Synthesis of spiro(cyclohexa-diene-pyrazolo[1,5-a]pyrimidine-4-ylidene)- malononitrile derivatives

Article abstract of DOI:10.3184/030823409X466717

The reaction of 4-substituted aryldiazenyl-1H-pyrazole-3,5-diamines with 7,7',8,8'-tetra-cyanoquinodimethane gave 2-(2',7'-diamino-6'-cyano-3'- (aryldiazenyl)-4'H-spiro(cyclohexa[2,5]-diene-1,5'-pyrazolo[1,5-a] pyrimidine-4-ylidene) malononitriles in 63-7

Full text of DOI:10.3184/030823409X466717

JOURNAL OF CHEMICAL RESEARCH 2009
AUGUST, 495–498
RESEARCH PAPER 495
Synthesis of spiro(cyclohexa-diene-pyrazolo[1,5-a]pyrimidine-4-ylidene)-
malononitrile derivatives
Yusria R. Ibrahim*
Chemistry Department, Faculty of Science, Minia University, 61519 Minia, A. R. Egypt
The reaction of 4-substituted aryldiazenyl-1H-pyrazole-3,5-diamines with 7,7',8,8'-tetra-cyanoquinodimethane gave
2-(2',7'-diamino-6'-cyano-3'-(aryldiazenyl)-4'H-spiro(cyclohexa[2,5]-diene-1,5'-pyrazolo[1,5-a]pyrimidine-4-ylidene)
malononitriles in 63–79% yield, while, by reaction of 2-aminobenzimidazole with 7,7',8,8'-tetracyanoquinodimethane,
2-(3'-amino-4'-cyano-6'H-spiro-(cyclohexa[2',5']diene-1,5'-benzo(d)-imidazo[1,2-a]pyrimidine)-4-ylidene)malononitrile
was formed in 71% yield. Rationales for these transformations are presented.
Keywords: aminopyrazole, tetracyanoquinodimethane, spiropyrazolo[1,5-a]pyrimidines
In recent years, attention has been increasing regarding
the synthesis of spiroheterocyclic compounds which
exhibit various biological activities,1-6 pharmaceutical7 and
antitumor properties.8 Pyrazolopyrimidines and related fused
heterocycles have been identified as bioactive molecules.1-6
They are known to function as CNS (Central Nervous System)
depressants9 and can be tuberculostatic.10
The biological and medicinal activities of condensed
pyrazoles initiated considerable interest in the development
of the synthesis of these molecules.11-13 The synthesis and
chemistry of pyrazolo[1,5-a]pyrimidines has recently been
revived as revealed by the vast number of papers and patents
which report routes for the synthesis of different biologically
active pyrazolo[1,5-a]pyrimidine derivatives.14-16
Robins and co-workers reported that certain 3-substituted
pyrazolo[1,5-a]pyrimidines inhibit the metabolism of snails of
Schistosomiasis.17,18 Since, schistosomiasis is a health problem
in Egypt, it has been reported that 2-aminopyrazolo[1,5-a]-
pyrimidines showed strong antischistosomiasal activity.19,20
The reaction of 4-substituted aryldiazenyl-1H-pyrazole-
3,5-diamines 1a–d with ethenetetracarbonitrile21,22 and (1,3-
dioxo-2,3-dihydro-1H-inden-2-ylidene)propanedinitrile23-25
afforded pyrazolo[1,5-a]pyrimidine derivatives.
Tetracyanoquinodimethane (3, TCNQ) has been widely used
as an acceptor molecule to form highly conducting charge-
transfer complexes.26 It has been reported that the addition
of 3 to acylthiosemicarbazides,27 2,5-dithiobiureas,28 as well
as aldehydic 4-phenylthiosemicarbazones gave different
spiroheterocyclic compounds.29
We report an extension to our strategy based upon synthesis
of heterocycles which have prospective biological and
pharmaceutical activities,30,31 In this publication we investigate
the reaction of 4-substituted aryldiazenyl-1H-pyrazole-3,5-
diamine 1a–d and 2-aminobenzimidazole (2) with tetracyano-
quinodimethane (3, TCNQ) as a p-electron deficient acceptor
aiming to obtain spiropyrazolopyrimidines which might have
prospective biological activities towards Schistosomiasal.
Compounds 1a–d (Fig. 1) have two exocyclic nitrogen and one
endocyclic nitrogen that do enjoy nucleophilic sites.
Solutions of 1a–d in dry pyridine were added dropwise
to a solution of 3 (TCNQ) in the same solvent. The mixture
were gently warmed to 50–60°C and kept at this temperature
for 3 h with stirring and finally warmed to 80°C for 5 min.
The residue obtained from concentration at 50°C consisted
of complex mixture containing a deep blue main component
and numerous coloured byproducts each in small quantities.
From their gross composition and spectroscopic evidence, the
main products from 6a–d were found to be formed from one
molecule of 1 and one molecule of 3. The visible absorptions
in acetonitrile solution are around 650 nm. The IR spectra are
Ar
H2N
NH2
NH
NC
NC
CN
CN
N
NH2
N
H
2
N
1a-d
3, TCNQ
a
, Ar = NNC6H5
b, Ar = NNC6H4-p-CH3
c, Ar = NNC6H4-p-OCH3
d, Ar = NNC6H4-p-Cl
Fig. 1
characterised by strong cyano-absorptions (2210–2220 cm-1),
NH2 (3440–3446, 3387–3395 cm-1), NH (3170–3186 cm-1)
and aryl C=C at 1590–1600 cm-1 as expected. The H NMR
1
spectrum of 6b, for example clearly shows three broad signals
with the ratio of 1:2:2 centred at dH = 9.88, 8.68 and 7.20
ppm. due to pyrimidine-NH, NH2 attached to pyrimindine ring
and NH2 attached to pyrazole ring, respectively. The expected
signals for CH3 (dH = 2.23 ppm), hexadiene-CH (dH = 6.24,
6.52 ppm) and phenyl protons are observed. The salient
features of 13C NMR spectra (including 13C DEPT spectra) of
6b are the signals at dc = 18.62 (CH3), 47.13 (q-C-1,5'), 73.18
[C(CN)2], 78.92 (C-3'), 118.02, 118.56, 118.63 (CN), 152.42
(C-2) and 160.66 ppm (C-4).32,33 Further peaks for C-6' and
C-7' resonated at dc = 66.98 and 155.69 ppm., respectively,
are in accordance with the observed trends in the d values for
C-atoms in push-pull alkenes.34,35
The EI mass spectra of 6a–d are characterised by molecular
ions of low intensity. The following common fragmentation
patterns lend support to the assigned structures: Loss of CH3
giving intense [M+-15] ions and loss of ArN2 giving rise to the
ion m/z = 301 common in the spectra of all four compounds.
Compounds 1a–d reacted with 3 to yield pyrazolo[1,5-
a]pyrimidines that may be formulated as 6a–d or isomeric
7a–d. Thus if the initial addition involves ring nitrogen atom
N-2, as has been assumed earlier,21-25 Michael adduct 5 would
be formed. This then cyclises to yield 7. On the other hand,
if the exocyclic amino function reacts with the acceptor 3,
compound 4 would be formed. Its cyclisation would then
afford 6 (Scheme 1).
The a priori possible isomeric structures 7 were ruled out
on the bases of 13C NMR of compounds 6a–d, the pyrimidine
C-7' is regularly upfield shifted; 6a (C-7' = 155.81 ppm);
6b (C-7' = 155.69); 6c (C-7' = 155.44); 6d (C-7' = 155.31)
compared to pyrimidine-C-5' in compound 7 which resonates
downfield in 3-aminopyridazine derivatives at 166.59 ppm36
and in 2-aminopyrrole derivatives at 166.25 ppm,36 due to the
presence of NH2 and NH attached to pyrimidine-C-5'.
Attempts to react the product of 1a and 3 with another
molecule of 3 by heating them in pyridine failed and the
reaction does not take place to form compound 8.
* Correspondent. E-mail: dryusria2009@yahoo.com

496 JOURNAL OF CHEMICAL RESEARCH 2009
CN
CN
Ar
N
H
N
H2N
Ar
CN
CN
NH
C
C
NH
N
CN
N
H2N
N
H
CN
H2N
4
6
1
+
3
Ar
H
N
NH2
CN
NH
CN
Ar
NH2
H2N
C
N
N
C
N
H2N
N
NC
CN
CN
7
NC
+ 3
5
CN
Ar
CN
NC
NH2
NH
N
H2N
N
N
CN
NC
CN
8
Scheme 1
Interestingly, the molecular modelling (MM2)37 of 6a as
an example suggested structural feature of 6a as indicated
in Scheme 1. Since, the steric energy value of compound
6a is found to be DE = 672.038 kcal mol-1 based on the
aforementioned semi-empirical calculations using the MM2
level of theory,37 whereas this value is increased in the case of
7 by 13 kcal mol-1. The stability of compound 6 in this form
supports the exclusion of any other expected isomeric forms.
Furthermore, Elnagdi et al.38 reported recently, the
reaction of 4-(arylazo)-5-ethyl-1H-pyrazol-3-ylamine with
benzylidenemalononitrileinpyridinetoaffordpyrazolo[1,5-a]-
pyrimidines via the reaction of exocyclic amino function
followed by cyclisation. The regioorientation of the reagents
has been determined by 15N, 1H/HMBC measurements as well
as an X-ray crystal structure.
As shown in Fig. 2, structure 6b fits best to all the spectroscopic
data (see experimental).
2-Aminobenzimidazole (2) was reacted similarly to 3
(TCNQ) with 1a–d in pyridine with the formation of 2-
(3'-amino-4'-cyano-6'H-spiro(cyclohexa[2',5']diene-1,5'-
benzo(d)-imidazo[1,2-a]pyrimidine)-4-ylidene)malononitrile
12 (Scheme 2).
The structure assignment of 12 was supported by the
following spectral data. In its 13C NMR spectrum, the
characteristic resonance signals of [C(CN)2] and (C-4)
appeared at dC = 72.94 and 160.08 ppm, respectively. Also,
13C NMR spectrum shows signals at dC = 57.29 (q-C-1,5'),
66.85 (C-4'), 152.11 (C-1') and 155.37 (C-3'). The low-field
pyrimidine-NH is presented at dH = 9.86 ppm, whereas another
broad signals centred at 8.67 due to exocyclic pyrimidine-
NH2. The AA'BB' system of (3-H and 6-H) and (4-H and 5-H)
appear as base line separated, AA' and BB' parts instead of
narrow multiplets at 7.38 and 7.29 ppm, respectively.
From the elemental analysis and mass spectrometry, a net
release of H2N-C=C-CN (M wt, 66) had occurred. The mass
spectrum showed also the following fragments 337 [M+-66],
m/z 90 (C6H4N), as well as dicyanomethylenehexadienyl
fragment at m/z 141. The spectroscopic data found for the
reaction product between 2 and 3 fit best for structure 12
which is perfectly analogous to structure 6.
The analytical data of compound 6b could also match
for other isomers of products 9–11 (Fig. 2). The alternative
1
structures 10 and 11 could be ruled out on the bases of H
NMR, due to the presence of one group NH2 and three or four
NH, whereas our spectral data of 6a–d showed two groups of
NH2 and one NH. On the other hand, the alternative structure
9 could be ruled out also due to the presence of only one C=N
group in 13C NMR spectrum of 6a–d.
N
N
NC
NC
CN
CN
N
NH
NH2
+
N
H
H2N
CN
CN
3
CN
12
2
Scheme 2

JOURNAL OF CHEMICAL RESEARCH 2009 497
H3C
H3C
NH
N
N
N
N
H2N
H2N
CN
NH
CN
CN
NH
N
N
N
CN
CN
CN
H2N
H2N
6b
9
i) 2 NH2
i) 2 NH2
ii) 2 NH
iii) 3 CN
iv) 2 C=N
ii) one NH
iii) 3 CN
iv) one C=N
H3C
H3C
NH
N
N
N
HN
HN
CN
CN
CN
CN
NH
NH
HN
HN
N
N
CN
CN
H2N
H2N
10
11
i) one NH2
ii) 4 NH
i) one NH2
ii) 3 NH
iii) 3 CN
iii) 3 CN
iv) 2 C=N
iv) one C=N
Fig. 2
other mostly coloured zones were observed but it always contained
too little materials to allow for isolation of significant amounts and
had to be discarded as well as the tarry materials remaining at the
start line.
Experimental
Melting points have been determined using open glass capillaries on
a Gallenkamp melting point apparatus and are uncorrected. Elemental
analyses were determined by the Microanalytical Centre, Cairo
University, Egypt. The IR spectra were recorded on Perkin-Elmer
397 and Shimadzu 480 spectrometers using potassium bromide
pellets. The UV-vis spectra were recorded on Perkin-Elmer Lambda-
2 spectrophotometer, stoppered 1.0 cm silica cell. 1H NMR 300 MHz
and 13C NMR 75 MHz spectra were recorded on Bruker WM300
instrument and Bruker AM 400 (400.134 MHz and 100.60 MHz).
The chemical shifts are expressed as d [ppm] with reference
tetramethylsilane as internal standard, s = singlet, d = doublet,
dd = doublet of doublet and b = broad. 13C assignments (qC = sp2
quaternary carbon atoms) were made with the aid of DEPT 135/90
spectra. For EI (70 eV) mass spectra Varian MAT CH-7 was used.
For preparation layer chromatography (plc) 1.0 mm thick air-dried
layers of slurry applied silica gel Merck Pf254 on 48 cm wide and
20 cm high glass plates were used. Zones were detected by their
colour and indicator fluorescence quenching upon 254 nm light and
extracted with acetone.
2-(2',7'-Diamino-6'-cyano-3'-(phenyldiazenyl)-4'H-spiro(cyclohexa-
[2,5]diene-1,5'-pyrazolo[1,5-a]pyrimidine)-4-ylidene)malononitrile
(6a): Blue crystals (0.304 g, 75%), m.p. 284–286°C (acetonitrile).
IR (KBr): 3445, 3390 (NH2), 3170 (NH), 2220, 2215 (CN), 1600
1
(ArC=C). UV-vis (acetonitrile) lmax (log e) = 653 (3.84). H NMR
(DMSO-d6):ꢀ dꢀ =ꢀ 6.26, 6.55 (dd, 4H, cyclohexadiene-H), 7.22 (br,
2H, NH2 attached to pyrazole ring), 7.37–7.52 (m, 5H, ArH), 8.64
(br, 2H, NH2 attached to pyrimidine ring), 9.91 (br, 1H, pyrimidine-
NH). 13C NMR (DMSO-d6): d = 56.93 (q-C-5'), 67.14 (C-6'), 73.26
(C(CN)2), 79.12 (C-3'), 117.87, 118.41, 118.67 (CN), 124.14, 125.73
(cyclohexadiene-CH), 127.98, 128.41, 128.45 (ArCH), 131.23 (ArC),
151.74 (C-3'a), 152.36 (C-2'), 155.81 (C-7'), 161.12 (C-4). MS (m/z,
%): 406 (M+, 29), 301 (44), 235 (22), 179 (14), 105 (100), 77 (86), 66
(51). C21H14N10 (406.40): Calcd C, 62.06; H, 3.47; N, 34.47. Found:
C, 61.89; H, 3.61; N, 34.29%.
2-(2',7'-Diamino-6'-cyano-3'-(4-methylphenyldiazenyl)-4'H-
spiro(cyclohexa[2,5]diene-1,5'-pyrazolo[1,5-a]pyrimidine)-4-
ylidene)malononitrile (6b): Blue crystals (0.332 g, 79%), m.p. 311–
313°C (acetonitrile). IR (KBr): 3440, 3395 (NH2), 3180 (NH), 2220,
2215 (CN), 1595 (ArC=C). UV-vis (acetonitrile) lmax (log e) = 660
Starting materials: 4-Aryldiazenyl-1H-pyrazole-3,5-diamines
1a–d, were prepared utilising the procedure originally reported
by Elnagdi et al.39,40 2-Aminobenzimidazole (2) and 7,7',8,8'-
tetracyanoquinodimethane (3, TCNQ) were purchased from Aldrich
and used as purchased.
1
(3.96). H NMR (DMSO-d6):ꢀdꢀ=ꢀ2.23 (s, 3H, CH3), 6.52, 6.28 (dd,
4H, cyclohexadiene-H, J = 8.41 Hz), 7.20 (br, 2H, NH2 attached to
pyrazole ring), 7.31 (d, 2H, 3',5'-ArH, J = 8.0 Hz), 7.49 (d, 2H, 2',6'-
ArH, J = 8.0 Hz), 8.68 (br, 2H, NH2 attached to pyrimidine ring), 9.88
(br, 1H, pyrimidine-NH). 13C NMR (DMSO-d6): d = 18.02 (CH3),
57.13 (q-C-5'), 66.98 (C-6'), 73.18 (C(CN)2), 78.92 (C-3'), 118.02,
118.56, 118.63 (CN), 124.19, 125.69 (cyclohexadiene-CH), 127.81,
128.39 (ArCH), 132.16, 139.22 (ArC), 152.14 (C-3'a), 152.42 (C-2'),
155.69 (C-7'), 160.66 (C-4). MS (m/z,%): 420 (M+, 41), 405 (22),
301 (35), 235 (18), 179 (11), 119 (93), 91 (100), 77 (56), 66 (63).
C22H16N10 (420.43): Calcd C, 62.85; H, 3.84; N, 33.32. Found: C,
63.04; H, 3.95; N, 33.19%.
2-(2',7'-Diamino-6'-cyano-3'-(4-methoxyphenyldiazenyl)-4'H-
spiro(cyclohexa[2,5]diene-1,5'-pyrazolo[1,5-a]pyrimidine)-4-
ylidene)malononitrile (6c): Blue crystals (0.314 g, 72%), m.p. 332–
334°C (acetonitrile). IR (KBr): 3445, 3390 (NH2), 3186 (NH), 2218,
2210 (CN), 1600 (ArC=C). UV-vis (acetonitrile) lmax (log e) = 664
(4.02). 1H NMR (DMSO-d6):ꢀdꢀ=ꢀ3.87 (s, 3H, OCH3), 6.25, 6.54 (dd,
4H, cyclohexadiene-H, J = 8.03 Hz), 7.18 (br, 2H, NH2 attached to
Reaction of 7,7',8,8'-tetracyanoquinodimethane (3, TCNQ) with 4-
aryldiazenyl-1H-pyrazol-3,5-diamines1a–dor2-aminobenzimidazole
(2): To a solution of 3 (TCNQ) (416 mg, 2.0 mmol) in dry pyridine
(15 mL) a solution of 1a–d or 2 (1.0 mmol each) in (5 mL) of dry
pyridine was add dropwise over 5 minutes at room temperature with
stirring. The mixture was warmed gently to 50–60°C and kept at this
temperature with stirring and admission of air for 3 h., then warmed
to maximum 80°C for 5 minutes and concentrated to dryness 50°C.
The residue was taken up several times with cold ethanol (15 mL) and
the slurry was concentrated again to remove any residual pyridine.
This operation was repeated four times. The residue was dissolved in
(5 mL) acetone, this solution in each case was applied to five (PLC)
plates and developed with toluene/ethyl acetate (2:1) for the run with
1a,d, toluene/ethyl acetate (3:1) for the run with 1b,c and 2. Intense
blue main zones from 1a–d and from 2 were extracted. Crystallisation
from acetonitrile afforded pure samples of 6a–d and 12, all appearing
black (but tinted to some extent) with a metallic shine in incident
light, but giving blue solutions in acetone or methanol. Numerous

498 JOURNAL OF CHEMICAL RESEARCH 2009
6
7
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pyrazole ring), 7.27 (d, 2H, 3',5'-ArH, J = 8.27 Hz), 7.47 (d, 2H, 2',6'-
ArH, J = 8.27 Hz), 8.65 (br, 2H, NH2 attached to pyrimidine ring),
9.90 (br, 1H, pyrimidine-NH). 13C NMR (DMSO-d6): d = 56.97
(q-C-5'), 59.27 (OCH3), 67.08 (C-6'), 73.22 (C(CN)2), 79.06 (C-3'),
117.92, 118.49, 118.58 (CN), 124.22, 125.62 (cyclohexadiene-CH),
127.85, 128.41 (ArCH), 139.65 (ArC), 151.94 (C-3'a), 152.51 (C-2'),
154.16 (ArC-O), 155.44 (C-7'), 159.96 (C-4). MS (m/z,%): 436 (M+,
37), 421 (278), 301 (19), 235 (26), 179 (18), 135 (69), 107 (81), 92
(100), 77 (93), 66 (57). C22H16N10O (436.43): Calcd C, 60.54; H,
3.70; N, 32.09. Found: C, 60.71; H, 3.58; N, 31.88%.
8
9
10 M.M. Ghoralb, Z.H. Ismail, S.M. Abdel-Gawad and A. Abdel Aziem,
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2-(2',7'-Diamino-6'-cyano-3'-(4-chlorophenyldiazenyl)-4'H-
spiro(cyclohexa[2,5]diene-1,5'-pyrazolo[1,5-a]pyrimidine)-4-
ylidene)malononitrile (6d): Blue crystals (0.277 g, 63%), m.p. 347–
349°C (acetonitrile). IR (KBr): 3440, 3387 (NH2), 3175 (NH), 2215,
2210 (CN), 1590 (ArC=C). UV-vis (acetonitrile) lmax (log e) = 649
(3.90). 1H NMR (DMSO-d6):ꢀdꢀ=ꢀ6.22, 6.52 (dd, 4H, cyclohexadiene-
H, J = 7.96 Hz), 7.22 (br, 2H, NH2 attached to pyrazole ring), 7.30 (d,
2H, 3',5'-ArH, J = 8.14 Hz), 7.55 (d, 2H, 2',6'-ArH, J = 8.14 Hz), 8.61
(br, 2H, NH2 attached to pyrimidine ring), 9.87 (br, 1H, pyrimidine-
NH). 13C NMR (DMSO-d6): d = 56.92 (q-C-5'), 66.90 (C-6'), 73.19
(C(CN)2), 78.94 (C-3'), 117.91, 118.42, 118.55 (CN), 124.44, 125.28
(cyclohexadiene-CH), 127.35, 128.51 (ArCH), 130.26, 138.26 (ArC),
152.08 (C-3'a), 152.46 (C-2'), 155.31 (C-7'), 159.93 (C-4). MS (m/z,
%): 442/440 (M+, 29), 405 (55), 301 (38), 235 (22), 179 (17), 140
(55), 112 (36), 77 (100), 66 (84). C21H13ClN10 (440.85): Calcd C,
57.21; H, 2.97; Cl, 8.04; N, 31.77. Found: C, 56.98; H, 3.09; Cl, 7.87;
N, 31.92%.
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2-(3-Amino-4-cyano-6'H-spiro(cyclohexa[2',5']diene-1,5-benzo-
[d]imidazo[1,2-a]-pyrimidine)-4-ylidene)malononitrile (12): Blue
crystals (0.239 g, 71%), m.p. 243–245°C (acetonitrile). IR (KBr):
3420 (NH2), 3190 (NH), 2220, 2215 (CN), 1630 (C=N), 1590
1
(ArC=C). UV-vis (acetonitrile) lmax (log e) = 610 (3.76). H NMR
(DMSO-d6):ꢀdꢀ=ꢀ6.27, 6.58 (dd, 4H, cyclohexadiene-H, J = 8.11 Hz),
7.29 (m, BB', 2H, 4,5-ArH), 7.38 (m, 2H, AA', 3,6-A.r-H), 8.67 (br,
2H, NH2 attached to pyrimidine ring), 9.86 (br, 1H, pyrimidine-
NH). 13C NMR (DMSO-d6): d = 57.29 (q-C-1,5), 67.05 (C-4), 72.96
(C(CN)2), 124.27, 125.43 (cyclohexadiene-CH), 126.87, 127.32
(ArCH), 13218, 139.66 (ArC), 152.11 (C-1), 155.23 (C-3), 160.08
(C-4). MS (m/z,%): 337 (M+, 29), 271 (37), 181 (21), 141 (47), 90
(100), 77 (82), 66 (55). C19H11N7 (337.34): Calcd C, 67.65; H, 3.29;
N, 29.06. Found: C, 67.81; H, 3.40; N, 28.87%.
32 N. Martin and M. Hanack, J. Chem. Soc. Chem. Commun., 1988, 1522.
33 T. Kawase, T. Okada, T. Enomoto, J. Kikuchi, Y. Miyake and M. Oda,
Bull. Chem. Soc. Jpn, 2003, 76, 1793.
Received 23 March 2009; accepted 25 May 2009
Paper 09/0515 doi: 10.3184/030823409X466717
Published online: 10 August 2009
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36 S.M. Al-Mousawi, M.S. Moustafa, H. Meier, H. Kolshorn and
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37 N.L. Allinger, MM2 (91) Force Field Program, Obtained from Quantum
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38 H.F. Anwar, D.H. Fleita, H. Kolshorn, H. Meier and M.H. Elnagdi,
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