Simple ultrasound-assisted synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine-2(1H)-thione-fused steroidal derivatives by a three-component reaction

Article abstract of DOI:10.1055/s-0032-1316564

Compounds containing fused 3,4-dihydropyrimidin-2(1H)-one or 3,4-dihydropyrimidine-2(1H)-thione moieties were prepared by three-component reactions of a steroidal or nonsteroidal ketone, an alkyl or aryl aldehyde, and urea or thiourea in the presence of sodium ethoxide. The products were isolated in good yields after short reaction times under mild conditions. Georg Thieme Verlag Stuttgart · New York.

Full text of DOI:10.1055/s-0032-1316564

2614▌
PAPER
paper
Simple Ultrasound-Assisted Synthesis of 3,4-Dihydropyrimidin-2(1H)-one and
3,4-Dihydropyrimidine-2(1H)-thione-Fused Steroidal Derivatives by a Three-
Component Reaction
3,4-Dihydropyrimidin-2(1H)-(thi)one-Fused Steroids
Mandakini Dutta, Junali Gogoi, Kommoori Shekarrao, Jonalee Goswami, Sanjib Gogoi,* Romesh Chandra Boruah*
Medicinal Chemistry Division, CSIR-North East Institute of Science and Technology, Jorhat 785006, India
Fax +91(376)2370011; E-mail: skgogoi1@gmail.com; E-mail: rc_boruah@yahoo.co.in
Received: 26.04.2012; Accepted after revision: 30.05.2012
metallic salts,11 Dowex-50W,12 or polyaniline, tetrafluo-
Abstract: Compounds containing fused 3,4-dihydropyrimidin-
roboric acid, and dodecyl hydrogen sulfate.13 Unfortu-
2(1H)-one or 3,4-dihydropyrimidine-2(1H)-thione moieties were
nately, many of these methods suffer from major or minor
limitations, such as harsh reaction conditions, low yields,
prepared by three-component reactions of a steroidal or nonsteroi-
dal ketone, an alkyl or aryl aldehyde, and urea or thiourea in the
presence of sodium ethoxide. The products were isolated in good expensive or toxic reagents, stoichiometric requirements
yields after short reaction times under mild conditions.
for catalysts, strongly acidic conditions, long reaction
times, or incompatibility with various functional groups.
Therefore, the development of a milder, faster, eco-friend-
ly, and high-yielding protocol for the synthesis of com-
pounds containing a 3,4-dihydropyrimidin-2(1H)-one or a
3,4-dihydropyrimidine-2(1H)-thione moiety remains of
great importance and represents a considerable challenge.
Key words: steroids, heterocycles, multicomponent reactions, ul-
trasound
Dihydropyrimidinones and dihydropyrimidinethiones are
important classes of bioactive molecules that can exhibit
a wide range of properties, such as antiviral, antitumor,
antibacterial, or antiinflammatory activities.1 These com-
pounds can also act as calcium-channel blockers, antihy-
The recent development of synthetic protocols that use
ultrasound irradiation has led to epoch-making changes in
organic chemistry, as it permits the activation of sub-
strates that have low reactivities.14 Among the notable fea-
tures of ultrasound-promoted reactions that are
recognized as having value in green chemistry14c,d are en-
hanced reaction rates, the formation of purer products in
improved yields, greater ease of manipulation, improved
energy conservation, and minimization of wastes.15
pertensives, anticancer agents, neuropeptide
Y
antagonists, and α1a adrenergic antagonists.2 The biologi-
cal activity of some recently isolated alkaloids has been
attributed to the presence of a dihydropyrimidinone moi-
ety,1a,3 the most prominent of these alkaloids being the
batzalladine alkaloids, which are potent inhibitors of HIV-
gp-120-CD4.3a
Multicomponent reactions form an important class of re-
actions that are related to tandem reactions and that can be
used to generate vast libraries of compounds with great ra-
pidity. The highly flexible and selective nature of multi-
component reactions makes them convenient tools for the
construction of many heterocyclic compounds.16 It is
known that the Biginelli reaction catalyzed by acids such
as hydrochloric, trifluoroacetic, or aminosulfonic acid is
accelerated by ultrasound.17 Even Bignelli reactions cata-
lyzed by ceric ammonium nitrate, ionic liquids, iodine,
ammonium chloride, silica, or magnesium perchlorate are
The synthesis of dihydropyrimidinones and their thione
analogues was first reported by Biginelli in 1893.4 Im-
proved procedures and new Biginelli-like scaffolds have
been reported over the past decade, and considerable ef-
forts have been made to develop new methods for the syn-
thesis of such compounds because of their therapeutic and
pharmacological properties.2c,5 There are several reports
on the synthesis of derivatives of dihydropyrimidinone
and dihydropyrimidinethione by using protic acids,6 Lewis
acids,7 triflates,8 microwave irradiation,9 ionic liquids,10
NaOEt
i-PrOH
X
Ar
ArCHO
2a–d
+
+
H2N
NH2
ultrasound
r.t., 15 min
HN
3 (X = O, S)
O
X
N
H
1a
4a–j
Scheme 1 Ultrasound-promoted, one-pot, three-component synthesis of 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidine-2(1H)-
thiones
SYNTHESIS 2012, 44, 2614–2622
Advanced online publication: 13.07.2012
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8
1
1
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0
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DOI: 10.1055/s-0032-1316564; Art ID: SS-2012-Z0392-OP
© Georg Thieme Verlag Stuttgart · New York

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3,4-Dihydropyrimidin-2(1H)-(thi)one-Fused Steroids
2615
promoted by ultrasound.18 However, there are few reports
on base-catalyzed Biginelli reactions19 and, the best of our
knowledge, there is no report of an ultrasound-assisted,
base-mediated, one-pot, Biginelli-type, three-component
reaction of a cyclic ketone, an aldehyde, and urea or thio-
urea. In a continuation of our studies on heterosteroids,20
we present a very simple, mild, economic, and efficient
strategy for the synthesis of dihydropyrimidinone- or di-
hydropyrimidinethione-fused steroids and nonsteroids
through an ultrasound-promoted, three-component, one-
pot condensation of a ketone, an aldehyde, and thiourea or
urea in the presence of an equimolar amount of base using
2-propanol as an environmentally benign solvent.21
Table 1 Optimization of the Conditions for the Synthesis of the
Fused 3,4-Dihydropyrimidin-2(1H)-One 4a
Entry Solvent
Methoda Time
(h)
Temp Yield
(°C)
(%)b
1
2
3
4
5
6
7
8
9
EtOH
US
0.25
0.25
6
r.t.
90
90
r.t.
90
90
r.t.
90
r.t.
77
50
56
94
63
65
33
39
70
EtOH
MW
TH
EtOH
i-PrOH
i-PrOH
i-PrOH
H2O
US
0.25
0.25
6
MW
TH
We began our study by investigating the reaction of cho-
lestan-3-one (1a) with benzaldehyde (2a) and urea (3a) in
presence of an equimolar amount of sodium ethoxide as
the base (Scheme 1). We performed an extensive optimi-
zation of the three-component reaction to determine the
best condition for the synthesis of the 3,4-dihydropyrimi-
dine-2(1H)one-fused steroid product 4a (Table 1). Initial-
ly, we examined the synthesis of 4a by three different
methods involving ultrasound irradiation (US), micro-
wave irradiation (MW), and conventional thermal heating
(TH), respectively. We selected the protic solvents etha-
US
0.25
0.25
0.25
neat
MW
US
H2O–i-PrOH (8:2)
a US: Ultrasound irradiation; MW: Microwave irradiation; TH: ther-
mal heating.
b Isolated yield of isolated product.
Table 2 Ultrasound-Assisted Syntheses of Steroidal A-Ring Fused 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidine-2(1H)-thi-
ones
NaOEt
i-PrOH
X
R
ultrasound, r.t.
NH2
15 min
+
RCHO
2a–g
+
H2N
HN
3a (X = O)
3b (X = S)
X
N
H
O
1a
4a–n
Entry
1
RCHO
X
O
O
O
O
O
O
O
S
Product (4a–j)
Yield (%)a
PhCHO (2a)
4a
4b
4c
4d
4e
4f
94
90
93
86
91
88
88
90
87
88
88
90
91
93
2
4-TolCHO (2b)
3
4-FC6H4CHO (2c)
3-BrC6H4CHO (2d)
PrCHO (2e)
4
5
6
BuCHO (2f)
7
Me(CH2)4CHO (2g)
PhCHO (2a)
4g
4h
4i
8
9
4-TolCHO (2b)
4-FC6H4CHO (2c)
3-BrC6H4CHO (2d)
PrCHO (2e)
S
10
11
12
13
14
S
4j
S
4k
4l
S
BuCHO (2f)
S
4m
4n
Me(CH2)4CHO (2g)
S
a Yield of the isolated product.
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2614–2622

2616
M. Dutta et al.
PAPER
nol, 2-propanol, and water as media for the reaction. tained by conducting the three-component reaction with
When the three-component reaction was carried in etha- ultrasound irradiation in 2-propanol as the solvent (entry
nol or 2-propanol under thermal condition for six hours, 4).
the product 4a was obtained in 56 and 65% yield, respec-
tively (Table 1, entries 3 and 6, respectively). Similarly,
the microwave-mediated reaction of 1a, 2a, and 3a in
protic solvent under basic condition gave 4a in 50–63%
yield (entries 2 and 5), whereas the solid-phase three-
component reaction with microwave heating for 15 min-
utes gave a 39% yield of 4a (entry 8). Our initial attempt
to carry out the three-component reaction with ultrasoni-
Next, we examined the three-component reaction of cho-
lestan-3-one (1a) with various aromatic or aliphatic alde-
hydes 2b–g and urea (3a) or thiourea (3b) under our
optimized reaction conditions (Table 2). The correspond-
ing products 4b–n were obtained in in 86–93% yields.
To evaluate the scope and limitations of the reaction fur-
ther, we extended it to the steroidal A-ring conjugated ke-
tone 1b, the D-ring oxo steroid 1c, the B-ring conjugated
cation in water as the solvent gave a poor yield (33%) of
ketone 1d, and the nonsteroidal cyclic ketones 1e–f under
4a (entry 7). However, we observed that the use of isopro-
our optimized condition, and we obtained products 4o–x
panol as a cosolvent (20%) improved the yield of 4a to
in 85–91% yields (Table 3).
70% (entry 9). The best yield (94%) was, however, ob-
Table 3 Ultrasound-Assisted Syntheses of Steroidal and Nonsteroidal 3,4-Dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidine-2(1H)-
thiones
Entry Ketone
RCHO
X
Product
Yield (%)a
1
1b
PhCHO (2a)
O
4o
90
HN
O
N
H
O
2
3
1b
1b
Me(CH2)4CHO (2g) O 4p
87
90
HN
O
N
H
PhCHO (2a)
S
4q
4r
HN
S
N
H
Br
4
5
1b
1b
3-BrC6H4CHO (2d) S
91
89
HN
S
N
H
4-TolCHO (2b)
S
4s
HN
S
N
H
Synthesis 2012, 44, 2614–2622
© Georg Thieme Verlag Stuttgart · New York

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3,4-Dihydropyrimidin-2(1H)-(thi)one-Fused Steroids
2617
Table 3 Ultrasound-Assisted Syntheses of Steroidal and Nonsteroidal 3,4-Dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidine-2(1H)-
thiones (continued)
Entry Ketone
RCHO
X
O
Product
Yield (%)a
O
O
HN
NH
6
7
1c
1c
PhCHO (2a)
4t
87
AcO
AcO
S
HN
NH
PhCHO (2a)
S
4u
90
AcO
8
1d
PhCHO (2a)
S
4v
86
Ph
AcO
AcO
HN
NH
O
S
S
O
HN
NH
9
1e
1f
PhCHO (2a)
PhCHO (2a)
S
S
4w
4x
86
85
S
O
HN
NH
10
MeO
MeO
a Yield of the isolated product.
The fused steroids and nonsteroids 4a–x were character- that cavitation creates bubbles that collapse, inducing me-
1
ized by means of H and 13C NMR spectroscopy and chanical stress that can be transmitted to a target bond.22
GC/MS.
In summary, we have developed a simple, rapid, and effi-
In relation to the mechanism, we believe that the initial cient base-catalyzed one-pot procedure for the annulation
condensation of benzaldehyde (2a) on the α-position of of a 3,4-dihydropyrimidin-2(1H)-one or 3,4-dihydropy-
ketone 1a under basic condition leads to the formation of rimidine-2(1H)-thione moiety onto the A-, B-, or D-ring
the intermediate exo-α,β-unsaturated ketone A; this read- of a steroid by a three-component reaction of a steroidal
ily undergoes a Michael addition reaction with thiourea to ketone, an aromatic or aliphatic aldehyde, and urea or
afford intermediate B. This intermediate then undergoes thiourea. We have compared the ultrasound-promoted
dehydrative cyclization to give the product 4h. To sub- Biginelli-type reaction with the corresponding reactions
stantiate this mechanism, we independently prepared the under conventional heating or microwave heating, and we
stable intermediate 2-benzylidenecholestan-3-one (A) by have shown that the ultrasound-mediated reaction produc-
condensation of cholestan-3-one (1a) with benzaldehyde es the best results. The reaction provides a new method for
(2a), and we treated intermediate A with thiourea under the preparation of A-, B- and D-ring-fused steroidal 3,4-
ultrasound to give the fused derivative 4h in high yield dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-
(88%). The most probable reason for the increase in the 2(1H)-thiones from keto steroids or endocyclic conjugat-
efficiency of the reaction in the presence of ultrasound is ed keto steroids. This new method provides significant ad-
vantages in comparison to previous methods6–13 for
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2614–2622

2618
M. Dutta et al.
PAPER
2a, NaOEt
i-PrOH
ultrasound
15 min
O
O
1a
A
thiourea, i-PrOH
ultrasound, 5 min
HN
HN
– H2O
S
S
N
O
NH2
H
4h
B
Scheme 2 Proposed mechanism for the formation of a steroidal 3,4-dihydropyrimidin-2(1H)-thione
4′-Phenyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestan-2′(1′H)-
one (4a)
synthesizing 3,4-dihydropyrimidin-2(1H)-ones and 3,4-
dihydropyrimidin-2(1H)-thiones, in that the reaction is
easy to perform and can be conducted at ambient temper-
ature with short reaction times and very simple workup to
give good yields (85–94%) of the required products.
Yield: 485 mg (94%); light-yellow solid; mp 174–176 °C.
IR (KBr): 3237, 2930, 2868, 1686, 1466, 1220, 770, 699 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.43–7.02 (m, 6 H), 5.32 (s, 1 H),
4.74 (s, 1 H), 2.00–0.50 (m, 44 H).
13C NMR (75 MHz, CDCl3): δ = 154.8, 143.2, 128.8, 128.7, 127.9,
127.3, 127.0, 126.9, 103.7, 61.7, 56.3, 53.3, 42.4, 40.9, 40.1, 39.8,
39.5, 36.1, 35.8, 35.4, 35.0, 31.5 (2C), 29.7, 28.2, 28.0, 24.2, 23.8
(2C), 22.8, 22.6, 21.0, 18.7 12.0, 11.9.
Melting points were measured with a Buchi B-540 melting-point
apparatus and are uncorrected. IR spectra were recorded on a
Perkin-Elmer FTIR-2000 spectrometer by using KBr pellets. NMR
spectra were recorded on a Bruker Avance DPX 300-MHz FT-
NMR spectrometer with TMS as the internal standard. Mass spectra
were recorded on a Trace DSQ GCMS instrument. All the commer-
cially available regents were used as received. All experiments were
monitored by TLC on pre-coated silica gel plates (Merck). Column
chromatography was performed on silica gel (60–120 mesh, Merck
Chemicals). Sonication was carried in round-bottom flasks im-
mersed in a standard ultrasonic bath producing sound waves at 44.2
kHz. All microwave reactions were carried out in a Synthos 3000
(Anton Paar) microwave reactor.
MS (EI): m/z = 516 [M]+.
Anal. Calcd for C35H52N2O: C, 81.34; H, 10.14; N, 5.42. Found: C,
81.19; H, 10.27; N, 5.73.
4′-(4-Tolyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestan-
2′(1′H)-one (4b)
Yield: 477 mg (90%); light-yellow solid; mp 202–204 °C.
IR (KBr): 3237, 2931, 2869, 1687, 1467, 1219, 770, 699 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.45–6.88 (m, 5 H), 5.26 (s, 1 H),
4.71 (s, 1 H), 2.38–0.52 (m, 47 H).
3,4-Dihydropyrimidin-2′(1H)-ones and 3,4-Dihydropyrimi-
dine-2′(1H)-thiones; General Procedures
13C NMR (75 MHz, CDCl3): δ = 155.0, 143.1, 129.3, 128.3 (2C),
128.0, 127.1 (2C), 105.1, 61.1, 56.3 (2C), 53.5, 42.3, 41.1, 40.1,
39.8 (2C), 39.4, 36.1, 35.7, 35.4, 34.1, 31.8 (2C), 28.2, 28.0, 24.2,
23.8 (2C), 22.8, 22.7, 21.0, 18.7, 12.1, 12.0.
Method I (Ultrasound)
A mixture of the ketone (1 mmol), aldehyde (1 mmol), urea or thio-
urea (1 mmol), and NaOEt (1 mmol) in i-PrOH (10 mL) was irradi-
ated with ultrasound for 15 min. The solvent was removed in a
rotatory evaporator, and the crude residue was purified by column
chromatography [silica gel, EtOAc–hexane (1:10)].
MS (EI): m/z = 530.4 [M+].
Anal. Calcd for C36H54N2O: C, 81.46; H, 10.25; N, 5.28. Found: C,
81.19; H, 10.21; N, 5.33.
Method II (Microwave Heating)
4′-(4-Fluorophenyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]choles-
tan-2′(1′H)-one (4c)
A mixture of the ketone (1 mmol), aldehyde (1 mmol), urea or thio-
urea (1 mmol), and NaOEt (1 mmol) in i-PrOH (10 mL) was irradi-
ated with microwaves in a closed vessel in a Synthos 3000
microwave reactor at 450 W (90 °C and 11 bar) for 15 min. The sol-
vent was removed in a rotatory evaporator, and the crude residue
was purified by column chromatography [silica gel, EtOAc–hexane
(1:10)].
Yield: 497 mg (93%); light-yellow solid; mp 228–229 °C.
IR (KBr): 3237, 2930, 2868, 1687, 1467, 1218, 772, 698 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.45–6.76 (m, 5 H), 5.38 (s, 1 H),
4.75 (s, 1 H), 2.27–0.64 (m, 44 H).
13C NMR (75 MHz, CDCl3): δ = 154.7, 142.9, 129.4, 128.5 (2C),
128.2, 127.2 (2C), 105.0, 61.1, 56.2 (2C), 53.4, 42.4, 40.9, 40.1,
39.8, 39.5, 36.2, 35.7, 35.4, 34.1, 31.8 (2C), 28.2, 28.1, 24.1, 23.7
(2C), 22.8, 22.7, 21.1, 18.7, 12.1, 11.9.
Method III (Thermal)
A mixture of the ketone (1 mmol), aldehyde (1 mmol), urea or thio-
urea (1 mmol), and NaOEt (1 mmol) was refluxed in i-PrOH (10
mL) for 6 h. The solvent was removed in a rotatory evaporator, and
the crude residue was purified by column chromatography [silica
gel, EtOAc–hexane (1:10)].
MS (EI): m/z = 534.4 [M+].
Anal. Calcd for C35H51FN2O: C, 78.61; H, 9.61; N, 5.24. Found: C,
78.66; H, 9.73; N, 5.50.
Synthesis 2012, 44, 2614–2622
© Georg Thieme Verlag Stuttgart · New York

PAPER
3,4-Dihydropyrimidin-2(1H)-(thi)one-Fused Steroids
2619
4′-(3-Bromophenyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]choles-
tan-2′(1′H)-one (4d)
13C NMR (75 MHz, CDCl3): δ = 172.3, 141.8, 130.1, 129.8, 128.9,
128.4, 127.2, 126.0, 107.0, 61.3, 56.3, 53.3, 42.4, 41.8, 39.8 (2C),
36.1, 35.8, 35.4, 35.3, 31.5 (2C), 29.8, 28.2, 28.0, 24.2, 23.8 (2C),
22.8, 22.6, 21.1, 18.7, 12.1, 12.0, 11.9.
Yield: 511 mg (86%); light-yellow solid; mp 232–234 °C.
IR (KBr): 3236, 2930, 2869, 1686, 1467, 1219, 770, 699 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.43–6.69 (m, 5 H), 5.37 (s, 1 H),
MS (EI): m/z = 532.4 [M+].
4.71 (s, 1 H), 2.28–0.54 (m, 44 H).
Anal. Calcd for C35H52N2S: C, 78.89; H, 9.84; N, 5.26. Found: C,
78.95; H, 9.90; N, 5.23.
13C NMR (75 MHz, CDCl3): δ = 154.5, 144.0, 130.0, 128.5, 128.2,
127.4, 126.6, 126.4, 104.3, 61.0, 56.2, 53.5, 42.4, 41.0, 40.1, 39.8,
39.5 (2C), 36.1, 35.8, 35.4, 34.1, 31.8 (2C), 28.2, 28.0, 24.2, 23.8
(2C), 22.9, 22.6, 21.1, 18.7, 12.1, 12.0.
4′-(4-Tolyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestane-
2′(1′H)-thione (4i)
Yield: 475 mg (87%); light-yellow solid; mp 212–214 °C.
IR (KBr): 3192, 2929, 2869, 1570, 1490, 1220, 756, 666 cm–1.
MS (EI): m/z = 516.4 [M – Br]+.
Anal. Calcd for C35H51BrN2O: C, 70.57; H, 8.63; N, 4.70. Found: C,
70.77; H, 8.69; N, 4.75.
1H NMR (300 MHz, CDCl3): δ = 8.27 (s, 1 H) 7.38–7.01 (m, 5 H),
4.55 (s, 1 H), 1.99–0.43 (m, 47 H).
4′-Propyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestan-2′(1′H)-
one (4e)
13C NMR (75 MHz, CDCl3): δ = 173.1, 141.6, 129.0, 128.1 (2C),
127.1 (2C), 125.5, 106.8, 61.9, 56.3 (2C), 53.3, 42.4, 40.9, 39.8
(2C), 39.5, 36.1, 35.8, 35.0, 31.4, 30.0, 28.1, 28.0 (2C), 24.2 (2C),
23.8 (2C), 22.8, 22.6, 21.0, 18.6, 12.0, 11.9.
Yield: 439 mg (91%); light-yellow solid; mp 183–184 °C.
IR (KBr): 3249, 2929, 2868, 1715, 1467, 1222, 771 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.05 (s, 1 H), 5.67 (s, 1 H), 3.73
MS (EI): m/z = 546 [M+].
(m, 1 H), 2.19–0.66 (m, 51 H).
Anal. Calcd for C36H54N2S: C, 79.06; H, 9.95; N, 5.12. Found: C,
78.85; H, 9.80; N, 5.36.
13C NMR (75 MHz, CDCl3): δ = 153.2, 142.2, 105.4, 56.9, 56.3
(2C), 54.2, 44.6, 42.4, 39.8, 39.5 (2C), 36.2, 35.8, 35.4, 35.3, 31.8
(2C), 31.5, 29.8, 28.2, 28.0 (2C), 24.2 (2C), 23.9 (2C), 22.5, 18.7,
14.2, 11.9, 11.8.
4′-(4-Fluorophenyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]choles-
tane-2′(1′H)-thione (4j)
Yield: 484 mg (88%); light-yellow solid; mp 221–223 °C.
IR (KBr): 3192, 2926, 2868, 1570, 1493, 1219, 762, 664 cm–1.
MS (EI): m/z = 482.4 [M+].
Anal. Calcd for C32H54N2O: C, 79.61; H, 11.27; N, 5.80. Found: C,
79.82; H, 11.30; N, 5.73.
1H NMR (300 MHz, CDCl3): δ = 8.27 (s, 1 H) 7.67–6.96 (m, 5 H),
4.55 (s, 1 H), 1.99–0.43 (m, 44 H).
4′-Butyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestan-2′(1′H)-
one (4f)
13C NMR (75 MHz, CDCl3): δ = 173.1, 141.7, 129.1, 128.2 (2C),
127.2 (2C), 125.4, 106.9, 61.4, 56.1 (2C), 54.0, 42.8, 41.9, 39.9
(2C), 39.5, 36.1, 35.7, 34.8, 31.5, 30.0, 28.6, 28.0 (2C), 24.9, 23.1,
30.0, 22.6, 21.1, 18.5, 12.7, 12.0, 11.9.
Yield: 437 mg (88%); light-yellow solid; mp 187 °C.
IR (KBr): 3249, 2929, 2868, 1716, 1467, 1222, 771 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.04 (s, 1 H), 5.66 (s, 1 H), 3.74
MS (EI): m/z = 550 [M+].
(m, 1 H), 2.20–0.68 (m, 53 H).
Anal. Calcd for C35H51FN2S: C, 76.31; H, 9.33; N, 5.09. Found: C,
76.55; H, 9.54; N, 5.16.
13C NMR (75 MHz, CDCl3): δ = 153.2, 142.2, 105.4, 56.9, 56.3
(2C), 54.3, 44.8, 42.4, 39.8, 39.5 (2C), 36.1, 35.8, 35.4, 35.3, 31.8
(2C), 31.5, 29.7, 28.2, 28.0 (2C), 24.2 (2C), 23.8 (2C), 23.3, 22.6,
18.7, 14.1, 11.9, 11.8.
4′-(3-Bromophenyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]choles-
tane-2′(1′H)-thione (4k)
Yield: 537 mg (88%); light-yellow solid; mp 231–232 °C.
IR (KBr): 3186, 2932, 2869, 1570, 1471, 1219, 770, 699 cm–1.
MS (EI): m/z = 496.4 [M+].
Anal. Calcd for C33H56N2O: C, 79.78; H, 11.36; N, 5.64. Found: C,
79.83; H, 11.20; N, 5.79.
1H NMR (300 MHz, CDCl3): δ = 7.74 (s, 1 H), 7.46–7.19 (m, 4 H),
6.87 (s, 1 H), 4.73 (s, 1 H), 1.90–0.55 (m, 44 H).
4′-Pentyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestan-2′(1′H)-
one (4g)
13C NMR (75 MHz, CDCl3): δ = 172.4, 144.0, 131.5, 130.6, 130.2,
126.6, 126.4, 122.9, 106.3, 60.8, 59.5, 56.2, 53.5, 53.2, 42.4, 40.9,
40.1, 39.8, 39.5, 36.1, 35.8, 35.4, 35.0, 31.4, 28.2, 28.0, 24.2, 23.8,
22.9, 22.6, 21.1, 18.7, 12.1, 12.0, 11.9.
Yield: 449 mg (88%); light-yellow solid; mp 194–195 °C.
IR (KBr): 3249, 2929, 2868, 1716, 1467, 1221, 771 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.03 (s, 1 H), 5.70 (s, 1 H), 3.79
MS (EI): m/z = 531.4 [M – Br]+.
(s, 1 H), 2.19–0.66 (m, 55 H).
Anal. Calcd for C35H51BrN2S: C, 68.72; H, 8.40; N, 4.58. Found: C,
68.70; H, 8.20; N, 4.21.
13C NMR (75 MHz, CDCl3): δ = 153.3, 142.2, 105.4, 56.9, 56.2
(2C), 54.4, 44.9, 42.4, 39.9, 39.5 (2C), 36.1, 35.8, 35.4, 35.3, 31.8
(2C), 31.5, 29.7, 28.2, 28.0 (2C), 24.2 (2C), 23.9 (2C), 23.3, 22.9,
22.6, 18.7, 14.2, 11.9, 11.8.
4′-Propyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestane-
2′(1′H)-thione (4l)
Yield: 449 mg (90%); light-yellow solid; mp 187 °C.
IR (KBr): 3162, 2929, 2868, 1587, 1465, 1221, 772 cm–1.
MS (EI): m/z = 510.4 [M+].
Anal. Calcd for C34H58N2O: C, 79.94; H, 11.44; N, 5.48. Found: C,
79.78; H, 11.25; N, 5.72.
1H NMR (300 MHz, CDCl3): δ = 7.34 (s, 1 H), 6.58 (s, 1 H), 3.81
(m, 1 H), 2.17–0.64 (m, 51 H).
4′-Phenyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestane-
2′(1′H)-thione (4h)
13C NMR (75 MHz, CDCl3): δ = 173.2, 126.1, 106.4, 71.3, 56.9,
56.2 (2C), 54.3, 44.8, 41.9, 39.8, 39.5 (2C), 36.2, 35.7, 35.4, 35.3,
31.7, 31.5, 29.0, 28.2, 28.2, 24.2, 23.8 (2C), 23.3, 22.8, 22.6, 18.7,
14.1, 12.0, 11.7.
Yield: 479 mg (90%); light-yellow solid; mp 201–203 °C.
IR (KBr): 3190, 2928, 2868, 1567, 1468, 1208, 758, 699 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.40–7.13 (m, 6 H), 6.48 (s, 1 H),
MS (EI): m/z = 498.4 [M+], 455.4 [M – C3H7]+.
4.77 (s, 1 H), 1.87–0.63 (m, 44 H).
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2614–2622

2620
M. Dutta et al.
PAPER
Anal. Calcd for C32H54N2S: C, 77.05; H, 10.91; N, 5.62. Found: C,
77.35; H, 10.98; N, 5.75.
IR (KBr): 3189, 2929, 2869, 1600, 1569, 1467, 1208, 759, 699
cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.72–7.19 (m, 6 H), 6.82 (s, 1 H),
5.31 (s, 1 H), 4.98 (s, 1 H), 2.03–0.61 (m, 41 H).
13C NMR (75 MHz, CDCl3): δ = 172.0, 142.1, 137.8, 129.1, 128.9,
128.2, 128.0, 127.0, 126.7, 120.4, 107.9, 57.1, 56.1, 48.4, 47.9,
42.3, 39.7, 39.5, 36.2, 35.8, 35.4, 31.9, 31.1, 28.2, 28.0, 24.1, 23.8,
22.8, 22.6, 21.2, 19.0, 18.7, 18.6, 11.9, 11.8.
4′-Butyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestane-2′(1′H)-
thione (4m)
Yield: 466 mg (91%); light-yellow solid; mp 192 °C.
IR (KBr): 3172, 2928, 2868, 1583, 1467, 1222, 771 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.64 (s, 1 H), 6.96 (s, 1 H), 3.51
(m, 1 H), 2.56–0.58 (m, 53 H).
MS (EI): m/z = 530.4 [M]+.
13C NMR (75 MHz, CDCl3): δ = 173.2, 126.0, 106.5, 71.3, 56.8,
56.2 (2C), 54.4, 44.7, 42.4, 39.5 (2C), 39.1, 36.3, 35.8, 35.4, 35.2,
31.8, 31.5, 29.7, 28.2, 28.0 (2C), 24.2, 23.8 (2C), 23.3, 22.8, 22.6,
18.7, 14.2, 11.8, 11.6.
Anal. Calcd for C35H50N2S: C, 79.19; H, 9.49; N, 5.28. Found: C,
79.38; H, 9.41; N, 5.54.
4′-(3-Bromophenyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]cholest-
4-ene-2′(1′H)-thione (4r)
Yield: 553 mg (91%); yellow solid; mp 226–228 °C.
IR (KBr): 3186, 2931, 2869, 1571, 1471, 1219, 771, 699 cm–1.
MS (EI): m/z = 512.4 [M+], 455.4 [M – C4H9]+.
Anal. Calcd for C33H56N2S: C, 77.28; H, 11.01; N, 5.46. Found: C,
77.39; H, 10.94; N, 5.25.
1H NMR (300 MHz, CDCl3): δ = 7.73 (s, 1 H), 7.40–7.18 (m, 4 H),
6.86 (s, 1 H), 5.30 (s, 1 H), 4.78 (s, 1 H), 2.01–0.65 (m, 41 H).
13C NMR (75 MHz, CDCl3): δ = 172.4, 143.9, 137.5, 130.2, 129.2,
128.0, 127.0, 126.6, 126.4, 122.9, 106.3, 56.2, 53.5, 53.2, 42.4,
40.9, 40.1, 39.8, 39.5, 36.1, 35.8, 35.4, 35.0, 31.4, 28.2, 28.0, 24.2,
23.9, 22.8, 22.6, 21.0, 18.7, 12.1, 12.0, 11.9.
4′-Pentyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholestane-2′(1′H)-
thione (4n)
Yield: 489 mg (93%); light-yellow solid; mp 188–190 °C.
IR (KBr): 3171, 2929, 2868, 1583, 1467, 1222, 770 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.38 (s, 1 H), 6.64 (s, 1 H), 3.82
(m, 1 H), 2.17–0.64 (m, 55 H).
MS (EI): m/z = 529.4 [M – Br]+.
13C NMR (75 MHz, CDCl3): δ = 173.3, 126.1, 106.4, 71.3, 56.9,
56.3 (2C), 54.3, 44.8, 42.4, 39.9, 39.5 (2C), 36.2, 35.8, 35.4, 35.3,
31.8 (2C), 31.5, 29.7, 28.2, 28.0 (2C), 24.2, 23.8 (2C), 23.3, 22.8,
22.6, 18.7, 14.2, 12.0, 11.8.
Anal. Calcd for C35H49BrN2S: C, 68.94; H, 8.10; N, 4.59. Found: C,
68.74; H, 8.18; N, 4.33.
4′-(4-Tolyl)-3′,4′-dihydropyrimidino[6′,5′:2,3]cholest-4-ene-
2′(1′H)-thione (4s)
Yield: 485 mg (89%); light-yellow solid; mp 208–210 °C.
IR (KBr): 3192, 2929, 2867, 1569, 1490, 1220, 756, 666 cm–1.
MS (EI): m/z = 526.4 [M+], 455.4 [M – C5H11]+.
Anal. Calcd for C34H58N2S: C, 77.50; H, 11.10; N, 5.32. Found: C,
77.48; H, 11.03; N, 5.27.
1H NMR (300 MHz, CDCl3): δ = 8.11 (s, 1 H), 7.36–7.04 (m, 5 H),
5.31 (s, 1 H), 4.56 (s, 1 H), 1.98–0.43 (m, 44 H).
13C NMR (75 MHz, CDCl3): δ = 173.1, 141.6, 137.2, 129.0, 128.1
(2C), 127.1 (2C), 125.5, 120.0, 106.8, 56.3 (2C), 53.1, 42.4, 40.9,
39.9 (2C), 39.8, 39.5, 36.2, 35.8, 34.9, 31.4, 30.0, 28.1, 28.0 (2C),
24.1, 23.8, 22.8, 22.5, 21.0, 18.5, 12.0, 11.9.
4′-Phenyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholest-4-en-
2′(1′H)-one (4o)
Yield: 463 mg (90%); light-yellow solid; mp 202–204 °C.
IR (KBr): 3189, 2929, 2869, 1600, 1569, 1467, 1208, 759, 699
cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.72–7.19 (m, 6 H), 6.82 (s, 1 H),
MS (EI): m/z = 544 [M+].
5.31(s, 1 H), 4.98 (s, 1 H), 2.03–0.61 (m, 41 H).
13C NMR (75 MHz, CDCl3): δ = 154.2, 142.1, 137.8, 129.1, 128.9,
128.2, 128.0, 127.0, 126.7, 120.4, 107.9, 57.1, 56.1, 48.4, 47.9,
42.3, 39.7, 39.5, 36.2, 35.8, 35.4, 31.9, 31.1, 28.2, 28.0, 24.1, 23.8,
22.8, 22.7, 21.2, 19.0, 18.7, 18.6, 11.9, 11.8.
Anal. Calcd for C36H52N2S: C, 79.35; H, 9.62; N, 5.14. Found: C,
79.70; H, 9.78; N, 5.10.
3β-Acetoxy-3′,4′-dihydropyrimidino[6′,5′:16,17]androst-5-en-
2′(1′H)-one (4t)
Yield: 400 mg (87%); gum.
MS (EI): m/z = 530.4 [M]+.
Anal. Calcd for C35H50N2O: C, 81.66; H, 9.79; N, 5.44. Found: C,
81.78; H, 9.73; N, 5.47.
IR (KBr): 2928, 2853, 1732, 1612, 1245, 1037 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.85–7.03 (m, 7 H), 6.73 (d, J =
6.0 Hz, 1 H), 5.50–5.33 (m, 1 H), 4.63–4.50 (m, 1 H), 2.50–0.85 (m,
26 H).
13C NMR (75 MHz, CDCl3): δ = 172.9, 154.6, 139.9, 137.1, 129.5,
128.4 (2C), 127.8 (2C), 125.2, 122.0, 73.7, 51.7, 50.1, 47.5, 38.1,
36.9 (2C), 35.9, 31.5, 30.8, 29.7, 27.7, 21.9, 21.4, 20.3, 19.6, 13.6,
11.6.
4′-Pentyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholest-4-en-
2′(1′H)-one (4p)
Yield: 442 mg (87%); white solid; mp 180–181 °C.
IR (KBr): 3249, 2928, 2867, 1716, 1467, 1221, 771 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.78 (s, 1 H), 6.90 (s, 1 H), 5.33
(s, 1 H), 4.96 (s, 1 H), 2.23–0.61 (m, 52 H).
MS (EI): m/z = 400.6 [M – CH3COOH]+.
13C NMR (75 MHz, CDCl3): δ = 154.0, 144.1, 126.0, 122.0, 107.5,
71.3, 56.8, 56.1 (2C), 54.4, 44.7, 42.4, 39.6 (2C), 39.1, 36.3, 35.8,
35.4 35.2, 31.8, 31.5, 29.7, 28.2, 28.0, 24.4, 23.8 (2C), 23.3, 22.8,
22.6, 18.7, 14.2, 11.8, 11.7.
Anal. Calcd for C29H36N2O3: C, 75.62; H, 7.88; N, 6.08. Found: C,
75.72; H, 7.74; N, 6.16.
3β-Acetoxy-3′,4′-dihydropyrimidino[6′,5′:16,17]androst-5-ene-
2′(1′H)-thione (4u)
Yield: 429 mg (90%); gum.
IR (KBr): 2929, 2856, 1738, 1666, 1246, 1031 cm–1.
MS (EI): m/z = 508.4 [M]+.
Anal. Calcd for C34H56N2O: C, 80.26; H, 11.09; N, 5.51. Found: C,
80.28; H, 11.14; N, 5.57.
1H NMR (300 MHz, CDCl3): δ = 7.89–7.00 (m, 7 H), 6.71 (d, J =
6.0 Hz, 1 H), 5.50–5.30 (m, 1 H), 4.63–4.50 (m, 1 H), 2.47–0.85 (m,
26 H).
4′-Phenyl-3′,4′-dihydropyrimidino[6′,5′:2,3]cholest-4-ene-
2′(1′H)-thione (4q)
Yield: 477 mg (90%); white solid; mp 209–210 °C.
Synthesis 2012, 44, 2614–2622
© Georg Thieme Verlag Stuttgart · New York

PAPER
3,4-Dihydropyrimidin-2(1H)-(thi)one-Fused Steroids
2621
13C NMR (75 MHz, CDCl3): δ = 173.4, 170.6, 140.1, 137.4 (2C),
129.7, 128.2 (2C), 127.8 (2C), 125.1, 122.4, 73.9, 51.5, 50.1, 47.7,
38.8, 36.8, 35.8, 31.8, 30.5, 29.7, 27.4, 21.9, 21.4, 20.1, 19.7, 13.5,
11.4.
39.5 (2C), 36.2, 35.9, 35.8, 35.4, 31.5 (2C), 28.7, 28.3, 24.3, 23.9
(2C), 22.9, 21.4, 18.7, 12.0, 11.9.
MS (EI): m/z = 474.4 [M]+.
Anal. Calcd for C34H50O: C, 86.01; H, 10.62. Found: C, 86.27; H,
10.75.
MS (EI): m/z = 416.6 [M – CH3COOH]+, 359.2.
Anal. Calcd for C29H36N2O2S: C, 73.07; H, 7.61; N, 5.88. Found: C,
73.32; H, 7.74; N, 5.93.
Conversion of 2-Benzylidenecholestan-3-one (A) into 4′-Phenyl-
3′,4′-dihydropyrimidino[6′,5′:2,3]cholestane-2′(1′H)-thione
(4h)
3β-Acetoxy-4′-phenyl-3′,4′-dihydropyrimidi-
no[6′,5′:6,7]cholest-4-ene-2′(1′H)-thione (4v)
Yield: 506 mg (86%); white solid; mp 182 °C.
A mixture of ketone A (200 mg, 0.42 mmol) and thiourea (32 mg,
0.42 mmol) in i-PrOH (10 mL) was irradiated with ultrasound for 5
min. The solvent was removed in a rotatory evaporator and the
crude residue was purified by column chromatography [silica gel,
EtOAc–hexane (1:10)] to give 4h; yield: 195 mg (87%). The ana-
lytical and spectral data for this compound were similar to those re-
ported above.
IR (KBr): 2950, 2932, 2868, 1706, 1566, 1450, 1381, 1238, 765
cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.70–7.08 (m, 8 H), 6.15 (m, 1 H),
4.23 (m, 1 H), 2.82–0.6 (m, 42 H).
13C NMR (75 MHz, CDCl3): δ = 172.5, 170.8, 141.2, 133.5, 130.2,
129.7, 129.2, 128.6 (2C), 128.2, 127.0 (2C), 82.0, 65.3, 56.1, 44.1,
42.9, 41.5, 39.5 (2C), 37.4, 36.1, 35.7, 31.0 (2C), 29.7, 28.0 (2C),
27.7 (2C), 23.8, 22.8, 22.6, 21.7, 18.7, 14.2, 11.7.
Acknowledgment
We thank the Department of Science and Technology, New Delhi,
for financial support. M.D. thanks CSIR, New Delhi, for the award
of a senior research fellowship (SRF). We are grateful to the Direc-
tor of CSIR-NEIST for his keen interest.
MS (EI): m/z = 528.4 [M – CH3COOH]+.
Anal. Calcd for C37H52N2O2S: C, 75.46; H, 8.90; N, 4.76. Found C,
75.68; H, 8.82; N, 4.56.
4-Phenyl-3,4,5,6-tetrahydrobenzo[h]quinazoline-2(1H)-thione
References
(4w)
Yield: 251 mg (86%); gum.
(1) (a) Snider, B. B.; Shi, Z. J. Org. Chem. 1993, 58, 3828.
(b) Overman, L. E.; Rabinowitz, M. H.; Renhowe, P. A.
J. Am. Chem. Soc. 1995, 117, 2657. (c) Amr, A. E.; Ashraf,
M. M.; Salwa, F. M.; Nagla, A. A.; Hammam, A. G. Bioorg.
Med. Chem. 2006, 14, 5488. (d) Kappe, C. O. Eur. J. Med.
Chem. 2000, 35, 1043; and references cited therein.
(2) (a) Atwal, K. S.; Swanson, B. N.; Unger, S. E.; Floyd, D. M.;
Moreland, S.; Hodberg, A.; O’Reilly, B. C. J. Med. Chem.
1991, 34, 806. (b) Atwal, K. S.; Rovnyak, G. C.; Kimball, S.
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J. Z.; Schwartz, J.; Smillie, K. M.; Malley, M. F. J. Med.
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Kumar, R.; Luthra, P. M. Chem. Pharm. Bull. 2010, 58,
1320.
(3) (a) Rao, R. A. V.; Gurjar, M. K.; Vasudevan, J. J. Chem.
Soc., Chem. Commun. 1995, 13, 1369. (b) Patil, A. D.;
Kumar, N. V.; Kokke, W. C.; Bean, M. F.; Freyer, A. J.; De
Brosse, C.; Mai, S.; Truneh, A.; Faulkner, D. J.; Carte, B.;
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(5) (a) Kappe, C. O. Tetrahedron 1993, 49, 6937. (b) Abelman,
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65, 6777. (b) Atwal, K. S.; O’Reilly, B. C.; Gougoutas, J. Z.;
Malley, M. F. Heterocycles 1987, 26, 1189.
IR (KBr): 2927, 1692, 1566, 1493, 1453, 1192, 1026 cm–1.
1H NMR (300 MHz, DMSO-d6): δ = 9.79 (s, 1 H), 9.12 (s, 1 H), 7.96
(d, J = 9.0 Hz, 1 H), 7.82–6.54 (m, 8 H), 4.96 (d, J = 2.4 Hz, 1 H),
2.62 (t, J = 7.2 Hz, 2 H), 2.08 (t, J = 7.0 Hz, 2 H).
13C NMR (75 MHz, DMSO-d6): δ = 174.5, 143.2, 135.9, 129.7,
129.1, 128.5 (2C), 128.3, 128.1, 128.0, 127.4, 126.9 (2C), 121.8,
111.7, 58.9, 27.7, 23.0.
MS (EI): m/z = 292 [M]+.
Anal. Calcd for C18H16N2S: C, 73.94; H, 5.52; N, 9.58. Found: C,
73.75; H, 5.72; N, 9.68.
8-Methoxy-4-phenyl-3,4,5,6-tetrahydrobenzo[h]quinazoline-
2(1H)-thione (4x)
Yield: 274 mg (85%); gum.
IR (KBr): 2927, 1692, 1601, 1538, 1493, 1251 cm–1.
1H NMR (300 MHz, DMSO-d6): δ = 9.72 (s, 1 H), 9.06 (s, 1 H),
8.20–6.50 (m, 8 H), 4.92 (s, 1 H), 3.5 (s, 3 H), 2.68 (t, J = 7.2 Hz, 2
H), 2.14 (t, J = 7.2 Hz, 2 H).
13C NMR (75 MHz, DMSO-d6): δ = 174.7, 142.8, 135.5, 129.9,
129.6, 128.1, 128.6 (2C), 128.0 (2C), 127.1 (2C), 127.0, 121.9,
111.8, 59.4, 55.9, 27.5, 23.3.
MS (EI): m/z = 322.0 [M]+.
Anal. Calcd for C19H18N2OS: C, 70.78; H, 5.63; N, 8.69. Found: C,
70.42; H, 5.70; N, 8.78.
2-Benzylidenecholestan-3-one (A)
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Synlett 2004, 537. (b) Gohain, M.; Prajapati, D.; Sandhu, J.
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A mixture of ketone 1a (400 mg, 1.04 mmol), PhCHO (110 mg,
1.04 mmol), and NaOEt (71 mg, 1.04 mmol) in i-PrOH (10 mL) was
irradiated with ultrasound for 10 min. The solvent was removed in
a rotatory evaporator and the crude residue was purified by column
chromatography [silica gel, EtOAc–hexane (1:10)] to give a light-
yellow solid; yield: 443 mg (90%); mp 176 °C.
IR (KBr): 2929, 1678, 1445, 1193, 696 cm–1.
1H NMR (300 MHz, CDCl3): δ = 7.60–7.28 (m, 5 H), 7.26 (s, 1 H),
3.13–3.08 (m, 2 H), 2.49–0.64 (m, 42 H).
13C NMR (75 MHz, CDCl3): δ = 201.7, 137.1, 135.7, 135.4, 129.7,
129.6, 128.9, 128.6, 128.4, 66.7, 66.3, 56.4, 53.6, 42.9, 42.4, 39.9,
© Georg Thieme Verlag Stuttgart · New York
Synthesis 2012, 44, 2614–2622

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