Utility of nitrogen nucleophiles: A simple route for the synthesis of 2-substituted benzimidazolylpyrimidines

Article abstract of DOI:10.1080/10426507.2014.947409

An efficient and simple route for the synthesis of 2-substituted benzimidazolylpyrimidines 5a-i has been developed from benzimidazolylunsaturated nitriles 2 using nitrogen nucleophiles. Treatment of 2 with thiourea/urea/guanidine hydrochloride in aq. KOH under reflux for 30 min gave 3, which on further alkylation with an alkylating agent under PTC conditions gave 5a-i. Alternatively 5a-i could also be prepared by treatment of 2 with an alkylating agent under PTC conditions followed by treatment with thiourea /urea/guanidine hydrochloride in aq. KOH for 30 min.

Full text of DOI:10.1080/10426507.2014.947409

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Phosphorus, Sulfur, and Silicon and the
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Utility of Nitrogen Nucleophiles: a Simple
Route for the Synthesis of 2-Substituted
Benzimidazolylpyrimidines
S. Srinivas Raoa, Ch.Venkata Ramana Reddya & Pramod Kumar
Dubeya
a Department of Chemistry, Jawaharlal Nehru Technological
University Hyderabad, College of Engineering, Kukatpally,
Hyderabad 500 085, India
Accepted author version posted online: 30 Jul 2014.
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To cite this article: S. Srinivas Rao, Ch.Venkata Ramana Reddy & Pramod Kumar Dubey
(2015) Utility of Nitrogen Nucleophiles: a Simple Route for the Synthesis of 2-Substituted
Benzimidazolylpyrimidines, Phosphorus, Sulfur, and Silicon and the Related Elements, 190:3, 380-386,
DOI: 10.1080/10426507.2014.947409
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Phosphorus, Sulfur, and Silicon, 190:380–386, 2015
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2014.947409
UTILITY OF NITROGEN NUCLEOPHILES:
A SIMPLE ROUTE FOR THE SYNTHESIS
OF 2-SUBSTITUTED BENZIMIDAZOLYLPYRIMIDINES
S. Srinivas Rao, Ch.Venkata Ramana Reddy,
and Pramod Kumar Dubey
Department of Chemistry, Jawaharlal Nehru Technological University Hyderabad,
College of Engineering, Kukatpally, Hyderabad 500 085, India
GRAPHICAL ABSTRACT
Abstract An efficient and simple route for the synthesis of 2-substituted benzimidazolylpyrim-
idines 5a-i has been developed from benzimidazolylunsaturated nitriles 2 using nitrogen nucle-
ophiles. Treatment of 2 with thiourea/urea/guanidine hydrochloride in aq. KOH under reflux
for 30 min gave 3, which on further alkylation with an alkylating agent under PTC conditions
gave 5a-i. Alternatively 5a-i could also be prepared by treatment of 2 with an alkylating agent
under PTC conditions followed by treatment with thiourea /urea/guanidine hydrochloride in
aq. KOH for 30 min.
Keywords Benzimidazolylpyrimidines; 2-mercaptobenzimidazole; benzaldehyde; nitrogen
nucleophiles; phase transfer catalyst
INTRODUCTION
Benzimidazole derivatives have been found to possess various pharmacological ac-
tivities.1–7 Pyrimidines and their derivatives are known for their pharmacological properties
including antiviral, antibacterial8–13 effects. As a result of their pharmacological, biologi-
cal, physiological, and medical significance, substituted and condensed pyrimidines form
a class of compounds of importance and still growing interests. Keeping this in view, it
was thought of interest to synthesize certain pyrimidobenzimidazoles with the expecta-
tion of their activities supplemented or at least comparable to those of benzimidazole and
pyrimidine derivatives.14.
Received 31 March 2014; accepted 16 July 2014.
Address correspondence to S. Srinivas Rao, Department of Chemistry, Jawaharlal Nehru Technological Uni-
versity Hyderabad, College of Engineering, Kukatpally, Hyderabad, 500 085 India. E-mail: seenu604@gmail.com
380

2-SUBSTITUTED BENZIMIDAZOLYLPYRIMIDINES
381
Table 1 Physical data of the synthesized compounds 5a-i
Substrate
Reagent
Product
3a
3a
3a
3b
3b
3b
3c
3c
3c
4a
4a
4a
4b
4b
4b
4c
4c
4c
DMS
DES
PhCH2Cl
DMS
DES
PhCH2Cl
DMS
DES
PhCH2Cl
thiourea
urea
Guanidine hydrochloride
thiourea
urea
5a
5b
5c
5d
5e
5f
5g
5h
5i
5a
5b
5c
5d
5e
5f
5g
5h
5i
Guanidine hydrochloride
thiourea
urea
Guanidine hydrochloride
Mohsen et al.15 reported that dihydropyrimidines can be prepared by ternary
condensation of benzaldehyde with thiourea and ethyl cyanoacetate. Preparation of
4-(4-methylbenzylidene)-1-phenyl-3,4-dihydropyrimido[1,6]benzimidazole by conden-
sation of 5-(4-methylbenzylidene)-2-phenyl-5,6-dihydro-4H-[1,3]oxazin-6-one with
o-phenylenediamine in 1:1 molar ratio in the presence of dry benzene was reported16
by Sharma et al. Zeynizadeh et al. reported17 that 3,4-dihydropyrimidin-2-(1H)-ones (or
thiones) could be prepared by the reaction of aromatic aldehydes with β-dicarbonyls, and
urea/thiourea using NaHSO4.H2O/ultrasound. Elgemei et al. 18 reported that tetrahydropy-
rimidines can be prepared by treatment of α, β-unsaturated nitriles with urea or thiourea
and K2CO3 under were reflux for 5 h.
It is obvious from the few literature citations given above that these types of re-
actions (i.e., reaction between unsaturated nitriles with nitrogen nucelophiles) will be of
much interest from organic synthesis considerations. In continuation of our earlier stud-
ies,19 we now wish to report our extensive and intensive studies on the preparation of
benzimidazolylmercaptopyrazoles.
RESULTS AND DISCUSSION
2-((1H-benzimidazol-2-yl)thio)acetonitrile 1 on reaction with benzaldehyde in
methanol containing piperidine as a base at RT for 3 h gave previously reported19
2-((1H-benzimidazol-2-yl)thio)-3-phenylacrylonitrile 2, which on treatment with nitrogen
nucleophiles such as thiourea/urea/guanidine in aq. KOH under reflux for 30 min
gave 5-((1H-benzimidazol-2-yl)thio)-6-amino-4-phenylpyrimidine-2(1H)-thione 3a,
5-((1H-benzimidazol-2-yl)thio)-6-amino-4-phenylpyrimidin-2(1H)-one 3b and 5-((1H-
benzimidazol-2-yl)thio)-2-imino-6-phenyl-2,3-dihydropyrimidin-4-amine 3c respectively.
The structures of 3a-c have been assigned on the basis of their spectral data. Thus, its
infrared spectrum showed absorptions for 3a at 3400–2800 cm−1 (br, m, NH, NH2),

382
S. SRINIVAS RAO ET AL.
1
2560 ( SH). H-NMR showed signals at 7.05–6.80 (m, 4H, Ar-H), 7.24 (s, 2H, J =
7.68 Hz, Ar-H), 7.58 (d, 2H, NH2), 7.72–6.99 (m, 3H, Ar-H), 10.82 (s, 1H, NH of
imadazole), 12.27 (s, 1H, SH) and its CI mass spectrum showed an ion peak at 352
(M++1) corresponding to the mass of 351. For 3b and 3c, see Experimental Section for
further details.
3a–c on further treatment with each of an alkylating agent, i.e., dimethylsulfate,
diethylsulfate and benzyl chloride individually in CH3CN containing K2CO3 as a base
and tetrabutylammonium bromide (TBAB) as a phase transfer catalyst (PTC) at RT for
3 h gave respectively 5 ((1 alkylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-
2-(thiol/ol/amine) 5a–i. 5a–i could also be prepared in an alternative way by alkylation
of 2-((1H-benzimidazol-2-yl)thio)-3-phenylacrylonitrile 2 under Phase Transfer Catalyst
(PTC) conditions for 3 h giving 2-((1-alkylbenzimidazol-2-yl)thio)-3-phenylacrylonitrile
4a–c followed by treatment with thiourea / urea / guanidine hydrochloride in aq KOH under
reflux for 30 min. (For details please see Table 1). Its IR spectrum showed absorptions for 5a
is 3400–2800 cm−1 (br, m, NH2), 2550 ( SH); 1H-NMR (400 MHz, DMSO-d6/ TMS):
δ 3.54 (s, 3H, CH3), 7.10–6.78 (m, 4H, Ar-H), 7.22 (s, 2H, J = 7.51 Hz, Ar-H), 7.55
(s, 2H, NH2), 7.79 -6.89 (m, 3H, Ar-H), 12.25 (s, 1H, SH), and its CI mass spectrum
showed an ion peak at 366 (M++1) corresponding to the mass of 365.
Scheme 1
EXPERIMENTAL SECTION
General
Melting points were determined in open capillaries in sulfuric acid bath and are
uncorrected. Thin-layer chromatography (TLC) analyses were done on glass plates coated
1
with silica gel GF-254 and spotting was done using Iodine or UV lamp. H NMR
were recorded in CDCl3 / DMSO using Varian 400-MHz instrument, 13C NMR were
recorded in DMSO/CDCl3 using VNMR100 MHz instrument and Mass spectra were
recorded on an Agilent LC-MS instrument giving only M+ values in Q+1 mode. The
1
Supplemental Materials contains sample H and 13C spectra for 5a and 5c (Figures S1–
S4)

2-SUBSTITUTED BENZIMIDAZOLYLPYRIMIDINES
383
General Procedure for the Preparation of 3 from 220
A mixture of 2 (5 mM), thiourea (5 mM) in aq. KOH was reflux for 30 min. After
completion of the reaction, the reaction mixture was poured into ice-cold water (≈50 mL).
The separated solid was filtered, washed with water (2 × 10 mL) and dried to obtain crude
3 which on recrystallization from ethyl acetate gave pure 3.
General Procedure for the Preparation of 4a–c from 2
A mixture of 2 (5 mM), K2CO3 (10 mM), TBAB (10 mg), CH3CN (20 mL), and
the alkylating agent (i.e., dimethylsulfate, diethylsulfate or benzyl chloride) (5 mM) was
stirred at room temp for 3 h. At the end of this period, the reaction mixture was poured into
ice-cold water (≈50 mL). The separated solid was filtered, washed with water (2 × 10 mL)
and dried to obtain crude 4a-c which on recrystallization from ethyl acetate gave pure 4a-c.
General Procedure for Preparation of 5a–i from 3a–c
A mixture of 3a-c (5 mM), K2CO3 (10 mM), TBAB (10 mg), CH3CN (20 mL)
and the alkylating agent (i.e. dimethylsulfate, diethylsulfate, or benzyl chloride) (5 mM)
individually was stirred at room temp for 3 h. At the end of this period, the reaction mixture
was poured into ice-cold water (≈50 mL). The separated solid was filtered, washed with
water (2 × 10 mL) and dried to obtain crude 5a–i which on recrystallization from ethyl
acetate gave pure 5a-i.
Alternative Procedure for Preparation of 5a–i from 4a–c
A mixture of 4a–c (5 mM), thiourea/urea/guanidine (5 mM) in aq. KOH individually
was reflux for 30 min. After completion of the reaction, the reaction mixture was poured into
ice-cold water (≈50 mL). The separated solid was filtered, washed with water (2×10 mL)
and dried to obtain crude 5a–i which on recrystallization from ethyl acetate gave pure 5a–i.
CHARACTERIZATION DATA
5-((1H-benzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-thiol 3a: yield:
72%; m.p. 223–225◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH, NH2), 2560 ( SH);
1H-NMR (400 MHz, DMSO-d6/ TMS): δ 7.05–6.80 (m, 4H, Ar-H), 7.24 (s, 2H, J =
7.68 Hz, Ar-H), 7.58 (d, 2H, NH2), 7.72–6.99 (m, 3H, Ar-H), 10.82 (s, 1H, NH of
imadazole), 12.27 (s, 1H, SH); 13C NMR: δ 156.5 (C N), 154.7 (C C Ph), 138.2
(Ar-C), 133.2 (Ar-C), 129.7 (Ar-C), 127.4 (2 Ar-C), 123.3 (2 Ar-C), 115.3 (C CH) ppm;
MS (CI): m/z 352 [M.++1]; HRMS (C17H13N5S2): Calcd for [M.++H], 352.4641 found
352.4638.
5-((1H-benzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-ol 3b: yield: 72%;
1
m.p. 199–201◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH-, NH2), 3200 ( OH); H-
NMR (400 MHz, DMSO-d6/ TMS): δ 7.09–6.93 (m, 4H, Ar-H), 7.52–6.65 (m, 3H, Ar-H),
7.80 (d, 2H, J = 7.58 Hz, Ar-H), 11.0 (s, 1H, NH of imadazole), 12.16 (s, 1H, OH);
13C NMR: δ 158.5 (C N), 154.2 (C C Ph), 136.2 (Ar-C), 132.2 (Ar-C), 128.7 (Ar-C),
127.4 (2 Ar-C), 122.3 (2 Ar-C), 114.3 (C CH) ppm; MS (CI): m/z 336 [M.++1]; HRMS
(C17H13N5OS): Calcd for [M.++H], 336.4641 found 336.4638.

384
S. SRINIVAS RAO ET AL.
5-((1H-Benzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-amine 3c: yield:
1
72%; m.p. 212–214◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH-, NH2); H-NMR
(400 MHz, DMSO-d6/ TMS): δ 6.55 (m, 4H, Ar-H), 7.25 (s, 4H, NH2), 7.48–7.52 (d,
2H, J = 7.73 Hz, Ar-H), 7.62–6.80 (m, 3H, Ar-H), 11.2 (s, 1H, NH of imadazole); 13
C
NMR: δ 155.5 (C N), 151.7 (C C Ph), 136.2 (Ar-C), 133.2 (2 Ar-C), 128.7 (Ar-C),
121.3 (Ar-C), 114.3 (C CH) ppm; MS (CI): m/z 335 [M.++1]; HRMS (C17H14N6S):
Calcd for [M.++H], 335.3153 found 335.3146.
2-((1-Methylbenzimidazol-2-yl)thio)-3-phenylacrylonitrile 4a: yield: 72%; m.p.
1
228–230◦C; IR (KBr): 2169 cm−1 ( CN); H-NMR (400 MHz, DMSO-d6/ TMS): δ
3.71 (s, 3H, -NCH3), 7.66–7.33 (m, 3H, Ar-H), 7.85–7.13 (m, 4H, J = 7.65 Hz, Ar-H), 8.10
(d, 2H, Ar-H), 8.23 (s, 1H,-C CH-); 13C NMR: δ 140.5 (C N), 138.5 (2 Ar-C), 135.0
(C CH), 132.4 (C≡N), 128.5 (2 Ar-C), 128.3 (Ar-C), 126.9 (2 Ar-C), 124.5 (2 Ar-C),
115.5 (C CH), 33.4 (CH3) ppm; MS (CI): m/z 292 [M.++1]; HRMS (C17H13N3S): Calcd
for [M.++H], 292.5848 found 292.5842.
2-((1-Ethylbenzimidazol-2-yl)thio)-3-phenylacrylonitrile 4b: yield: 76%; m.p.
206–208◦C; IR (KBr): 2234 cm−1 ( CN); 1H- NMR (400 MHz, DMSO-d6/ TMS): δ 1.28
(m, 2H, J = 6.76 Hz, NCH2 of ethyl), 3.62 (t, 3H, J = 7.10 Hz, CH3 of ethyl), 7.72–7.15
(m, 3H, Ar-H), 7.05–6.84 (m, 4H, J = 7.48 Hz, Ar-H), 8.19 (d, 2H, Ar-H), 8.42 (s, 1H,-C =
CH-); 13C NMR: δ 141.5 (C N), 136.4 (2 Ar-C), 134.0 (C CH), 133.4 (C≡N), 127.3
(2 Ar-C), 121.7 (Ar-C), 110.0 (2 Ar-C), 124.5 (2 Ar-C), 114.5 (C CH), 32.4 (CH3),
27.2 (CH2) ppm; MS (CI): m/z 306 [M.++1]; HRMS (C18H15N3S): Calcd for [M.++H],
306.0565 found 306.0573.
2-((1-Benzylbenzimidazol-2-yl)thio)-3-phenylacrylonitrile 4c: yield: 79%; m.p.
232–234◦C; IR (KBr): 2256 cm−1 ( CN); 1H-NMR (400 MHz, DMSO-d6/ TMS): δ 2.96
(s, 2H), 7.12–6.34 (m, 6H, Ar-H), 7.66–7.33 (m, 6H, Ar-H), 8.16 (d, 2H, J = 7.57 Hz, Ar-
H), 8.25 (s,1H, C CH ); 13C NMR: δ 139.5 (C N), 137.5 (2 Ar-C), 134.0 (C CH),
130.4 (C≡N), 126.3 (2 Ar-C), 122.7 (4 Ar-C), 118.5 (2 Ar-C), 112.5 (2 Ar-C), 109.5
(C CH), 28.4 (CH2) ppm; MS (CI): m/z 368 [M.++1]; HRMS (C23H17N3S): Calcd for
[M.++H], 368.4641 found 368.4638.
5-((1-Methylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-thiol 5a:
yield: 72%; m.p. 212–214◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH2), 2550 ( SH);
1H-NMR (400 MHz, DMSO-d6/ TMS): δ 3.84 (s, 3H, CH3), 7.10–6.58 (m, 4H, Ar-H),
7.22 (s, 2H, J = 7.51 Hz, Ar-H), 7.55 (s, 2H, NH2), 7.79–6.89 (m, 3H, Ar-H), 12.25
(s, 1H, SH); 13C NMR: δ 144.5 (C C), 138.2 (C Ph), 134.5 (Ar-C), 131.2 (2 Ar-
C), 127.7 (2 Ar-C), 125.8 (2 Ar-C), 123.5 (Ar-C), 118.3 (Ar-C), 34.6 ( CH3) ppm; MS
(CI): m/z 366 [M.++1]; HRMS (C18H15N5S2): Calcd for [M.++H], 366.5623 found 366.
5629.
5-((1-Methylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-ol 5b: yield:
68%; m.p. 202–205◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH2), 3220 ( OH); 1H NMR
(400 MHz, DMSO-d6/ TMS): δ 3.52 (s, 3H, CH3), 7.15–6.95 (m, 4H, Ar-H), 7.56–6.68
(m, 3H, Ar-H), 7.85 (d, 2H, J = 7.45 Hz, Ar-H), 12.16 (s, 1H, OH); 13C NMR: δ
155.5 (C C), 154.2 (C Ph), 134.2 (Ar-C), 130.2 (2 Ar-C), 126.7 (2 Ar-C), 125.4 (2
Ar-C), 122.5 (Ar-C),115.3 (Ar-C), 33.6 ( CH3) ppm; MS (CI): m/z 350 [M.++1]; HRMS
(C18H15N5OS): Calcd for [M.++H], 350.0571 found 350.0565.
5-((1-Methylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-amine 5c:
yield: 63%; m.p. 252–255◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH-, NH2), 1H NMR
(400 MHz, DMSO-d6/TMS): δ 3.82 (s, 3H, CH3), 6.32 (s, 4H, NH2), 7.46–6.83 (m,
4H, Ar-H), 7.55 (d, 2H, J = 7.75 Hz, Ar-H), 7.65–6.83 (m, 3H, Ar-H), 13C NMR: δ 162.5

2-SUBSTITUTED BENZIMIDAZOLYLPYRIMIDINES
385
(C C), 159.2 (C Ph), 144.2 (Ar-C), 138.2 (2 Ar-C), 127.7 (2 Ar-C), 125.6 (2 Ar-C), 121.5
(Ar-C), 116.3 (Ar-C), 32.4 ( CH3) ppm; MS (CI): m/z 349 [M.++1]; HRMS (C18H16N6S):
Calcd for [M.++H], 349.5642 found 349.5637.
5-((1-Ethylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-thiol 5d: yield:
75%; m.p. 189–191◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH2), 2550 ( SH); 1H NMR
(400 MHz, DMSO-d6/ TMS): δ 1.27 (m, 2H, J = 7.14 Hz, NCH2 of ethyl), 3.65 (t, 3H,
J = 7.24 Hz, CH3 of ethyl), 7.12–6.79 (m, 4H, Ar-H), 7.12 (s, 2H, J = 7.56 Hz, Ar-H),
7.59 (s, 2H, NH2), 7.72–6.86 (m, 3H, Ar-H),12.20 (s, 1H, SH); 13C NMR: δ 156.5 (C
C), 151.2 (C Ph), 134.5 (Ar-C), 131.7 (2 Ar-C), 127.6 (2 Ar-C), 124.6 (2 Ar-C), 125.9
(Ar-C),114.8 (Ar-C), 33.2 ( CH3), 28.6 ( CH2) ppm; MS (CI): m/z 390 [M.++1]; HRMS
(C18H16N6S): Calcd for [M.++H], 390.5848 found 390.5842.
5-((1-Ethylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-ol 5e: yield:
66%; m.p. 164–166◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH2), 3220 ( OH);
1H NMR (400 MHz, DMSO-d6/ TMS): δ 1.32 (m, 2H, J = 7.36 Hz NCH2 of ethyl), 3.75
(t, 3H, J = 7.28 Hz, CH3 of ethyl),7.14–6.95 (m, 4H, Ar-H), 7.58–6.68 (m, 3H, Ar-H), 7.84
(d, 2H, J = 7.78 Hz, Ar-H), 12.18 (s, 1H, OH); 13C NMR: δ 154.5 (C C), 152.2 (C Ph),
139.2 (Ar-C), 132.2 (2 Ar-C), 124.7 (2 Ar-C), 125.4 (2 Ar-C), 120.5 (Ar-C),115.5 (Ar-C),
33.6 ( CH3), 27.6 ( CH2) ppm; MS (CI): m/z 365 [M.++1]; HRMS (C19H17N5OS):
Calcd for [M.++H], 365.0571 found 365.0565.
5-((1-Ethylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-amine
5f:
yield: 61%; m.p. 205–207◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH-, NH2),
1H NMR (400 MHz, DMSO-d6/ TMS): δ 1.17 (m, 2H, J = 7.29 Hz NCH2 of ethyl), 3.60
(t, 3H, J = 7.22 Hz, CH3 of ethyl), 7.35 (s, 4H, NH2), 7.48–6.59 (m, 4H, Ar-H),
7.52 (d, 2H, J = 7.85 Hz, Ar-H), 7.60–6.81 (m, 3H, Ar-H), 13C NMR: δ 155.8 (C C),
152.7 (C Ph), 137.2 (Ar-C), 131.2 (2 Ar-C), 125.7 (2 Ar-C), 122.4 (2 Ar-C), 120.5
(Ar-C),118.5 (Ar-C), 32.6 ( CH3), 28.6 ( CH2) ppm; MS (CI): m/z 364 [M.++1]; HRMS
(C19H18N6S): Calcd for [M.++H], 364.0521 found 364.0527.
5-((1-Benzylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-thiol 5g:
yield: 69%; m.p. 191–194◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH2), 2550 ( SH);
1H NMR (400 MHz, DMSO-d6/ TMS): δ 2.89 (s, 2H), 7.10–6.78 (m, 4H, Ar-H), 7.22
(d, 4H, J = 7.90 Hz, Ar-H), 7.55 (s, 2H, NH2), 7.68–6.89 (m, 6H, Ar-H), 12.20 (s, 1H,
SH); 13C NMR: δ 156.5 (C C), 152.7 (C Ph), 134.5 (2 Ar-C), 133.9 (2 Ar-C), 128.7
(2 Ar-C), 126.4 (2 Ar-C), 123.9 (2 Ar-C),112.4 (2 Ar-C), 27.4 ( CH2) ppm; MS (CI): m/z
443 [M.++1]; HRMS (C24H19N5S2): Calcd for [M.++H], 443.1613 found 443.1607.
5-((1-Benzylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-ol 5h: yield:
71%; m.p. 236–238◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH2), 3220 ( OH);
1H NMR (400 MHz, DMSO-d6/ TMS): δ 2.79 (s, 2H), 7.14–6.95 (m, 6H, Ar-H), 7.66 -6.58
(m, 6H, Ar-H), 7.82 (d, 2H, J = 7.61 Hz, Ar-H), 12.18 (s, 1H, OH); 13C NMR: δ 154.5 (C =
C), 154.2 (C Ph), 134.2 (2 Ar-C), 131.9 (2 Ar-C), 126.7 (2 Ar-C), 122.4 (2 Ar-C),
120.5 (2 Ar-C),115.3 (2 Ar-C), 28.6 ( CH2) ppm; MS (CI): m/z 427 [M.++1]; HRMS
(C24H19N5OS): Calcd for [M.++H], 427.6246 found 427.6252.
5-((1-Benzylbenzimidazol-2-yl)thio)-4-amino-6-phenylpyrimidine-2-amine 5i:
yield: 65%; m.p. 185–187◦C; IR (KBr): 3400–2800 cm−1 (br, m, NH-, NH2), 1H NMR
(400 MHz, DMSO-d6/ TMS): δ 2.68 (s, 2H), 7.36 (s, 4H, NH2), 7.56–6.53 (m, 6H, Ar-H),
7.51 (d, 2H, J = 7.69 Hz, Ar-H), 7.61–6.82 (m, 6H, Ar-H); 13C NMR: δ 154.8 (C C),
150.7 (C Ph), 138.2 (2 Ar-C), 132.2 (2 Ar-C), 126.7 (2 Ar-C), 123.4 (2 Ar-C), 121.5 (2
Ar-C),114.8 (2 Ar-C), 27.6 ( CH2) ppm; MS (CI): m/z 349 [M.++1]; HRMS (C24H20N6S):
Calcd for [M.++H], 349.5752 found 349.5744.

386
S. SRINIVAS RAO ET AL.
ACKNOWLEDGMENTS
The authors are indebted to the authorities of Jawaharlal Nehru Technological
University Hyderabad for providing facilities.
SUPPLEMENTAL MATERIAL
Supplementary data for this article can be accessed on the publisher’s website, at
http://dx.doi.org/10.1080/10426507.2014.947409
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