Design, synthesis, and antimicrobial activity of fused triheterocyclic nitrogen systems involving tetrazolo[1,5-b][1,2,4]triazines [1]

Article abstract of DOI:10.1007/s00706-008-0902-8

Dehydrogenative cyclization of the 6-substituted 7- arylidenehydrazinotetrazolo[1,5-b][1,2,4]triazines derived from 6-methyl and 6-phenyl derivatives of 7-hydrazinotetrazolo[1,5-b][1,2,4]triazines and aromatic aldehydes gave the corresponding 6-substituted 9-aryl-[1,2,4]triazolo[4,3-d] tetrazolo-[1,5-b][1,2,4]triazines. The latter compounds were also obtained by an alternative route involving dehydrative cyclization of 6-methyl and 6-phenyl derivatives of 7-chlorotetrazolo[1,5-b][1,2,4]triazines with aromatic hydrazides through the isolable aroylhydrazino intermediates. Also, the triazolotetrazolotriazine rings were accomplished by one-pot cyclization of cyclic amidrazones with aromatic acid chlorides. The ditetrazolo[1,5-b:1′, 5′-d][1,2,4]triazine systems were synthesized by cyclization of the former cyclic amidrazones with nitrous acid, or cyclic imidoyl chlorides with sodium azide. The bis-triazolotetrazolotriazine derivatives were synthesized by cyclization of two equivalents of each cyclic imidoyl chloride with acid dihydrazides through the isolable bis-hydrazide products. The antimicrobial activity of representative compounds was studied.

Full text of DOI:10.1007/s00706-008-0902-8

Monatsh Chem 139, 1261–1267 (2008)
DOI 10.1007/s00706-008-0902-8
Printed in The Netherlands
Design, synthesis, and antimicrobial activity of fused triheterocyclic
nitrogen systems involving tetrazolo[1,5-b][1,2,4]triazines [1]
Mamdouh A. M. Taha1, Susan M. El-Badry2
1
Chemistry Department, Faculty of Science, Faiyoum University, Faiyoum, Egypt
2
Physics and Chemistry Department, Faculty of Education, Alexandria University, Alexandria, Egypt
Received 18 January 2008; Accepted 26 January 2008; Published online 21 April 2008
# Springer-Verlag 2008
Abstract Dehydrogenative cyclization of the 6-substi-
tuted 7-arylidenehydrazinotetrazolo[1,5-b][1,2,4]tri-
azines derived from 6-methyl and 6-phenyl derivatives
of 7-hydrazinotetrazolo[1,5-b][1,2,4]triazines and
aromatic aldehydes gave the corresponding 6-substi-
tuted 9-aryl-[1,2,4]triazolo[4,3-d]tetrazolo-[1,5-b]-
[1,2,4]triazines. The latter compounds were also
obtained by an alternative route involving dehydrative
cyclization of 6-methyl and 6-phenyl derivatives of
7-chlorotetrazolo[1,5-b][1,2,4]triazines with aromatic
hydrazides through the isolable aroylhydrazino in-
termediates. Also, the triazolotetrazolotriazine rings
were accomplished by one-pot cyclization of cyclic
amidrazones with aromatic acid chlorides. The di-
tetrazolo[1,5-b:10,50-d][1,2,4]triazine systems were
synthesized by cyclization of the former cyclic amid-
razones with nitrous acid, or cyclic imidoyl chlorides
with sodium azide. The bis-triazolotetrazolotriazine
derivatives were synthesized by cyclization of two
equivalents of each cyclic imidoyl chloride with acid
dihydrazides through the isolable bis-hydrazide pro-
ducts. The antimicrobial activity of representative
compounds was studied.
Introduction
A review of several compounds comprising the tet-
razole nucleus has been published [2]. Recently,
numerous biological properties have been reported
for tetrazolo heterocycles, such as being useful due
to their antibacterial [1, 3, 4], antiproliferation [5],
anticancer [5], and anticonvulsant [6] activities. The
chemistry of condensed 1,2,4-triazines has been
surveyed in recent reviews [7, 8]; various members
of these compounds have received considerable
attention over the past years due to their thera-
peutic and pharmacological properties [1, 9–11].
Consequently, tetrazole and 1,2,4-triazine rings have
proven to be valuable synthons for the synthesis of a
wide range of biologically active compounds. Within
this context, it seemed of interest to synthesize the
title compounds and to evaluate their antimicrobial
activities.
Results and discussion
Condensation of 7-hydrazino-6-methyltetrazolo[1,5-
b][1,2,4]triazine (1) [1] or 7-hydrazino-6-phenyl-
tetrazolo[1,5-b][1,2,4]triazine (2) [1] with equimolar
amounts of the appropriate aromatic aldehyde in
boiling methanol afforded the corresponding 6-sub-
stituted 7-arylidenehydrazinotetrozolo[1,5-b][1,2,4]-
triazines 5a–5d and 6a–6d (Scheme 1) in 80–90%
overall yields, showing the expected NH in IR ab-
Keywords Cyclic amidrazones; Cyclic imidoyl chlorides;
Hydrazides; Fused nitrogen triheterocycles; Antimicrobial
activity.
Correspondence: Mamdouh A. M. Taha, Chemistry Depart-
ment, Faculty of Science, Faiyoum University, Faiyoum
63514, Egypt. E-mail: mamdouhamtaha@yahoo.com
1
sorption as well as H NMR signals characteristic

1262
M. A. M. Taha, S. M. El-Badry
Scheme 1
of NH (D2O-exchangeable), methylenic (–CH¼N–),
and aromatic protons. Their MS revealed the correct
molecular ions which were supported by elemental
analysis. Subjecting these hydrazone derivatives 5a–
5d and 6a–6d to dehydrogenative cyclization [12, 13]
with bromine in acetic acid in the presence of anhy-
drous sodium acetate or ethanolic iron(III) chloride
solution yielded the corresponding 6-substituted 9-
aryl-[1,2,4]triazolo-[4,3-d]tetrazolo[1,5-b][1,2,4]tri-
azines 9a–9d and 10a–10d. These structures lacked
the NH absorption in IR and methylenic proton sig-
were decisively assigned on the basis of their IR spec-
1
tra which showed NH and CON bands, and their H
NMR which exhibited two NH (D2O-exchangeable)
and aromatic proton signals. In addition, the chemical
proof for the assigned triazolotetrazolotriazine struc-
tures 9a–9d and 10a–10d was also obtained by one-
pot cyclization of 1 or 2 with aromatic acid chlorides
through the un-isolable aroylhydrazino intermediates
7a–7d and 8a–8d which were formed and concomi-
tantly dehydratively cyclized to compounds 9a–9d
and 10a–10d (Scheme 1). The aforementioned pro-
ducts 9a–9d and 10a–10d were proved to be identical
in all respects (mp, mixed mp, TLC, and IR) with
methods of cyclization mentioned above this article.
When cyclic amidrazones 1 or 2 were treated with
sodium nitrite in hydrochloric acid at 0ꢀC, they
cyclized into the corresponding 6-methyl(phenyl)-
ditetrazolo[1,5-b:10,50-d][1,2,4]triazines 11 or 12
(Scheme 1). The IR and 1H NMR spectra showed the
1
nal in H NMR. Alternatively, compounds 9a–9d
and 10a–10d were also prepared by reaction of 7-
chloro-6-methyltetrazolo[1,5-b][1,2,4]triazine (3) or
7-chloro-6-phenyltetrazolo[1,5-b][1,2,4]triazine (4)
with the equimolar amounts of the corresponding
aromatic hydrazides followed by dehydrative cycli-
zation using phosphorus oxychloride. The isolable
aroylhydrazino intermediates 7a–7d and 8a–8d

Tetrazolo[1,5-b][1,2,4]triazines
1263
Scheme 2
Table 1 Minimal inhibitory concentration (MIC=ꢀg ꢂ cmꢁ3
)
disappearance of NH and NH2 groups. Alternatively,
stirring the cyclic imidoyl chlorides 3 or 4 with equi-
molar amounts of sodium azide in a dipolar aprotic
solvent like dimethylformamide resulted in better
yields and purity of the desired products 11 or 12
identical with those prepared by the aforementioned
route. The IR spectra of the products 11 or 12 did
not show absorption bands at 2160–2120 cmꢁ1 diag-
nostic of azido functions [14, 15], and may be con-
sidered as existing in a tautomeric equilibrium with
tetrazole system [16].
of the prepared compounds
Test compound
S. aureus
E. coli
C. albicans
5d
6d
50
50
25
50
>200
12.5
7b
8b
100
50
>200
50
200
25
9a
>200
100
100
100
>200
>200
>200
>200
>200
>100
>200
>100
100
100
200
100
100
100
10c
13a
14b
15a
16b
Reaction of two molar equivalents of 3 or 4 with
one molar equivalent of oxalic, malonic, or succinic
dihydrazide in refluxing methanol caused a product
in each case whose structure was deduced from spec-
troscopic data. Its IR spectrum showed absorptions
characteristic of NH and CON as well as 4NH (D2O-
Ampicillin
Clotrimazole
12.5
–
25
–
–
12.5
ing that 5d, 6d, and 8b exhibit an antimicrobial ac-
tivity against S. aureus (25%). While compound 5d
possessed activity comparable to that of ampicillin
against E. coli, but the action of 6d and 8b were
50%. Moreover, compound 6d exhibited antimycotic
activity against C. albicans comparable to that of
clotrimazole, while the activity of 8b is 50% of that
clotrimazole. The rest of compounds showed lower
activity than the reference standards (ampicillin and
clotrimazole) against the test organisms.
In conclusion, the foregoing results demonstrated
the utility of 7-hydrazino(chloro)-6-methyl(phenyl)-
tetrazolo[1,5-b][1,2,4]triazines as synthons for the
construction of fused triheterocyclic nitrogen sys-
tems by different cyclization reagents. The antibac-
terial and antifungal activities of the synthesized
compounds were even comparable to ampicillin
and clotrimazole.
1
exchangeable) H NMR signals. The products were
assigned [17] therefore, proposed as bishydrazides
13a–13c and 14a–14c (Scheme 2). The latter com-
pounds underwent cyclodehydration by phosphorus
oxychloride to provide the bistriazolotetrazolotriazine
structures 15a–15c and 16a–16c which revealed only
a C¼N absorption and, most importantly, lacked any
NH and CON absorption bands in the IR region.
Moreover, the MS of these compounds showed molec-
ular ions in agreement with the assigned structures.
The products 5d, 6d, 7b, 8b, 9a, 10c, 13a,
14b, 15a, and 16b were in vitro evaluated [18] for
their antimicrobial properties against Gram-positive
(Staphylococcus aureus) and Gram-negative bacteria
(Escherichia coli) in addition to a fungus (Candida
albicans). The minimal inhibitory concentration
(MIC=ꢀg ꢂ cmꢁ3) [19] is displayed in Table 1 show-

1264
M. A. M. Taha, S. M. El-Badry
7-p-Tolylmethylidenehydrazino-6-phenyltetrazolo[1,5-b]-
[1,2,4]triazine (6b, C17H14N8)
Experimental
Melting points were determined in capillary tubes in a Stuart
Scientific SMP1 apparatus. The IR spectra were recorded
(KBr) on a Satellite 1000 spectrophotometer. 1H NMR spectra
were obtained on a Varian Mercury VXR-3000 and Jeol ECA
500 spectrometers and chemical shifts are expressed in ꢁ=ppm
using TMS as an internal standard. MS were recorded on a HP
model MS-5988 spectrometer at electron ionizing energy of
70eV. Microanalyses were performed by the Microanalytical
Unit, Cairo University, Egypt; their results agreed with the
calculated values.
Yield: 0.85g (84%); yellow; mp 148–150ꢀC; IR: ꢂꢀ¼ 33600
(NH), 1634 (C¼N) cmꢁ1; 1H NMR (DMSO-d6): ꢁ ¼ 11.80 (s,
NH, D2O-exchangeable), 8.25–7.90 (m, 9 ArH þ methylenic
H), 2.30 (s, CH3) ppm; MS: m=z (%) ¼ 330 (Mþ, 35).
7-p-Chlorobenzylidenehydrazino-6-phenyltetrazolo[1,5-b]-
[1,2,4]triazine (6c, C16H11ClN8)
Yield: 0.89 g (82%); yellow; mp 160–162ꢀC; IR: ꢂꢀ¼ 3340
(NH), 1620 (C¼N) cmꢁ1; MS: m=z (%) ¼ 350 (Mþ, 12).
7-p-Nitrobenzylidenehydrazino-6-phenyltetrazolo[1,5-b]-
[1,2,4]triazine (6d, C16H11N9O2)
Synthesis of 6-substituted 7-arylidehydrazinotetrazolo-
[1,5-b][1,2,4]triazines 5a–5d and 6a–6d
Yield: 0.95g (86%); red; mp 190–192ꢀC; IR: ꢂꢀ¼ 3290 (NH),
A solution of 3 mmol 1 or 2 in 15 cm3 methanol was added
to 3 mmol appropriate aromatic aldehyde and the mixture was
heated at 100ꢀC for 10 min. The reaction mixture was kept
at ambient temperature for 24 h and the product which sepa-
rated was filtered off, washed with ether, dried, and crys-
tallized from methanol.
1
1620 (C¼N) cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 12.10 (s, NH,
D2O-exchangeable), 8.10–7.75 (m, 9 ArH þ methylenic H)
ppm; MS: m=z (%) ¼ 361 (Mþ, 14).
Synthesis of 7-aroylhydrazino-6-substituted tetrazolo-
[1,5-b][1,2,4]triazine 7a–7d and 8a–8d
To a solution of 3 mmol 3 or 4 in 10cm3 methanol, a solution
of 3 mmol suitable aromatic hydrazide in 10cm3 methanol
was added, and the mixture was heated at reflux for 1 h and
then allowed to cool at room temperature. The separated prod-
uct was filtered off, washed several times with ether, dried,
and crystallized from methanol.
7-Benzylidenehydrazino-6-methyltetrazolo[1,5-b][1,2,4]-
triazine (5a, C11H10N8)
Yield: 0.66g (86%); pale yellow; mp 152–154ꢀC; IR:
ꢂꢀ¼ 3320 (NH), 1625 (C¼N) cmꢁ1
;
1H NMR (DMSO-d6):
ꢁ ¼ 11.60 (s, NH, D2O-exchangeable), 8.20–7.90 (m, 5 ArH),
7.61 (s, 1H, methylenic H), 2.40 (s, CH3) ppm; MS: m=z
(%) ¼ 254 (Mþ, 13), 255 (Mþ þ 1, 6).
7-Benzoylhydrazino-6-methyltetrazolo[1,5-b][1,2,4]triazine
(7a, C11H10N8O)
7-p-Tolylmethylidenehydrazino-6-methyltetrazolo[1,5-b]-
[1,2,4]triazine (5b, C12H12N8)
Yield: 0.61g (81%); mp 180–182ꢀC; IR: ꢂꢀ¼ 3340, 3280 (2
NH), 1680 (CON), 1630 (C¼N) cmꢁ1; 1H NMR (DMSO-d6):
ꢁ ¼ 12.65 (s, 2NH, D2O-exchangeable), 8.35–7.20 (m, 5ArH),
2.47 (s, CH3) ppm; MS: m=z (%) ¼ 270 (Mþ, 40).
Yield: 0.71 g (88%); yellow; mp 160–162ꢀC; IR: ꢂꢀ¼ 3340
(NH), 1615 (C¼N) cm-1; 1H NMR (DMSO-d6): ꢁ ¼ 10.85
(s, NH, D2O-exchangeable), 8.15–7.82 (m, 4 ArH), 7.70 (s,
1H, methylenic H), 2.40, 2.35 (2s, 2CH3) ppm; MS: m=z
(%) ¼ 268 (Mþ, 28).
7-p-Toluoylhydrazino-6-methyltetrazolo[1,5-b][1,2,4]-
triazine (7b, C12H12N8O)
Yield: 0.65 g (78%); mp 190–192ꢀC; IR: ꢂꢀ¼ 3330, 3290
7-p-Chlorobenzylidenehydrazino-6-methyltetrazolo[1,5-b]-
[1,2,4]triazine (5c, C11H9ClN8)
1
(2NH), 1670 (CON), 1625 (C¼N) cmꢁ1; H NMR (DMSO-
d6): ꢁ ¼ 12.82 (s, 2NH, D2O-exchangeable), 8.65–7.75 (m,
4ArH), 2.45, 2.30 (2s, 2CH3) ppm; MS: m=z (%) ¼ 285
(Mþ þ 1, 45).
Yield: 0.75 g (86%); yellow; mp 165–166ꢀC; IR: ꢂꢀ¼ 3290
(NH), 1620 (C¼N) cm-1; MS: m=z (%) ¼ 288 (Mþ, 30).
7-p-Nitrobenzylidenehydrazino-6-methyltetrazolo[1,5-b]-
[1,2,4]triazine (5d, C11H9N9O2)
7-p-Chlorobenzoylhydrazino-6-methyltetrazolo[15,b]-
[1,2,4]triazine (7c, C11H9ClN8O)
Yield: 0.81g (90%); organe; mp 181–182ꢀC; IR: ꢂꢀ¼ 3345
Yield: 0.72g (81%); mp 198–200ꢀC; IR: ꢂꢀ¼ 3340, 3325 (2
NH), 1685 (CON), 1630 (C¼N) cmꢁ1; 1H NMR (DMSO-d6):
ꢁ ¼ 12.71 (s, 2NH, D2O-exchangeable), 8.40–7.70 (m, 4 ArH),
2.40 (s, CH3) ppm; MS: m=z (%) ¼ 304 (Mþ, 38).
1
(NH), 1625 (C¼N) cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 10.66
(s, NH, D2O-exchangeable), 8.20–7.61 (m, 4 ArlI), 7.25 (s,
1H, methylenic H), 2.45 (s, CH3) ppm; MS: m=z (%) ¼ 299
(Mþ, 15).
7-p-Nitrobenzoylhydrazino-6-methyltetrazolo[1,5-b][1,2,4]-
triazine (7d, C11H9N9O3)
7-Benzylidenehydrazino-6-phenyltetrazolo[1,5-b][1,2,4]-
triazine (6a, C16H12N8)
Yield: 0.84 g (91%); mp 225–257ꢀC; IR: ꢂꢀ¼ 3350, 3310
1
Yield: 0.78 g (80%); yellow; mp 145–146ꢀC; IR: ꢂꢀ¼ 3340
(2NH), 1690 (CON), 1610 (C¼N) cmꢁ1; H NMR (DMSO-
1
(NH), 1630 (C¼N) cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 11.42
d6): ꢁ ¼ 12.65, 12.40 (2s, 2NH, D2O-exchangeable), 8.60–
7.35 (m, 4ArH), 2.40 (s, CH3) ppm; MS: m=z (%) ¼ 315
(Mþ, 27).
(s, NH, D2O-exchangeable), 8.15–7.85 (m, 10 ArH þ meth-
ylenic H) ppm; MS: m=z (%) ¼ 316 (Mþ, 42).

Tetrazolo[1,5-b][1,2,4]triazines
1265
6-Methyl-9-phenyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b]-
7-Benzoylhydrazino-6-phenyltetrazolo[1,5-b][1,2,4]triazine
(8a, C16H12N8O)
[1,2,4]triazine (9a, C11H8N8)
Yield: 0.78 g (78%); mp 165–166ꢀC; IR: ꢂꢀ¼ 3310, 3290
Yield: method A 0.27g (54%), method B 0.22 g (44%), meth-
od C 0.26 g (56%); mp 220ꢀC, identical with authentic sample
prepared from method D according to Ref. [1].
1
(2NH), 1675 (CON), 1620 (C¼N) cmꢁ1; H NMR (DMSO-
d6): ꢁ ¼ 12.61, 12.22 (2 s, 2NH, D2O-exchangeable), 8.75–
7.89 (m, 10 ArH) ppm; MS: m=z (%) ¼ 333 (Mþ þ 1, 50).
6-Methyl-9-p-tolyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b]-
[1,2,4]triazine (9b, C12H10N8)
7-p-Toluoylhydrazino-6-phenyltetrazolo[1,5-b][1,2,4]-
triazine (8b, C17H14N8O)
Yield: method A 0.28g (57%), method B 0.25 g (50%), meth-
od C 0.29g, method D 0.61 g (76%); mp 225–227ꢀC; IR:
Yield: 0.77 g (74%); mp 175–177ꢀC; IR: ꢂꢀ¼ 3290, 3270 (2
1
ꢂꢀ¼ 1630 (C¼N) cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 8.25–7.88
1
NH), 1670 (CON), 1610 (C¼N) cmꢁ1; H NMR (DMSO-
(m, 4 ArH), 2.45, 2.30 (2 s, 2CH3) ppm; MS: m=z (%) ¼ 266
(Mþ, 25), 267 (Mþ þ 1, 40).
d6): ꢁ ¼ 12.42, 12.95 (2s, 2NH, D2O-exchangeable), 8.85–
7.60 (m, 9ArH), 2.30 (s, CH3) ppm; MS: m=z (%) ¼ 346
(Mþ, 18).
9-p-Chlorophenyl-6-methyl-[1,2,4]triazolo[4,3-d]tetrazolo-
[1,5-b][1,2,4]triazine (9c, C11H7ClN8)
7-p-Chlorobenzoylhydrazino-6-phenyltetrazolo[1,5-b]-
[1,2,4]triazine (8c, C16H11ClN8O)
Yield: 0.85g (77%), mp 190–191ꢀC; IR: ꢂꢀ¼ 3320, 3280
(2NH), 1660 (CON), 1618 (C¼N) cmꢁ1; MS: m=z (%) ¼ 366
(Mþ, 36).
Yield: method A 0.31g (62%), method B 0.27 g (54%), meth-
od C 0.33 g (70%), method D 0.66g (77%); mp 235–236ꢀC;
1
IR: ꢂꢀ¼ 1635 (C¼N) cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 8.40–
7.63 (m, 4ArH), 2.50 (s, CH3) ppm; MS: m=z (%) ¼ 286
(Mþ, 22).
7-p-Nitrobenzoylhydrazino-6-phenyltetrazolo[1,5-b][1,2,4]-
triazine (8d, C16H11N9O3)
6-Methyl-9-p-nitrophenyl-[1,2,4]triazolo[4,3-d]tetrazolo-
[1,5-b][1,2,4]triazine (9d, C11H7N9O2)
Yield: 0.79g (85%), mp 240–242ꢀC; IR: ꢂꢀ¼ 3400, 3380
Yield: method A 0.37 g (74%), method B 0.26g (52%),
method C 0.38g (81%), method D 0.70g (78%); mp 250ꢀC;
1
(2NH), 1620 (CON), 1630 (C¼N) cmꢁ1; H NMR (DMSO-
1
d6): ꢁ ¼ 12.70 (s, 2NH, D2O-exchangeable), 8.80–7.90 (m, 9
ArH) ppm; MS: m=z (%) ¼ 377 (Mþ, 12).
IR: ꢂꢀ¼ 1620 (C¼N) cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 8.45–
7.88 (m, 4ArH), 2.40 (s, CH3) ppm; MS: m=z (%) ¼ 298
(Mþ þ 1, 15).
Synthesis of 6-substituted 9-aryl[1,2,4]triazolo[4,3-d]-
tetrazolo[1,5-b][1,2,4]triazines 9a–9d and 10a–10d
Method A. To a solution of 2 mmol of each 5a–5d and 6a–
6d in 15 cm3 glacial acetic acid containing 2 mmol anhy-
drous sodium acetate, 2 mmol bromine in 10 cm3 glacial
acetic acid were added gradually with stirring. The reaction
mixture was then warmed on a boiling water bath for 5 min,
left to cool and then poured onto water. The precipitated
solid was filtered off, washed thoroughly with water, and
crystallized from methanol.
Method B. A solution of 2 mmol of the respective hydra-
zone 5a–5d and 6a–6d in 20 cm3 ethanolic iron(III) chlo-
ride solution (10%) was boiled for 10 min, and then left at
room temperature overnight. The separated product was
filtered off, washed with water, dried, and crystallized from
methanol.
Method C. A mixture of 2 mmol of the particular aroyl hy-
drazine 7a–7d and 8a–8d, and 10cm3 phosphorus oxychloride
was heated under reflux for 1 h, then cooled and poured onto of
30cm3 cold saturated solution of sodium bicorbonate. The
crude solid that precipitated was filtered off, washed with
water, dried, and finally crystallized from methanol.
Method D. A 3 mmol of 1 or 2 was dissolved in 2 cm3
pyridine, 3 mmol of freshly distilled appropriate aromatic
acid chloride were added, and the mixture was heated under
reflux at 100ꢀC for 1 h. It was cooled at ambient temper-
ature, poured onto ice-water, the crude solid that precipi-
tated was filtered, washed with water and crystallized from
methanol.
6,9-Diphenyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]-
triazine (10a, C16H10N8)
Yield: method A 0.35g (50%), method B 0.29 g (42%), meth-
od C 0.39g (59%); mp 240–241ꢀC, identical with authentic
sample prepared from method D according to Ref. [1].
6-Phenyl-9-p-tolyl-[1,2,4][triazolo[4,3-d]tetrazolo[1,5-b]-
[1,2,4]triazine (10b, C17H12N8)
Yield: method A, 0.38 g (55%), method B 0.35 g (50%),
method C 0.39 g (59%), method D, 0.61 g (60%); mp 210–
212ꢀC; IR: ꢂꢀ¼ 1640 (C¼N) cmꢁ1
(%) ¼ 328 (Mþ, 35).
;
1H NMR (DMSO-d6):
ꢁ ¼ 8.60–7.90 (m, 9 ArH), 2.25 (s, CH3) ppm; MS: m=z
9-p-Chlorophenyl-6-phenyl-[1,2,4]triazolo[4,3-d]tetrazolo-
[1,5-b][1,2,4]triazine (10c, C16H9ClN8)
Yield: method A 0.41 g (59%), method B 0.36g (52%); meth-
od C 0.46g (69%); method D 0.80 g (75%); mp 218–220ꢀC;
1
IR: ꢂꢀ¼ 1625 (C ¼ N) cmꢁ1; H NMR (DMSO-d6). ꢁ ¼ 8.42–
7.80 (m, 9ArH) ppm; MS: m=z (%) ¼ 348 (Mþ, 35).
9-p-Nitrophenyl-6-phenyl-[1,2,4]triazolo[4,3-d]tetrazolo-
[1,5-b][1,2,4]triazine (10d, C16H9N9O2)
Yield: method A 0.51g (73%), method B 0.34 g (49%), meth-
od C 0.53 g (80%); method D 0.85g (77%); mp 270–272ꢀC;
1
IR: ꢂꢀ¼ 1620 (C¼N) cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 8.60–
7.45 (m, 9ArH) ppm; MS: m=z (%) ¼ 359 (Mþ, 45).

1266
M. A. M. Taha, S. M. El-Badry
Synthesis of 11 and 12
Oxalyl bis{(6-phenyltetrazolo[1,5-b][1,2,4]triazin-7-yl)-
hydrazide} (14a, C20H14N16O2)
Method A. A 3 mmol of 1 or 2 were dissolved in 10cm3
hydrochloric acid (2N) and the solution was cooled to 0ꢀC.
An aqueous solution of (0.2g) sodium nitrite 3 mmol in
10cm3 water was added portionwise to the above cooled so-
lution, with stirring. The solid which separated, it was filtered
off after 1 h of stirring, washed with cold water, dried, and
crystallized from a mixture of water and methanol.
Method B. A mixture of 3 mmol 3 or 4 and (0.2g) sodium
azide 3 mmol in 15cm3 dry dimethylformamide was stirred at
room temperature for 30 min, when a clear solution resulted.
The reaction mixture was thereafter heated on a water-bath for
1 h, then poured onto ice-water whereby the solid product
which precipitated was filtered off, dried, and crystallized
water=methanol.
Yield: 0.77 g (78%); mp 190–192ꢀC; IR: ꢂꢀ¼ 3350, 3295
(2 NH), 1670 (CON), 1625 (C¼N) cmꢁ1; 1H NMR (DMSO-
d6): ꢁ ¼ 12.55, 11.93 (2s, 2NH each, D2O-exchange-
able), 8.65–7.50 (m, 10 ArH) ppm; MS: m=z (%) ¼ 510
(Mþ, 28).
Malonyl bis{(6-phenyltetrazolo[1,5-b][1,2,4]triazin-7-yl)-
hydrazide} (14b, C21H16N16O2)
Yield: 0.72 g (71%); mp 175–177ꢀC; IR: ꢂꢀ¼ 3380, 3295
1
(2NH), 1655 (CON), 1615 (C¼N) cmꢁ1; H NMR (DMSO-
d6): ꢁ ¼ 12.50, 12.10 (2s, 4NH, D2O-exchangeable), 8.60–
7.50 (m, 10ArH), 4.20 (s, CH2) ppm; MS: m=z (%) ¼ 525
(Mþ þ 1, 35).
6-Methylditetrazolo[1,5-b:10,50-d][1,2,4]triazine
(11, C4H3N9)
Yield: method A 0.37 g (69%), method B 0.43 g (81%); mp
Succinyl bis{(6-phenyltetrazolo[1,5-b][1,2,4]triazin-7-yl)-
hydrazide} (14c, C22H18N16O2)
Yield: 0.67 g (64%); mp 180–182ꢀC; IR: ꢂꢀ¼ 3360, 3320
1
240–242ꢀC; IR: ꢂꢀ¼ 1635 (C¼N) cmꢁ1; H NMR (DMSO-
1
(2NH), 1655 (CON), 1610 (C¼N) cmꢁ1; H NMR (DMSO-
d6): ꢁ ¼ 2.45 (s, CH3) ppm; MS: m=z (%) ¼ 178 (Mþ þ 1, 55).
d6): ꢁ ¼ 12.40, 11.94 (2s, 4NH, D2O-exchangeable), 8.65–
7.95 (m, 10ArH), 4.40 (s, 2CH2) ppm; MS: m=z (%) ¼ 538
(Mþ, 26).
6-Phenylditetrazolo[1,5-b: 10,50-d][1,2,4]triazine
(12, C9H5N9)
Yield: method A 0.48 g (67%), method B 0.57 g (79%); mp
Synthesis of 15a–15c and 16a–16c
1
255–257ꢀC; IR: ꢂꢀ¼ 1630 (C¼N) cmꢁ1; H NMR (DMSO-
The respective of 2 mmol 13a–13c and 14a–14c was treated
with 10cm3 phosphorus oxychloride and heated under reflux
for 1 h. After attaining ambient temperature, the mixture was
poured onto a cold saturated solution of sodium bicarbonate
and the crude solid which separated was filtered off, washed
with water, dried, and crystallized from a mixture of water and
methanol.
d6): ꢁ ¼ 8.60–7.95 (m, 5 ArH) ppm; MS: m=z (%) ¼ 239
(Mþ, 48).
Synthesis of 13a–13c and 14a–14c
To a solution of 2 mmol 3 or 4 in 15 cm3 methanol, a solution
of 2 mmol acid dihydrazide in 20 cm3 methanol was gradually
added, and the mixture was heated under reflux at 100ꢀC for
1 h. The product which separated upon cooling was filtered
off, washed with methanol, and crystallized from a mixture of
water and methanol.
Bis{6-methyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]-
triazin-9-yl} (15a, C10H6N16)
Yield: 0.49 g (77%); mp 240–241ꢀC, IR: ꢂꢀ¼ 1620 (C¼N)
1
cmꢁ1; MS: m=z (%) ¼ 350 (Mþ, 38); H NMR (DMSO-d6):
Oxalyl bis{(6-methyltetrazolo[1,5-b][1,2,4]triazin-7-yl)-
hydrazide} (13a, C10H10N16O2)
ꢁ ¼ 2.50, 2.45 (2s, 2CH3) ppm.
Yield: 0.63g (80%); mp 215–217ꢀC; IR: ꢂꢀ¼ 3290, 3265 (2
NH), 1665 (CON), 1625 (C¼N) cmꢁ1; 1H NMR (DMSO-d6):
ꢁ ¼ 12.20, 12.05 (2s, 4NH, D2O-exchangeable), 2.45, 2.40 (2s,
CH3 each) ppm; MS: m=z (%) ¼ 386 (Mþ, 40).
Bis{6-methyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]-
triazin-9-yl}methane (15b, C11H8N16)
Yield: 0.43 g (67%), mp 210–212ꢀC; IR: ꢂꢀ¼ 1625 (C¼N)
cmꢁ1
;
1H NMR (DMSO-d6): ꢁ ¼ 4.15 (s, CH2), 2.55, 2.40
(2s, 2CH3) ppm; MS: m=z (%) ¼ 364 (Mþ, 42).
Malonyl bis{(6-methyltetrazolo[1,5-b][1,2,4]triazin-7-yl)-
hydrazide} (13b, C11H12N16O2)
Yield: 0.64 g (78%); mp 190–191ꢀC; IR: ꢂꢀ¼ 3320, 3280
(2NH), 1660 (CON), 1615 (C¼N) cmꢁ1; 1H NMR (DMSO-
d6): ꢁ ¼ 11.85, 11.40 (2s, 2NH each, D2O-exchangeable),
4.25 (s, CH2), 2.55 (s, 2CH3) ppm; MS: m=z (%) ¼ 400
(Mþ, 27).
Bis{6-methyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]-
triazin-9-yl}ethane (15c, C12H10N16)
Yield: 0.33 g (52%), mp 220–222ꢀC; IR: ꢂꢀ¼ 1620, (C¼N)
1
cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 4.45 (s, 2CH2), 2.50, 2.40
(2s, CH3) ppm.
Succinyl bis{(6-methyltetrazolo[1,5-b][1,2,4]triazin-7-yl)-
hydrazide} (13c, C12H14N16O2)
Yield: 0.55 g (65%); mp 198–200ꢀC; IR: ꢂꢀ¼ 3330, 3308
(2NH), 1665 (CON), 1620 (C¼N) cmꢁ1; MS: m=z (%) ¼
415 (Mþ þ 1, 18).
Bis{6-phenyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]-
triazin-9-yl} (16a, C20H10N16)
Yield: 0.63 g (75%), mp 215–217ꢀC; IR: ꢂꢀ¼ 1625 (C¼N)
cmꢁ1
;
1H NMR (DMSO-d6): ꢁ ¼ 8.25–7.92 (m, 10ArH)
ppm; MS: m=z (%) ¼ 474 (Mþ, 48).

Tetrazolo[1,5-b][1,2,4]triazines
1267
4. Karnik AV, Malviya NJ, Kulkarni AM, Jadhav BL (2006)
Eur J Med Chem 41:891
5. Jantova S, Ruzekova L, Stankovsky S, Spirkova K (1997)
Neoplasma 44:240
6. Rubat C, Coudert P, Couquelet JM, Tronche P, Bastide J,
Bastide P (1990) Farmaco 45:331
Bis{6-phenyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]-
triazin-9-yl}methane (16b, C21H12N16)
Yield: 0.52 g (62%), mp 205–207ꢀC; IR: ꢂꢀ¼ 1625 (C¼N)
1
cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 8.70–7.90 (m, 10ArH), 4.10
(s, CH2) ppm.
7. El-Ashry ESH, Rashed N, Taha M, Ramadan E (1994)
Adv Heterocycl Chem 59:39
8. El-Ashry ESH, Rashed N, Mousaad A, Ramadan E
(1994) Adv Heterocycl Chem 61:207
9. Ashok M, Holla BS (2007) phosphorus, Sulfur Silicon
182:981
Bis{6-phenyl-[1,2,4]triazolo[4,3-d]tetrazolo[1,5-b][1,2,4]-
triazin-9-yl}ethane (16c, C22H14N16)
Yield: 0.43 g (51%), mp 230–232ꢀC; IR: ꢂꢀ¼ 1618 (C¼N)
1
cmꢁ1; H NMR (DMSO-d6): ꢁ ¼ 8.80–7.20 (m, 10ArH), 4.35
(s, 2CH2) ppm; MS: m=z (%) ¼ 502 (Mþ, 37).
10. Shaban MAE, Taha MAM, Morgaan AEA (2000)
Monatsh Chem 131:487
11. Dudfield PJ, Le VD, Lindell SD, Rees CW (1999) J Chem
Soc Perkin Trans 1:2937
12. Abdel-Fattah A-SM, Sherif SM, Youssef MM, Ahmed
NSE (1994) J Chem Res (S) 412, (M) 2266
13. Shaban MAE, Taha MAM, Sharshira EM (1992) Alex J
Pharm Sci 6:219
14. Moustafa MAA, Ismaiel AM, Eisa HM, El-Emam AA
(1991) J Chin Chem Soc 38:199
Antimicrobial screening
Solutions of the test compounds, ampicillin trihydrate and
clotrimazole were prepared in DMSO at a concentration of
1600 ꢀg=cm3 and twofold dilutions of the compounds were
prepared (800, 400, . . . 6.25ꢀg=cm3). The microorganism sus-
pensions at 106 Colony Forming Unit=cm3 (CFU=cm3) con-
centration were inoculated to the corrosponding wells. Plates
were incubated at 36ꢀC for 24 to 48h. The incubation cham-
ber was kept sufficiently humid. At the end of the incubation
period, the minimial inhibitory concentrations (MIC) were
determined. Controls with DMSO and uninoculated media
were also investigated.
15. Lovelette CA (1979) J Heterocycl Chem 16:555
16. Shishoo CJ, Jain KS (1992) J Heterocycl Chem 29:883
17. Shaban MAE, Taha MAM, Nasr Az (1990) J Islamic
Acad Sci 3:98
18. Conducted in the Extension Laboratory, Faculty of
Agriculture, University of Alexandria, Egypt
19. Murray PR, Baron EJ, Pfaller MA, Tenovee FC, Yolken RT
(1995) Manual of Clinical Microbiology In: Woods GL,
Washington JA (eds) Antimicrobial Agents and Suscepti-
bility Testing, Am Soc Microbiol, Washington DC, p 1327
References
1. Taha MAM (2007) Monatsh Chem 138:505
2. Moderhack D (1998) J Prakt Chem 340:687
3. Taha MAM, El Badry SM (2007) Phosphorus. Sulfur
Silicon 182:1011