Synthesis and antibacterial activity of some novel triazolothienopyrimidines

Article abstract of DOI:10.1248/cpb.55.557

A novel series of some novel 5-substituted-1,2,4-triazolo[4,3-c]8,9,10- trihydrocyclopenta/8,9,10,11,12-pentahydrocyclohepta[ b]thieno[3,2-e]pyrimidin- 3-thiones has been synthesized. The intermediates 4-chloro-2-substituted-5,6,7- trihydrocyclopenta/5,6,

Full text of DOI:10.1248/cpb.55.557

April 2007
Chem. Pharm. Bull. 55(4) 557—560 (2007)
557
Synthesis and Antibacterial Activity of Some Novel Triazolothienopyrimidines
Mailavaram RAGHU PRASAD,* John PRASHANTH, Kalghatgi SHILPA, and Deb PRAN KISHORE
Medicinal Chemistry Division, P.E.S. College of Pharmacy; Hanumanthnagar, Bangalore–560 050, Karnataka, India.
Received November 7, 2006; accepted December 26, 2006
A novel series of some novel 5-substituted-1,2,4-triazolo[4,3-c]8,9,10-trihydrocyclopenta/8,9,10,11,12-penta-
hydrocyclohepta[b]thieno[3,2-e]pyrimidin-3-thiones has been synthesized. The intermediates 4-chloro-2-sub-
stituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines were prepared by
warming 2-substituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidin-4[3H]-
ones with oxalyl chloride. Thieno[2,3-d]pyrimidin-4[3H]-ones were prepared by a novel, microwave assisted, sol-
vent free, synthetic route under basic conditions hitherto unreported in the literature from ortho amino ester of
thiophene. The chloro derivatives, without further purification, were hydrazinated to yield 2-substituted-4-hy-
drazino-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines. These compounds
were cyclized with carbon disulphide to give the title compounds in quantitative yields. The final compounds
were screened for antibacterial activity by Kirby Bauer’s method using ampicillin as the standard against vari-
ous gram positive and gram negative bacteria. All the compounds showed antibacterial activity comparable with
the standard.
Key words triazolothienopyrimidine; antibacterial agent; Kirby Bauer’s method; bioisosteres; microwave assisted synthesis
dure Ortho amino ester of thiophenes 1a, b (0.0083 mol), potassium salt
of tertiary butoxide (0.089 g, 0.0008 mol) and various nitriles (0.016 mol)
were taken in a 5 ml microwave reaction vial equipped with a magnetic stir
bar. The reaction mixture was capped and irradiated in the microwave oven
(CEM, Discover) at 120 °C for 45—150 s. To the reaction mixture at room
Antibiotics have revolutionized the medical care in the
20th century. With the discovery of antibiotics people were
convinced that infectious diseases might some day be wiped
out. Diseases that were once life threatening, such as pneu-
monia, had become curable. The success of antibiotics in temperature, crushed ice was added and neutralized using dilute hydrochlo-
ric acid. The precipitate obtained was filtered, dried and recrystalized from
ethylacetate to give the target compounds in 50—80% yields.
2-Methyl-5,6,7-trihydrocyclopenta[b]thieno[2,3-d]pyrimidin-4[3H]-one
therapy related fields has made them one of the most impor-
tant products of the drug industry today.1) However, the
emergence of super bugs ie. bacteria that resists the effects of
the most powerful antibiotics are posing a great challenge to
the field of medicines. Thus scientists are working to find
new ways to defeat bacteria that are increasingly resistant to
the antibiotics already available.2)
(2a): Reacn time: 40 s. Yieldꢂ68%, mp 217 °C; IR (KBr) cmꢀ1: 3421, 2856,
1674. 1H-NMR (CDCl3) d: 1.64 (3H, s), 2.43—2.49 (2H, pentet, Jꢂ7.1 Hz),
2.93—2.97 (2H, t, Jꢂ7.0 Hz), 3.04—3.08 (2H, t, Jꢂ7.0 Hz), 11.84—12.05
(1H, s). MS m/z: 206 (Mꢃ). Anal. Calcd for C10H10N2OS: C, 58.25; H, 4.85;
N, 13.59. Found: C, 58.50; H, 5.05; N, 13.79.
2-Phenyl-5,6,7-trihydrocyclopenta[b]thieno[2,3-d]pyrimidin-4[3H]-one
(2b): Reacn time: 45 s. Yieldꢂ72%, mp 210 °C; IR (KBr) cmꢀ1: 3368, 2932,
Literature survey shows that several fused pyrimidines and
pyridines like triazolo quinazolines and triazoloquinolines3)
have shown good antibacterial activity. Further condensed
triazoles have been reported to possess large number of phar-
macological activities like fungicidal, pesticidal etc.4—7)
Thienopyrimidines has been reported to exhibit antimicrobial
activities too.8) Based on the concept of bioisosterism and all
the above observations have led us to the proposal to incor-
porate triazole ring system into thienopyrimidines leading to
the synthesis of novel class of triazolothienopyrimidines as
bioisosteres of triazoloquinolines and quinazolines and to
1
1670. H-NMR (CDCl3) d: 2.48—2.54 (2H, pentet, Jꢂ7.2 Hz), 2.98—3.01
(2H, t, Jꢂ7.1 Hz), 3.10—3.14 (2H, t, Jꢂ7.2 Hz), 7.44—8.09 (5H, m),
10.47—10.52 (1H, s). MS m/z: 268 (Mꢃ). Anal. Calcd for C15H12N2OS: C,
67.16; H, 4.47; N, 10.44. Found: C, 67.50; H, 4.59; N, 10.65.
2-Pyridyl-5,6,7-trihydrocyclopenta[b]thieno[2,3-d]pyrimidin-4[3H]-one
(2c): Reacn time: 45 s. Yieldꢂ65%, mp 214 °C; IR (KBr) cmꢀ1: 3420, 3100,
1
1650. H-NMR (CDCl3) d: 2.52—2.56 (2H, pentet, Jꢂ7.4 Hz), 3.01—3.05
(2H, t, Jꢂ7.4 Hz), 3.13—3.17 (2H, t, Jꢂ7.3 Hz), 8.10—8.12 (2H, d,
Jꢂ5.7 Hz), 8.82—8.83 (2H, d, Jꢂ5.6 Hz), 11.92 (1H, s). MS m/z: 269 (Mꢃ).
Anal. Calcd for C14H11N3OS: C, 62.45; H, 4.08; N, 15.61. Found: C, 62.55;
H, 4.25; N, 15.75.
2-[p-Chloro-phenyl]-5,6,7-trihydrocyclopenta[b]thieno[2,3-d]pyrimidin-
test for its efficacy as antibacterial agents. Herewith we are 4[3H]-one (2c): Reacn time: 45 s. Yieldꢂ76%, mp 254 °C; IR (KBr) cmꢀ1
:
3411, 3200, 1651. 1H-NMR (CDCl3) d: 2.30—2.38 (2H, m), 2.95—3.00
(2H, t, Jꢂ7.0 Hz), 3.05—3.10 (2H, t, Jꢂ7.1 Hz), 7.23—7.25 (2H, d,
Jꢂ5.3 Hz), 7.33—7.35 (2H, d, Jꢂ5.3 Hz), 10.55 (1H, s). MS m/z: 302 (Mꢃ).
Anal. Calcd for C15H11ClN2OS: C, 59.60; H, 3.64; N, 9.27. Found: C, 59.78;
H, 3.78; N, 9.35.
reporting the synthesis of some novel 5-substiuted-1,2,4-tria-
zolo[4,3-c]8,9,10,11,12-pentahydrocyclohepta/8,9,10-trihy-
drocyclopenta[b]thieno[3,2-e]pyrimidin-3-thiones as possible
antibacterial agents.
2-Methyl-5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidin-
Experimental
4[3H]-one (2e) Reacn time: 45 s. Yieldꢂ75%, mp 196 °C; IR (KBr) cmꢀ1
:
Analytical TLC was performed on Silica Gel F254 plates (Merck) with vi- 3375.96, 2970, 750. 1H-NMR (CDCl3) d: 1.54 (3H, s), 1.67—1.74 (4H, m),
sualisation by UV or iodine vapours. Melting points were determined in 1.87—1.90 (2H, pentet, Jꢂ5.6 Hz), 2.82—2.85 (2H, t, Jꢂ5.7 Hz), 3.30—
open capillaries on a Gallenkemp Melting point apparatus and are uncor-
3.33 (2H, t, Jꢂ5.6 Hz), 11.12 (1H, s). MS m/z: 234 (Mꢃ). Anal. Calcd for
rected. The IR spectra (KBr, nMax, cmꢀ1) were run on Perkin Elmer FTIR C12H14N2OS: C, 61.53; H, 5.98; N, 11.96. Found: C, 61.80; H, 6.20; N,
Spectrophotometer. 1H-NMR (d ppm, CDCl3/DMSO-d6) spectra were 12.15.
recorded using AMX-400 with TMS as internal standard. MS spectra were
recorded on Autospec. Elemental analyses were performed on Carlo Erba
2-Phenyl-5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidin-
4[3H]-one (2f): Yieldꢂ48%, mp 214 °C; IR (KBr) cmꢀ1: 3346.96, 2950.
1108 elemental analyzer and were withinꢁ0.4% of theoretical values. All 1H-NMR (CDCl3) d: 1.74—1.75 (4H, m), 1.94—2.16 (2H, m), 2.87—2.90
the chemicals used were of analytical grade.
(2H, t, Jꢂ5.2 Hz), 3.40—3.42 (2H, t, Jꢂ5.2 Hz), 7.35—7.53 (3H, m),
2-Substituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclo- 8.16—8.17 (2H, d, Jꢂ5.8 Hz), 11.37 (1H, s). MS m/z: 296 (Mꢃ). Anal.
hepta[b]thieno[2,3-d]pyrimidin-4[3H]-ones (2a—h). General Proce- Calcd for C17H16N2OS: C, 68.91; H, 5.40; N, 9.45. Found: C, 69.15; H, 5.65;
∗ To whom correspondence should be addressed. e-mail: raghumrp@mailcity.com
© 2007 Pharmaceutical Society of Japan

558
Vol. 55, No. 4
pyrimidine (4g): Yieldꢂ61%, mp 216 °C; IR (KBr) cmꢀ1: 3450, 3295,
3108.1H-NMR (CDCl3) d: 1.54—1.72 (4H, m), 1.93—2.12 (2H, m), 2.81—
2.84 (2H, t, Jꢂ5.7 Hz), 3.42—3.44 (2H, t, Jꢂ5.7 Hz), 4.68—4.88 (2H, d,
Jꢂ4.1 Hz), 8.14—8.16 (2H, d, Jꢂ4.8 Hz), 8.82—8.84 (2H, d, Jꢂ4.4 Hz),
12.36 (1H, t, Jꢂ4.1 Hz). MS m/z: 313.4 (Mꢃ). Anal. Calcd for C16H19N5S:
C, 61.26; H, 6.06; N, 22.33. Found: C, 61.35; H, 6.20; N, 22.45.
N, 9.75.
2-Pyridyl-5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidin-
4[3H]-one (2g): Reacn time: 45 s. Yieldꢂ66%, mp 182 °C; IR (KBr) cmꢀ1
:
1
3397.96, 2920. H-NMR (CDCl3) d: 1.75—1.80 (4H, m), 1.95—2.00 (2H,
m), 2.95—2.98 (2H, t, Jꢂ5.4 Hz), 3.41—3.44 (2H, t, Jꢂ5.3 Hz), 8.08—8.09
(3H, d, Jꢂ5.4 Hz), 8.80—8.81 (2H, d, Jꢂ5.4 Hz), 11.65 (1H, s). MS m/z:
297 (Mꢃ). Anal. Calcd for C16H15N3OS: C, 64.64; H, 5.05; N, 14.14. Found:
C, 64.75; H, 5.25; N, 14.28.
2-[p-Chloro-phenyl]-4-hydrazino-5,6,7,8,9-pentahydrocyclohepta[b]-
thieno[2,3-d]pyrimidine (4h): Yieldꢂ79%, mp 201 °C; IR (KBr) cmꢀ1
:
1
2-[p-Chloro-phenyl]-5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]-
pyrimidin-4[3H]-one (2h): Reacn time: 45 s. Yieldꢂ60%, mp 236 °C; IR
(KBr) cmꢀ1: 3350.96, 2925, 750. 1H-NMR (CDCl3) d: 1.68—1.72 (4H, m),
1.89—1.94 (2H, pentet, Jꢂ5.5 Hz), 2.83—2.86 (2H, t, Jꢂ5.4 Hz), 3.35—
3.38 (2H, t, Jꢂ5.4 Hz), 7.27—7.28 (2H, d, Jꢂ5.3 Hz), 7.36—7.37 (2H,
d, Jꢂ5.3 Hz), 11.23 (1H, s). MS m/z: 330.8 (Mꢃ). Anal. Calcd for
C17H15ClN2OS: C, 61.66; H, 4.53; N, 8.46. Found: C, 61.75; H, 4.75; N,
8.55.
2-Substituted-4-chloro-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydro-
cyclohepta[b]thieno[2,3-d]pyrimidines (3a—h). General Procedure
2-Substituted-5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]-
thieno[2,3-d]pyrimidin-4[3H]-ones [0.01 mol] [2a—h] and oxalyl chloride
[10.0 ml] were taken in a round bottomed flask and heated to reflux for 3 h.
The excess of oxalyl chloride was removed from the reaction mixture by ro-
toevoporator and the resulting free flowing solid (yield 75—85%) was taken
to next step without any further purification.
3440, 3293, 3008, 750. H-NMR (CDCl3) d: 1.72—1.77 (4H, m), 1.95—
2.12 (2H, m), 2.85—2.87 (2H, t, Jꢂ5.6 Hz), 3.35—3.37 (2H, t, Jꢂ5.6 Hz),
4.72—4.82 (2H, d, Jꢂ5.0 Hz), 7.25—7.27 (2H, d, Jꢂ4.3 Hz), 7.35—7.36
(2H, d, Jꢂ4.3 Hz), 10.25 (1H, t, Jꢂ5.0 Hz). MS m/z: 346.8 (Mꢃ). Anal.
Calcd for C17H19ClN4S: C, 58.82; H, 5.47; N, 16.14. Found: C, 58.95; H,
5.55; N, 16.20.
5-Alkyl/Aryl-1,2,4-triazolo[4,3-c]-8,9,10,11,12-pentahydrocyclohepta/
8,9,10-trihydrocyclopenta[b]thieno[3,2-e]pyrimidin-3-thiones (5a—h).
General Procedure A mixture of 2-alkyl-4-hydrazino-5,6,7-trihydrocy-
clopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines [4a—
h] [0.01 mmol] and carbondisulphide [0.1 mol, 7.6 g, 10 ml] in 10% alco-
holic potassium hydroxide (20 ml) solution was heated under reflux for 9 h.
The reaction mixture was cooled and added onto crushed ice. The solid
product obtained was filtered, dried and recrystallized from DMF–water
(1 : 1) mixture.
5-Methyl-1,2,4-triazolo[4,3-c]-8,9,10-trihydrocyclopenta[b]thieno[3,2-
e]pyrimidin-3-thione (5a): Yieldꢂ62%, mp 242 °C; IR (KBr) cmꢀ1: 3442,
2854. 1H-NMR (CDCl3) d: 1.58 (3H, s), 2.43—2.48 (2H, pentet, Jꢂ7.1 Hz),
2.93—2.97 (2H, t, Jꢂ6.9 Hz), 3.04—3.08 (2H, t, Jꢂ6.9 Hz), 11.86 (1H,
br s). MS m/z: 262 (Mꢃ). Anal. Calcd for C11H10N4S2: C, 50.38; H, 3.81; N,
21.37. Found: C, 50.58; H, 3.95; N, 21.48.
2-Alkyl/Aryl-4-hydrazino-5,6,7-trihydrocyclopenta/ 5,6,7,8,9-pentahy-
drocyclohepta[b]thieno[2,3-d]pyrimidines (4a—h). General Procedure
To
a warm solution of 2-alkyl/aryl-4-chloro-5,6,7-trihydrocyclopenta/
5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]pyrimidines [0.01 mol] [4a—
h] in ethanol (95%, 20 ml) was added a solution of hydrazine hydrate [99%,
4.3 g, 0.1 mol] drop-wise and heated under reflux for 2 h. Then the reaction
mixture was cooled and poured onto crushed ice. The solid precipitate ob-
tained was filtered, dried and recrystallized from 95% ethanol.
5-Phenyl-1,2,4-triazolo[4,3-c]-8,9,10-trihydrocyclopenta[b]thieno[3,2-e]-
pyrimidin-3-thione (5b): Yieldꢂ64%, mp 228 °C; IR (KBr) cmꢀ1: 3426,
1
2924. H-NMR (CDCl3) d: 2.25—2.28 (2H, pentet, Jꢂ7.3 Hz), 2.95—2.97
2-Methyl-4-hydrazino-5,6,7-trihydrocyclopenta[b]thieno[2,3-d]pyrimi-
(2H, t, Jꢂ7.3 Hz), 3.12—3.16 (2H, t, Jꢂ7.3 Hz), 7.45—8.10 (5H, m),
10.37—10.42 (1H, br s). MS m/z: 324 (Mꢃ). Anal. Calcd for C16H12N4S2: C,
59.25; H, 3.70; N, 17.28. Found: C, 59.45; H, 3.88; N, 17.45.
1
dine (4a): Yieldꢂ78%, mp 260 °C; IR (KBr) cmꢀ1: 3421, 3210, 2856. H-
NMR (CDCl3) d: 1.65 (3H, s), 2.45—2.50 (2H, pentet, Jꢂ6.9 Hz), 2.95—
2.98 (2H, t, Jꢂ6.9 Hz), 3.05—3.09 (2H, t, Jꢂ6.9 Hz), 4.6—4.8 (2H, d,
Jꢂ4.7 Hz), 11.92 (1H, t, Jꢂ4.8 Hz). MS m/z: 220 (Mꢃ). Anal. Calcd for
C10H12N4S: C, 54.54; H, 5.45; N, 25.45. Found: C, 54.66; H, 5.76; N, 25.35.
2-Phenyl-4-hydrazino-5,6,7-trihydrocyclopenta[b]thieno[2,3-d]pyrimi-
5-Pyridyl-1,2,4-triazolo[4,3-c]-8,9,10-trihydrocyclopenta[b]thieno[3,2-e]-
pyrimidin-3-thione (5c): Yieldꢂ60%, mp 240 °C; IR (KBr) cmꢀ1: 3448,
1
3381. H-NMR (CDCl3) d: 2.49—2.53 (2H, pentet, Jꢂ7.2 Hz), 3.02—3.07
(2H, t, Jꢂ7.2 Hz), 3.14—3.17 (2H, t, Jꢂ7.2 Hz), 8.12—8.14 (2H, d,
Jꢂ5.5 Hz), 8.84—8.85 (2H, d, Jꢂ5.5 Hz), 11.90 (1H, br s). MS m/z: 325
(Mꢃ). Anal. Calcd for C15H11N5S2: C, 55.38; H, 3.38; N, 21.53. Found: C,
55.54; H, 3.56; N, 21.77.
1
dine (4b): Yieldꢂ65%, mp 191 °C; IR (KBr) cmꢀ1: 3425, 3225, 2856. H-
NMR (CDCl3) d: 2.46—2.52 (2H, pentet, Jꢂ7.0 Hz), 2.97—3.00 (2H, t,
Jꢂ7.0 Hz), 3.07—3.12 (2H, t, Jꢂ7.0 Hz), 4.65—4.85 (2H, d, Jꢂ4.8 Hz),
7.45—8.10 (5H, m), 11.85 (1H, t, Jꢂ4.8 Hz). MS m/z: 282 (Mꢃ). Anal.
Calcd for C15H14N4S: C, 63.82; H, 4.96; N, 19.85. Found: C, 63.96; H, 5.06;
N, 20.05.
5-[p-Chloro-phenyl]-1,2,4-triazolo[4,3-c]-8,9,10-trihydrocyclopenta[b]-
thieno[3,2-e]pyrimidin-3-thione (5d): Yieldꢂ72%, mp 230 °C; IR (KBr)
cmꢀ1: 3432, 3012, 750. 1H-NMR (CDCl3) d: 2.20—2.27 (2H, pentet,
Jꢂ7.2 Hz), 2.98—3.02 (2H, t, Jꢂ7.1 Hz), 3.07—3.12 (2H, t, Jꢂ7.2 Hz)
7.22—7.24 (2H, d, Jꢂ5.4 Hz), 7.30—7.33 (2H, d, Jꢂ5.3 Hz), 10.89 (1H, s).
MS m/z: 358 (Mꢃ). Anal. Calcd for C16H11ClN4S2: C, 53.63; H, 3.07; N,
15.64. Found: C, 53.78; H, 3.29; N, 15.73.
2-Pyridyl-4-hydrazino-5,6,7-trihydrocyclopenta[b]thieno[2,3-d]pyrimi-
1
dine (4c): Yieldꢂ65%, mp 230 °C; IR (KBr) cmꢀ1: 3321, 3230, 2856. H-
NMR (CDCl3) d: 2.50—2.54 (2H, pentet, Jꢂ7.3 Hz), 2.99—3.03 (2H, t,
Jꢂ7.3 Hz), 3.15—3.19 (2H, t, Jꢂ7.3 Hz), 4.62—4.82 (2H, d, Jꢂ4.9 Hz),
8.13—8.15 (2H, d, Jꢂ5.5 Hz), 8.83—8.85 (2H, d, Jꢂ5.5 Hz), 12.20 (1H, t,
Jꢂ4.9 Hz). MS m/z: 283 (Mꢃ). Anal. Calcd for C14H13N5S: C, 59.36; H,
4.59; N, 24.73. Found: C, 59.45; H, 4.65; N, 24.89.
5-Methyl-1,2,4-triazolo[4,3-c]-8,9,10,11,12-pentahydrocyclohepta[b]-
thieno[3,2-e]pyrimidin-3-thione (5e): Yieldꢂ61%, mp 232 °C; IR (KBr)
cmꢀ1: 3300, 2900. 1H-NMR (CDCl3) 1.60 (3H, s), 1.65—1.70 (4H, m),
1.85—1.87 (2H, pentet, Jꢂ5.3 Hz), 2.80—2.82 (2H, t, Jꢂ5.3 Hz), 3.32—
3.34 (2H, t, Jꢂ5.3 Hz), 11.14 (1H, s). MS m/z: 290.4 (Mꢃ). Anal. Calcd for
C13H14N4S2: C, 53.71; H, 4.82; N, 19.28. Found: C, 53.84; H, 4.97; N, 19.43.
5-Phenyl-1,2,4-triazolo[4,3-c]-8,9,10,11,12-pentahydrocyclohepta[b]-
thieno[3,2-e]pyrimidin-3-thione (5f): Yieldꢂ56%, mp 248 °C; IR (KBr)
2-[4-Chloro-phenyl]-4-hydrazino-5,6,7-trihydrocyclopenta[b]thieno[2,3-
d]pyrimidine (4d): Yieldꢂ76%, mp 215 °C; IR (KBr) cmꢀ1: 3356, 3245,
1
2856. H-NMR (CDCl3) d: 2.35—2.40 (2H, pentet, Jꢂ6.9 Hz), 2.97—3.02
(2H, t, Jꢂ6.9 Hz), 3.02—3.07 (2H, t, Jꢂ6.9 Hz), 4.63—4.84 (2H, d,
Jꢂ5.0 Hz), 7.24—7.26 (2H, d, Jꢂ5.1 Hz), 7.34—1.36 (2H, d, Jꢂ5.1 Hz),
11.95 (1H, t, Jꢂ5.0 Hz). MS m/z: 317 (Mꢃ). Anal. Calcd for C15H13ClN4S:
C, 56.78; H, 4.10; N, 17.66. Found: C, 56.89; H, 4.20; N, 17.82.
1
cmꢀ1: 3300, 2900, 2850. H-NMR (CDCl3) d: 1.74—1.75 (4H, m), 1.94—
2.17 (2H, m), 2.88—2.90 (2H, t, Jꢂ5.3 Hz), 3.40—3.42 (2H, t, Jꢂ5.2 Hz),
7.52—7.54 (3H, m), 8.15—8.17 (2H, d, Jꢂ5.9 Hz), 11.36 (1H, s). MS m/z:
352.5 (Mꢃ). Anal. Calcd for C18H16N4S2: C, 61.10; H, 4.53; N, 15.88.
Found: C, 61.25; H, 4.68; N, 15.97.
2-Methyl-4-hydrazino-5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]-
pyrimidine (4e): Yieldꢂ75%, mp 182 °C; IR (KBr) cmꢀ1: 3370.96, 2820.
1H-NMR (CDCl3) d: 1.63 (3H, s), 1.67—1.71 (4H, m), 1.82—1.85 (2H,
pentet, Jꢂ5.1 Hz), 2.80—2.82 (2H, t, Jꢂ5.1 Hz), 3.34—3.36 (2H, t,
Jꢂ5.1 Hz), 4.8—4.0 (2H, d, Jꢂ4.8 Hz), 11.20 (1H, t, Jꢂ4.8 Hz). MS m/z:
250.4 (Mꢃ). Anal. Calcd for C12H18N4S: C, 57.50; H, 7.18; N, 22.36. Found:
C, 57.62; H, 7.30; N, 22.45.
2-Phenyl-4-hydrazino-5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]-
pyrimidine (4f): Yieldꢂ70%, mp 191 °C; IR (KBr) cmꢀ1: 3340, 3250, 2970.
1H-NMR (CDCl3) d: 1.75—1.78 (4H, m), 1.95—2.20 (2H, m), 2.90—2.92
(2H, t, Jꢂ5.2 Hz), 3.44—3.46 (2H, t, Jꢂ5.2 Hz), 4.62—4.85 (2H, d,
Jꢂ4.4 Hz), 7.51—7.52 (3H, m), 8.16—8.17 (2H, d, Jꢂ5.9 Hz), 11.26 (1H, t,
Jꢂ4.4 Hz). MS m/z: 312.4 (Mꢃ). Anal. Calcd for C17H20N4S: C, 65.30; H,
6.40; N, 17.92. Found: C, 65.44; H, 6.72; N, 18.08.
5-Pyridyl-1,2,4-triazolo[4,3-c]-8,9,10,11,12-pentahydrocyclohepta[b]-
thieno[3,2-e]pyrimidin-3-thione (5g): Yieldꢂ57%, mp 238 °C; IR (KBr)
1
cmꢀ1: 3050, 2900, 2850. H-NMR (CDCl3) d: 1.58—1.77 (4H, m), 1.97—
2.17 (2H, m), 2.91—2.94 (2H, t, Jꢂ5.4 Hz), 3.43—3.46 (2H, t, Jꢂ5.4 Hz),
8.15—8.17 (2H, d, Jꢂ4.4 Hz), 8.80—8.81 (2H, d, Jꢂ4.4 Hz), 12.36 (1H, s).
MS m/z: 353.5 (Mꢃ). Anal. Calcd for C17H15N5S: C, 57.70; H, 4.24; N,
19.80. Found: C, 57.88; H, 4.57; N, 19.98.
5-[p-Chloro-phenyl]-1,2,4-triazolo[4,3-c]-8,9,10,11,12-pentahydrocyclo-
hepta[b]thieno[3,2-e]pyrimidin-3-thione (5h): Yieldꢂ78%, mp 255 °C; IR
(KBr) cmꢀ1: 3440, 3012, 750. 1H-NMR (CDCl3) d: 1.70—1.73 (4H, m),
1.96—2.15 (2H, m), 2.80—2.83 (2H, t, Jꢂ5.4 Hz), 3.32—3.36 (2H, t,
Jꢂ5.4 Hz), 7.25—7.27 (2H, d, Jꢂ4.2 Hz), 7.35—7.36 (2H, d, Jꢂ4.2 Hz),
2-Pyridyl-4-hydrazino-5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-d]-

April 2007
559
10.25 (1H, s). MS m/z: 387 (Mꢃ). Anal. Calcd for C18H15ClN4S2: C, 55.81;
H, 3.87; N, 14.47. Found: C, 55.94; H, 3.96; N, 14.55.
Antibacterial Activity—Kirby Bauer’s Method Peptone water was
prepared and autoclaved. Four broth cultures were prepared using peptone
water containing one type of organism each from stock cultures. A sterile
cotton swab was dipped into one of the broth cultures and used to inoculate
a Mueller Hinton agar plate. Inoculation of the plate in this way ensured a
lawn of bacterial growth after incubation. Repeated this inoculation proce-
dure for four plates from four different broth cultures and the plates were la-
beled. After inoculation the plates were allowed to dry for 15 min before
proceeding to the next step. 70% ethanol was poured into a 250 ml beaker.
The forceps was dipped into the alcohol and then passed the forceps over the
Bunsen burner flame to sterilize it. The standard antibiotic disk (ampicillin)
was picked up and placed it in the centre of the plate. The Whatman filter
paper disc impregnated with newly synthesized drugs (0.005 ml, 50 mg) was
picked and placed it in the corners. This procedure was repeated for the four
plates for four newly synthesized drugs and incubated for 18 h at 35 °C. The
plates were examined for zones of inhibition. They were measured with mil-
limeter ruler across the disk. The diameter of the zone to the nearest whole
millimeter was recorded. The disk impregnated with solvent (DMSO) and
evaporated to dryness was used as negative control.
Chart 1. 5-Substituted-1,2,4-triazolo[4,3-c]8,9,10-trihydrocyclopenta/
8,9,10,11,12-pentahydrocyclohepta[b]thieno[3,2-e]pyrimidin-3-thiones
(5a—h)
Results and Discussion
The ortho amino ester of thiophenes (1a, b) were prepared
by following the reported procedures.9,10) Although various
synthetic procedures are available for the synthesis of
thieno[2,3-d]pyrimidines,11—19) no efforts were made to syn-
thesize this moiety utilizing microwaves. Hence we are here-
with reporting the synthesis of 2-substituted 5,6,7-trihydro-
cyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]thieno[2,3-
d]pyrimidines (2a—h) by a novel, microwave assisted sol-
vent free, synthetic route in which starting material 1a, b was
irradiated with various equimolar quantities of aryl/alkyl ni-
triles in presence 10% potassium tertiary butoxide in a mi-
crowave oven at 120 °C (CEM, Discover) for 40 to 45 s. The
resulting reaction mixture was added onto crushed ice and
neutralized with 5% hydrochloric acid to yield the target
compounds 2a—h in good yields. The disappearance of two
peaks of primary amino group and appearance of secondary
amino peak in the range of 3200 to 3400 cmꢀ1 and shift of
Table 1. Antibacterial Activity of 5-Substituted-1,2,4-triazolo[4,3-c]-
8,9,10-trihydrocyclopenta/8,9,10,11,12-pentahydrocyclohepta[b]thieno[3,2-
e]pyrimidin-3-thiones (5a—h)
Zones of inhibition (in mm )ꢁS.E.M.
Compd. code
Concn.
S. coagꢃ
E. coli
K. pneumoniae
5a
5b
5c
5d
5e
5f
5g
50 mg
50 mg
50 mg
50 mg
50 mg
50 mg
50 mg
50 mg
50 mg
7.0ꢁ0.48
7.0ꢁ0.37
10.0ꢁ0.44
9.0ꢁ0.24
7.0ꢁ0.31
8.0ꢁ0.30
9.0ꢁ0.31
6.0ꢁ0.31
15.5ꢁ0.32
8.0ꢁ0.12
9.0ꢁ0.34
8.0ꢁ0.31
8.0ꢁ0.44
7.0ꢁ0.24
10.0ꢁ0.24
9.0ꢁ0.30
6.0ꢁ0.30
9.0ꢁ0.30
8.0ꢁ0.14
7.0ꢁ0.13
7.0ꢁ0.28
6.0ꢁ0.31
6.0ꢁ0.31
7.0ꢁ0.30
7.0ꢁ0.24
6.0ꢁ0.37
11.1ꢁ0.30
5h
Ampicillin
carbonyl peak from 1724 cmꢀ1 to 1650—1680 cmꢀ1 indi- thieno[2,3-d]pyrimidines (4a—h) in good yields.20) The IR
cated the cyclization of ortho amino ester of thiophene. The spectra of the compounds showed the presence of primary
1H-NMR spectra showed D2O exchangeable secondary and secondary amino peaks at 3200—3400 cmꢀ1 respectively
amino signals as broad singlet at around d 11.9 ppm and which indicated the formation of the product. The NMR
mass spectra exhibited molecular ion peaks (as base peaks) spectra showed the NH and NH2 peaks at around d 11.92 and
corresponding to the molecular weight of the compounds. 4.80 ppm respectively which confirmed the formation of the
This further confirmed the formation of the product. The de- product. Further the mass spectra revealed the molecular ion
tails of reaction time and physical data are given in Experi- peak as base peak with characteristic fragmentation pattern.
mental.
The hydrazinated products 4a—h was heated to reflux
Compounds 2a—h were taken in excess amount of oxalyl with carbon disulphide in an alkaline medium for 9 h. The
chloride and warmed for 3 h to replace the hydroxyl group at white precipitate obtained on neutralization was recrys-
4th position by chloro group. The excess of oxalyl chloride tallised using DMF–water mixture to give the target com-
was removed by warming in a roto evaporator to get the com- pounds 5-substiuted-1,2,4-triazolo[4,3-c]8,9,10,11,12-penta-
pounds in good yields (75—85%). The chlorination was also hydrocyclohepta/8,9,10-trihydrocyclopenta[b]thieno[3,2-e]-
tried out using phosphorus oxychloride as per the reported pyrimidin-3-thiones (5a—h) in pure form. The IR spectra of
procedures20) but it took long time (12 h), high temperatures the compounds showed a single peak at 3050 to 3300 cmꢀ1
(120 °C) and tedious workup procedures resulting in lower for secondary amino group and weak CꢂS peak around
yields (40—50%). Thus oxalyl chloride was used for the 1200 cmꢀ1 indicating the formation of the product. The
chlorination of thienopyrimidines. The compounds 3a—h NMR spectra showed the NH peak at d 11.9—12.1 ppm and
were taken to next step immediately without any purification the disappearance of primary amino signal at around d
as they were unstable.
4.60—4.90 ppm confirmed the formation of the product. The
The chloro group in compounds 3a—h was replaced by mass spectra showed the molecular ion peak corresponding
hydrazine by heating them with hydrazine hydrate 99% in to its molecular weight which further gave the confirmation
presence of ethanol to yield the 2-substituted-4-hydrazino- for product formation. The elemental analyses showed that
5,6,7-trihydrocyclopenta/5,6,7,8,9-pentahydrocyclohepta[b]- all the newly synthesized compounds were having purity

560
Vol. 55, No. 4
University, Chandigarh for moral support. We thank IISC, Bangalore for
Spectral Data.
withinꢁ0.4% of theoretical values.
The synthesized compounds were evaluated for antimicro-
bial activity against various gram-positive and gram-negative
bacteria like Klebsiella, E. coli, Staphylococcus coagulase
and Pneumococci using Kirby Bauer’s Method.21) The nega-
tive control did not show any zone of inhibition in all the
bacterial strains used for the study. Pneumococcus was found
to be resistant and E. coli was the most susceptible organism.
Klebsiella and Staphylococcus coagulase showed intermedi-
ate activity.
Activity of 5c (9ꢁ0.34), 5f (10ꢁ0.24) and 5g (9ꢁ0.30)
was comparable with the activity of ampicillin (9ꢁ0.30)
against E. coli. Compound 5h showed less activity against E.
coli.
Compound 5c (10.0ꢁ0.44) 5d (9.0ꢁ0.24) and 5g (9.0ꢁ
0.31) showed better activity than other compounds against
Staphylococcus coagulase positive. However the activity of
the compounds was not comparable with the standard drug
ampicillin (15.5ꢁ0.32).
Compound 5a (8.0ꢁ0.14) was the most active against
Klebsiella among the other compound in the series although
not comparable with ampicillin (11.1ꢁ0.30).
As all the compounds showed antibacterial activity against
the bacteria tested, it indicates that this basic moiety can be a
potential scaffold for antibacterial drugs. Further the activity
of these compounds was comparable with ampicillin against
E. coli only. None of the compounds were having activity
comparable with standard drug against Staphylococcus coag-
ulase positive and Klebsiella respectively. Thus it shows that
further lead optimization should be carried out for the better
antibacterial activity.
References
1) John M. B., “Wilson and Gisvold’s, Text Book of Organic Medicinal
and Pharmaceutical Chemistry,” XI ed., Chap. 10, ed. by John H. B.,
John M. B., Jr., Lippincott Williams and Wilkins, A Wolters Kluwer
Company, Philadelphia, 2004, pp. 299—300.
2) Wistreich G. A., Lechtman M. D., “Mechanism of Drug Resistance in
Microbiology,” V ed., Macmallan Publishing Company, New York,
1988, pp. 353—354.
3) Savini L., Chiasserini L., Pellerano C., Filippelli W., Falcone G., Far-
maco, 56, 939—945 (2001).
4) Leisner S., Guetschow M., Droessler K., Wagner G., Kluge S., Dieter
L., Appl. 340,044, Ger. Pat. 293824 [Chem Abstr., 117, 48589k
(1992)].
5) Edie R., Gerald H., Ronald E., Krumkains E., Viktors, Appl. EP
452,002, Eur. Pat. 452002 [Chem. Abstr., 116, 21069h (1992)].
6) Obata I., Tokio F., Katsutoshi N., Isamu S., Shoji, Appl. EP 356,158
Eur. Pat. 356158 [Chem. Abstr., 113, 59210y (1990)].
7) Yamamoto S., Yokoi S., Matsumoto K., Honda T., Kobayashi T., Appl.
EP 103,114, Eur. Pat. 103114 [Chem. Abstr., 101, 23494g (1984)].
8) Chambhare R. V., Bobade A. S., Khadse B. G., Indian J. Heterocycl.
Chem., 12, 67—70 (2002).
9) Gewald K., Schinke E., Bottcher H., Chem. Ber., 99, 94—100 (1966).
10) Gewald K., Chem. Ber., 98, 3571—3577 (1965).
11) Ried W., Gieße R., Justus Liebigs Ann. Chem., 713, 143—148 (1968).
12) Dave K. G., Shishoo C. J., Devani M. B., Kalyanaraman R., Ananthan
S., Ullas G. V., Bhadti V. S., J. Heterocycl. Chem., 17, 1497—1500
(1980).
13) Boehm R., Pech R., Pharmazie, 38, 136—137 (1983).
14) Miyashita A., Fujimoto K., Okado T., Higashino T., Heterocycles, 42,
691—699 (1996).
15) Ibrahim Y. A., Elwahy A. H. M., Kadry A. M., Adv. Heterocycl.
Chem., 65, 235—281 (1996).
16) Mkrtchyan A. P., Kazaryan I. A., Akopyan N. E., Akopyan A. G.,
Khim-Farm. Zh., 20, 1312—1315 (1986).
17) Kazaryan S. G., Noravyan A. S., Gevorkyan G. A., Khim. Geterotsikl.
Soedin., 35, 825—828 (1999).
18) Taylor E. C., Patel H. H., Sabitha C. R., Heterocycles, 43, 349—355
(1996).
19) Yoon D. S., Han Y., Stark T. M., Haber J. C., Gregg B. T., Stankovich
S. B., Org. Lett., 6, 4775—4778 (2004).
20) Shishoo C. J., Devani M. B., Karvekar M. D., Ullas G. V., Ananthan S.,
Bhadti V. S., Indian J. Chem., 21B, 666—668 (1982).
21) Bauer A. W., Kirby W. M. M., Sherris J. C., Tuck M., Am. J. Clin.
Pathol., 45, 493—496 (1966).
Acknowledgements One of the authors (Raghu Prasad M) is thankful to
All India Council for Technical Education (AICTE) for granting Career
Award for Young Teachers (CAYT). The necessary facilities extended by
Principal and management, P.E.S. College of Pharmacy, Hanumanthnagar,
Bangalore—560 050 to carry out this work is gratefully acknowledged. We
profusely thank Prof. Dr. Christa Mueller, Universitat Bonn, Pharmazeutis-
ches Institut, Pharmazeutische Chemie, Poppelsdorf Kreuzbergweg 26 D-
53115 Bonn, Germany for providing facilities to carry out microwave as-
sisted synthesis and Prof. Dr. Akkinepally Raghuram Rao, UCPSC, Panjab