GdCl3 catalysed Grieco condensation: A facile approach for the synthesis of novel pyrimidine and annulated pyrimidine fused indazole derivatives in single pot under mild conditions and their anti-microbial activity

Article abstract of DOI:10.1016/j.ejmech.2007.03.031

Indazole regioisomers such as 3-amino-4-(trifluoromethyl)-6-phenyl-1H-indazole-7-carbonitrile 1 and 3-amino-6-(trifluoromethyl)-4-phenyl-1H-indazole-7-carbonitrile 2 were independently reacted with formaldehyde followed by unsymmetrical, symmetrical and cyclic electron rich olefins in presence of GdCl₃ as catalyst and obtained pyrimidine fused indazole derivatives 3 and 4, respectively. The reaction is found to be concerted and an exclusive product is formed. Representative examples of compounds 3 and 4 were screened against Gram-positive, Gram-negative bacteria and fungal species such as yeast and filamentous fungi in vitro. Compound 3f showed significant activity against all species of Gram-positive and Gram-negative bacteria, whereas compounds 3h and 4a showed the least activity with reference to penicillin as well as streptomycin. Similarly compound 3c showed promising activity against yeast and filamentous fungi whereas compound 3f is inactive at the maximum concentration of 150 μg/mL.

Full text of DOI:10.1016/j.ejmech.2007.03.031

Available online at www.sciencedirect.com
European Journal of Medicinal Chemistry 43 (2008) 341e347
http://www.elsevier.com/locate/ejmech
Original article
GdCl3 catalysed Grieco condensation: A facile approach for the
synthesis of novel pyrimidine and annulated pyrimidine fused
indazole derivatives in single pot under mild conditions
and their anti-microbial activity*
b
b
T. Yakaiah a, B.P.V. Lingaiah a, B. Narsaiah a, , K. Pranay Kumar , U.S.N. Murthy
*
a Fluoroorganic Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India
b Biology Division (Bioinformatics), Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India
Received 8 January 2007; received in revised form 20 March 2007; accepted 26 March 2007
Available online 14 April 2007
Abstract
Indazole regioisomers such as 3-amino-4-(trifluoromethyl)-6-phenyl-1H-indazole-7-carbonitrile 1 and 3-amino-6-(trifluoromethyl)-4-phenyl-
1H-indazole-7-carbonitrile 2 were independently reacted with formaldehyde followed by unsymmetrical, symmetrical and cyclic electron rich
olefins in presence of GdCl3 as catalyst and obtained pyrimidine fused indazole derivatives 3 and 4, respectively. The reaction is found to be
concerted and an exclusive product is formed. Representative examples of compounds 3 and 4 were screened against Gram-positive, Gram-neg-
ative bacteria and fungal species such as yeast and filamentous fungi in vitro. Compound 3f showed significant activity against all species of
Gram-positive and Gram-negative bacteria, whereas compounds 3h and 4a showed the least activity with reference to penicillin as well as strep-
tomycin. Similarly compound 3c showed promising activity against yeast and filamentous fungi whereas compound 3f is inactive at the max-
imum concentration of 150 mg/mL.
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: Regioisomers; Indazoles; Pyrimidines; Cyclisation; Olefins; Diazadiene
1. Introduction
pyrimidine ring over indazoles as a result, pyrimidine fused in-
dazoles are formed which are considered to have promising
activity against many infections. Thus our attention was di-
rected towards synthesis of a series of novel pyrimidine fused
indazole derivatives with trifluoromethyl group at an appropri-
ate position to find an organic molecule as potential drug.
Paul A. Grieco and Ali Bhasas [8] for the first time in 1988
devised a methodology for three-component condensation reac-
tion called Grieco condensation. It involves reaction of amine
with aldehydes followed by electron rich olefins to have tetrahy-
dro quinolines. Thus multicomponent reactions overriding lin-
ear reactions to combat the environmental legislations. Earlier
reports based on Grieco condensation were mainly about
aromatic amines [9e12] condensed with formaldehyde to
have azadiene followed by reaction with electron rich olefins
in order to get tetrahydroquinolines. Alternately imines
[13,14] are generated from amines and carbonyl compounds
The modern trend in organic synthesis is driving towards
discovery of new organic molecules as potential drugs by
adopting various synthetic strategies. Among the prominent
ring systems such as pyrazole-fused benzenes are also called
indazole derivatives, known to be active against cancer cell
proliferative disorders [1], protein kinases [2,3], Alzeimer’s
diseases [4]. Similarly pyrimidine ring in an organic molecule
also shows prominent activity as anti-malarial [5], anti-infec-
tive agents [6], and pyridoxol antagonist diseases [7]. There-
fore interest is continuously increasing on fusion of
*
IICT Communication No. 070105.
* Corresponding author. Tel.: þ91 40 27193630; fax: þ91 40 27160387.
E-mail address: narsaiah@iict.res.in (B. Narsaiah).
0223-5234/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2007.03.031

342
T. Yakaiah et al. / European Journal of Medicinal Chemistry 43 (2008) 341e347
then reacted with various dienes to have cyclo addition products.
However, generation of diazadiene is not known so far except
our report [15]. In continuation of our efforts [16e19], we
have chosen 3-amino indazole regioisomers 1 and 2 [20] and re-
acted with formaldehyde as a result, diazadienes are formed in
situ followed by cyclisation with various electron rich olefins
resulted in novel pyrimidine fused indazole derivatives 3 and
4, respectively. Representative examples were screened for anti-
bacterial and anti-fungal activity. Compounds 3f and 3c are con-
sidered as interesting lead compounds and further studies are in
progress to develop more potent anti-bacterial and anti-fungal
compounds, respectively.
1H NMR, mass spectra and elemental analysis data. The small
coupling constant (J ) of the ring junction protons (4aS,12aS )
of 9.6 Hz in compound 3a indicates a cis ring junction and is
in agreement with earlier reports [11,12]. The similar trend is
followed in other compounds and products formed in each
case are tabulated in Table 1.
3. In vitro anti-bacterial assays
Four bacterial test organisms such as Bacillus subtilis
(MTCC 441), Staphylococcus aureus (MTCC 96), Pseudomo-
nas aeruginosa (MTCC 1688), and Escherichia coli (MTCC
443) were selected and obtained from the Institute of Micro-
bial Technology, Chandigarh. Cultures of test organisms
were maintained on Nutrient agar slants and were sub-cultured
in Petri dishes prior to testing. The media used was Nutrient
agar, Nutrient broth procured from Himedia Laboratories,
Mumbai. The minimum inhibitory concentration was deter-
mined by broth dilution method [21].
Compounds 3aeh, 4a and 4h were dissolved in acetone
and screened for their in vitro anti-bacterial activity. The
anti-bacterial activity was tested against Gram-positive
(B. subtilis, S. aureus) and Gram-negative (P. aeruginosa,
E. coli) bacteria in vitro. Compound 3f showed significant ac-
tivity against all species of Gram-positive and Gram-negative
bacteria with reference to penicillin as well as streptomycin.
Compounds 3d, 3e and 3g showed moderate activity whereas
3h and 4a showed the least activity. Among regioisomers 3a
and 4a, compound 3a is more active than compound 4a
against S. aureus. Similarly among other regioisomers 3h
and 4h, compound 4h is more active than compound 3h
against B. subtilis and P. aeruginosa and less active against
S. aureus. In conclusion 4,8-diphenyl-10-(trifluoromethyl)-
1,2,3,4-tetrahydropyrimido[1,2-b]indazole-7-carbonitrile 3f is
the most active among the screened compounds while com-
pounds 3h and 4a showed the least activity. The MIC values
of the compounds were compared with those obtained with
penicillin and streptomycin. The details of compounds and
their activity against various microorganisms are tabulated in
Table 2.
2. Chemistry
The regioisomers of indazoles such as 3-amino-4-(trifluoro-
methyl)-6-phenyl-1H-indazole-7-carbonitrile 1 and 3-amino-6-
(trifluoromethyl)-4-phenyl-1H-indazole-7-carbonitrile 2 were
selected as suitable amines for generation of diazadienes, as
amine functional group is in conjugation with imine in pyrazole
ring. Thus compounds 1 and 2 were independently reacted with
formaldehyde in acetonitrile at room temperature and diaza-
dienes were formed in situ. The generated diazadienes are re-
acted with various substituted electron rich olefins using
GdCl3 as catalyst. Solvent was removed and residue is treated
with water, extraction with dichloromethane and column chro-
matography resulted in cyclic products 3 and 4, respectively, in
high yields. A typical sequence of reaction is drawn in Scheme 1.
The mode of reaction is mainly formation of Schiff’s base
in situ, which acts as a diazadiene and is complexed with
GdCl3. The complex is further reacted with various electron
rich alkenes in order to get cyclised adducts. In a typical ex-
ample when isoprene, an unsymmetrical olefin is reacted
with diazadiene, an exclusive product 3h or 4h is formed de-
pending upon the regioisomer. It is attributed to an attack of
nucleophile from diazadiene on tertiary carbon of olefin as
a result, only one product is formed, as unsaturated tertiary
carbon being relatively more nucleophilic than unsaturated
secondary carbon followed by primary carbon. The probable
sequence of mechanism is drawn in Scheme 2.
In order to see the versatility of the reaction, indazole re-
gioisomers 1 and 2 were further reacted with formaldehyde
followed by various cyclic olefins and cis products were ob-
tained exclusively in high yields. The structure and stereo-
chemistry of all the products were identified based on IR,
4. In vitro anti-fungal activity assays
The in vitro anti-fungal activity of compounds 3aeh, 4a
and 4h was screened against the fungal strains, viz., Candida
R
R
R
N=CH2
N
HN
NH2
HCHO / CH3CN / r.t.
N
N
N
N
/ GdCi3
r.t
R'
N
H
R'
R'
H
CN
CN
CN
0°C
30 - 60 min
3) R = CF3, R' = Ph
4) R = Ph, R' = CF3
1) R = CF3, R' = Ph
2) R = Ph, R' = CF3
Scheme 1.

T. Yakaiah et al. / European Journal of Medicinal Chemistry 43 (2008) 341e347
343
R
R
R
N=CH2
N
N=CH2
N
NH2
N
HCHO
GdCl3
N
H
N
N
R'
R'
R'
H
H
CN
CN
CN
1) R = CF3, R'= Ph
2) R = Ph, R'= CF3
Gd
R
R
N
HN
N
N
N
H
N
R'
R'
CN
CN
3) R = CF3, R'= Ph
4) R = Ph, R'= CF3
Scheme 2.
albicans (MTCC 227), Saccharomyces cereviseae (MTCC 36)
and filamentous fungal cultures like Rhizopus oryzae (MTCC
262) and Aspergillus niger (MTCC 1344) by agar cup diffu-
sion method [22]. The strains were obtained from the Institute
of Microbial Technology, Chandigarh.
Compound 3c showed promising activity against all the
fungi at different concentrations except with S. cereviseae.
It is found that the inhibition diameter is concentration depen-
dent and increases with concentration. Compound 3f is inac-
tive against all the fungal cultures screened. Comparing the
Table 1
Preparation of annulated pyrimidine indazole derivatives 3aeh, and 4aeh
6
5
H
N
R
H
R
NH2
4
2
7
8
3
N
N
12
O
H
N
N
R'
9
R'
10
CN
1
H
CN
11
1) R = CF3, R' = Ph
3) R = CF3, R'= Ph
4) R = Ph, R'= CF3
2) R = Ph, R'= CF3
Alkene
Product
CF3
Yield (%)
85
Product
Yield (%)
84
4a
H
HN
N
O
O
N
H
Ph
CN
3a
88
4b
89
H
CF3
HN
N
N
H
Ph
CN
3b
89
94
4c
91
CF3
H
HN
N
N
H
Ph
3c
CN
4d
96
CF3
H
HN
N
N
H
Ph
3d
CN
(continued on next page)

344
T. Yakaiah et al. / European Journal of Medicinal Chemistry 43 (2008) 341e347
Table 1 (continued)
Alkene
Product
Yield (%)
89
Product
4e
Yield (%)
87
CF3
H
HN
N
Ph
N
Ph
Ph
CN
3e
93
91
78
4f
95
93
79
CF3
HN
N
Ph
Ph
H
N
Ph
3f
CN
4g
CF3
HN
N
N
CH3
Ph
Ph
CN
3g
4h
CF3
HN
N
N
CH3
3h
CN
regioisomers 3a and 4a, compound 4a is found to be more ac-
tive. Similarly regioisomer 4f is more active than 3f. Com-
pounds 3e and 3g also showed significant activity. However,
all compounds 3aeh, 4a and 4f are inactive against yeast fun-
gal culture S. cereviseae upto a maximum concentration of
150 mg/mL. In conclusion, annulated pyrimidine fused inda-
zoles are more active than pyimidine fused indazoles. The
inhibitory zone diameters of the compounds are compared
with those obtained with 50 mg/mL. The details of the results
have been tabulated in Table 3.
5. Conclusion
A single pot method has been developed for the synthesis of
pyrimidine fused and annulated pyrimidine fused indazoles us-
ing GdCl3 as catalyst in high yields. Representative examples
were screened against Gram-positive, Gram-negative bacteria,
yeasts and filamentous fungi. Compound 3f showed promising
activity against bacteria and compound 3c against fungi.
Table 2
Minimum inhibitory concentration (MIC in mg/mL) of compounds 3aeh, 4a
and 4h for various bacterial microorganisms
Compound
Microorganism
Gram-positive
B. subtilis
Gram-negative
S. aureus
P. aeruginosa
E. coli
6. Experimental
3a
3b
150.0
75.0
75.0
150.0
75.0
150.0
150.0
75.0
75.0
75.0
37.5
37.5
37.5
25.0
37.5
150.0
75.0
150.0
12. 5
Melting points were recorded on Casia-Siamia (VMP-AM)
melting point apparatus and are uncorrected. IR spectra were
recorded on a Perkin-Elmer FT-IR 240-C spectrophotometer
3c
3d
150.0
150.0
75.0
37.5
37.5
75.0
75.0
3e
1
3f
3g
50.0
75.0
50.0
75.0
50.0
75.0
using KBr optics. H NMR spectra were recorded on Varian
Gemini varion 200 MHz, Bruker AV 300 MHz and Unity
400 MHz spectrometer in CDCl3 using TMS as an internal
standard. LSIMS mass spectra were recorded on a VG 7070
H instrument at 70 eV. All reactions were monitored by thin
layer chromatography (TLC) on precoated silicagel 60 F254
(mesh); spots were visualized with UV light. Merck silicagel
3h
4a
150.0
150.0
75.0
75.0
150.0
150.0
75.0
150.0
150.0
1.562
6.25
4h
Penicillin
Streptomycin
1.562
6.25
6.25
1.562
1.562
Negative control; acetone showed no activity.

T. Yakaiah et al. / European Journal of Medicinal Chemistry 43 (2008) 341e347
345
Table 3
Inhibitory zone diameters of compounds 3aeh, 4a and 4h for various fungal cultures at different concentrations
Compound
C. albicans (mg/mL)
S. cerviseae (mg/mL)
R. oryzae (mg/mL)
A. niger (mg/mL)
100
150
100
150
100
150
100
150
3a
3b
e
e
e
e
e
e
e
e
e
e
e
e
e
9 mm
7 mm
8 mm
e
e
e
e
e
e
e
9 mm
12 mm
e
e
10 mm
9 mm
12 mm
10 mm
10 mm
e
3c
3d
7 mm
e
8 mm
9 mm
11 mm
e
e
e
e
3e
9 mm
e
e
e
9 mm
e
e
3f
3g
e
e
e
8 mm
7 mm
8 mm
e
9 mm
8 mm
10 mm
e
e
e
e
e
12 mm
e
e
7 mm
e
e
8 mm
e
3h
4a
e
e
9 mm
10 mm
4f
Amphotericin-B (50 mg/mL)
e
22 mm
8 mm
23 mm
e
26 mm
e
23.5 mm
Negative control; DMSO showed no activity; well or cup method; the concentrations are expressed in mg/mL and inhibitory zone diameters are expressed in mm.
(60e120 mesh) was used for chromatography. CHN analyses
were recorded on a Vario EL analyzer.
(2H þ 1H þ 1H, m, CH2, CH, CH2eN), 3.58e3.68 (1H, m,
CH2eN), 5.52 (1H, br s, NH), 5.7 (1H, d, J 8.9 Hz, HCeN),
7.8 (1H, m, Ar-H), 7.20e7.30 (3H, m, Ar-H), 7.48e7.68 (5H,
m, Ar-H), 7.85e7.98 (1H, m, Ar-H). IR (KBr): 3356 (NeH),
2933 (CeH), 2226 (C^N), 1606 (C]N) cmꢁ1. LSIMS m/z:
431 (MHþ). Anal. calcd. for C25H17F3N4: C, 69.76; H, 3.98; N,
13.01; found: C, 69.97; H, 4.48; N, 12.77%.
6.1. General procedure
6.1.1. Preparation of annulated pyrimidine fused indazoles
(3aeh and 4aeh)
To a solution of indazole regioisomers (1 or 2) (500 mg,
1.65 mmol) in acetonitrile (8 mL), 40% formaldehyde solution
(3 mL) was added and the mixture was stirred for 15e20 min
under N2 atmosphere at room temperature. The solution was
cooled to 0 ꢀC and GdCl3 (2.64 mg, 10 mol%) was added fol-
lowed by the addition of corresponding olefin (2 equiv.). The to-
tal mixture was stirred for 30e60 min, under N2 atmosphere at
room temperature. Acetonitrile was removed under vacuo and
the residue reaction mixture was treated with water, extracted
with dichloromethane and dried over sodium sulphate. The di-
chloromethane extract was concentrated to give the crude prod-
ucts 3 or 4 and were purified by column chromatography using
60e120 mesh silicagel. The desired products were eluted with
20% EtOAc/hexane mixture and obtained in high yields.
6.1.1.3. (4aS,12aS)-9-Phenyl-7-(trifluoromethyl)-3,4,4a,5,6,12a-
hexahydroindazolo[2,3-a]quinazoline-10-carbonitrile (3c). Yield:
1
580 mg (89%); yellow coloured solid; mp 175 ꢀC. H NMR
(200 MHz, CDCl3): d ¼ 1.83e2.0 (2H, m, CH2eCH2eHC]
CH), 2.06e2.24 (2H, m, CH2eHC]CH, CH), 2.48e2.56 (1H,
m, CH ), 3.42e3.58 (2H, m, CH2eN), 5.14 (1H, s, HCeN), 5.60
(1H, br s, NH), 5.92 (1H, d, J 17.9 Hz, HC]CH), 6.20 (1H, m,
HC]CH), 7.40e7.56 (4H, m, Ar-H), 7.58e7.68 (2H, m, Ar-H).
IR (KBr): 3405 (NeH), 2936 (CeH), 2228 (C^N), 1615
(C]N) cmꢁ1. LSIMS m/z: 395 (MHþ). Anal. calcd. for
C22H17F3N4: C, 66.99; H, 4.34; N, 14.20; found: C, 66.81; H,
4.59; N, 13.90%.
6.1.1.4. (3aS,11aS )-8-Phenyl-6-(trifluoromethyl)-3a,4,5,11a-tet-
rahydro-1H-cyclopenta[5,6]pyrimido[1,2-b]indazole-9-carboni-
trile (3d). Yield: 590 mg (94%); yellow coloured solid; mp
6.1.1.1. (4aS,12aS)-9-Phenyl-7-(trifluoromethyl)-3,4,4a,5,6,12a-
hexahydro-2H-pyrano[30,20,5,6]pyrimido[1,2-b]indazole-10-car-
bonitrile (3a). Yield: 560 mg (85%); yellow coloured solid;
mp þ300 ꢀC. 1H NMR (200 MHz, CDCl3): d ¼ 1.41e1.62
(1H, m, OCH2CH2), 2.12e2.18 (1H þ 2H, m, OCH2CH2,
CH2eCH), 2.24e2.42 (1H, m, CH ), 3.26e3.48 (1H, m,
CH2eN), 3.64e3.96 (1H þ 1H, m, CH2eO, CH2eN), 4.12e
4.16 (1H, m, CH2eO), 5.68e5.76 (1H, d, J 9.6 Hz, HCeO),
5.84 (1H, br s, NH ), 7.14 (1H, s, HeC(8), Ar-H), 7.42e
7.85 (5H, m, Ar-H). IR (KBr): 3381 (NeH), 2934 (CeH),
2229 (C^N), 1606 (C]N), 2210 (CN) cmꢁ1. LSIMS m/z:
399 (MHþ). Anal. calcd. for C21H17F3N4O: C, 63.31; H,
4.30; N, 14.06; found: C, 63.10; H, 4.11; N, 14.24%.
1
186 ꢀC. H NMR (200 MHz, CDCl3): d ¼ 2.2 (2H, m, CH2),
2.3e2.48 (1H, m, CH ), 2.68e2.88 (1H, m, CH2eN), 3.12e
3.28 (1H, m, CH2eN), 3.46e3.58 (1H, m, CHeN), 5.70 (1H,
br s, NH ), 5.96 (1H, d, J 17.1 Hz, HC]CH), 6.20 (1H, d, J
17.1 Hz, HC]CH ), 7.40e7.65 (6H, m, Ar-H). IR (KBr): 3351
(NeH), 2928 (CeH), 2230 (C^N), 1604 (C]N) cmꢁ1. LSIMS
m/z: 381(MHþ). Anal. calcd. for C21H15F3N4: C, 66.31; H, 3.97;
N, 14.72; found: C, 66.54; H, 3.81; N, 14.89%.
6.1.1.5. (4aS,12aS )-9,12a-Diphenyl-7-(trifluoromethyl)-1,2,3,4,
4a,5,6,12a-octahydroindazolo[2,3-a]quinazoline-10-carboni-
trile (3e). Yield: 690 mg (89%); bright yellow coloured
1
solid; mp 266 ꢀC. H NMR (200 MHz, CDCl3): d ¼ 1.4e1.6
6.1.1.2. (6aS,11aS)-2-Phenyl-4-(trifluoromethyl)-6,6a,11,11a-
tetrahydro-5H-indeno[10,20:5,6]pyrimido[1,2-b]indazole-1-car-
bonitrile (3b). Yield: 620 mg (88%); bright yellow coloured
solid; mp 203 ꢀC. 1H NMR (200 MHz, CDCl3): d ¼ 2.82e2.90
(2H þ 1H, m, CH2CH2eCH, CH2CH2eCPh), 1.68e1.81
(2H þ 1H, m, CH2eHC, CH2CH2eCPh), 1.95e2.05 (1H, m,
CH2eCPh), 2.43 (1H, d, J 16.8 Hz, CH ), 3.0e3.1 (1H, m,

346
T. Yakaiah et al. / European Journal of Medicinal Chemistry 43 (2008) 341e347
CH2eCPh), 3.14e3.22 (2H, m, CH2eN), 5.55 (1H, br s, NH ),
6.65e6.75 (2H, m, Ar-H), 7.10e7.28 (4H, m, Ar-H), 7.41e
7.55 (3H, m, Ar-H), 7.58e7.68 (2H, m, Ar-H). IR (KBr): 3343
(NeH), 2932 (CeH), 2228 (C^N), 1606 (C]N) cmꢁ1. LSIMS
m/z: 473 (MHþ). Anal. calcd. for C28H23F3N4: C, 71.17; H, 4.90;
N, 11.85; found: C, 71.35; H, 5.12; N, 11.61%.
6.1.1.10. (6aS,11aS )-4-Phenyl-2-(trifluoromethyl)-6,6a,11,11a-
tetrahydro-5H-indeno[10,20:5,6]pyrimido[1,2-b]indazole-1-car-
bonitrile (4b). Yield: 630 mg (89%); bright yellow coloured
1
solid; mp þ300 ꢀC. H NMR (200 MHz, CDCl3): d ¼ 2.91e
3.08 (2H þ 1H, m, CH2, CH2eN), 3.25e3.40(1H, m, CH ),
3.48 (1H, m, CH2eN), 4.85 (1H, br s, NH), 5.95 (1H, d, J
8.9 Hz, HCeN), 7.21e7.29 (4H, m, Ar-H), 7.48e7.58 (6H,
m, Ar-H). IR (KBr): 3359 (NeH), 2928 (CeH), 2228
(C^N), 1603 (C]N) cmꢁ1. LSIMS m/z: 431 (MHþ). Anal.
calcd. for C25H17F3N4: C, 69.76; H, 3.98; N, 13.01; found:
C, 70.01; H, 3.80; N, 12.86%.
6.1.1.6. 4,8-Diphenyl-10-(trifluoromethyl)-1,2,3,4-tetrahydro-
pyrimido[1,2-b] indazole-7-carbonitrile (3f). Yield: 0.64 g
1
(93%); bright yellow coloured solid, mp þ300 ꢀC, H NMR
(200 MHz, CDCl3): d ¼ 2.48e2.62 (2H, m, CH2), 3.26e3.58
(2H, m, CH2eN), 5.82 (1H, br s, NH), 5.84 (1H, t, J 8.2 Hz,
CH-Ph), 6.92 (2H, d, J 16.8 Hz, Ar-H), 7.18e7.3 (1H, s, Ar-
H), 7.26e7.41 (3H, m, Ar-H), 7.42e7.58 (3H, m, Ar-H),
7.59e7.72 (2H, d, J 16.8 Hz, AreH). IR (KBr): 3470 (Ne
H), 2929 (CeH), 2232 (C^N), 1609 (C]N) cmꢁ1. LSIMS
m/z: 419 (MHþ), Anal. calcd. for C24H17 F3N4: C, 68.89; H,
4.09; N, 13.39; found: C, 68.73; H, 3.88; N, 13.59%.
6.1.1.11. (4aS,12aS)-7-Phenyl-9-(trifluoromethyl)-3,4,4a,5,6,12a-
hexahydroindazolo[2,3-a]quinazoline-10-carbonitrile (4c). Yield:
1
590 mg (89%); yellow coloured solid; mp þ300 ꢀC. H NMR
(200 MHz, CDCl3): d ¼ 1.80e1.96 (2H, m, CH2eCH2e
HC]CH), 2.12e2.26 (2H, m, CH2eHC]CH), 2.51e2.55 (1H,
m, CH), 3.40e3.56 (2H, m, CH2eN), 5.18 (1H, s, HCeN), 5.62
(1H, br s, NH), 5.90 (1H, d, J 18 Hz, HC]CH), 6.22 (1H, d, J
17 Hz, HC]CH) 6.96e7.12 (3H, m, Ar-H), 7.22e7.42 (3H, m,
Ar-H). IR (KBr): 3405 (NeH), 2934 (CeH), 2233 (C^N), 1610
6.1.1.7. 4-Methyl-4,8-diphenyl-10-(trifluoromethyl)-1,2,3,4-tet-
rahydropyrimido[1,2-b]indazole-7-carbonitrile (3g). Yield:
.
(C]N) cmꢁ1 LSIMS m/z: 395(MHþ). Anal. calcd. for
1
650 mg (91%); yellow coloured solid; mp 193 ꢀC. H NMR
C22H17F3N4: C, 66.99; H, 4.34; N, 14.20; found: C, 66.83; H,
4.13; N, 14.40%.
(200 MHz, CDCl3): d ¼ 2.15 (3H, s, CH3), 2.32e2.48 (1H,
m, CeCH2), 2.52e2.65 (1H, m, CeCH2), 3.05e3.15 (1H,
m, CH2eN), 3.41e3.58 (1H, m, CH2eN), 5.85 (1H, br s,
NH ), 6.81e6.92 (2H, m, Ar-H), 7.12 (1H, s, Ar-H), 7.22e
7.38 (3H, m, Ar-H), 7.48e7.61 (3H, m, Ar-H), 7.62e7.72
(2H, m, Ar-H). IR (KBr): 3398 (NeH), 2934 (CeH), 2226
(C^N), 1605 (C]N) cmꢁ1. ESIMS m/z: 433 (MHþ). Anal.
calcd. for C25H19F3N4: C, 69.43; H, 4.42; N, 12.95; found:
C, 69.68; H, 4.24; N, 12.80%.
6.1.1.12. (3aS,11aS )-6-Phenyl-8-(trifluoromethyl)-3a,4,5,11a-
tetrahydro-1H-cyclopenta[5,6]pyrimido[1,2-b]indazole-9-car-
bonitrile (4d). Yield: 60 mg (96%); yellow coloured solid;
1
mp 218 ꢀC. H NMR (200 MHz, CDCl3): d ¼ 2.22 (2H, m,
CH2), 2.32e3.51 (1H, m, CH), 2.70e2.89 (1H, m, CH2e
N), 3.18e3.30 (1H, m, CH2eN), 5.56 (1H, d, J 7.5 Hz,
HCeN) 5.68 (1H, br s, NH ), 5.98 (1H, d, J 17.8 Hz,
HC]CH), 6.25 (1H, d, J 17.8 Hz, HC]CH ), 7.58e7.68
(4H, m, Ar-H), 8.08e8.18 (2H, m, Ar-H). IR (KBr): 3352
(NeH), 2933 (CeH), 2229 (C^N), 1604 (C]N), 2928
(CeH) cmꢁ1. LSIMS m/z: 381(MHþ). Anal. calcd. for
C21H15F3N4: C, 66.31; H, 3.97; N, 14.72; found: C, 66.49;
H, 4.19; N, 14.48%.
6.1.1.8. 4-Methyl-8-phenyl-10-(trifluoromethyl)-4-vinyl-1,2,3,4-
tetrahydropyrimido[1,2-b]indazole-7-carbonitrile (3h). Yield:
1
490 mg (78%); yellow coloured solid; mp 174 ꢀC. H NMR
(200 MHz, CDCl3): d ¼ 1.84 (3H, s, CH3eC), 2.1e2.24 (2H,
m, CH2), 3.48e3.58 (2H, m, CH2eNH), 4.71 (1H, d, J
18.4 Hz, HC]CH2), 5.22 (1H, d, J 18.5 Hz, HC]CH2), 5.5
(1H, br s, NH ), 5.95e6.1 (1H, m, HC]CH2), 7.4e7.68 (6H,
m, Ar-H). IR (KBr): 3395 (NeH), 2931 (CeH), 2221
(C^N), 1606 (C]N) cmꢁ1. LSIMS m/z: 383 (MHþ). Anal.
calcd. for C21H17F3N4: C, 65.96; H, 4.48; N, 14.65; found:
C, 65.80; H, 4.71; N, 14.82%.
6.1.1.13. (4aS )-7,12a-Diphenyl-9-trifluoromethyl)1,2,3,4,4a,5,
6,12a-octahydroindazolo[2,3-a]quinazoline-10-carbonitrile (4e).
Yield: 670 mg (87%); bright yellow coloured solid; mp
242 ꢀC. 1H NMR (200 MHz, CDCl3): d ¼ 1.48e1.61
(2H þ 1H, m, CH2CH2eCH, CH2CH2eCPh), 1.70e1.90
(2H þ 1H, m, CH2eHC, CH2CH2eCPh), 2.02e2.22 (1H, m,
CH2eCPh), 2.48 (1H, d, J 16 Hz, CH ), 3.02e3.10 (1H, m,
CH2eCPh), 3.20e3.36 (2H, m, CH2eN), 4.90 (1H, br s,
NH ), 6.70e6.79 (2H, m, Ar-H), 6.92 (1H, s, Ar-H), 7.24e
7.32 (3H, m, Ar-H), 7.51e7.61(5H, m, Ar-H). IR (KBr):
3322 (NeH), 2932 (CeH), 2230(C^N), 1605 (C]N), 2932
(CeH) cmꢁ1. LSIMS m/z: 472 (MHþ). Anal. calcd. for
C28H23F3N4: C, 71.17; H, 4.90; N, 11.85; found: C, 71.40;
H, 4.74; N, 12.02%.
6.1.1.9. (4aS, 12aS )-7-Phenyl-9-(trifluoromethyl)-3,4,4a,5,6,12a-
hexahydro-2H-pyrano[30,20:5,6] pyrimido [1,2-b] indazole-10-
carbonitrile (4a). Yield: 550 mg (84%); yellow coloured solid;
mp þ300 ꢀC. 1H NMR (200 MHz, CDCl3): d ¼ 1.48e1.53
(2H, m, OCH2CH2), 1.85e2.04 (2H, m, OCH2CH2eCH2e
CH), 2.56e2.61 (1H, m, CH ), 3.22e3.51 (1H, m, CH2eN),
3.74e3.9 (2H, m, CH2eO, CH2eN), 4.01e4.18 (1H, m,
CH2eO), 5.19 (1H, d, J 9.6 Hz, HCeO), 5.78 (1H, br s, NH ),
7.42e7.61 (6H, m, Ar-H). IR (KBr): 3387 (NeH), 2938
(CeH), 2226 (C^N), 1607 (C]N) cmꢁ1. LSIMS m/z: 399
(MHþ). Anal. calcd. for C21H17F3N4O: C, 63.31; H, 4.30; N,
14.06; found: C, 63.15; H, 4.53; N, 14.23%.
6.1.1.14. 4,10-Diphenyl-8-(trifluoromethyl)-1,2,3,4-tetrahydro-
pyrimido[1,2-b]indazole-7-carbonitrile (4f). Yield: 650 mg
1
(95%); bright yellow coloured solid; mp 202 ꢀC. H NMR

T. Yakaiah et al. / European Journal of Medicinal Chemistry 43 (2008) 341e347
347
(200 MHz, CDCl3): d ¼ 2.46e2.68 (2H, m, CH2), 2.50e2.60
(2H, m, CH2eN), 5.12 (1H, br s, NH), 5.94 (1H, t, J 8.2 Hz,
CHePh) 6.92e7.08 (3H, m, Ar-H), 7.28e7.38 (3H, m, Ar-
H), 7.52e7.61 (5H, m, Ar-H). IR (KBr): 3469 (NeH), 2928
(CeH), 2228(C^N), 1606(C]N) cmꢁ1. LSIMS m/z: 419
(MHþ). Anal. calcd. for C24H17F3N4: C, 68.89; H, 4.09; N,
13.39; found: C, 68.71; H, 4.34; N, 13.09%.
were calculated in millimeters. Three to four replicates were
maintained for each treatment. Media potato dextrose broth
and potato dextrose agar were procured from M/s Himedia
Laboratories, Mumbai.
Acknowledgements
The authors are thankful to Dr. J.S. Yadav, Director, IICT
and Shri. S. Narayan Reddy, Head, Fluoroorganic Division,
IICT, Hyderabad, for their constant encouragement and finan-
cial support from industry-sponsored project.
6.1.1.15. 4-Methyl-4,10-diphenyl-8-(trifluoromethyl)-1,2,3,4-
tetrahydropyrimido[1,2-b]indazole-7-carbonitrile (4g). Yield:
1
660 mg (93%); yellow coloured solid; mp 230 ꢀC. H NMR
(200 MHz, CDCl3): d ¼ 2.04 (3H, s, CH3), 2.30e2.44 (1H,
m, CeCH2), 2.54e2.62 (1H, m, CeCH2), 3.12e3.17 (1H,
m, CH2eN), 3.40e3.60(1H, m, CH2eN), 5.62 (1H, br s,
NH ), 6.90e7.06 (3H, m, Ar-H), 7.22e7.36 (3H, m, Ar-H),
7.50e7.63 (5H, m, Ar-H). IR (KBr): 3397 (NeH), 2929
(CeH), 2220 (C^N), 1607 (C]N) cmꢁ1. ESIMS m/z: 433
(MHþ). Anal. calcd. for C25H19F3N4: C, 69.43; H, 4.42; N,
12.95; found: C, 69.22; H, 4.23; N, 13.13%.
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1
Yield: 0.50 g (79%); yellow coloured solid; mp 198 ꢀC. H
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2.22 (2H, m, CH2), 3.28e3.38 (2H, m, CH2eNH), 4.68
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