Scientific paper
Synthesis and Cyclization Reactions with Pyrazolopyrimidinyl Keto-esters and their Enzymaic Activity
Mohamed Abdel Hamid Abd el Gawaad Awas*
Department of Chemistry, Faculty of Education, Ain-Shams University Roxy, 11711 Cairo, Egypt * Corresponding author: E-mail: dr.mohamedawas1@hotmail.com
Received: 30-08-2007
Abstract
Ethyl 2,4-dioxo-4-(4-oxo-1-phenyl-1,4-dihydo-5ff-pyrazolo [3,4-d]pyrimidin-5-yl)butanoate, ethyl 5-(4-oxo-1-phenyl-1,4-dihydro-5ff-pyrazolo[3,4-d]pyrimidin-5-yl)-1ff-pyrazole-3-carboxylate and their acid hydrazide derivatives have been prepared and reacted with hydrazines, ortho-phenylenediamine, triethyl orthoformate, carbon disulfide and thiose-micarbazides in order to obtain some new 5-substituted pyrazolopyrimidin-4-ones as pyrazolines, isoxazolines, imidazoles, pyrazolotriazines, thiadiazoles and triazoles. All newly prepared compounds revealed the potent effect on increasing reactivity of cellobiase. Structures of new compounds were established upon their elemental analysis, IR, 1H NMR and mass fragmentation spectra.
Keywords: Pyrazolines, isoxazolines, imidazoles, pyrazolotriazines, thiadiazoles and triazoles
1. Introduction
In connection with previous studies of the chemistry of substituted pyrazolopyrimidin-4-ones,1-4 this work deals with the synthesis of new pyrazolopyrimidinones substituted at position 5 with pyrazolyl, isoxazolyl, tria-zinyl and thiadiazolyl moieties. This stems from the recent notable biological applications of pyrazolopyrimidino-nes,5-7 pyrazoles,8'9 isoxazoles,1011 triazines,1213 and thiadiazoles.14-17 This encouraged us to prepare new hete-rocycles containing pyrazolopyrimidinone skeletone loaded with the latter substrates with the aim to improve the biological activity of pyrazolopyrimidine a,y-diketoesters.
2. Results and Discussion
Due to the considerable chemical reactivity of pyrazolopyrimidine a,y-diketoesters, ethyl 5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-d]pyrimidin-5-yl)-1H-pyra-zole-3-carboxylate (3) was synthesized (Scheme 1) and used as starting material to obtain some new 5-substituted pyrazolopyrimidinone derivatives.
The structure of a,y-diketoester 2 was inferred on the basis of its spectral and analytical data. IR spectrum of
the ester 2 revealed the presence of carbonyl ester at its characteristic wave number 1725 cm-1 in addition to the vibrational bands at 1660, 1650 and 1630 cm-1 (a-C=O, y-C=0 and C=Opyrimidinone, respectively). 1H NMR spectrum of compound 2 showed signals at 5 1.25 (t) and 4.3 (q) specific for ethoxy group and at 5 4.1 specific for COCH2CO. The mass fragmentation pattern of the ester 2 revealed molecular ion peak at m/z 354 (2%) and the base peak at m/z 281 corresponding to [C14H9N403]+.
For the purpose of obtaining various 5-substituted pyrazolopyrimidinones 2, reaction with some N-nucleop-hiles, such as hydrazine, phenylhydrazine and hydroxyla-mine was checked at various molar ratio and conditions. Thus, when 2 reacted with hydrazine hydrate at the molar ratio 1:1 in boiling ethanol, ethyl 5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-d]pyrimidin-5-yl)-1H-pyrazo-le-3-carboxylate (3) was formed (Scheme 1). On the other hand, using excess amount of hydrazine under fusion condition resulted in the acid hydrazide 4, which was also obtained by the hydrazinolysis of 3 using excess of hydrazine. Elemental analyses and spectral data of compounds 3 and 4 are in good accordance with the suggested structures. IR spectrum of 3 showed the disappearance of the vibrational bands specific for a- and y-carbonyl groups and the presence of absorption bands specific for the ester group at position 3 of the pyrazole. On the other
p o
JL..^.
OLJ
IN Me
"■M N'
I
Ph I



COOEt

(COOEDj/Na

N
EtOH
Fh ■ :

o o OH
ElUM
I

Ph
fusion I hr
^JH^ (eictss)
OLJ
o H\-
NaOH ( 5 %)
tOOEl NjHj(«ce!!)
I
fusion
I
Pil
P HN-[JI
N'' "^^----^CONHNHj

Scheme 1
hand, IR spectrum of 4 revealed bands at 3420 and 3300 5, which gave positive acidity test. When compound 5 was cm-1 specific for NH2 group and its 1H NMR spectrum heated above its melting point in the absence of a solvent showed signal at 5 3.4 specific for NH2 group of the acid a decomposition product was obtained, which was charac-
hydrazide.
terized by its analytical and spectral data and was deduced
Hydrolysis of the ester 3, using aqueous solution of to be 1-phenyl-5-(1H-pyrazol-5-yl)-1,5-dihydro-4H-pyra-sodium hydroxide furnished the carboxylic acid derivative zolo[3,4-rf]pyrimidin-4-one (6).
m/z 77(100.0%)	m/! 105(37.5%)
Chart 1. Fragmentation pattern of compound 2
Additional support for the structure of 3 was achieved by its reaction with ortho-phenylenediamine, where benzoimidazole derivative 7 was obtained.
In continuation of the study devoted to the investigation of the chemical reactivity of pyrazolopyrimidinone derivatives, the ketoester 2 was reacted with hydroxyla-monium chloride in boiling ethanol to give isoxazole derivative 8. The hydrazinolysis of the latter product, using the excess amount of hydrazine hydrate led to the formation of acid hydrazide 9. The structures of both compounds 8 and 9 met satisfactory elemental analyses and spectral data.
For the purpose of obtaining various pyrazolotriazi-nes attached directly to pyrazolopyrimidinone at position 5, the acid hydrazide 4 was reacted with some selected reagents. Thus, 4 was treated with triethyl orthoformate in ethylene glycol to give the pyrazolotriazine derivative 10 (Scheme 2).
Treatment of the acid hydrazide 4 with equimolar amount of 4-oxo-4H-1-benzopyran-3-carboxaldehyde (13) in boiling ethanol afforded the corresponding hydrazone 14, while the reaction of the compound 4 with the ester 3 led to the formation of the interesting bis(pyrazolop-yrimidinylpyrazole)hydrazide 15. IR spectra of the hydrazone 14 and the hydrazide 15 showed characteristic absence of the vibrational bands specific for the NH2 group. Also elemental microanalyses of these compounds proved their proposed formulas.
Cyclocondensation between the diketoester 2 and phenylhydrazine was performed in ethanol to produce ethyl 5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-1-phenyl-1H-pyrazole-3-carboxylate (16) (Scheme 3), which is considered as an appropriate precursor for synthesizing target compounds. Thus, the reaction of 16 with excess hydrazine hydrate gave the corresponding acid hydrazide 17, while the condensation
O HN-N
II I
AXV^
Ph
CS;
q HN-
II I f*^ JK
W.
o HN-[S
11 H
I
- I
Ph
'CONHNH, CH«>Et
Rthylene glycnl
PhCOCl
pjridii
Scheme 2
When the acid hydrazide 4 was allowed to react with benzoyl chloride in dry pyridine, cyclocondensation product 11 was obtained. The IR and 1H NMR spectra of compounds 10 and 11 showed the inclusion of both amino groups due to the acid hydrazide along with NH group due to the pyrazole ring system in the cyclization process.
For obtaining another derivative of pyrazolopyrimi-dinone bearing pyrazolotriazine moiety, the reaction of the acid hydrazide 4 with carbon disulfide in the presence of alcoholic potassium hydroxide was investigated. Product was the desired pyrazolotriazine derivative 12, IR spectrum of which revealed the presence of absorption band at 2660 cm-1 specific for SH group.
reaction between the ester 16 and 4-substituted thiosemi-carbazides afforded the corresponding pyrazole-3-car-bonyl thiosemicarbazides 18a,b. The same products were obtained when the acid hydrazide 17 was reacted with ammonium thiocyanate in boiling ethanol in the presence of hydrochloride acid and/or phenylisothiocyanate in DMF, respectively.
When compound 18b was treated with alcoholic potassium hydroxide cyclization took place. In this reaction carbonylthiosemicarbazide side chain underwent intramolecular cyclocondensation and gave 1-phenyl-5-[1-phenyl-3-(4-phenyl-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-yl)-1H-pyrazol-5-yl]-1,5-dihydro-
Rimimi,
VK
KM IE I
NaOH (S%)
Ph ift KNHC-SNHNH
COOEt
DM K
PK
O N-N
CXCCM
lliMtS/llMF
N N
I
I'h
Jecarhoxylätton
Ph O IN
Ph^
O ^—N
X JL X
COOH II-|f'''^N'''^'-'''''^CO\HNHCS>HR »nim.tlikjn-jnah.alc/HC1 II
N- A. ^	'^-IM- -N
\ \	a R = H	NN
IS„,m	=	Ph
PK
o \-N
A. ^
C0^HNH3
Ph
Jii'ut ]0 min
Ml, O N-
N N


Ph
\ N
I
Ph
NKPh
22
Scheme 3
Ph
O N-N
A ■ ■
N'
^ N
I
I'h
NH
PhW
4H-pyrazolo[3,4-rf]pyrimidin-4-one (19). 1H NMR spectrum of 19 revealed the presence of skeletal NH at 5 10.5 ppm, fortifying the proposed cyclization to triazole system. On the other hand, treatment of 18b with polyp-
hosphoric acid (PPA), furnished 5-[3-(5-phenylamino-1,3,4-thiadiazol-2-yl)-1-phenyl-1H-pyrazol-5-yl]-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-rf]pyrimidin-4-one (20).
-► JK, ^ o
liOH/pipcrìdine
N N
I
Pil
23

o
EtOH
NjH,(2:1)
EtOH
II ( Vo^
1	^-nV
Ph

25
Scheme 4
N,Hj(l!l)
ücetic uckl
H
Ì r? M ^
A,

I
PK
^^ V/
COCOjEt 26
O N—N


I
rh
11
24
O
OFa

Such cyclization reaction found support in the spectral data which proved the elimination of a molecule of water besides the presence of a signal for NH at the H-aro-matic zone due to phenylamino group.
The reactivity of the ester group of the pyrazole derivative 16 towards basic hydrolysis was also studied. Thus, hydrolysis of the ester 16 led to the carboxylic acid derivative 21, which gave positive acidity test. When the acid 21 was subjected to decarboxylation reaction 1-phenyl-5-(1-phenyl-1H-pyrazol-5-yl)-1,5-dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one (22) was formed. The elemental analysis of compound 22 is in good accordance with calculated values and IR spectrum shows the disappearance of the characteristic bands for carboxylic group.
Comparative study of the reactivity of a,ß-unsatura-ted carbonyl group against ketoester group, when present in one molecular frame, has been carried out; thus, ethyl 4-(1,3-benzodioxol-5-yl)-2-oxo-3-[(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-d]pyrimidin-5-yl)carbonyl]-3-butenoate (23) (Scheme 4) was synthesized by the action of piperonal on 2 in the presence of piperidine as a catalyst. 1H NMR spectrum of the butenoic acid ester 23 showed distinctive chemical shifts at 5 5.55 (s) due to 0CH20 and 5 6.62 (s) due to an olefinic CH which revealed that condensation of piperonal took place at the active ß-methylene of the diketoester.
On treatment of compound 23 with hydrazine at the molar ratio 1:1 in glacial acetic acid, condensation reaction took place to give ethyl 4-(1,3-benzodioxol-5-ylmethylene)-5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazo-lo[3,4-d]pyrimidin-5-yl)-4H-pyrazole-3-carboxylate (24). IR spectrum of compound 24 showed the disappearance of the vibrational bands specific for a- and y-carbonyl groups and the presence of absorption bands due to the ester group at the position 3 of the pyrazole. 1H NMR spectrum of the ester 24 gave much more information about the structure of this compound, showing peaks at 5 1.25 (t) and 4.14 (q) specific for ethoxy indicating that ester group is not participating in the cyclocondensation.
Surprisingly, on repeating the latter reaction at the same ratio but in ethanol instead of acetic acid the corresponding ethyl 5-(1,3-benzodioxol-5-yl)-4-[(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-d]pyrimidin-5-yl)carbonyl]-4,5-dihydro-1H-pyrazole-3-carboxylate (25) was obtained, however neither 24 nor 26 were formed. The IR spectrum of the product revealed the presence of C=O and COOEt characterized by vibrational absorption at 1670 cm-1 for keto C=O and 1730 cm-1 for C=Oester indicating that the ester group was still present and not involved in the cyclization process.
Beside the analytical and spectral evidences for the structure of 25 a good support for its chemical structure was achieved by the reaction of 25 with another mole of hydrazine hydrate in ethanol to give 5-[3-(1,3-benzodio-xol-5-yl)-7-hydroxy-2,3-dihydro-1H-pyrazolo[ 3,4-d]pyridazin-4-yl]-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-
d]pyrimidin-4-one (27). The evident formation of the latter product indicated that compound 25 must contain a free carbonyl group and an ethoxycarbonyl group, which are involved in the cyclization reaction to form the fused pyrazolopyridazine system. On the other hand, when compound 25 was condensated with hydrazine hydrate at the ratio 1:2 in ethanol, the product formed was found to be identical in every respect to the product that was obtained by the action of N2H4 on compound 25. The formation of 27 by these two pathways is considered a good support for the structure of both 25 and 27.
3. Cellobiase Activity Test
The effect of the newly prepared compounds on the activity of cellobiase, an enzyme produced by a thermoto-lerant fungus Absidia corymbifera, was investigated.18 The results showed (Table 1) that most of the tested compounds enhanced the effect of the enzyme in the production of glucose (pgiucose 1.37-3.25 ^g cm-3). The data obtained proved that compound 23 is the most active one (3.25 ^g cm-3), this may be due to the presence of a,y-diketoester and a,ß-unsaturated system in one molecular frame; this might also be supported by the amount of glucose produced by the effect of a,y-diketoester derivative 2 (2.60 ^g cm-3). On the other hand, these results also showed that the relatively high values (2.10-2.35 ^g cm-3) may be due to the presence of pyrazolotriazines, substituted pyrazoles or triazoles and thiadiazoles bearing pyrazolopyrimidinone.
Generally all compounds activate enzyme, activity may be due to the presence of more than one heterocyclic ring and hetero atoms. The most active one was 23 whereas the least active was 7. The compounds could be arranged in relation to their promoting effect in the following order: 23 > 24 > 25 > 27 > 2 > 20 > 13 > 21 > 11 > 12-18a > 15.
Table 1. Effect of new compounds on activity of cellobiase.a
Compound	p (Glucose) ^g cm-3	Compound	p (Glucose) ^g cm-3
2	2.60	16	1.87
3	1.55	17	1.73
4	1.75	18	1.89
5	1.83	18a	2.00
6	2.10	18b	1.97
7	1.37	20	2.35
8	1.70	21	2.23
9	1.77	22	2.15
10	1.80	23	3.25
11	2.10	24	3.23
12	2.00	25	2.95
13	2.30	27	2.89
14	1.60	Blanka	0.59
15	1.99	Controlb	0.28
a Blank test using bidistillated water produced 0.592 ^g cm 3. b Using DMF (0.1 mL) without sample.
4. Experimental
Melting points are uncorrected and measured in open capillary tubes using a Gallenkamp electric melting point apparatus. IR spectra were recorded on Perkin-El-mer 598 and FT-IR 1650 spectrophotometers, using samples in KBr disks. 1H NMR spectra were taken on an EM-NMR spectrometer (300 MHz) using DMS0-d6 or CDCl3 as solvent and TMS as the internal standard. Mass spectra were obtained on a HP MS-5988 by direct inlet (E = 70 eV). Elemental microanalyses were performed at Cairo University, Microanalytical Center.
5-Acetyl-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-rf]pyrimidin-4-one (1)
A mixture of 4-hydroxy-1-phenylpyrazolo[3,4-d]pyri-midine (0.01 mol) and acetyl chloride (0.01 mol) in dry benzene (10 mL) and triethylamine (one drop) was heated under reflux for 12 h. The reaction mixture was concentrated and cooled. The solid was filtered off and recrystallized to give 1.19 IR: uS/cm-1 2980 (CHa,iphatic), 1775 (C=0acetyl), 1660
(C=0p^,mid.none), 1610-1600 (C=N, C=C). 1H NMR (DM-S0-d6) 5 2.56 (s, 3H, C0CH3), 7.31-8.22 (m, 5H, Ar-H),
8.61 (s, 1H, CHpyrazole), 8.72 (s, 1H, CH
).
pyrimidinone-
Ethyl 2,4-dioxo-4-(4-oxo-1-phenyl-1,4-dihydo-5H-py razolo[3,4-rf]pyrimidin-5-yl)butanoate (2)
A mixture of 1 (0.03 mol), finely divided sodium metal (0.15 mol) and dry diethyloxalate (0.68 mol), was refluxed for 4 h. The reaction mixture was kept at room temperature over night, then poured into diluted acetic acid. The precipitate that formed was filtered off, washed with water and recrystallized from Et0H to give 2, m.p. 170 °C. Anal. Calcd for C17H14N405: C, 57.63; H, 3.95; N, 15.82. Found: C, 57.65; H, ^.00; N, 15.80. IR: UU/cm-1 2980 (CHaliphatic), 1725 (C=0ester), 1660, 1650 and 1630 (a-C=0, y-C=0 and C=0pyrimidinone), 1610-1585 (C=N, C=C). 1H NMR (DMS0-d6) 5 1.25 (t, 3H, 0CH2CH3), 4.32 (q, 2H, 0CH2CH3), 6.611 (s, 1H, CH=C), 7.312-8.232 (m, 5H, Ar-H), 8.61 (s, 1H, CHp^ra^ole), 8.72 (s, 1H, CHp^ri.
midinone), 14.42 (s, 1H, exchangeable with D20, 0H).
Ethyl 5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-1H-pyrazole-3-carboxylate (3)
A mixture of compound 2 (0.01 mol) and hydrazine hydrate (0.01 mol), in ethanol (10 mL), was refluxed for 4 h. The reaction mixture was left to cool at room temperature and the precipitate that formed was filtered off and re-crystallized from DMF to give 3, m.p. 240 °C. Anal. Calcd for C17H14Ng03: C, 58.28; H, 4.00; N, 24.00.
Found: C, 58.3(3; H, 3.98; N, 24.10. IR: UU/cm-1 3167 (NH), 2990-2930 (CHaliphatic), 1728 (C=0ester), 1630 (C=0pyrimidinone),1610-1585(C=N, C=C). 1H NMR (DM-S0-dg) 5 1.25 (t, 3H, 0CH2CH3), 4.32 (q, 2H, 0CH2CH3),
6.90-8.25 (m, 7H, Ar-H, C-4-Hp^azoline, NHpyrazoline), 8.61 (S, 1H, CHp^azole), 8.72 (S, 1H, CHpyrimidinone).
5-(4-Oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf] pyrimidin-5-yl)-1H-pyrazole-3-carbohydrazide (4)
A mixture of compound 3 and/or 2 (0.01 mol) and hydrazine hydrate (0.09 mol), was heated under fusion condition for 1 h, then the reaction mixture was treated with 20 mL of ethanol and the mixture was refluxed for another 4 h. The product formed was collected by filtration and recrystallized from Me0H to give 4, m.p. 210 °C. Anal. Calcd for C15H12N802: C, 53.57; H, 3.57; N, 33.33. Found: C, 53.51; H, 3.60; N, 33.29. IR: UU/cm-1 3420, 3300 (NH2), 3163 (NH), 2990 (CHa^phati^), 1680 (C=0acid
hydrazide), 1628 (C=0pyrimidinone), 1610-1590 (C=N, C=C).
1H NMR (DMS0-dg) 5 3.42 (bs, 2H, NH2), 7.30-8.25 (m,
7H, Ar-H, C-4-Hpyrazoline, NHpyrazoline), 8.61 (S, 1H, CHp^azo-,e), 8.72 (S, 1H, CHp^imidinone), 10.00 (bS, 1H, NHhydrazide).
5-(4-Oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf] pyrimidin-5-yl)-1H-pyrazole-3-carboxylic acid (5)
A solution of compound 3 (0.01 mol) in sodium hydroxide (25 mL, 5%) was heated under reflux on a water bath for 2 h. The clear solution was filtered off from any insoluble materials and neutralized with hydrochloric acid, the solid product that formed was filtered off and re-crystallized from Et0H to give 5, m.p. 260 °C. Anal. Calcd for C15H10Ng03: C, 55.90; H, 3.10; N, 26.09. Found: C, 55.85; H, 3.15; N, 26.10. IR: UU/cm-1 3168 (NH), 2975-2935 (CHaliphatic), 2600 (H-bonded 0H, the
carboxylic 0H), 1729 a(i:=0carboxylic), 1628 (C=0pyrimidino-
ne), 1610-1590 (C=N, C=C). 1H NMR (DMS0-dg) 5 7.30-8.25 (m, 6H, Ar-H, Ho^efi^i^), 8.61 (s, 1H, CHp^azole),
8.72 (S, 1H, CHpyrimidinone), 9.61 (S, 1H, NHpyrazoline), 13.52 (bs, 1H, 0Hcarboxylic).
1-Phenyl-5-(1H-pyrazol-5-yl)-1,5-dihydro-4H-pyrazo-lo[3,4-rf]pyrimidin-4-one (6)
0ne g of the acid 5 was heated until it melts and the temperature of the molten phase was kept constant above the melting point of the acid by 283 K for 10 min, then the residue after cooling was treated with 20 mL of ethanol and the solid product that formed was collected and recry-stallized from Me0H to give 6, m.p. 210 °C. Anal. Calcd for C14H10N60: C, 60.43; H, 3.59; N, 25.89. Found: C, 60.40; H, 3.60; N, 25.91. IR: UU/cm-1 3175 (NH), 2975 (CHaliphatic), 1630 (C=0pyrimidinone), 1610-1590 (C=N, C=C). 1H NMR (DMS0-dg) 5 7.20-8.20 (m, 7H, Ar-H,
2Hpyrazole), 8.61 (S, 1H, CHp^azole), 8.72 (S, 1H, CHpyrimidino-
ne), 9.71 (S, 1H, NHp^azoline).
5-[3-(1H-Benzimidazol-2-yl)-1H-pyrazol-5-yl]-1-ph enyl-1,5-dihydro-4H-pyrazolo[3,4-rf]pyrimidin-4-one
(7)
To a solution of compound 3 (0.01 mol) in DMF (30 mL), o-phenylendiamine (0.01 mol) was added and the reaction mixture was refluxed for 5 h, afterwards, the mixture was poured into ice-cold water. The precipitate formed was filtered off and recrystallized from Et0H to give
7, m.p. > 300 °C. Anal. Calcd for C21H14N8O: C, 63.96; H, 3.55; N, 28.43. Found: C, 63.94; H, 3.60; N, 28.40. IR: uu/cm-1 3235-3125 (NH), 2975 (CH^^^ph^tic), 1630 (C=Opyri_ midinone), 1610-1590 (C=N, C=C). 1H NMR (DMSO-dg) 5
7.20-8.20 (m, 10H, Ar-H, 1Hpy^azo,e), 8.61 (s, 1H, CHpyrazo-,e), 8.72 (s, 1H, CHpyrimidinone), 9.22 (s, 1H, NH imidazole^'
9.73 (s, 1H, NH
).
pyrazoline
Ethyl 5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-3-isoxazolecarboxylate (8)
Compound 2 was cured with hydroxylamine utilizing the same procedure described for compound 3, and worked up as there. The precipitate so formed was filtered off and recrystallized from DMF to give 8, m.p. 210 °C. Anal. Calcd for C17H13N5O4: C, 58.12; H, 3.70; N, 19.94. Found: C, 58.10; H, 3.68; N, 19.88. IR: UU/cm-1 2975
(CHaliphatic), 1730 (C=Oester), 1630 (C=Opyrimidinone),
1610-1590 (C=N, C=C), 1044 (C-O-C). 1H NMR (DM-SO-dg) 5 1.28 (t, 3H, OCH2CH3), 4.31 (q, 2H, OCH2CH3),
7.25-8.21 (m, 6H, Ar-H, 1Hisoxazole), 8.61 (s, 1H, CH yrazo-,e), 8.72 (s, 1H, CHpyrimid.none).
5-(4-Oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf] pyrimidin-5-yl)-3-isoxazolecarbohydrazide (9)
A mixture of compound 8 (0.01 mol) and hydrazine hydrate (5 mL, 0.09 mol), was heated under fusion condition (503 K) for 1 h, then the reaction mixture was treated with ethanol (20 mL) and refluxed for 4 h. The reaction mixture was cooled and the precipitate was collected by filtration. The precipitate was dissolved in 10 mL of 3:7 DMF/H2O at 200 °C. The solution was cooled and the crystalline solid collected by filtration. The solid was washed with cold EtOH and vacuum dried to provide 9 as colorless needles, m.p. 235 °C. Anal. Calcd for C15H11N7O3: C, 53.41; H, 3.26; N, 29.08. Found: C, 53.88; H15, 31.1247; N3, 29.11. IR: ió/cm-1 3322 (NH2), 3190 (NH), 2997 (CHajjpha tic), 1715 (C=Oacid
hydrazide ), 1625 (C=Opyrimidinone),
1615-1595 (C=N, C=C). 1H NMR (DMSO-d,) 5 3.41 (bs, 2H, NH2), 7.25-8.21 (m, 6H, Ar-H, 1Hisoxaz6ole), 8.61 (s,
1H, CHpyrazole), 8.72 (s, 1H, CHpy^imid.none), 10.00 (bS, 1H, NHhydrazide).
5-(4-Oxo-4,5-dihydropyrazolo[1,5-rf][1,2,4]triazin-2-yl)-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-rf]pyrimi-din-4-one (10)
A mixture of compound 4 (0.01 mol) and triethyl orthoformate (0.015 mol) was heated at the boiling point of the mixture for 2 h, using a short air condenser. The reaction mixture was allowed to cool and treated with 20 mL of diethyl ether. The solid that formed was filtered off and recrystallized from EtOH to give 10, m.p. 220 °C. Anal. Calcd for C1gH10N8O2: C, 55.49; H, 2.89; N, 32.37. Found: C, 55.50; H1 2.90; N, 32.41. IR: UU/cm-1 3170 (NH), 2970 (CHaliphatic), 1680 (C=Otriazinone), 1630 (C=Op^imidinone), 1610-1590 (C=N, C=C). 1H NMR (DM-
pyrimidinone
SO-dg) 5 7.25-8.25 (m, 7H, Ar-H, CH
pyrazole
CHtriazine),
8.61 (s, 1H, CHpyrazole), 8.72 (s, 1H, CHpyrimidinone), 9.92 (bs, 1H, NHtriazine).
5-(4-Oxo-7-phenyl-4,5-dihydropyrazolo[1,5-rf] [1,2,4] triazin-2-yl)-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-rf] pyrimidine-4-one (11)
A mixture of compound 4 (0.01 mol) and benzoyl chloride (0.01 mol) in dry pyridine, was refluxed for 6 h, the product so formed was filtered off, washed with diluted hydrochloric acid and recrystallized from DMF/H2O to give 11, m.p. 260 °C. Anal. Calcd for C22H14N8O2: C, 62.56; H, 3.32; N, 26.54. Found: C, 62.50; H, 3.30; N, 26.50. IR: uU/cm-1 3195 (NH), 2980 (CHajjphatjc), 1675 ), 1625 (C=^	), 1610-1595 (C=N,
triazinone	pyrimidinone
C=C). 1H NMR (DMSO-dg) 5 7.20-8.22 (m, 11H, Ar-H,
CHpyrazole), 8.61 (S, 1H, CHpyrazole), 8.72 (S, 1H, CHpyr.midino-ne), 9.90 (bS, 1H, NHtriaz.ne).
5-(4-Oxo-7-sulfanyl-4,5-dihydropyrazolo[1,5-rf][1,2,4] triazin-2-yl)-1-phenyl-1,5-dihydro-4H-pyrazolo[3,4-rf] pyrimidin-4-one (12)
A mixture of 4 (0.01 mol), carbon disulfide (0.02 mol) and potassium hydroxide (5 mL,10%) in ethanol (30 mL),was refluxed on a water bath for 4 h, then the mixture was poured into ice-cold ether, acidified with dilute hydrochloric acid and the solid formed was collected and recrystallized from EtOH to give 12, m.p. 245 °C. Anal. Calcd for C1gH10N8O2S: C, 50.79; H, 2.64; N, 29.63. Found: C, ^0.78; H, 2.70; N, 29.60. IR: uU/cm-1 3195-3165 (NH), 2975 (CHajjphatjc), 2660 (SH), 1675 (C=Otriazinone), 1630 (C=Opyrimidinone), 1610-1590 (C=N, C=C). 1H NMR (DMSO-dg) 5 1.95 (bs, 1H, SH), 7.25-8.25 (m, 6H, Ar-H, CHp^^zole), 8.61 (s, 1H, CHp^^zo-
,e), 8.72 (S, 1H, CHp^imid.none), 10.40 (bS, 1H, NHtriaz.ne).
^'-[(4-Oxo-4H-chromen-3-yl)methylidene]-3-(4-oxo-1 -phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-1H-pyrazole-5-carbohydrazide (14)
Equimolar amounts of 4 and 13 (0.01 mol) in absolute ethanol (25 mL) was refluxed for 4 h, the product formed was filtered off and recrystallized from MeOH to give 14, m.p. 170 °C. Anal. Calcd for C25H1gN8O4: C, 60.97; H, 3.25; N, 22.76. Found: C, 60.95; H, 3.22; N, 22.80. IR: uu/cm-1 3190-3175 (NH), 2975 (CHajiphatic), 1680
(HNC=O), 1640 (C=Opyrone), 1630 (C=Opyrimidinone),
1610-1590 (C=N, C=C). ^H NMR (DMSO-dg) 5 6.55 (s, 1H, CHolefinic), 7.30-8.25 (m, 11H, Ar-H, C-4-HpyrazoUne,
NHp^azoline), 8.61 (S, 1H, CHp^azole), 8.72 (S, 1H, CHpyr.midi-
none), 9.21 (s, 1H, pyrone), 10.10 (bs, 1H, NH).
3-(4-Oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf] pyrimidin-5-yl)-^'-{[3-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-1H-pyrazol-5-yl]carbonyl}-1H-pyrazole-5-carbohydrazide (15)
A mixture of compound 4 (0.01 mol) and the ester 3 (0.01 mol) in DMF (10 mL) was heated under reflux for 2
h. Then, the reaction mixture was poured into cold water and the precipitate that formed was filtered off and recry-stallized from AcOH/H2O to give 15, m.p. 250 °C. Anal. Calcd for C30H20N14O4: C, 56.25; H, 3.12; N, 30.62. Found: C, 56.200; H, 3.10; N, 30.59. IR: UU/cm-1 3250-3182 (NH), 2995 (CHajjphatjc), 1675 (NHC=O), 1630 (C=Opyr.mid.none), 1610-1595 (C=N, C=C). 1H NMR (DM-SO-d6) 5 7.30-8.25 (m, 14H, Ar-H, 2C-4-HpyrazoUne,
2NHpyrazoline), 8.61 (s, 2H, CHpyrazole), 8.72 (s, 2H, CHpyr.mi-dinone
), 10.00 (bs, 2H, NHhydrazide).
Ethyl 5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-1-phenyl-1H-pyrazole-3-carboxyla-te (16)
Similarly, using the same method as for the preparation of compound 3, treatment of compound 2 with phenylhydrazine afforded compound 16 which was recry-stallized from anisole, m.p. 200 °C. Anal. Calcd for C23H18N603: C, 64.78; H, 4.22; N, 19.71. Found: C, 642.72; H, 43.25; N, 19.70. IR: uU/cm-1 2975 (CHajiphatic),
1725 (C=Oester), 1630 (C=Opyrimidinone), 1610-1595 (C=N,
C=C). 1H NMR (DMSO-dg) 5 1.25 (t, 3H, OCH2CH3), 4.30 (q, 2H, OCH2CH3), 6.90 (s, 1H, CHpyr^^ole), 7.25-8.20 (m, 10H, Ar-H), 8.61 (s, 1H, CHpyrazoje), 8.72 (s,
1H, CHpyrimidinone).
5-(4-Oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf] pyrimidin-5-yl)-1-phenyl-1H-pyrazole-3-carbohydra-zide (17)
Using the same procedure described for compounds 4 and 9, treatment of 16 with hydrazine hydrate gave compound 17, which was recrystallized from EtOH, m.p. 235 °C. Anal. Calcd for C21H1gN8O2: C, 61.16; H, 3.88; N, 27.18. Found: C, 61.20; ^.90; N, 27.15. IR: uU/cm-1 3320-3260, 3178 (NH2 NH), 2977 (CHajiphatic), 1675
(C=Oacid hydrazide), 1630 (C=Opy^imidinone), 1610-1585 (C=N,
C=C). 1H NMR (DMSO-dg) 5 3.28 (bs, 2H, NH2), 7.32-8.20 (m, 11H, Ar-H, CHp^r^^oiine), 8.61 (s, 1H, CHp^r^.
zo,e), 8.72 (S, 1H, CHpyrimidinone), 10.20 (bS, 1H, NH).
2-{[5-(4-Oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-1-phenyl-1H-pyrazol-3-yl]car-bonyl}hydrazinecarbothioamide (18a) and 2-{[5-(4-oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimi-din-5-yl)-1-phenyl-1H-pyrazol-3-yl]carbonyl}-^-phenylhydrazinecarbothioamide (18b)
Method A. To a solution of compound 16 (0.01 mol), in DMF (10 mL), thiosemicarbazide or phenylthiosemi-carbazide (0.01 mol) was added and the reaction mixture was refluxed for 6 h. The mixture was then cooled and poured onto crushed ice and the precipitate formed was filtered off and recrystallized from benzene to give 18a, m.p. 280 °C. Anal. Calcd for C28H21N9O2S: C, 61.42; H, 3.83; N, 23.03. Found C, 61.3(2; H, 3.8(2; N, 23.11. IR: UU/cm-1 3381, 3276 (NH), 2970 (CHajiphatic), 2660 (SH), 1695 (HNC=0),1630 (C=Opyrimidinone), 1610-1585 (C=N,
C=C), 1165, 1278 (NHC=S). 1H NMR (DMSO-dg) 5 7.32-8.20 (m, 17H, Ar-H, CH j, , CSNH), 8.61 (s,
1H, CH pyrazole), 8.72 (S, 1H, CIP[^yzi„Jidinone), 9.42 (bS, 1H,
CSNH), 10.85 (bs, 1H, CONH).
Method B. To a solution of acid hydrazide 17 (0.01 mol) in hydrochloric acid (10 mL, 10%) and ethanol (20 mL), ammonium thiocyanate (0.012 mol) was added, and the reaction mixture was heated under reflux for 4 h. The mixture was then poured into ice-cold water containing DMF and the obtained precipitate was filtered off and crystallized to produce 18a.
Method C. To a solution of compound 17 (0.01 mol) in DMF (20 mL), phenylisothiocyanate (0.01 mol) was added. The reaction mixture was refluxed for 2 h, and then poured into ice-cold water. The precipitate formed was filtered off and crystallized to give 18b.
1-Phenyl-5-[1-phenyl-3-(4-phenyl-5-thioxo-4,5-dihy-dro-1H-1,2,4-triazol-3-yl)-1H-pyrazol-5-yl]-1,5-dihy-dro-4H-pyrazolo[3,4-rf]pyrimidin-4-one (19)
To a solution of compound 18b (0.01 mol) in ethanol (30 mL, 95%), potassium hydroxide (0.015 mol) was added. The reaction mixture was heated under reflux for 4 h. The mixture was filtered and acidified with dilute hydrochloric acid. The precipitate was collected by filtration and re-crystallized from DMF to give 19, m.p. 240 °C. Anal. Calcd for C28H19N9OS: C, 63.52; H, 3.59; N, 23.82. Found C, 63.50; H, 3.60; N, 23.78. IR: UU/cm-1 3191 (NH), 2970
(CHyliphytic), 1630 (C=Opy^imidinone), 1610-1585 (C=N, C=C),
1396, 1258, 1198 (NHC=S). 1H NMR (DMSO-dg) 5
7.20-8.20 (m, 16H, Ar-H, CHp^yzo,ine), 8.61 (S, 1H, CHp^yzo-,e), 8.72 (s, 1H, CHpy^imidinone), 10.60 (bS, 1H, CSNH).
5-[3-(5-phenylamino-1,3,4-thiadiazol-2-yl)-1-phenyl-1H-pyrazol-5-yl]-1-phenyl-1,5-dihydro-4H-pyrazo-lo[3,4-rf]pyrimidin-4-one (20)
Compound 18b (0.01 mol) was heated under fusion condition with PPA for 2 h. The mass of the reaction was allowed to cool and poured into cold water containing sodium acetate (20 g). The solid that formed was filtered off and recrystallized from MeOH to give 20, m.p. 150 °C. Anal. Calcd for C28H19N9OS: C, 63.52; H, 3.59; N, 23.82. Found C, 63.49; H, 3.55; N, 23.80. IR: UU/cm-1 3250 (NH),
2977 (CHyliphytic), 1630 (C=Opyrimidinone), 1610-1585 (C=N,
C=C). 1H NMR (DMSO-dg) 5 7.30-8.20 (m, 16H, Ar-H,
CHpyryzoline), 8.61 (S, 1H, CHpyryzole), 8.72 (S, 1H, CHpyrimidi-
e), 12.70 (bs, 1H, NHt,
e).
5-(4-Oxo-1-phenyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-1-phenyl-1H-pyrazole-3-carboxylic
acid (21)
Using the same method described for compound 5, treatment of 16 with sodium hydroxide (5%) afforded compound 21, which was recrystallized from MeOH, m.p. 225 °C. Anal. Calcd for C21H14NgO3: C, 63.32; H, 3.52; N, 21.10. Found C, 63.30; H, 3.55; N, 21.00. IR: vcm-1 2985
(CHajjphatjc), 2600 (H-bonded OH, carboxylic OH), 1730 (C=^ ^ ), 1630 (C=^	), 1610-1595
^	carboxylic grou^^^ ^^ ^	pyrimidinone^ '
(C=N, C=C). 1H NMR (DMSO-dg) 5 7.10-8.25 (m, 11H,
Ar-H, CHpyrazollne), 8.61 (s, 1H, CHpyrazole), 8.72 (s, 1H,
CH
), 13.50 (bs, 1H, OHaci,).
pyrimidinone
1-Phenyl-5-(1-phenyl-1H-pyrazol-5-yl)-1,5-dihydro-4H-pyrazolo[3,4-rf]pyrimidin-4-one (22)
Using the same method as for the preparation of compound 6, compound 21 was subjected to decarboxyla-tion and yielded compound 22, which was recrystallized from EtOH, m.p. 150 °C. Anal. Calcd for C20H14NgO: C, 67.79; H, 3.95; N, 23.73. Found C, 67.77; H, 3.^2; N,
23.70. IR: uS/cm-1 2990 (CHa,lphatlc), 1630 (C=Opyrlmldlnone),
1610-1585 (C=N, C=C). ^H NMR (DMSO-dg) 5 7.20-8.20 (m, 12H, Ar-H, 2CHpyrazoline), 8.61 (s, 1H,
CHpyrazole), 8.72 (s, 1H, CHpyrimidinone).
Ethyl 4-(1,3-benzodioxol-5-yl)-2-oxo-3-[(4-oxo-1-phen yl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)car-bonyl]-3-butenoate (23)
A mixture of 2 (0.01 mol), piperonal (0.01 mol) and one drop of piperidine was heated on boiling water-bath for 4 h. The reaction mixture was triturated with ethanol and the solid obtained was filtered off, washed with di-ethyl ether and recrystallized from DMF to give 23, m.p. 195 °C. Anal. Calcd for C25H18N4O7: C, 61.73; H, 3.70; N, 11.52. Found C, 61.70; H, 3.6^; NN, 11.50. IR: UU/cm-1 2977
(CHallphatlc), 1715 (C=Oester), 1695 (C=Oa-keto), 1665
(C=OY_keto), 1630 (C=Opyrimidinone), 1610-1585 (C=N, C=C), 1033, 1093 (C-O-C). 1H NMR (DMSO-d,) 5 1.26 (t, 3H, 0CH2CH3), 4.20 (q, 2H, OCH2CH3), 5.5^ (s, 2H, 0CH20), 6.62 (s, 1H, H jfi. ), 6.98-8.25 (m, 8H, Ar-H),
8.61 (S, 1H, CHpyrazole), 8.7fi (s, 1H, CHp^imidinone).
Ethyl 4-(1,3-benzodioxol-5-ylmethylene)-5-(4-oxo-1-p henyl-1,4-dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)-4H-pyrazole-3-carboxylate (24)
To a solution of compound 23 (0.01 mol) in glacial acetic acid (20 mL), hydrazine hydrate (0.01 mol) was ad ded, the reaction mixture was refluxed for 4 h and poured into ice-cold water, the solid formed was collected and re crystallized from MeOH to give 24, m.p.155 °C. Anal Calcd for C25H18NgO5: C, 62.24; H, 3.73; N, 17.43. Found C, 62.20; H, 3.75; N, 17.50. IR: UU/cm-1 2980 (CH j,ht, )
1735 (C=Oester), 1625 (C=Opyrimldinone), 1610-1590 ((^at^
C=C), 1033, 1093 (C-O-C). 'h NMR (DMSO-d,) 5 1.25 (t, 3H, 0CH2CH3), 4.22 (q, 2H, OCH2CH3), 5.95 (s, 2H 0CH20), 6.95-8.25 (m, 9H, Ar-H, CHojefinlc) 8.61 (s, 1H
CHpyrazole), 8.72 (S, 1H, CHp^imidinone).
Ethyl 5-(1,3-benzodioxol-5-yl)-4-[(4-oxo-1-phenyl-1,4 dihydro-5H-pyrazolo[3,4-rf]pyrimidin-5-yl)carbonyl] 4,5-dihydro-1H-pyrazole-3-carboxylate (25)
To a solution of compound 23 (0.01 mol) in absolute ethanol, hydrazine hydrate (0.01 mol) was added and the
mixture was refluxed for 4 h. The reaction mixture was then cooled, and poured into cold water. The formed deposits were filtered off and recrystallized from EtOH/DMF to give 25, m.p. 140 °C. Anal. Calcd for C^jH^gNgOg: C, 60.00; H, 4.00; N, 16.80. Found C, 60.10; H, 3.98; Nf,16.77. IR: uU/cm-1 3250 (NH), 2985 (CHajlphatlc), 1730 (C=Oester), 1678
(C=Oketonlc), 1630 (C=Opyrimldlnone), 1610-1590 (C=N,
C=C), 1033, 1093 (C-O-C). 'H NMR (DMSO-dg) 5 1.26 (t, 3H, OCH2CH3), 3.39 (d, 1H, C-5-Hp^azoline), 4.22 (q, 2H, 0CH2CH3), 5.94 (s, 2H, OCH2O), 6.55 (d, 1H, C-4-Hpyrazo line), 7.10^8.20 (m, 8H, Ar-H) 8.61 (s, 1H, CHp^raz^^e), 88.-72!
(s, 1H, CH
), 10.20 (bs, 1H, NH).
pyrimidinone
5-[3-(1,3-Benzodioxol-5-yl)-7-hydroxy-2,3-dihydro-1H-pyrazolo[3,4-rf]pyridazin-4-yl]-1-phenyl-1,5-dihy-dro-4H-pyrazolo[3,4-rf]pyrimidin-4-one (27)
Method A. A mixture of compound 23 (0.01 mol) and hydrazine hydrate (0.02 mol) in absolute ethanol was refluxed for 4 h. The solid formed was filtered off and re-crystallized from EtOH to give 27, m.p. 220 °C. Anal. Calcd for C23H1gN8O4: C, 58.97; H, 3.42; N, 23.93. Found C, 58.95; H, 3.40; N, 23.85. IR: uu/cm-1 3253-3165 (NH), 2995 (CHaliphatic), »2500 (H-bonded OH), 1630 (C=Opyrimi_ dlnone), 1610-1590 (C=N, C=C), 1033, 1093 (C-O-C). 'H Nif^R (DMSO-dg) 5 3.65 (d, 1H, C-3-Hpyra7oline), 5.95 (s, 2H, 0CH20), 6.90-8.20 (m, 8H, Ar-H) 8.61 (s, 1H,
CHpyra7ole), 8.72 (S, 1H, CHp^lmldinone), 9.72 (bS, 1H, NHpyra-7oline), 9.95 (bS, 1H, NHpyra7ollne), 13.50 (bS, 1H, OH).
Method B. A mixture of equimolar amounts of 25 and hydrazine hydrate (0.01 mol) was treated with absolute ethanol. The reaction mixture was then refluxed for 4 h. The solid formed was filtered off and crystallized.
5. Acknowledgments
The author thanks Dr. U. F. Ali, Department of Biological and Geological Sciences, Faculty of Education, Ain Shams University, for evaluation of enzymic activity.
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Povzetek
Pripravljeni sta bila etil 2,4-diokso-4-(4-okso-1-fenil-1,4-dihido-5ff-pirazolo[3,4-d]pirimidin-5-il)butanoat in etil 5-(4-okso-1-fenil-1,4-dihidro-5ff-pirazolo[3,4-d]pirimidin-5-il)-1ff-pirazol-3-karboksilat ter njuni kislinski hidrazidi. Te spojine so reagirale s hidrazini, orto-fenilendiaminom, trietil ortoformatom, ogljikovim disulfidom in tiosemikarbazidi pri čemer so nastali nekateri novi 5-substituirani pirazolopirimidin-4-oni kot pirazolini, izoksazolini, imidazoli, pirazo-lotriazini, tiadiazoli in triazoli. Vse nove spojine so pokazale precejšenj učinek na povečaje reaktivnosti celobiaze. Strukture novih spojin so bile dokazane s pomočjo elementnih analiz, IR in 'H NMR spektrov ter masnih fragmentacij.