117.4, 120.0, 128.6, 130.3, 132.3, 132.5, 141.8, 150.6, 160.5.
MS (ESI): m/z = 338.1 (36%) [M + Na]+.
Anal. Calcd for C16H17N3O4: C, 60.94; H, 5.43; N, 13.33. Found: C,
60.77; H, 5.40; N, 13.40.
1-Ethyl-10-hydroxy-7,9-dimethyl-4-phenyl-1,7,9-triazaspi-
ro[4.5]dec-3-ene-2,6,8-trione (10d)
Yield: 96 mg (91%); colorless solid; mp 212–214 °C.
MS (ESI): m/z = 312.0 (100%) [M + H]+.
IR (KBr): 3283, 1719, 1675 cm–1.
Anal. Calcd for C17H17N3O3: C, 65.58; H, 5.50; N, 13.50. Found: C,
65.34; H, 5.39; N, 13.66.
1H NMR (400 MHz, CDCl3): δ = 0.86 (t, J = 7.2 Hz, 3 H), 2.94–
3.07 (m, 5 H), 3.26 (s, 3 H), 4.84 (d, J = 4.8 Hz, 1 H), 5.20 (d,
J = 4.8 Hz, 1 H), 6.21 (s, 1 H), 7.02 (d, J = 6.8 Hz, 2 H), 7.39 (t,
J = 6.8 Hz, 3 H).
N-(1,3-Dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)-
3-phenylpropiolamide (9g)
Yield: 168 mg (92%); colorless solid; mp 184–186 °C.
IR (KBr): 3278, 2218, 1669, 1655, 1591 cm–1.
1H NMR (400 MHz, CDCl3): δ = 3.41 (s, 3 H), 3.44 (s, 3 H), 7.38–
7.45 (m, 3 H), 7.57 (d, J = 6.8 Hz, 2 H), 8.20 (s, 1 H), 8.49 (s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 13.6, 28.4, 33.3, 40.1, 75.8, 83.0,
126.4, 126.9, 128.7, 129.7, 132.1, 151.5, 157.7, 164.9, 172.4.
MS (ESI): m/z = 352.2 (76%) [M + Na]+.
13C NMR (100 MHz, CDCl3): δ = 28.5, 37.5, 82.5, 86.9, 113.9,
119.6, 128.6, 130.6, 130.7, 132.7, 149.8, 150.7, 159.4.
Anal. Calcd for C17H19N3O4: C, 62.00; H, 5.81; N, 12.76. Found: C,
61.87; H, 5.87; N, 12.87.
Synthesis 2013, 45, 3164–3172
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Synthesis of Functionalized Spiropyrimidines
3171
1,1′-Diethyl-5′-hydroxy-3-phenyl-1′H-spiro[pyrrole-2,6′-quin-
oline]-2′,5(1H,5'H)-dione (10e)
13C NMR (100 MHz, CDCl3): δ = 28.3, 37.0, 55.3, 60.1, 82.0, 88.5,
114.0, 130.9, 132.3, 133.3, 150.7, 160.0, 160.2.
MS (ESI): m/z = 301.1 (39%) [M + H]+.
Yield: 86.3 mg (82%); colorless solid; mp 192–196 °C.
IR (KBr): 3291, 1693, 1651, 1620 cm–1.
Anal. Calcd for C16H16N2O4: C, 63.99; H, 5.37; N, 9.33. Found: C,
63.78; H, 5.42; N, 9.39.
1H NMR (400 MHz, CDCl3): δ = 1.03 (t, J = 7.2 Hz, 3 H), 1.36 (t,
J = 7.2 Hz, 3 H), 3.63 (d, J = 5.6 Hz, 2 H), 4.31–4.39 (m, 3 H), 6.38
(s, 1 H), 6.73 (d, J = 9.6 Hz, 1 H), 6.84 (d, J = 8.4 Hz, 1 H), 7.20–
7.25 (m, 2 H), 7.34–7.41 (m, 3 H), 7.46 (t, J = 7.2 Hz, 2 H), 7.65 (d,
J = 10.0 Hz, 1 H).
13C NMR (100 MHz, CDCl3): δ = 12.4, 12.7, 37.6, 44.6, 77.2,
114.4, 120.8, 122.9, 126.4, 128.2, 128.8, 129.0, 130.1, 133.7, 134.0,
135.3, 138.18, 138.21, 161.6, 163.6.
1-Ethyl-5-{[3-(4-methoxyphenyl)prop-2-yn-1-yl]oxy}-3-meth-
ylpyrimidine-2,4(1H,3H)-dione (13c)
Yield: 124 mg (82%); light yellow solid; mp 134–136 °C.
IR (KBr): 2221, 1714, 1653, 1642 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.26 (t, J = 7.2 Hz, 3 H), 3.37 (s,
3 H), 3.76–3.81 (m, 5 H), 4.88 (s, 2 H), 6.84 (d, J = 8.4 Hz, 2 H),
7.11 (s, 1 H), 7.34 (d, J = 8.4 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 14.2, 28.2, 44.8, 55.3, 60.0, 81.9,
88.6, 114.0, 128.4, 129.8, 132.3, 133.2, 150.2, 160.0, 160.2.
MS (ESI): m/z = 384.8 (100%) [M + Na]+.
Anal. Calcd for C22H22N2O3: C, 72.91; H, 6.12; N, 7.73. Found: C,
73.09; H, 6.07; N, 7.66.
MS (ESI): m/z = 337.0 (100%) [M + Na]+.
9-Ethyl-10-hydroxy-1,7-dimethyl-4-phenyl-1,7,9-triazaspi-
ro[4.5]dec-3-ene-2,6,8-trione (10f)
Yield: 93 mg (88%); colorless solid; mp 170–172 °C.
Anal. Calcd for C17H18N2O4: C, 64.96; H, 5.77; N, 8.91. Found: C,
64.72; H, 5.71; N, 8.82.
IR (KBr): 3328, 1720, 1675 cm–1.
5-{[3-(4-Ethoxyphenyl)prop-2-yn-1-yl]oxy}-1-ethyl-3-methyl-
pyrimidine-2,4(1H,3H)-dione (13d)
1H NMR (400 MHz, CDCl3): δ = 0.85–0.86 (m, 3 H), 3.08 (s, 5 H),
3.42 (s, 3 H), 4.85 (s, 1 H), 5.30 (br s, 1 H), 6.22 (s, 1 H), 7.03 (s, 2
H), 7.38–7.40 (m, 3 H).
13C NMR (100 MHz, CDCl3): δ = 12.9, 28.5, 30.0, 42.5, 74.9, 82.4,
126.1, 126.7, 128.9, 130.0, 132.0, 151.2, 158.6, 164.3, 172.3.
Yield: 134 mg (85%); light yellow solid; mp 122–124 °C.
IR (KBr): 2231, 1715, 1653, 1641 cm–1.
1H NMR (400 MHz, CDCl3): δ = 1.27 (t, J = 7.2 Hz, 3 H), 1.41 (t,
J = 6.8 Hz, 3 H), 3.38 (s, 3 H), 3.80 (q, J = 7.2 Hz, 2 H), 4.04 (q,
J = 6.8 Hz, 2 H), 4.89 (s, 2 H), 6.83 (d, J = 8.4 Hz, 2 H), 7.12 (s, 1
H), 7.34 (d, J = 8.4 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 14.2, 14.7, 28.2, 44.8, 60.1, 63.5,
81.9, 88.7, 113.7, 114.5, 129.9, 132.3, 133.2, 150.2, 159.4, 160.2.
MS (ESI): m/z = 330.0 (50%) [M + H]+.
Anal. Calcd for C17H19N3O4: C, 62.00; H, 5.81; N, 12.76. Found: C,
62.23; H, 5.72; N, 12.87.
1,3-Dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl 3-
Phenylpropiolate (12)
MS (ESI): m/z = 351.3 (100%) [M + Na]+.
Yield: 136.5 mg (75%); white crystalline solid; mp 130–132 °C.
Anal. Calcd for C18H20N2O4: C, 65.84; H, 6.14; N, 8.53. Found: C,
65.96; H, 6.11; N, 8.62.
IR (KBr): 2222, 1747, 1703, 1673, 1651 cm–1.
Compounds 13e–k were prepared according to the earlier published
1H NMR (400 MHz, CDCl3): δ = 3.39 (s, 3 H), 3.43 (s, 3 H), 7.30
(s, 1 H), 7.39–7.42 (m, 2 H), 7.45–7.50 (m, 1 H), 7.63 (d, J = 7.2 Hz,
1 H), 8.11 (d, J = 6.8 Hz, 1 H).
13C NMR (100 MHz, DMSO-d6): δ = 28.5, 37.2, 79.7, 89.7, 118.2,
128.7, 129.3, 129.7, 132.4, 133.6, 136.9, 151.3, 158.3.
procedure.14b
4-(4-Ethoxyphenyl)-10-hydroxy-7,9-dimethyl-1-oxa-7,9-diaza-
spiro[4.5]dec-3-ene-6,8-dione (14a)
Yield: 98.3 mg (93%); colorless solid; mp 138–140 °C.
IR (KBr): 3428, 1720, 1674 cm–1.
MS (ESI): m/z = 307.1 (100%) [M + Na]+.
1H NMR (400 MHz, CDCl3): δ = 1.40 (t, J = 7.2 Hz, 3 H), 2.81 (s,
3 H), 3.18 (d, J = 3.2 Hz, 1 H), 3.21 (s, 3 H), 4.01 (q, J = 7.2 Hz, 2
H), 4.77 (d, J = 3.2 Hz, 1 H), 4.90 (d, J = 13.2 Hz, 1 H), 5.12 (d,
J = 13.2 Hz, 1 H), 6.11 (s, 1 H), 6.82 (d, J = 8.4 Hz, 2 H), 6.93 (d,
J = 8.4 Hz, 2 H).
Anal. Calcd for C15H12N2O4: C, 63.38; H, 4.25; N, 9.85. Found: C,
63.57; H, 4.29; N, 9.80.
5-{[3-(4-Ethoxyphenyl)prop-2-yn-1-yl]oxy}-1,3-dimethyl-
pyrimidine-2,4(1H,3H)-dione (13a)
Yield: 139 mg (86%); light gray solid; mp 140–142 °C.
IR (KBr): 2227, 1712, 1655, 1643 cm–1.
Following D2O exchange the signal at δ = 3.18 disappeared and the
resonance at δ = 4.77 was transformed into a singlet at δ = 4.78.
1H NMR (400 MHz, CDCl3): δ = 1.41 (t, J = 7.3 Hz, 3 H), 3.38 (s,
6 H), 4.02 (q, J = 7.3 Hz, 2 H), 4.89 (s, 2 H), 6.84 (d, J = 8.7 Hz, 2
H), 7.11 (s, 1 H), 7.35 (d, J = 8.7 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 14.7, 28.3, 37.0, 60.0, 63.5, 81.9,
88.6, 113.7, 114.5, 130.8, 132.3, 133.3, 150.7, 159.4, 160.3.
13C NMR (100 MHz, CDCl3): δ = 14.7, 28.1, 33.9, 63.4, 76.2, 82.7,
89.6, 114.5, 124.1, 128.2, 128.4, 138.8, 151.6, 159.1, 168.7.
MS (EI): m/z = 332.0 (100%) [M]+.
Anal. Calcd for C17H20N2O5: C, 61.44; H, 6.07; N, 8.43. Found: C,
61.61; H, 6.12; N, 8.35.
MS (ESI): m/z = 337.0 (100%) [M + Na]+.
10-Hydroxy-4-(4-methoxyphenyl)-7,9-dimethyl-1-oxa-7,9-di-
azaspiro[4.5]dec-3-ene-6,8-dione (14b)
Yield: 97.5 mg (92%); colorless solid; mp 144–146 °C.
Anal. Calcd for C17H18N2O4: C, 64.96; H, 5.77; N, 8.91. Found: C,
64.81; H, 5.74; N, 8.99.
5-{[3-(4-Methoxyphenyl)prop-2-yn-1-yl]oxy}-1,3-dimethyl-
pyrimidine-2,4(1H,3H)-dione (13b)
IR (KBr): 3425, 1712, 1673 cm–1.
1H NMR (400 MHz, CDCl3): δ = 2.81 (s, 3 H), 3.18 (s, 1 H), 3.21
(s, 3 H), 3.79 (s, 3 H), 4.77 (s, 1 H), 4.90 (d, J = 13.2 Hz, 1 H), 5.12
(d, J = 13.2 Hz, 1 H), 6.11 (s, 1 H), 6.84 (d, J = 7.2 Hz, 2 H), 6.94
(d, J = 6.8 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 28.0, 33.9, 55.2, 76.1, 82.7, 89.7,
113.9, 124.4, 128.4, 132.0, 138.8, 151.6, 159.7, 168.8.
Yield: 130 mg (84%); light gray solid; mp 138–140 °C.
IR (KBr): 2228, 1717, 1658, 1647 cm–1.
1H NMR (400 MHz, CDCl3): δ = 3.38 (s, 6 H), 3.81 (s, 3 H), 4.89
(s, 2 H), 6.85 (d, J = 8.0 Hz, 2 H), 7.10 (s, 1 H), 7.36 (d, J = 8.0 Hz,
2 H).
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2013, 45, 3164–3172

3172
K. C. Majumdar et al.
PAPER
MS (ESI): m/z = 341.1 (100%) [M + Na]+.
(7) Fu, Y.; Xie, J.-H.; Hu, A.-G.; Zhou, H.; Wang, L.-X.; Zhou,
Q.-L. Chem. Commun. 2002, 480.
Anal. Calcd for C16H18N2O5: C, 60.37; H, 5.70; N, 8.80. Found: C,
60.21; H, 5.74; N, 8.89.
(8) (a) Hu, A.-G.; Fu, Y.; Xie, J.-H.; Zhou, H.; Wang, L.-X.;
Zhou, Q.-L. Angew. Chem. Int. Ed. 2002, 41, 2348.
(b) Amutha, P.; Nagarajan, S. Helv. Chim. Acta 2010, 93,
430. (c) Gozalishvili, L. L.; Beryozkina, T. V.; Omelchenko,
I. V.; Zubatyuk, R. I.; Shishkin, O. V.; Kolos, N. N.
Tetrahedron 2008, 64, 8759. (d) Dandia, A.; Jain, A. K.;
Sharma, S. RSC Adv. 2013, 3, 2924. (e) Kanawade, S. B.;
Patil, S. P.; Nikam, P. S.; Gangurde, S. A.; Jachak, M. N.;
Toche, R. B. J. Heterocycl. Chem. 2012, 49, 363.
(9) (a) Nieczypor, P.; Mol, J. C.; Bespalova, N. B.; Bubnov, Y.
N. Eur. J. Org. Chem. 2004, 812. (b) Krasnov, K. A.;
Kartsev, V. G. Chem. Nat. Compd. 2011, 46, 915.
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Barton, D.; Ollis, W. D., Eds.; Pergamon Press: Oxford,
1974, 493. (b) Sasaki, T.; Minamoto, K.; Sujuki, T.;
Yamashita, S. Tetrahedron 1980, 36, 865. (c) Bradshaw, T.
K.; Hutchinson, D. W. Chem. Soc. Rev. 1977, 6, 43.
(11) (a) Marumoto, R.; Furukawa, Y. Chem. Pharm. Bull. 1977,
25, 2974. (b) Cheng, C. C.; Roth, B. Prog. Med. Chem.
1971, 8, 61. (c) Jones, S. A.; Sayers, J. R.; Walker, R. T.; De
Clercq, E. J. Med. Chem. 1988, 31, 268.
(12) (a) Macilwain, C. Nature 1993, 365, 378. (b) Balzarini, J.;
Pauwels, R.; Hardewijn, P.; Clercq, E. D.; Cooney, D. A.;
Kanj, G. J.; Dalai, M.; Jones, D. G.; Breder, S. Biochem.
Biophys. Res. Commun. 1986, 140, 735.
(13) (a) Mangiavacchi, S.; Calistri, M. T. Ann. Chim. 1973, 63,
883. (b) Wolf, M.; Diebold, J. L. US Patent 3714093, 1973;
Chem. Abstr. 1973, 78, 111344. (c) Mamaev, V. P.; Borovik,
V. P.; Gorfinkel, M. I.; Ivanovskaya, L. Yu. Izv. Akad. Nauk
SSSR, Ser. Khim. 1970, 7, 1637.
9-Ethyl-10-hydroxy-4-(4-methoxyphenyl)-7-methyl-1-oxa-7,9-
diazaspiro[4.5]dec-3-ene-6,8-dione (14c)
Yield: 96.2 mg (91%); colorless solid; mp 132–134 °C.
IR (KBr): 3413, 1712, 1669 cm–1.
1H NMR (400 MHz, CDCl3): δ = 0.88 (t, J = 6.8 Hz, 3 H), 3.17 (s,
1 H), 3.20–3.25 (m, 5 H), 3.78 (s, 3 H), 4.79 (s, 1 H), 4.89 (d,
J = 13.2 Hz, 1 H), 5.13 (d, J = 13.2 Hz, 1 H), 6.10 (s, 1 H), 6.83 (d,
J = 8.0 Hz, 2 H), 6.93 (d, J = 7.6 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 13.2, 28.0, 42.6, 55.3, 75.9, 81.8,
89.4, 114.0, 124.6, 128.5, 132.2, 139.0, 151.4, 159.8, 169.0.
MS (EI): m/z = 332.0 (100%) [M]+.
Anal. Calcd for C17H20N2O5: C, 61.44; H, 6.07; N, 8.43. Found: C,
61.28; H, 6.14; N, 8.52.
4-(4-Ethoxyphenyl)-9-ethyl-10-hydroxy-7-methyl-1-oxa-7,9-di-
azaspiro[4.5]dec-3-ene-6,8-dione (14d)
Yield: 96 mg (91%); colorless solid; mp 152–154 °C.
IR (KBr): 3465, 1719, 1675 cm–1.
1H NMR (400 MHz, CDCl3): δ = 0.87 (t, J = 7.2 Hz, 3 H), 1.39 (t,
J = 6.8 Hz, 3 H), 3.19–3.29 (m, 5 H), 3.34 (s, 1 H), 3.99–4.07 (m, 2
H), 4.78 (s, 1 H), 4.88 (d, J = 13.2 Hz, 1 H), 5.13 (d, J = 13.2 Hz, 1
H), 6.10 (s, 1 H), 6.84 (d, J = 8.4 Hz, 2 H), 6.92 (d, J = 8.4 Hz, 2 H).
13C NMR (100 MHz, CDCl3): δ = 14.6, 14.7, 29.7, 42.5, 63.8, 75.9,
81.8, 89.4, 117.5, 124.4, 128.6, 132.1, 139.0, 151.3, 159.2, 169.0.
MS (EI): m/z = 346.0 (100%) [M]+.
Anal. Calcd for C18H22N2O5: C, 62.42; H, 6.40; N, 8.09. Found: C,
62.69; H, 6.35; N, 7.94.
Compounds 14e–i have been prepared previously.14b
(14) (a) Majumdar, K. C.; Ghosh, T.; Shyam, P. K. Synlett 2011,
2657. (b) Majumdar, K. C.; Ganai, S.; Nandi, R. K. New J.
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Acknowledgment
We thank UGC (New Delhi) and CSIR (New Delhi) for financial
assistance. K.C.M. is thankful to UGC, (New Delhi) for a UGC
Emeritus Fellowship, and S.P. and T.G. are grateful to CSIR (New
Delhi) for their senior research fellowships. We also thank DST
(New Delhi) for providing Bruker NMR (400 MHz) and Perkin-
Elmer FT-IR spectrometers, a UV/Vis spectrophotometer and a
Perkin-Elmer CHN Analyzer under the FIST program.
Supporting Information for this article is available online at
http://www.thieme-connect.com/ejournals/toc/synthesis.SnuIomprifgtooatrinSugpIoi
nnfomartit
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