Utility of the enaminonitrile moiety in the synthesis of some biologically active thienopyrimidine derivatives

Article abstract of DOI:10.1080/10426500701734802

Because of its broad spectrum of biological activities, a novel series of thienopyrimidines and fused thienopyrimidines have been synthesized by reacting the enaminonitrile 1 with different reagents. Thus, reaction of 1 with urea, thiourea, formic acid and/or formamide afforded pyrimidine derivatives 2, 3, 4, and 5, respectively. Compound 4 reacted with POCl3/PCl5 giving the chloro-derivative 7 which upon treatment with thiourea, hydrazine, piperidine and/or thiols, produced 4-thio, 4-hydrazino, 4-piperidino- and 4-S-substituted pyrimidine derivatives 8-11, respectively. Treatment of 9 with ethyl chloroformate, sodium nitrite/hydrochloric acid, benzoyl chloride, acetic and/or formic acid, benzaldehyde/piperidine and CS2/pyridine provided the carbazate 13, tetrazole 14, triazoles 15, and 16a, b, Schiff's base 17 and triazole 18, respectively. Some of the new synthesized compounds were screened for antibacterial activity. The structures of these compounds were confirmed by FT-IR, 1H NMR and correct elemental analysis. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/10426500701734802

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Utility of the Enaminonitrile
Moiety in the Synthesis of
Some Biologically Active
Thienopyrimidine Derivatives
Mohammad Emad Azab a
a Synthetic Organic Chemistry Laboratory, Chemistry
Department, Faculty of Science, Ain Shams
University, Cairo, Egypt
Version of record first published: 24 Jun 2008.
To cite this article: Mohammad Emad Azab (2008): Utility of the Enaminonitrile
Moiety in the Synthesis of Some Biologically Active Thienopyrimidine Derivatives,
Phosphorus, Sulfur, and Silicon and the Related Elements, 183:7, 1766-1782
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Phosphorus, Sulfur, and Silicon, 183:1766–1782, 2008
Copyright © Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500701734802
Utility of the Enaminonitrile Moiety in the Synthesis of
Some Biologically Active Thienopyrimidine Derivatives
Mohammad Emad Azab
Synthetic Organic Chemistry Laboratory, Chemistry Department,
Faculty of Science, Ain Shams University, Cairo, Egypt
Because of its broad spectrum of biological activities, a novel series of thienopyrim-
idines and fused thienopyrimidines have been synthesized by reacting the enam-
inonitrile 1 with different reagents. Thus, reaction of 1 with urea, thiourea, formic
acid and/or formamide afforded pyrimidine derivatives 2, 3, 4, and 5, respec-
tively. Compound 4 reacted with POCl3/PCl5 giving the chloro-derivative 7 which
upon treatment with thiourea, hydrazine, piperidine and/or thiols, produced 4-
thio, 4-hydrazino, 4-piperidino- and 4-S-substituted pyrimidine derivatives 8–11,
respectively. Treatment of 9 with ethyl chloroformate, sodium nitrite/hydrochloric
acid, benzoyl chloride, acetic and/or formic acid, benzaldehyde/piperidine and
CS2/pyridine provided the carbazate 13, tetrazole 14, triazoles 15, and 16a, b,
Schiff’s base 17 and triazole 18, respectively. Some of the new synthesized com-
pounds were screened for antibacterial activity. The structures of these compounds
were confirmed by FT-IR, 1H NMR and correct elemental analysis.
Keywords Carbazate; t-Butyltetrahydrobenzo[b]thiophene; tetrazole; thienopyrimi-
dine; triazole
INTRODUCTION
Thienopyrimidines are a class of heterocyclic compounds which
possess antiallergic,1 antiatherosclerotic,2 antibacterial,3 antiviral,4
antihypertensive,5 antihistaminic activities.6 In addition to the
above mentioned activities, thienopyrimidine derivatives have
Received 24 July 2007; accepted 5 September 2007.
The author is greatly appreciative to Prof. Dr. Fatma Farag, Biochemistry Depart-
ment, Faculty of Science, Ain Shams University, for helping in doing the antibacterial
activity for the newly synthesized compounds. Also, the author would like to express his
deep appreciation to Prof. Dr. Hassan M.F. Madkour Prof. of Organic Chemistry, Chem-
istry Department, Faculty of Science, Ain Shams University for helping in revising this
manuscript.
Address correspondence to Mohammad Emad, Azab Synthetic Organic Chemistry
Lab., Chemistry Department, Faculty of Science, Ain Shams University, Abbassiya, Cairo,
Egypt. E-mail: meazab63@hotmail.com
1766

Biologically Active Thienopyrimidine Derivatives
1767
antimicrobial,7−9 spasmolytic,10 antitumor,11,12 and anti-inflammatory
properties.13,14 They are also used as receptor antagonists.15,16
In continuation of our efforts17−21 on the development of simple syn-
thetic routes for the synthesis of heterocyclic compounds having biolog-
ical activity, the enaminonitrile 1, which was prepared by a previously
reported method,22 was used as a key starting material for the synthesis
of the target thienopyrimidine derivatives. Some of the new synthesized
compounds showed antibacterial activity. The spectroscopic data were
in accordance with the proposed structures.
RESULTS AND DISCUSSION
Enaminonitrile 1, were fused with urea and thiourea,23 providing 4-
aminopyrimidin-2(1H)-one 2 and 4-aminopyrimidin-2(1H)-thione 3, re-
spectively. The structures of 2 and 3 were confirmed by the spectral
data, where the IR spectra showed the disappearance of C≡N band,
and the presence of the C=O and C=S bands 1655 and 1234 cm−1, re-
spectively. Also, the 1H NMR spectra of both compounds indicated the
presence of the NH proton at 11.23 and 11.12, respectively (Scheme 1).
SCHEME 1
In the other hand, refluxing compound 1 with formic acid and/or
formamide24 afforded pyrimidin-4(3H)-one 4 and 4-aminopyrimidine
5 derivatives, respectively (Scheme 1). The IR spectrum of 4 showed
the absence of the NH2 and C N absorption bands and the presence

1768
M. E. Azab
of C O band. The proposed structures got a further support from
1H NMR spectra which showed a peak at δ 8.47 and 8.35 corresponding
to the H of the pyrimidine ring.
Compound 4 underwent an N-methylation reaction through treat-
ment with MeI in DMF, in the presence of anhydrous potassium car-
bonate, to furnish the 3N-methyl derivative 6. While, the enol-form of 4
was chlorinated upon reaction with a mixture of PCl5/POCl25 to afford
chloropyrimidine derivative 7 (Scheme 2). The structures 3of 6 and 7
were elucidated from their spectral data, where the IR showed the ab-
sence of the NH and the C O bands (for compound 7) and the 1H NMR
for compound 6 displayed peak at δ 3.56 for N CH3 and the absence of
the NH peak.
SCHEME 2
The chloropyrimidine derivative 7 underwent nucleophilic substitu-
tion reactions to provide several substituted thienopyrimidine deriva-
tives. Thus, reflux 7 with thiourea in n-butanol 26, gave the correspond-
ing pyrimidin-4(3H)-thione 8. The presence of NH peak at 3197 and a
signal at δ 12.22 was in accord with the proposed structure.
Reaction of compound 7 with hydrazine hydrate (98%) and/or piperi-
dine in ethanol furnished 4-hydrazinopyrimidine 9 and pipepiridopy-
rimidine 10, respectively. The IR of compound 9 showed absorption
1
bands at 3417–3198 cm−1 and the H NMR displayed peaks at δ 3.62
and 6.48 (D2O exchangeable) corresponding to NH2 and NH. While the
1H NMR of 10 displayed peaks at δ 1.91–3.09 (several m, 17H, cyclohex-
ane, piperidine rings) which indicated the presence of piperidine moiety
attached to the pyrimidine ring.
When compound
7
was allowed to react with thiophe-
nol and/or 1-methylimidazol-2-thiol, in refluxing pyridine, the

Biologically Active Thienopyrimidine Derivatives
1769
SCHEME 3
4-S-substitutedthiopyrimidines 11a, b were produced, respectively
1
(Scheme 3). The H NMR spectra of compounds 11a, b displayed the
following signals at δ 1.00 (s, 9H, tert-butyl group), 1.82–2.86 (m,
7H, cyclohexane ring), 3.61 (s, 3H, N CH3 of the imidazole ring),
7.23–7.42 (2d, 2H, imidazole ring), 8.44 (s, 1H, of the pyrimidine ring)
for compound 11a, and at δ 0.86 (s, 9H, tert-butyl group), 1.82–2.98
(several m, 7H, cyclohexane ring), 7.39–7.61 (m, 5H, benzene ring),
and 8.45 (s, 1H, pyrimidine ring). This indicates the displacement of
the chlorine atom by 1-methylimidazol and phenyl rings, respectively.
Furthermore, compound
8 reacted with ethyl chloroacetate,
in the presence of anhydrous sodium acetate, and/or hydrazine
hydrate in ethanol producing ethyl acetate derivative 12 and
4-hydrazinopyrimidine 9, respectively (Scheme 4). The structure of the
SCHEME 4

1770
M. E. Azab
ester 12 was fully supported by its spectral data, where the IR spectrum
showed absorption band at 1745 corresponding to the carbonyl of the
ester group, the 1H NMR displayed signals at δ 1.3 (t, 3H, OCH2CH3),
4.05 (s, 2H, S CH2 CO), 4.25 (q, 2H, OCH2CH3), which revealed the
presence of the CH2CO2CH2CH3 group attached to the sulfur atom.
The hydrazine derivative 9 was used as a key starting material for
the preparation of novel fused thienopyrimidine systems. Thus, when
compound 9 was refluxed with ethyl chloroformate, in dry pyridine, the
carbazate derivative 13 was obtained in a good yield. The structure of
13 was elucidated from its spectral data, where its IR showed a strong
absorption band at 1741 corresponding to the carbonyl of the ester group
1
and the H NMR displayed signals at δ 1.25 (t, 3H, OCH2CH3), 4.25
(q, 2H, OCH2CH3).
On the other hand, when concentrated hydrochloric acid was added
dropwise (at 0–5C) to a mixture of hydrazine 9 and sodium nitrite so-
lution, the tetrazolo-derivative 14 was produced in a fair yield. The
structure of 14 was supported by the absence of any absorption bands
for the NH and NH2 groups in the IR, and also the absence of their
signals in the 1H NMR spectra.
An interesting reaction was carried by reacting compound 9 with ben-
zoyl chloride then the non-identified residue was treated with POCl3 to
1
furnish the triazolpyrimidine27 derivative 15. Its H NMR indicated
the presence of the aromatic protons at δ 7.24–7.46. Also, when the hy-
drazine derivative 9 was refluxed with acetic acid and/or formic acid the
triazol derivatives 16a, b were provided. The structures of compounds
16a, b were supported by the 1H NMR spectra, which displayed signals
at δ 8.18 for the proton of the triazole ring for 16a, and at 3.4 (3H) for
the CH3 group in compound 16b (Scheme 5).
The investigation was extended to study the reactivity of compound 9
towards benzaldehyde, in the presence of piperidine, which produce the
Schiff’s base 17. The 1H NMR of 17 indicate the presence of 5H of the
benzene ring at 7.33–7.67, 1H, N CH at 8.08, and 1H, NH N (D2O
exchangeable) at 8.91. Refluxing compound 17 with thionyl chloride28
led to the formation of compound 15. This reaction can be considered
as a chemical support for the proposed structure of compound 15.
In the meantime, 9 was treated with carbon disulphide in dry pyri-
dine to afford triazole derivative 18 which underwent Mannich reaction
through the treatment with piperidine (as secondary amine) to furnish
compound 19. 1H NMR of 19 showed the absence of NH signal and the
presence of two signals at δ 1.51–3.05 (several m, 17H, cyclohexane and
piperidine rings), 3.9 (s, 2H, N CH2 N). The Methylation of 18 pro-
duced the S-methyl derivative 20, which was supported by its 1H NMR
spectrum, which displayed a signal at 3.27 (3H, S CH3), (Scheme 6).

Biologically Active Thienopyrimidine Derivatives
1771
SCHEME 5
SCHEME 6

1772
M. E. Azab
ANTIBACTERIAL ACTIVITY
The new synthesized compounds were screened in vitro for their an-
tibacterial activities against two strains of bacteria Bacillus subtillis
(NCTC 10400) and Escherichia coli (NCTC 10416) by using the serial
agar dilution method29 to select the most potent compounds and sensi-
tive bacterial species for further investigation.
One mg of each compound was dissolved in dimethyl sulfoxide
(DMSO, 1 mL) then made up to 10 mL with sterile water to give a
concentration of 100 µg/mL. Serial dilution was done to determine the
MIC for each compound.
The bacteria was maintained on nutrient agar media. DMF showed
no inhibition zones. The agar media was incubated with different mi-
croorganisms culture tested. After 180 min. of incubation at 30◦C, the
diameter of inhibition zone was measured. The minimal inhibitory con-
centration (MIC) of some of the tested compounds was measured by a
two-fold serial dilution method.30 The results are presented in Table I.
Table I showed that most of the tested compounds had an inhibition
activity at concentration more than 100 µg/mL, while compounds 7 and
9 showed a minimum inhibitory effect against Bacillus subtillis (gram
+ve) at concentrations 50 and 12.5 µg/mL, respectively. Compound 9
had inhibitory effect against Escherichia coli (gram +ve) at concentra-
tions 50 µg/mL. From these results, it could be concluded that com-
pounds 7 and 9 had the highest antibacterial activity among the tested
compounds.
TABLE I Antibacterial Activities of the Newly
Synthesized Compounds
MIC∗ (µg/ml)
Test organism
Compound number
B.subtilis
E.coli
1
2
3
7
8
9
>100
>100
>100
50
>100
12.5
>100
>100
>100
>100
>100
50
11b
13
>100
>100
>100
>100
∗MIC = minimum inhibitory concentration.

Biologically Active Thienopyrimidine Derivatives
1773
Extraction of Bacillus Subtilis Intracellular Component
Acid soluble phosphorus was extracted from treated and untreated B.
subtilis cells using 5% ice cold TCA, proteins were solublized in 1 N
KOH at 37◦C for 20 h; RNA was extracted by 10% TCA after addition
of 6N HCl and DNA was hydrolyzed by 5% TCA in boiling water bath
for 5 minutes.31
Acid soluble phosphorus was assessed according to the method of
Toribarn et al.32 Total proteins was determined using the method of
Daughaday,33 RNA was measured as described by Merchant et al.34
and DNA as in Dische et al.35
After cell fractionation and extraction of acid soluble phosphorus,
total proteins, RNA and DNA content of B.subtilis cells (at MIC level)
treated with compounds 7 and 9, the percentage of inhibition was cal-
culated from the equation:
% of inhibition
Value of untreated B.subtilis − Value of treated B.subtilis
=
× 100
Value of untreated B.subtilis
(1)
The results are presented in Table II.
Table II showed the effect of either 7 or 9 on different B. subtilis cell
targets at MIC level after 180 minutes incubation. Data revealed that
9 had a more inhibitory effect than 7. Inhibition at 180 min was −72.55
% and −31.37% for acid soluble phosphorus; −45.32% and −11.78% for
total proteins; −37.59% and −9.02 for RNA; and −45.22% and −28.10
for DNA content in 9 and 7 treated cells, respectively.
TABLE II Effect of 7 and 9 on Acid Soluble Phosphorus,
Total Proteins, RNA and DNA Content of B.subtilis Cells
at MIC Level
mg/g wt
Acid soluble Total
Parameter
phosphorus proteins RNA
DNA
Treatment
Untreated B.subtilis
B.subtilis treated with compd.
7 % of inhibition
0.51
0.35
33.1
29.2
13.3
12.1
1.15
0.82
−31.37
−11.78
−9.02 −28.70
B.subtilis treated with compd.
0.14
18.10
8.3 0.63
9 % of inhibition
−72.55
−45.32 −37.59 −45.22
Incubation period was 180 min at 37◦C.

1774
M. E. Azab
Acid soluble phosphorus, proteins, RNA and DNA contents of
B.subtilis cells were significantly decreased by 7 and 9 at MIC concen-
tration. The results indicated that the inhibitory effect of 9 on bacterial
cells macromolecules was more pronounced than that of 7.
These results indicate that compounds 7 and 9 inhibited protein and
nucleic acid synthesis in bacterial cells due to increased destruction of
ATP in the drug-treated cells. In conclusion, these compounds may be
used as antibacterial drugs after further studies to investigate their
toxicity and biochemical effect on living animals.
CONCLUSION
Novel thienopyrimidine and fused thienopyrimidine compounds were
prepared via a simple route methodology using commercially available
compounds. Some of the new synthesized compounds have antibacte-
rial activity against gram +ve and gram –ve bacteria and also have
inhibitory effect for acid soluble phosphorus, total proteins, RNA and
DNA content in treated cells.
EXPERIMENTAL
All melting points reported are uncorrected and were determined on a
Stuart electric melting point apparatus. The microanalysis were within
0.3% of theoretical values and were measured at the microanalytical
unit of the Faculty of Science, Cairo University. The IR spectra were
measured on a Perkin-Elmer 1600 FT-IR using the KBr wafer tech-
nique. The 1H NMR spectra were recorded in CDCl3 or DMSO-d6 solu-
tions on a Bruker 200 MHz instrument (University of Regina, Regina,
Saskatchewan, Canada) using TMS as internal standard with chemical
shifts expressed in ppm. TLC was performed on ready-to-use silica gel
plates Merck 60 to monitor the reactions and test the purity of the new
synthesized compounds.
2-Amino-3-cyano-6-t-butyl-tetrahydrobenzo[b]thiophene (1)
This compound were prepared using the previously reported method.22
Yellowish green solid, m.p.: 199–201◦C, (from ethanol), yield : 90%; IR:
ν cm−1: 3418, 3320, 3214 (NH2), 2950, 2826 (CHal.), 2203 (C N), 1610
(C C); 1H NMR (DMSO d6): δ 0.89 (s, 9H, tert-butyl group), 1.87–
3.05 (several m, 7H, cyclohexane), 7.73 (bs, 2H, NH2); Anal. calcd. for
C13H18N2S (234) : C, 66.67; H, 7.69; N, 11.97; found: C, 66.86; H, 7.79;
N, 12.11.

Biologically Active Thienopyrimidine Derivatives
1775
4-Amino-7-t-butyltetrahydrobenzo[b]thieno[2,3-d]pyrimidin-
2(1H)-one (2) and 4-Amino-7-t-butyltetrahydrobenzo[b]thieno
[2,3-d]pyrimidin-2(1H)-thione (3)
Compound 1 (5 mmol, 1.17 g) and urea (5 mmol, 0.3 g) or thiourea
(5 mmol, 0.36 g) were fused at 200◦C in a sand bath for 3 h. The reac-
tion mixture was left to cool, washed with water, and triturated with
methanol (5 mL). The solid deposited was filtered off and recrystallized
from a suitable solvent.
Compound 2
Yellow solid , m.p.: 233–235◦C (from ethanol), yield: 0.82 g (72%);
IR, ν cm−1: 3421–3195 (NH2,NH), 1655 cm−1 (C O); 1H NMR (CDCl3):
δ 0.93 (s, 9H, tert-butyl group), 1.89–3.09 (several m, 7H, cyclohex-
ane), 7.95 (bs, 2H, NH2, D2O exchangeable), 11.23 (bs, 1H, NH, D2O
exchangeable); Anal. calcd. for C14H19N3OS (277): C, 60.65; H, 6.86; N,
15.16; found: C, 60.83; H, 7.01; N, 15.31.
Compound 3
Pale brown solid, m.p.: 245–247◦C (from dioxane-water), yield:
1
0.98 g (69%). IR: ν cm−1: 3413–3205 (NH2,NH), 1234 (C S); H NMR
(DMSO d6): δ 0.91 (s, 9H, tert-butyl group), 1.83–3.06 (several m, 7H,
cyclohexane), 7.85 (bs, 2H, NH2, D2O exchangeable), 11.12 (bs, 1H, NH,
D2O exchangeable); Anal. calcd. for C14H19N3S2 (293) : C, 57.34; H, 6.48;
N, 14.33; found: C, 57.17; H, 6.39; N, 14.15.
7-t-Butyltetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-one
(4)
A solution of 1 (10 mmol, 2.34 g) in formic acid (400 mmol, 15 mL,) was
refluxed for 6 h. The reaction mixture was poured into ice/H2O. The
solid that precipitated was filtered off and recrystallized from ethanol to
produce 4 as pale yellow crystals, m.p.: 268–270◦C, yield: 2.34 g (95%);
1
IR, ν cm−1: 3211 (NH), 1659 (C O); H NMR (CDCl3): δ 0.91 (s, 9H,
tert-butyl group), 1.88–2.98 (several m, 7H, cyclohexane), 8.47 (s, 1H,
pyrimidine), 10.90 (bs, 1H, NH, D2O exchangeable); Anal. calcd. for
C14H18N2OS (262) : C, 64.12; H, 6.87; N, 10.69; found: C, 64.30; H, 7.00;
N, 10.85.
4-Amino-7-t-butyltetrahydrobenzo[b]thieno[2,3-d]pyrimidine
(5)
A mixture of 1 (5 mmol, 1.17 g) and formamide (504 mmol, 20 mL) was
refluxed for 4h. The solid that precipitated on cooling was recrystallized

1776
M. E. Azab
from ethanol to give 5 as pale yellow crystals, m.p.: 155–157◦C, yield:
2.34 g (95%); IR, ν cm−1: 3419–3221 (NH2), 1H NMR (CDCl3): δ 0.92 (s,
9H, tert-butyl group), 1.87–3.09 (several m, 7H, cyclohexane), 7.92 (bs,
2H, NH2, D2O exchangeable), 8.35 (s, 1H, pyrimidine); Anal. calcd. for
C14H19N3S (261): C, 64.37; H, 7.28; N, 16.09; found: C, 64.20; H, 7.10;
N, 15.90.
7-t-Butyl-3-methyltetrahydrobenzo[b]thieno[2,3-d]pyrimidin-
4-one (6)
Compound 4 (5 mmol, 1.31 g) was added methyl iodide (20 mmol, 2.86
g), DMF (20 mL) and anhydrous K2CO3 (73 mmol, 1 g), the reaction
mixture was stirred for 2 h then poured into ice/water. The solid that
deposited was collected by filtration, dried and recrystallized from n-
hexane to produce the title compound 6 as a white powder, m.p.: 255–
1
257◦C; yield: 0.88g (64%); IR, ν cm−1: 1663 (C O); H NMR (CDCl3):
δ 0.89 (s, 9H, tert-butyl group), 1.80–2.99 (several m, 7H, cyclohex-
ane), 3.56 (s, 3H, N CH3) 8.25 (s, 1H, pyrimidine); Anal. calcd. for
C15H20N2OS (276): C, 65.22; H, 7.25; N, 10.14; found: C, 65.40; H, 7.37;
N, 10.30.
7-t-Butyl-4-chlorotetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4-
one (7)
Compound 4 (10 mmol, 2.62 g), PCl5 (12 mmol, 2.5 g) and POCl3 (75
mmol, 7 mL) were heated on a water bath for 3 h. When the reaction
mixture was poured carefully into ice and ammonia solution a pre-
cipitate was formed, that was filtered off and dried. Recrystallization
from n-hexane afforded 7 as yellow crystals, m.p.: 170–172◦C, yield: 2g
(71%); IR, ν cm−1: 1630 (C N); 1H NMR (CDCl3): δ 0.87 (s, 9H, tert-butyl
group), 1.85–2.94 (m, 7H, cyclohexane), 8.38 (s, 1H, pyrimidine); Anal.
calcd. for C14H17ClN2S (280.5): C, 59.89; H, 6.06; N, 9.98; Cl, 12.66;
found: C, 60.01; H, 6.18; N, 10.10; Cl, 12.85.
7-t-Butyltetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-
thione (8)
Thiourea (7 mmol, 0.5 g) was added to a solution of 7 (5 mmol, 1.4 g)
in dry methanol (15 mL) and refluxed for 2 h. The solid that deposited
after cooling was filtered off and recrystallized from ethanol to give 8
as orange crystals, m.p.: 248–250◦C, yield: 1.14 (82%); IR, ν cm−1: 3197
(NH), 1242 (C S); 1H NMR (DMSO-d6): δ 0.92 (s, 9H, tert-butyl group),
1.89–2.95 (several m, 7H, cyclohexane), 8.42 (s, 1H, pyrimidine); 12.22

Biologically Active Thienopyrimidine Derivatives
1777
(bs, 1H, NH, D2O exchangeable); Anal. calcd. for C14H18N2S2 (278): C,
60.43; H, 6.47; N, 10.07; found: C, 60.30; H, 6.37; N, 10.30.
7-t-Butyl-4-hydrazinotetrahydrobenzo[b]thieno[2,3-d]
pyrimidin-4-one (9)
A mixture of 7 (10 mmol, 2.8 g) and hydrazine hydrate (100 mmol,
3.2 mL) in ethanol (30 mL) was refluxed for 2 h. When the reaction
mixture was allowed to cool, a solid product was separated out which
upon recrystallized from ethanol produced a yellow crystals of the title
compound 9, m.p.: 193–195◦C, yield: 2.6 g (94%); IR, ν cm−1: 3417–3198
(NH2, NH); 1H NMR (CDCl3): δ 1.06 (s, 9H, tert-butyl group), 1.90–3.03
(several m, 7H, cyclohexane), 3.62 (s, 2H, NH2, D2O exchangeable), 6.48
(bs, 1H, NH, D2O exchangeable), 8.36 (s, 1H, pyrimidine); Anal. calcd.
for C14H20N4S (276): C, 60.87; H, 7.25; N, 20.29; found: C, 61.02; H,
7.37; N, 20.49.
Conversion of 8 to 9
When a mixture of 8 (5 mmol, 1.38 g) and hydrazine hydrate
(50 mmol, 1.6 mL) in ethanol (20 mL) was refluxed for 3 h; yellow
crystals precipitated after cooling. The solid product was filtered off
and dried. This solid was identified as 9 by m.p., mixed m.p., TLC, and
FT-IR.
7-t-Butyl-4-piperidinotetrahydrobenzo[b]thieno[2,3-d]
pyrimidin-4-one (10)
Compound 7 (5 mmol, 1.4 g) in ethanol (20 mL) was added piperidine
(10 mmol, 1 mL) and the reaction mixture was refluxed for 2 h. The solid
deposited after cooling was filtered off, dried and recrystallized from
ethanol affording 10 as pale yellow crystals, m.p.: 128–130◦C, yield:
1
0.92 g (56%); IR, ν cm−1: 1620 (C N); H NMR (CDCl3): δ 1.1 (s, 9H,
tert-butyl group), 1.91–3.09 (several m, 17H, cyclohexane, piperidine
rings), 8.48 (s, 1H, pyrimidine); Anal. calcd. for C19H27N3S (329): C,
69.36; H, 8.21; N, 12.77; found: C, 69.19; H, 8.07; N, 12.59.
7-t-Butyl-4-thiophenyl and thio(1-methylimidazol-2-yl)
tetrahydrobenzo[b]-thieno[2,3-d]-pyrimidin-4-one (11a,b)
Thiophenol (5 mmol, 0.51 mL) and/or 1-methylimadazol-2-thiol (5
mmol, 0.57) were added to 7 (5 mmol, 1.4 g) in pyridine (10 mL) and
refluxed for 3–4 h. After cooling, the reaction mixture was poured onto
ice/HCl. The solid separated out was collected by filtration, washed with
water, dried then recrystallized from the appropriate solvent.

1778
M. E. Azab
Compound 11a
Pale brown solid, m.p.: 160–162◦C (from n-hexane), yield: 1.11 g
(62%); IR, ν cm−1: 1623 (C N); 1H NMR (CDCl3): δ 1.00 (s, 9H, tert-butyl
group), 1.82–2.86 (m, 7H, cyclohexane), 3.61 (s, 3H, N CH3), 7.23-7.42
(2d, 2H, imidazole ring, J = 8, J = 9 Hz), 8.44 (s, 1H, pyrimidine); Anal.
calcd. for C18H22N4S2 (358): C, 60.34; H, 6.15; N, 15.64; found: C, 60.46;
H, 6.27; N, 15.79.
Compound 11b
Pale brown solid, m.p.: 140–142◦C, (from n-hexane), yield: 1.27 g
(72%); IR, νcm−1: 3067 (CHar), 1625 (C N); 1H NMR (CDCl3): δ
0.86 (s, 9H, tert-butyl group), 1.82–2.98 (several m, 7H, cyclohexane),
7.39–7.61 (m, 5H, benzene ring), 8.45 (s, 1H, pyrimidine); Anal. calcd.
for C20H22N2S2 (354): C, 67.80; H, 6.21; N, 7.91; found: C, 68.00; H, 6.37;
N, 8.09.
Ethyl 2-[7-t-butyltetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4-
yl-thio]acetate (12)
Compound 8 (5 mmol, 1.39 g) in ethanol (20 mL) was added fused anhy-
drous sodium acetate (12 mmol, 1 g) and ethyl chloroacetate (10 mmol,
1.22 g). The reaction mixture was refluxed for 6 h, cooled. and the
solid deposited was filtered off, washed with water, dried and then re-
crystallized from ethanol producing 12 as pale brown crystals, m.p.:
133–135◦C, yield: 1.29 g (71%); IR, ν cm−1: 1745 (C O), 1620 (C N);
1H NMR (CDCl3): δ 0.90 (s, 9H, tert-butyl group), 1.3 (t, 3H, OCH2CH3,
J = 6.1 Hz), 1.9–2.96 (m, 7H, cyclohexane), 4.05 (s, 2H, S CH2 ), 4.25
(q, 2H, OCH2CH3,J = 8.2 Hz), 8.35 (s, 1H, pyrimidine); Anal. calcd.
for C18H24N2O2S2 (364): C, 59.34; H, 6.59; N, 7.69; found: C, 59.42; H,
6.77; N, 7.89.
Ethyl [7-t-butyltetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4-yl]
carbazate (13)
A mixture of 9 (5 mmol, 1.38 g) and ethyl chloroformate (20 mmol, 2 g)
in dry pyridine (10 mL) was refluxed for 6 h. After cooling, the reac-
tion mixture was poured onto ice/HCl, the solid that separated out was
filtered off, washed with water several times, dried, and then recrystal-
lized from ethanol to give 13 as pale yellow crystals, m.p.: 244–246◦C,
yield: 1.44 g (83%); IR, ν cm−1: 3355, 3248 (NH), 1741 (C O), 1609
1
(C N); H NMR (DMSO-d6): δ 0.92 (s, 9H, tert-butyl group), 1.25 (t,
3H, OCH2CH3,J = 6.2 Hz), 1.89–2.99 (several m, 7H, cyclohexane),
4.25 (q, 2H, OCH2CH3, J = 8.2 Hz), 8.4 (s, 1H, pyrimidine), 8.6 (bs,

Biologically Active Thienopyrimidine Derivatives
1779
1H, NH NH CO, D2O exchangeable), 9.25 (bs, 1H, NH NH CO, D2O
exchangeable); Anal. calcd. for C17H24N4O2S (348): C, 58.62; H, 6.90;
N, 16.09; found: C, 58.42; H, 6.77; N, 15.91.
9-t-Butyltetrahydrobenzo[b]thieno[2,3-d]tetrazolo[5,1-f]
pyrimidine (14)
To a mixture of compound 9 (5 mmol, 1.38 g) and 7 mL of 5%NaNO2
(3.45 g in 100 mL water), conc. HCl (37%, 5 mL) was added dropwise
at 0◦C for 30 min with stirring. The solid thus formed was filtered off,
washed with water, dried, and recrystallized from ethanol affording
the title compound 14 as brown crystals, m.p.: 145–147◦C, yield: 0.83 g
1
(58%); IR, ν cm−1: 1615 (C N), 1597 (N N); H NMR (CDCl3): δ 0.91
(s, 9H, tert-butyl group), 1.82–2.98 (several m, 7H, cyclohexane), 8.42
(s, 1H, pyrimidine); Anal. calcd. for C14H17N5S (286): C, 58.74; H, 5.94;
N, 24.48; found: C, 58.62; H, 5.77; N, 24.29.
9-t-Butyl-3-phenyltetrahydrobenzo[b]thieno[2,3-d]1,2,4-
triazolo[5,4-f]-pyrimidine (15)
Benzoyl chloride (5 mmol, 0.7 g) was added dropwise to a solution
of 9 (5 mmol, 1.38 g) in dry dioxane (10 mL), and the reaction mix-
ture was refluxed for 8 h. After cooling, the volatile components were
removed under reduced pressure and POCl3 (53.6 mmol, 5 mL) was
added to the residue. The reaction mixture was heated to 100◦C for 1
h, then the excess POCl3 was removed under reduced pressure, and
the residue poured onto cooled concentrated NH4OH. The precipitated
was collected by filtration and recrystallized from ethanol to produce
15 as pale yellow crystals m.p.: < 300◦C, yield: 0.92 g (51%); IR, νcm−1
:
1
1612 (C N), 1599 (N N); H NMR (CDCl3): δ 0.91 (s, 9H, tert-butyl
group), 1.86–2.94 (several m, 7H, cyclohexane), 7.24–7.46 (m, 5H, ben-
zene ring), 8.42 (s, 1H, pyrimidine); Anal. calcd. for C21H22N4S (362):
C, 69.61; H, 6.08; N, 15.47; found: C, 69.40; H, 5.89; N, 15.28.
9-t-Butyltetrahydrobenzo[b]thieno[2,3-d]1,2,4-triazolo[5,4-
f]pyrimidine (16a) and 3-methyl-9-t-butyltetrahydrobenzo[b]
thieno[2,3-d]1,2,4-triazolo[5,4-f]pyrimidine (16b)
Compound 9 (5 mmol, 1.38 g) and formic acid (266 mmol, 10 mL) and/or
acetic acid (174 mmol, 10 mL) were refluxed for 3 h. After cooling,
the reaction mixture was poured onto ice/water with stirring, the solid
deposited was collected by filtration, washed with water, dried and crys-
tallized from ethanol to give 16a, b, respectively.

1780
M. E. Azab
Compound 16a
Yellowish white solid, m.p.: < 300◦C, yield: 0.77 g (54%); IR, ν cm−1
:
1
1614 (C N), 1600 (N N); H NMR (CDCl3): δ 0.91 (s, 9H, tert-butyl
group), 1.88–2.97 (several m, 7H, cyclohexane), 8.18 (s, 1H, triazole),
8.53 (s, 1H, pyrimidine); Anal. calcd. for C15H18N4S (286): C, 62.94; H,
6.29; N, 19.58; found: C, 63.12; H, 6.47; N, 19.75.
Compound 16a
16b, pale yellow solid, m.p.: < 300◦C, yield: 0.75 g (50%); IR, ν cm−1
:
1
1616 (C N), 1595 (N N); H NMR (CDCl3): δ 0.91 (s, 9H, tert-butyl
group), 1.88–2.99 (m, 7H, cyclohexane), 3.4 (s, 3H, CH3), 8.38 (s, 1H,
pyrimidine); Anal. calcd. for C16H20N4S (300): C, 64.00; H, 6.67; N,
18.67; found: C, 63.82; H, 6.53; N, 18.75.
[7-t-Butyltetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4-yl]
benzalhydrazone (17)
Benzaldehyde (10 mmol, 1.06 g) and catalytic amount of piperidine (5
drops) were added to 9 (10 mmol, 2.76 g) in ethanol (25 mL) and the
reaction mixture was refluxed for 4 h. The solid so formed on cooling was
filtered off, dried, and crystallized from ethanol producing 17 as yellow
crystals, m.p.: 255–256◦C, yield: 2.84 g (78%); IR, ν cm−1: 3203 (NH);
1H NMR (CDCl3): δ 0.90 (s, 9H, tert-butyl group), 1.83–2.94 (several m,
7H, cyclohexane), 7.33–7.67 (m, 5H, benzene ring), 8.08 (s, 1H, N CH),
8.35 (s, 1H, pyrimidine), 8.91 (bs, 1H, NH-N , D2O exchangeable); Anal.
calcd. for C21H24N4S (364): C, 69.23; H, 6.59; N, 15.38; found: C, 69.00;
H, 6.77; N, 15.19.
Conversion of 17 into 15
SOCl2 (137 mmol, 10 mL) was added to 17 (5 mmol, 1.82 g) and the re-
action mixture was refluxed for 3 h. After cooling, the excess SOCl2 was
removed by distillation under reduced pressure. Cold saturated sodium
bicarbonate was added to the residue The precipitated was collected by
filtration and recrystallized from ethanol to produce 15.
9-t-Butyl-3-thioxotetrahydrobenzo[b]thieno[2,3-d]1,2,4-
triazolo[5,4-f]-pyrimidine (18)
A mixture of 9 (10 mmol, 2.76 g) in dry pyridine (15 mL) and CS2
(83 mmol, 5 mL) was refluxed for 4 h. The reaction mixture was cooled
neutralized by ice/HCl, the solid precipitated was filtered off, washed
with water several times and crystallized from ethanol to furnish 18 as
deep yellow crystals, m.p.: 274–277◦C, yield: 2.35 g (74%); IR, ν cm−1
:

Biologically Active Thienopyrimidine Derivatives
1781
3226 (NH), 1618 (C N), 1597 (N N); 1H NMR (DMSO d6): δ 0.89 (s, 9H,
tert-butyl group), 1.86–2.97 (m, 7H, cyclohexane), 8.40 (s, 1H, pyrim-
idine), 8.6-8.8 (two s, 1H, -NH C S ꢀ N C SH); Anal. calcd. for
C15H18N4S2 (318): C, 56.60; H, 5.66; N, 17.61; found: C, 56.77; H, 5.77;
N, 17.79.
9-t-Butyl-2-[(piperidin-1-yl)methyl]-3-thioxotetrahydrobenzo
[b]thieno[2,3-d]-1,2,4-triazolo-[5,4-f]pyrimidine (19)
To a suspension of 18 (5 mmol, 1.59 g) in ethanol (20 mL), formalin
solution (37%, 1 mL) and piperidine (5 mmol, 0.5 mL) were added with
stirring for 1 h. and left overnight at room temperature. The solid
so formed was filtered off, washed with water and crystallized from
ethanol to give the title compound 19 as canary yellow crystals, m.p.:
294–297◦C, yield: 1.16 g (56%); IR, ν cm−1: 1620 (C N), 1596 (N N);
1H NMR (DMSO-d6): δ 0.87 (s, 9H, tert-butyl group), 1.51–3.05 (several
m, 17H, cyclohexane and piperidine rings), 3.9 (s, 2H, N CH2 N),
8.43 (s, 1H, pyrimidine); Anal. calcd. for C21H29N5S2 (415): C, 60.72; H,
6.99; N, 17.61; found: C, 60.87; H, 7.17; N, 17.83.
9-t-Butyl-3-methylthiotetrahydrobenzo[b]thieno[2,3-d]1,2,4-
triazolo[5,4-f]-pyrimidine (20)
Compound 18 (5 mmol, 1.59 g) and methyl iodide (10 mmol, 1.43 g)
were stirred in dry ethanol (20 mL), in the presence of fused anhy-
drous sodium acetate (24 mmol, 2 g), for 8 h. at room temperature.
The reaction mixture was diluted with water, the solid separated was
collected by filtration, dried and crystallized from ethanol affording 20
as yellow crystals, m.p.: 190–193◦C, yield: 1.31 g (79%); IR, ν cm−1
:
1617 (C N), 1599 (N N); 1H NMR (DMSO-d6): δ 0.90 (s, 9H, tert-butyl
group), 1.81–2.95 (m, 7H, cyclohexane), 3.27 (s, 3H, S CH3), 8.46 (s,
1H, pyrimidine); Anal. calcd. for C16H20N4S2 (332): C, 57.83; H, 6.02;
N, 16.87; found: C, 58.01; H, 6.17; N, 17.09.
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