Benzofuran-morpholinomethyl-pyrazoline hybrids as a new class of vasorelaxant agents: Synthesis and quantitative structure-activity relationship study

Article abstract of DOI:10.1248/cpb.c14-00572

The benzofuran-morpholinomethyl-pyrazoline hybrids 4a-e, 5a-e and 6a-j were synthesized via reaction of α,β-unsaturated carbonyl compounds 3a-e with hydrazine hydrate, semicarbazide or thiosemicarbazide. Applying the Mannich reaction to 5-(5-aryl-4,5-dihy

Full text of DOI:10.1248/cpb.c14-00572

1238
Regular Article
Chem. Pharm. Bull. 62(12) 1238–1251 (2014)
Vol. 62, No. 12
Benzofuran–Morpholinomethyl–Pyrazoline Hybrids as a New Class of
Vasorelaxant Agents: Synthesis and Quantitative Structure–Activity
Relationship Study
,a
Ghaneya Sayed Hassan,a Doaa Ezzat Abdel Rahman,* Dalia Osama Saleh,b and
Gehad Abdel Raheem Abdel Jaleelb
a Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Cairo University; Cairo 11562, Egypt: and
b Department of Pharmacology, National Research Centre; Dokki, Cairo 12622, Egypt.
Received August 8, 2014; accepted September 20, 2014
The benzofuran–morpholinomethyl–pyrazoline hybrids 4a–e, 5a–e and 6a–j were synthesized via reac-
tion of α,β-unsaturated carbonyl compounds 3a–e with hydrazine hydrate, semicarbazide or thiosemicarba-
zide. Applying the Mannich reaction to 5-(5-aryl-4,5-dihydro-1H-pyrazol-3-yl)-4-methoxybenzofuran-6-ols
7a–e with morpholine hydrochloride and paraformaldehyde afforded positional isomeric 7-morpholinomethyl
derivatives 4a–e and N-morpholinomethyl derivatives 8a–e. All the synthesized compounds showed sig-
nificant vasodilatation properties in isolated thoracic aortic rings of rats precontracted using the standard
norepinephrine hydrochloride technique. Compounds 3d, 3e, 5a–c, 6b, 6c, 6f, 6h and 6i exhibited activity
(IC50 0.3185–0.4577mM) superior to that of prazocin (IC50 0.487mM), while 5d, 6j and 8c showed comparable
activity (IC50 0.4789–0.4951mM). The quantitative structure–activity relationship study revealed a correla-
tion between the observed vasorelaxant activities of the newly synthesized compounds and their different
physicochemical parameters, especially solubility, in addition to structure connectivity and energetic quanti-
ties calculated from stored three dimensional (3D) conformations. Absorption, distribution, metabolism and
elimination (ADME) evaluation showed good agreement with the biological results obtained.
Key words benzofuran; morpholinomethyl; pyrazoline; vasorelaxant; quantitative structure–activity relation-
ship study
Vasodilators are smooth muscle relaxants which cause blood prazocin is (IC50 0.487mM) in isolated thoracic aortic rings of
vessels to dilate. They are prominently used to treat hyperten- rats pre-contracted with norepinephrine hydrochloride.29)
sion, heart failure and angina.1–4) This group of medication is
On the other hand, pyrazolines represented a common
known to cause several undesirable adverse reactions.5–7) This motif in pharmaceutically and remarkably active compounds
prompted us to attempt to design and synthesis new effective demonstrating a wide range of pharmacological activities
vasodilators which possess minimal side effects.
including anti-inflammatory,30) analgesic, antitubercular,31)
Benzofurans are promising candidates for this purpose as antimicrobial32) and antihypertensive agents.33–35) It was
they are known found to possess anti-arrhythmic, hypoten- reported that, 4,5-dihydro-1H-pyrazole derivatives were po-
sive and vasodilator effects.8,9) The benzofuran amiodarone tential inhibitors of neural nitric oxide synthase (nNOS) and
(A) and its analogue KB130015 (B) were reported to relax endothelial cell NOS (eNOS).36,37) In addition, they played a
vascular smooth muscle.10–12) A new noniodinated benzofuran role in neurotransmission38) and blood vessel dilation.39)
derivative dronedarone, SR33589 (C) was recently approved
In view of the biological significance of benzofuran,
by the Food and Drug Administration (FDA) for treatment morpholinomethyl and pyrazoline, hybrids whose chemi-
of atrial fibrillation and atrial flutter.13) Khellin (D) and vis- cal structure incorporated benzofuran directly attached
nagin (E) are the principle active constituents obtained from with morpholinomethyl and substituted at 5-position with
Ammi visnaga L. and which possess strong vasodilatation and aryl-4,5-dihydro-1H-pyrazoles, compounds 4a–e, 5a–e and
spasmolytic activities.9,14,15) Some 6-(aminoalkoxy)-5-cinnam- 6a–j were synthesized. Compounds 8a–e, benzofuran and
oyl-4,7-dimethoxybenzofuran (F) derivatives were previously morpholinomethyl systems linked through pyrazoline moiety
prepared and showed vasodilating and hypotensive activi- were also synthesized. Generally, the presence of electron-
ties,16) (A–F, Fig. 1).
donating groups on the phenyl ring intensifies the biological
The morpholine scaffold is very versatile and was featured activities27–29,40,41) These findings initiated the interest to ex-
in a number of biologically and pharmacologically active plore the contribution of methoxy and hydroxyl substituents
products such as vasorelaxant,17) anticancer,18) antioxidant,19,20) to the vasorelaxant activity. According to our hypothesis, the
analgesic,21) antimicrobial22,23) and antiparasitic agents.24)
combination of two or more biologically active moieties or
Mannich bases with morpholinomethyl of synthetic fla- substituents may bring significant improvement in biological
vonoids exhibited good effects during global ischemia and activity and may provide new classes of active vasorelaxant
perfusion in rat brain.25) In addition, morpholinomethyl compounds.
benzofurans were reported to exhibit promising hypotensive
Quantitative structure–activity relationship (QSAR) study
and antiarrhythimic activities.26–28) Other Mannich bases, for was also considered in the present work to validate the vaso-
instance, 7-piperazinomethylbenzofuran derivative showed relaxant activity of the investigated compounds and also for
promising vasorelaxant activity (IC50 0.21 mM) compared with determining the most important structure parameters control-
ling such activity. Furthermore, drug likeness evaluation of
The authors declare no conflict of interest.
the synthesized compounds as well as prazocin and amioda-
© 2014 The Pharmaceutical Society of Japan
*To whom correspondence should be addressed. e-mail: doaaezzat2004@yahoo.com

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Fig. 1. Structures of Some Benzofurans Have Anti-arrhythmic, Hypotensive and Vasodilator Activities
Reagents and conditions: (i) Appropriate aromatic aldehyde, NaOH, EtOH, rt 48h, (ii) Acetic acid, (iii) Morpholine hydrochloride, paraformaldehyde, EtOH, reflux, 24h,
(iv) Hydrazine hydrate 98%, EtOH, reflux, 6h, (v) Hydrazine hydrate 98%, glacial acetic acid, reflux, 6h, (vi) Semicarbazide or thiosemicarbazide, glacial acetic acid,
EtOH, reflux, 8h.
Chart 1
rone was applied to reveal the relation of molecular properties,
Upon reacting 3a–e with different nucleophiles such as
structure features and bioavailability of their vasorelaxant hydrazine hydrate in ethanol, the corresponding pyrazolines
activity.
4a, b,28) c–e were obtained through 1,4-addition on α,β-
unsaturated carbonyl system, followed by dehydration and
rearrangement.43) On the other hand, when 3a–e was reacted
Results and Discussion
Chemistry α,β-Unsaturated carbonyl compounds 2a,42) with hydrazine hydrate in glacial acetic acid, N-acetylpyr-
b,43) c, e44) and the new 2d were synthesized by reacting azolines 5a–e was obtained. 4,5-Dihydro-1H-pyrazole-1-car-
1-(6-hydroxy-4-methoxybenzofuran-5-yl)ethanone 145) with the boxamides 6a–e and 1-carbothioamides 6f–j were obtained
appropriate aromatic aldehydes in presence of sodium hydrox- through the reaction of 3a–e with semicarbazide or thios-
ide by the conventional Claisen–Schmidt condensation.
emicarbazide, respectively in ethanol/glacial acetic acid (few
On subjecting 2a–e to Mannich reactions using secondary drops) (Chart 1).
amine (morpholine hydrochloride) and paraformaldehyde, the
Similarly, compounds 7a, b43) and c–e were prepared start-
7-morpholinomethylbenzofuran derivatives 3a, b,28) c–e were ing with compounds 2a–e. Upon reacting 5-(5-aryl-4,5-di-
formed.
hydro-1H-pyrazol-3-yl)-4-methoxybenzofuran-6-ol 7a–e with

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Vol. 62, No. 12
Table 1. Concentration of Compounds Necessary to Reduce Maximal
Norepinephrine-Induced Contracture by 50% (IC50) in Rat Thoracic Aortic
Rings
Compd. No.
IC50 (mM)
3a
3b
3c
0.6585
0.5069
0.5342
0.4577
0.3185
0.7625
0.5502
0.5664
0.6021
0.5748
0.4171
0.4550
0.3704
0.4951
0.5340
0.6332
0.4475
0.4158
0.5564
0.5243
0.4212
0.5815
0.4041
0.3505
0.4789
0.7657
0.6681
0.4937
0.6916
0.8022
0.4870
3d
3e
4a
4b
4c
4d
4e
5a
5b
5c
5d
5e
Reagents and conditions: (i) Hydrazine hydrate 98%, EtOH, reflux, 3h, (ii)
Morpholine hydrochloride, paraformaldehyde, EtOH, reflux, 24h, preparative TLC.
6a
Chart 2
6b
6c
morpholine hydrochloride and paraformaldehyde (Mannich
reaction), two positional isomers were obtained 4a–e and
8a–e. The later compounds were separated by application of
preparative TLC technique (Chart 2).
All the new synthesized compounds were characterized by
spectral and elemental analyses which were in full agreement
with the proposed structures.
6d
6e
6f
6g
6h
6i
6j
Vasorelaxant Activity All synthesized compounds 3a–e,
4a–e, 5a–e, 6a–j and 8a–e were tested for their vasorelaxant
activities against nor-adrenaline-induced spasm on thoracic rat
aorta rings46–48) and were compared to the reference drug, pra-
zocin. The results are listed in Table 1 and illustrated in Fig. 2
as IC50 values (mM). These results exhibited the correct choice
of compounds’ design as hybrids of benzofuran scaffold with
morpholinemethyl and pyrazoline as vasorelaxant agents as all
the tested compounds showed biological activity.
8a
8b
8c
8d
8e
Prazocin
prazocin while compounds 6a, d and e (IC50 0.6332, 0.5564
Regarding the morpholinomethylbenzofuran chalcones and 0.5243 mM, respectively) were less active than prazocin.
3a–e, substitution of phenyl ring with methoxy and hydroxyl Carbothioamide derivatives 6f–j exhibited better vasorelaxant
substituent, (compound 3e, IC50 0.3185 mM) followed by tri- activity than carboxamide derivatives 6a–e as expressed with
methoxy substitution (compound 3d, IC50 0.4577 mM) gave lower IC50 values for most compounds. Compounds 6f, h and
better vasorelaxant activity than reference drug prazocin (IC50 i (IC50 0.4212, 0.4041 and 0.3505mM, respectively) showed
0.487mM) as expressed by lower IC50 values. Unsubstituted, better activity, while compound 6j (IC50 0.4789 mM) was com-
monomethoxy and dimethoxy substituted compounds gave ac- parable to prazocin and compound 6g (IC50 0.5815 mM) was
tivity less than prazocin (IC50 0.6585, 0.5069 and 0.5342mM, less active than prazocin.
respectively). This was in agreement with previous reports of
As for positional isomer N-morpholinomethlypyrazolines
8a–e, vasorelaxant activities were less than their isomers
vasorelaxant activity of the chalcone system.49–51)
Cyclization of compounds 3a–e to produce pyrazoline 4a–e. Except compound 8c (IC50 0.4937 mM) which exhibited
derivatives 4a–e resulted in slight decrease in activity as ex- activity comparable to prazocin and the rest of compounds 8a,
pressed with increase in IC50 values (IC50 0.5502–0.7625mM).
On the other hand cyclization of compounds 3a–e to
b, d and e (IC50 0.6681–0.8022mM) were less than prazocin.
Structure Activity Relationship Examination of the
produce N-acetylpyrazoline 5a–e, pyrazoline carboxamide vasorelaxant activity results revealed that separation of mor-
6a–e, pyrazoline carbothioamide 6f–j derivatives resulted in pholinomethyl moiety from benzofuran scaffold by pyrazoline
improvement of activity for most compounds. Results of N- spacer (compounds 8a–e) resulted in decrease in activity
acetylpyrazolines 5a–e revealed that compounds 5a–c (IC50 compared to their positional isomers 4a–e where morpholi-
0.4171, 0.4550 and 0.3704mM, respectively) showed better ac- nomethyl moiety was directly linked to benzofuran scaffold.
tivity than prazocin while compound 5d (IC50 0.4951 mM) was
Morpholinomethylbenzofuran chalcones 3a–e gave good
comparable to prazocin and compound 5e (IC50 0.5340 mM) vasorelaxant activity but cyclization to pyrazoline derivatives
was slight less active than prazocin. In case of pyrazoline car- 4a–e resulted in slight decrease in activity while cyclization to
boxamide derivatives 6a–e, compounds 6b and c (IC50 0.4475 N-acetylpyrazoline 5a–e, pyrazoline carboxamide 6a–e, pyr-
and 0.4158mM, respectively) showed activity better than azoline carbothioamide 6f–j derivatives resulted in improve-

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Fig. 2. Vasorelaxant Activity (IC50 Values) of Tested Compounds on Contracture Induced by Norepinephrine Hydrochloride on Thoracic Rat Aortic
Rings Compared to Prazocin
ment of activity for most compounds.
Table 2. The Molecular Descriptor Values of the Studied Compounds
N-Acetylpyrazoline derivatives 5a–e exhibited highest
activity followed by pyrazoline carbothioamide 6f–j then
pyrazoline carboxamide derivatives 6a–e while pyrazoline
derivatives 4a–e were the least active among this class of
compounds.
In addition, the influence of methoxy and hydroxyl substi-
tuted aryl pyrazolines on the vasorelaxant activity was ob-
served. At least one methoxy group substitution was essential
to increase vasorelaxant activity compared to unsubstituted
ring. The effect was increased with the second methoxy sub-
stituent and to a lesser extent with additional two methoxy or
one hydroxyl group substitution.
QSAR In order to correlate the vasorelaxant activity ex-
pressed as log IC50 (mM) with the structure conformation of
the synthesized benzofuran–morpholinomethyl–pyrazoline hy-
brids, QSAR study was undertaken. The study was performed
using MOE, Molecular Operating Environment software pack-
age (MOE version 2008.10.2).52)
Different molecular descriptors (Table 2) were selected
from an initial pole of 85 descriptors and were calculated for
compounds structure aiming to cover a wide range of dif-
ferent electronic, hydrophobic and topological characters. In
order to avoid multicolinearity between the calculated descrip-
tors the correlation matrix was calculated. The correlation
matrix indicated that some of the descriptors used were highly
correlated which suggests avoiding the combinations of such
intercorrelated descriptors.
Descriptors
Compd. No.
logS
VSA
E_sol
rgyr
3a
3b
3c
3d
3e
4a
4b
4c
4d
4e
5a
5b
5c
5d
5e
6a
6b
6c
6d
6e
6f
−5.2602
−5.3106
−5.3610
−5.4113
−4.9486
−4.5772
−4.6276
−4.6780
−4.7283
−4.2656
−5.0658
−5.1161
−5.1665
−5.2169
−4.7542
−5.0056
−5.0560
−5.1064
−5.1568
−4.6940
−6.0407
−6.0911
−6.1414
−6.1918
−5.7291
−4.3847
−4.4351
−4.4855
−4.5359
−4.0732
415.3450
444.1414
474.1896
501.4015
449.5437
419.5661
456.8181
490.1929
517.1149
464.8755
468.3897
496.8009
529.1497
560.5244
503.4925
461.2488
494.3793
524.4553
549.1744
496.1378
471.0862
506.7375
530.6677
562.1160
507.7466
426.4172
459.0730
490.3040
519.6377
462.5117
−5.9096
−10.1487
−2.9714
0.8602
4.2836
5.0438
5.3157
5.0932
5.1419
4.6045
4.9362
5.0422
5.0507
4.8255
4.4384
4.5314
4.8810
4.8320
4.6650
4.4359
4.7452
4.8093
4.6072
4.5096
4.4424
4.7773
4.8021
4.7922
4.7679
4.3002
4.4039
4.6997
4.7292
4.5672
−11.8534
−8.8021
−12.0295
−12.9473
−7.6016
−8.8987
−9.5429
−20.3672
−6.8252
−6.9133
−16.6703
−8.5186
−11.8881
−14.3439
−11.8380
−26.7391
2.8766
6g
6h
6i
−7.9529
−3.5103
−2.2115
−4.5232
−7.7219
−9.0937
0.6237
6j
Model Construction To test the best structural predictors
for activity, stepwise linear regression analysis (SLRA) tech-
nique was used.
For the current dataset of 30 compounds, the QSAR model
was derived by partial least square. The development of
QSAR model was restricted to a maximum of four variables
in accordance the general accepted rule for each compound:
descriptors ratio to be around 5:1.
8a
8b
8c
8d
8e
5.5265
−3.2103
cant correlation (Model 1), that was the correlation between
The simple linear regression analysis between the logIC50 the activity (logIC50) and the logS of the tested compounds.
and the different descriptors yields one statistically signifi- Compounds 3e and 6g were omitted as outliers while deriving

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Vol. 62, No. 12
the model. Detection of outliers was achieved through the Z was in good agreement with Jorgensen’s rule of three (log
score method. Z Score can be defined as absolute difference Swat>−5.7),54) which is considered essential for bioavail-
between the value of the model and the activity field, divided ability. All tested compounds were in compliance with this
by the square root of the mean square error of the data set. rule except compounds 6h and i that had slight lower log S
Any compound which shows a value of Z score higher than −6.1414 and −6.1918, respectively but this compensated with
2.5, during generation of a particular QSAR model, is consid- low value of rgyr and VSA descriptors (compounds 6f and g
ered as an outlier.53)
were considered outliers). QSAR results assured that the aque-
ous solubility of the compounds is one of the most important
determinants for the vasorelaxant activity due to increase in
bioavailability.
logIC50=3.35834+0.12660×logS
n= 28, RMSE=0.06457, r2=0.5279 (Model 1)
Cross-Validations Test Normal and cross-validation sta-
n: number of compounds used for construction of model. tistical techniques were applied to estimate the quality with
RMSE: root mean square error. r2: correlation coefficient.
regards to predictive ability of the generated Model 4 (Table
Stepwise regression analyses using different combinations 3) using MOE software. In the cross validation technique,
of logS and other structural descriptors resulted into bi-para- where a number of modified data sets were created by delet-
metric model (Model 2). The biparametric model correlated ing, in each case, one or a smaller group of objects from the
vasorelaxant activity (logIC50) with logS and VSA. Model 2 data in such a way that each object was taken away once and
showed better statistics than the mono-parametric model dis- only once. For each reduced data set, the model was calculat-
cussed above. Compounds 5a and c were omitted as outliers ed, and responses for the deleted objects were predicted from
while deriving the model.
the model. The simplest and most general cross-validation
procedure is the leave-one-out technique (LOO technique),
where each object of the data set is taken away, one at a time.
q2 (leave-one-out)=0.860459, it was calculated by the fol-
lowing equation53):
logIC50=3.63093+0.09961×logS − 0.00082×VSA
n=26, RMSE=0.04983, r2=0.6934
(Model 2)
Stepwise regression analyses using different combinations
of logS and VSA with other structural descriptors resulted in
tri-parametric model (Model 3). The triparametric model cor-
related logIC50 with logS, VSA and E_sol. Model 3 exhibited
better statistics than the mono-parametric and biparametric
(IC50 Obs.− IC50 Pred.)2
(IC50 Obs.− IC50 average)2
∑
∑
q2=1−
The logIC50 (observed) was plotted against their predicted
models discussed above. Compounds 6d and 8c were omitted values (LOO), Table 3 and Fig. 4.
as outliers while deriving the model.
Statistical Diagnosis Fraction of the Variance (r2): Repre-
sent the goodness of fit. The value of r2 may vary between 0
and 1, when multiplied by 100 gives explanation to variance in
biological activity, where 1 means a perfect model explaining
100% of the variance in the data, and 0 means a model with-
out any explanatory power. It has already been suggested that
logIC50=3.79347+0.12247×logS − 0.00084×VSA
+0.00409×E−sol
n=24, RMSE=0.03662, r2=0.8459
(Model 3)
Stepwise regression analyses using different combinations the only QSAR model having r2>0.6 will be considered for
of logIC50 with logS, VSA & E_sol with other structural de- validation.55) The value of r2 for this QSAR model is 0.9074.
scriptors resulted into tetraparametric model (Model 4). The
Cross-Validation Test (q2): A measure of quality of the
tetraparametric model correlated logIC50 with logIC50 with QSAR model. According to the literature, a QSAR model
logS, VSA, E_sol and rgyr. Model 4 revealed better statistics must have q2>0.5 for their predictive ability.55) The value of q2
than the other models discussed above. Compounds 4e and 6f for this QSAR model is 0.860459.
were omitted as outliers while deriving the model.
r2–q2<0.3: This difference between r2 and q2 for a QSAR
model should never be exceeded by 0.3. A large difference
between r2 and q2 suggests the following: over-fitted model,
presence of outliers or presence of irrelevant variables in
the data set.56) The value of r2−q2 for this QSAR model is
0.113541.
logIC50=4.05175+0.12029×logS − 0.00080×VSA
+0.00502×E−sol − 0.05864×rgyr
n=22, RMSE=0.0287, r2=0.9074
(Model 4)
The logIC50 (observed) was plotted against their predicted
values (MLR), Table 3 and Fig. 3.
ADME Evaluation As a part of our study, the compliance
of the benzofuran drug amiodarone, reference drug prazocin
From the obtained regression equation, vasorelaxant activ- and the synthesized compounds with the Lipinski’s rule of
ity was positively correlated (i.e., directly proportional) with five57) was evaluated. This was assessed using mipc—Molin-
logS (physical properties descriptor) and with E_sol (poten- spiration Property Calculator.58)
tial energy descriptor, used to calculate energetic quantities
Lipinski’s rule had been used in the evaluation of oral bio-
from stored 3D conformations) and negatively correlated availability of the compounds. Lipinski’s rule of five defines
(i.e., inverse proportional) with rgyr and VSA (surface area, molecular properties important to the drug’s pharmacokinetics
volume and shape descriptors which depend on the structure in the human body, including their (ADME) and is used to
connectivity and conformation). The high coefficient value insure that drug-like physicochemical properties. The rule de-
of logS and the comparatively lower value of E_sol, rgyr scribes a likely oral bioavailability molecule as (i) a molecular
and VSA suggested that the increase in aqueous solubil- weight (MW) less than 500 Daltons (Da), (ii) the logarithm of
ity of the compound lead to enhancement of activity. This the octanol/water partition coefficient representing the lipophi-

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Table 3. The Experimental and Predicted Activities (logIC50), Residuals and Z-Scores for the Tested Compounds Calculated Using MLR Validation and
the Corresponding Cross-Validation LOO
MLR validation
Residual
LOO validation
Residual
Compd. No.
log Obs. IC50
log Pred. IC50
Z-Score
log Pred. IC50
Z-Score
3a
3b
3c
3d
4a
4b
4c
4d
5b
5d
5e
6a
6b
6c
6e
6h
6i
2.8190
2.7050
2.7280
2.6610
2.8820
2.7410
2.7530
2.7800
2.6580
2.6950
2.7280
2.8020
2.6510
2.6190
2.7200
2.6060
2.5450
2.6800
2.8840
2.8250
2.8400
2.9040
2.8063
2.7114
2.7014
2.7059
2.8518
2.7803
2.7368
2.7355
2.6715
2.6584
2.7204
2.7783
2.7107
2.6645
2.6922
2.5898
2.5658
2.6547
2.8927
2.8476
2.8414
2.9084
0.0127
−0.0064
0.0266
0.4412
0.2240
0.9261
1.5642
1.0522
1.3705
0.5645
1.5488
0.4717
1.2760
0.2632
0.8266
2.0803
1.5867
0.9698
0.5632
0.7230
0.8826
0.3046
0.7887
0.0485
0.1520
2.7980
2.7140
2.6874
2.7160
2.8454
2.7879
2.7332
2.7258
2.6752
2.6483
2.7193
2.7750
2.7144
2.6710
2.6752
2.5840
2.5769
2.6506
2.8954
2.8516
2.8425
2.9100
0.0210
−0.0090
0.0406
0.7195
0.3084
1.4240
2.0148
1.2875
1.6828
0.6800
1.9813
0.5888
1.6715
0.2972
0.9351
2.4265
1.8976
1.5796
0.7571
1.1065
1.0216
0.3893
0.9205
0.0845
0.2035
−0.0449
0.0302
−0.0550
0.0366
−0.0393
0.0162
−0.0469
0.0198
0.0445
0.0542
−0.0135
0.0366
−0.0172
0.0467
0.0076
0.0087
0.0237
0.0270
−0.0597
−0.0455
0.0278
−0.0634
−0.0520
0.0448
0.0162
0.0220
−0.0208
0.0253
−0.0319
0.0294
6j
8a
8b
8d
8e
−0.0087
−0.0226
−0.0014
−0.0044
−0.0114
−0.0266
−0.0025
−0.0060
Fig. 3. Correlation of log Observed and log Predicted IC50 Using MLR (r2=0.9074)
licity factor (logP) less than 5, (iii) not more than 5 hydrogen tion depends on solubility and permeability of the compound
bond donors (OH and NH groups, HBD), (iv) not more than and interactions with metabolizing enzymes in the gut wall
10 hydrogen bond acceptors (HBA) and (v) not more than while functional group types present are responsible for me-
10 rotatable bonds (NRB). The number of violation to this tabolism.
rule must not exceed 2 and at least three parameters coincide
According to Jorgensen’s rule of three, the computed pa-
with the rule.57) In addition, the topological polar surface area rameters used to assess oral absorption should comply with
(TPSA) of the compounds was also calculated since it is an- the following values (logSwat>−5.7, BIPcaco-2>22nm/s and
other key property that has been linked to drug bioavailability, primary metabolites <7) to be orally available. The most
TPSA equal to or less than 140Å2 are considered to have good important parameters considered are the predicted aqueous
oral bioavailability.59) Absorption and liver first-pass metabo- solubility, logSwat
.
54)
lism determine the bioavailability of a compound.54) Absorp-
The size of a molecule, lipophilicity, capacity to make hy-

1244
Vol. 62, No. 12
Fig. 4. Correlation of log Observed and log Predicted IC50 Using LOO (q2=0. 860459)
Table 4. ADME of the Synthesized Compounds Using Mipc—Molinspiration Property Calculator
No. of
violation
Compd. No.
TPSA
MW
mi log P
HBA
HBD
NRB
3a
72.145
81.379
90.613
99.847
101.607
79.465
88.699
97.933
107.167
108.927
87.747
96.981
106.215
115.449
117.209
113.77
123.004
132.238
141.472
143.232
96.699
105.933
115.167
124.401
126.161
70.676
79.91
393.439
423.465
453.491
483.517
439.464
407.47
3.384
3.44
6
7
1
1
1
1
2
2
2
2
2
3
1
1
1
1
2
3
3
3
3
4
3
3
3
3
4
1
1
1
1
2
0
2
6
7
8
9
7
5
6
7
8
6
5
6
7
8
6
5
6
7
8
6
6
7
8
9
7
5
6
7
8
6
11
4
0
0
0
0
0
0
0
0
0
0
0
0
1
2
0
0
0
2
2
1
0
0
1
2
1
0
0
0
1
0
2
0
3b
3c
3.03
8
3d
3.015
2.723
2.89
9
3e
8
4a
7
4b
437.496
467.522
497.548
453.495
449.507
479.533
509.559
539.585
495.532
450.495
480.521
510.547
540.573
496.52
2.946
2.536
2.521
2.229
2.496
2.552
2.142
2.127
1.835
2.41
8
4c
9
4d
10
9
4e
5a
8
5b
9
5c
10
11
10
9
5d
5e
6a
6b
2.467
2.057
2.042
1.749
2.951
3.008
2.598
2.583
2.29
10
11
12
11
8
6c
6d
6e
6f
466.563
496.589
526.615
556.641
512.588
421.497
451.523
481.549
511.575
467.522
645.319
383.408
6g
9
6h
10
11
10
7
6i
6j
8a
3.797
3.853
3.443
3.428
3.136
8.31
8b
8c
8
89.144
98.378
100.138
42.683
106.962
9
8d
10
9
8e
Amiodarone
Prazocin
4
1.909
9
TPSA: Topological polar surface area. MW: Molecular weight. mi log P: Octanol–water partition coefficient (predicted log P at molinspiration). HBA: No. of H-bond ac-
ceptors. HBD: No. of H-bond donors. NRB: No. of rotatable bonds.
drogen bonds as well as shape and flexibility are important ability of studied compounds. Most compounds fulfilled
properties to consider when determining its oral bioavailabil- Lipinski’s rule similar to the clinically used drug prazocin.
ity.59)
Compounds 5c, 6h, j and 8d violated the rule of five in mo-
The calculated parameters (Table 4) showed good bioavail- lecular weight value while compounds 5d, 6c and i violated

December 2014
1245
in molecular weight value and HBA. In addition, compound was filtered off, washed with water and dried. The crude prod-
6e violated in HBA and had slightly large TPSA (143.232Å2). uct was crystallized from methanol (Chart 1).
Also, compound 6d violated in molecular weight value and
1-(6-Hydroxy-4-methoxybenzofuran-5-yl)-3-(3,4,5-
HBA and had slightly large TPSA (141.472Å2). Meanwhile, trimethoxyphenyl)prop-2-en-1-one (2d) Yield 85%. mp
1
amiodarone violated in molecular weight value and logP. 159–160°C. H-NMR (CDCl3) δ: 3.92 (9H, s, 3×OCH3), 4.13
Hence; theoretically, all of these compounds should present (3H, s, OCH3), 6.82 (1H, s, H-7 benzofuran), 6.87 (2H, s,
good passive oral absorption and differences in their bioactiv- H-2′,6′ Ar), 6.88 (1H, d, J=1.8Hz, H-3 furan), 7.48 (1H, d,
ity cannot be attributed to this property.
J=2.4Hz, H-2 furan), 7.76 (2H, d, J=16.9Hz, COCH=CH),
12.70 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3442 (OH), 3100
(CH Ar), 2941, 2837 (CH aliphatic), 1660 (C=O), 1604, 1577,
Conclusion
This study describes the design and synthesis of new ben- 1556, 1543, 1504 (C=C). MS (m/z) %: 384 (M+) 68.83%. Anal.
zofuran–morpholinomethyl–pyrazoline hybrids as vasorelax- Calcd for C21H20O7 (384.38): C, 65.62; H, 5.24. Found: 65.65;
ant agents. All the synthesized compounds showed significant H, 5.28.
vasodilatation properties using isolated thoracic aortic rings of
General Procedure for Synthesis of 1-[6-Hydroxy-4-
rats pre-contracted with norepinephrine hydrochloride stan- methoxy-7-(morpholin-4-ylmethyl)benzofuran-5-yl]-3-
dard technique and results were compared with reference drug ((un)substituted)phenylprop-2-en-1-one (3a–e) To a solu-
prazocin. Results revealed that direct linked morpholinometh- tion of the appropriate propenone derivative 2a–e (10mmol) in
yl moiety to benzofuran scaffold 4a–e gave better results than ethanol (20mL), morpholine hydrochloride (1.36g, 11mmol)
their positional isomers 8a–e with morpholinomethyl moiety and paraformaldehyde (0.6g, 20mmol) were added. The mix-
separated away from benzofuran scaffold by pyrazoline ture was refluxed for 24h. Excess solvent was removed under
spacer. N-Acetylpyrazoline derivatives 5a–e exhibited high- vacuum then cooled and water was added. The mixture was
est activity followed by pyrazoline carbothioamide 6f–j then neutralized with dilute ammonia and extracted with chloro-
pyrazoline carboxamide derivatives 6a–e while pyrazoline form. Chloroform extract was dried over anhydrous sodium
derivatives 4a–e were the least active among this class of sulfate and evaporated under vacuum. The product was crys-
compounds. In general, methoxy and hydroxyl substitution on tallized from methanol (Chart 1).
the phenyl ring at pyrazoline had good effect on activity.
3-(3,4-Dimethoxyphenyl)-1-[6-hydroxy-4-methoxy-
In addition QSAR and drug likeness studies results ac- 7-(morpholin-4-ylmethyl)benzofuran-5-yl]prop-2-en-1-one (3c)
1
counted for the importance of aqueous solubility on oral bio- Yield 60%. mp 158–160°C. H-NMR (CDCl3) δ: 2.90–3.00
availability and activity of tested compounds.
(4H, m, morpholine H), 3.45–3.65 (4H, m, morpholine H), 3.94
(6H, s, 2×OCH3), 4.11 (3H, s, OCH3), 4.81 (2H, s, CH2), 6.88
(1H, d, J=1.5Hz, H-3 furan), 6.92 (1H, d, J=6.6Hz, H-5′ Ar),
Experimental
Chemistry Melting points were determined by open cap- 7.70 (1H, s, H-2′ Ar), 7.27 (1H, d, J=5.4Hz, H-6′ Ar), 7.58
illary tube method using Gallen Kamp melting point appara- (1H, d, J=17.1Hz, COCH=CH), 7.73 (1H, d, J=1.5Hz, H-2
tus MFB-595-010M (Gallen Kamp, London, U.K.) and were furan), 7.79 (1H, d, J=17.1Hz, COCH=CH), 13.10 (1H, s, OH,
uncorrected. Microanalyses were carried out at The Regional exch. D2O). IR (KBr) cm−1: 3414 (OH), 3100 (CH Ar), 2920,
Center for Mycology and Biotechnology, Al-Azhar University. 2850 (CH aliphatic), 1670 (C=O), 1616, 1604, 1560, 1541,
Infrared spectra were recorded as potassium bromide discs 1508 (C=C). MS (m/z) %: 454 (M++1) 10.53%. Anal. Calcd
on Schimadzu FT-IR 8400S spectrophotometer (Shimadzu, for C25H27NO7 (453.48): C, 66.21; H, 6.00; N, 3.09. Found: C,
Kyoto, Japan) and expressed in wave number (cm−1). The 66.34; H, 6.09; N, 3.18.
NMR spectra were recorded on a Varian Mercury VX-300
NMR spectrometer. H spectra were run at 300MHz in deu- furan-5-yl]-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (3d)
1-[6-Hydroxy-4-methoxy-7-(morpholin-4-ylmethyl)benzo-
1
1
terated chloroform (CDCl3). Chemical shifts are quoted in δ Yield 70%. mp 134–136°C. H-NMR (CDCl3) δ: 3.46–3.51
as parts per million (ppm) downfield from tetramethylsilane (4H, m, morpholine H), 3.60–3.74 (4H, m, morpholine H),
(TMS) as internal standard. Mass spectra were recorded using 3.92 (9H, s, 3×OCH3), 4.11 (3H, s, OCH3), 4.82 (2H, s, CH2),
Hewlett Packard Varian (Varian, Polo, U.S.A.) and Shimadzu 6.87 (2H, s, H-2′,6′ Ar), 6.88 (1H, d, J=2.4Hz, H-3 furan),
Gas Chromatograph Mass spectrometer-QP 1000 EX (Shi- 7.52 (1H, d, J=2.4Hz, H-2 furan), 7.74 (2H, d, J=16.7Hz,
madzu). TLC were carried out using Art.DC-Plastikfolien, COCH=CH), 13.04 (1H, s, OH, exch. D2O). IR (KBr) cm−1:
Kieselgel 60 F254 sheets (Merck, Darmstadt, Germany), the 3400 (OH), 3040 (CH Ar), 2924, 2852 (CH aliphatic), 1670
developing solvents were chloroform/methanol (9:1) and the (C=O), 1579, 1560, 1546, 1504 (C=C). MS (m/z) %: 483 (M+)
spots were visualized at 366, 254nm by UV Vilber Lourmat 0.35%. Anal. Calcd for C26H29NO8 (483.51): C, 64.59; H, 6.05;
77202 (Vilber, Marne La Vallee, France).
N, 2.90. Found: C, 64.61; H, 6.11; N, 2.91.
3-(4-Hydroxy-3-methoxyphenyl)-1-[6-hydroxy-4-methoxy-
7-(morpholin-4-ylmethyl)benzofuran-5-yl]prop-2-en-1-one (3e)
Compounds 1,45) 2a,42) b,43) c, e,44) 3a, b, 4a, b,28) 7a and b43)
were prepared according to reported procedures.
General Procedure for Synthesis of 1-(6-Hydroxy- Yield 62%. mp 117–118°C. 1H-NMR (CDCl3) δ: 2.64–2.68
4-methoxybenzofuran-5-yl)-3-((un)substituted)phenylprop- (4H, m, morpholine H), 2.71–2.77 (4H, m, morpholine H), 3.49
2-en-1-one (2a–e) The warmed solution of 5-acetyl-4-me- (3H, s, OCH3), 4.18 (3H, s, OCH3), 4.32 (2H, s, CH2), 6.72
thoxybenzofuran-6-ol 1 (1.9g, 10mmol) and the appropriate (1H, s, H-2′ Ar), 6.87 (2H, d, J=9.4Hz, H-5′,6′ Ar), 6.89 (1H,
aromatic aldehyde (11mmol) in ethanol (20mL) was treated d, J=2.4Hz, H-3 furan), 7.43 (2H, d, J=16.9Hz, COCH=CH),
with 30% sodium hydroxide solution (5mL) and was left for 7.44 (1H, d, J=2.4Hz, H-2 furan), 13.11 (2H, s, 2×OH exch.
48h at room temperature. The reaction mixture was diluted D2O). IR (KBr) cm−1: 3446 (OH), 3040 (CH Ar), 2924, 2852
with ice water and acidified with acetic acid. The precipitate (CH aliphatic), 1670 (C=O), 1612, 1585, 1548 (C=C). MS (m/z)

1246
Vol. 62, No. 12
%: 442 (M++3) 8.52%. Anal. Calcd for C24H25NO7 (439.46): dried. The crude product was crystallized from acetic acid
C, 65.59; H, 5.73; N, 3.19. Found: C, 65.63; H, 5.78; N, 3.28.
General Procedure for Synthesis of 4-Methoxy-7-
(Chart 1).
5-[1-Acetyl-5-phenyl-4,5-dihydro-1H-pyrazol-3-yl]-4-me-
(morpholin-4-ylmethyl)-5-[5-((un)substituted)phenyl-4,5- thoxy-7-(morpholin-4-ylmethyl)benzofuran-6-ol (5a) Yield
1
dihydro-1H-pyrazol-3-yl]benzofuran-6-ol (4a–e) Hydra- 60%. mp 79–80°C. H-NMR (CDCl3) δ: 2.09 (3H, s, COCH3),
zine hydrate 98% (0.55g, 0.55mL, 11mmol) was added to 2.20–2.50 (4H, m, morpholine H), 3.40–3.65 (4H, m, mor-
a solution of the appropriate Mannich base compound 3a–e pholine H), 3.73 (1H, dd, J=14.1, 6.9Hz, CH2 pyrazoline),
(10mmol) in ethanol (20mL) and the reaction mixture was 3.98 (3H, s, OCH3), 4.08 (2H, s, CH2), 4.46 (1H, dd, J=14.4,
refluxed for 6h. The solvent was concentrated under reduced 7.2Hz, CH2 pyrazoline), 5.49 (1H, t, CH pyrazoline), 6.88
pressure and the residue was crystallized from methanol (1H, d, J=2.3Hz, H-3 furan), 7.26–7.48 (3H, m, H-3′,4′,5′ Ar),
(Chart 1).
7.59 (2H, d, J=7.2Hz, H-2′,6′ Ar), 8.08 (1H, d, J=2.2Hz, H-2
5-[5-(3,4-Dimethoxyphenyl)-4,5-dihydro-1H-pyrazol-3- furan), 12.70 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3417
yl]-4-methoxy-7-(morpholin-4-ylmethyl)benzofuran-6-ol (4c) (OH), 3061 (CH Ar), 2926, 2850 (CH aliphatic), 1666 (C=O),
Yield 64%. mp 145–148°C. H-NMR (CDCl3) δ: 2.88–3.00 1620, 1492 (C=C). MS (m/z) %: 449 (M+) 0.11%. Anal. Calcd
(4H, m, morpholine H), 3.21–3.49 (4H, m, morpholine H), for C25H27N3O5 (449.50): C, 66.80; H, 6.05; N, 9.35. Found: C,
1
3.64 (1H, dd, J=14.1, 7.5Hz, CH2 pyrazoline), 3.93 (6H, s, 66.87; H, 6.11; N, 9.44.
2×OCH3), 4.02 (3H, s, OCH3), 4.09 (2H, s, CH2), 4.16 (1H, dd,
5-[1-Acetyl-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazol-3-
J=14.1, 7.8Hz, CH2 pyrazoline), 4.85 (1H, t, CH pyrazoline), yl]-4-methoxy-7-(morpholin-4-ylmethyl)benzofuran-6-ol (5b)
1
6.76 (1H, s, H-2′ Ar), 6.84 (1H, d, J=2.4Hz, H-3 furan), 6.95 Yield 64%. mp 124–125°C. H-NMR (CDCl3) δ: 2.08 (3H,
(1H, d, J=9.4Hz, H-5′ Ar), 7.49 (1H, d, J=9.3Hz, H-6′ Ar), s, COCH3), 2.34–2.43 (4H, m, morpholine H), 3.54 (1H, dd,
7.80 (1H, d, J=2.4Hz, H-2 furan), 11.75 (1H, s, NH, exch. J=18.9, 7.5Hz, CH2 pyrazoline), 3.71–3.85 (4H, m, morpholine
D2O), 13.00 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3400 H), 3.99 (3H, s, OCH3), 4.04 (1H, dd, J=17.3, 7.9Hz, CH2
(OH), 3323 (NH), 3040 (CH Ar), 2922, 2850 (CH aliphatic), pyrazoline), 4.11 (3H, s, OCH3), 4.21 (2H, s, CH2), 5.43 (1H, t,
1620, 1516 (NH, C=C). MS (m/z) %: 465 (M+−2) 2.53%. CH pyrazoline), 6.81 (1H, d, J=2.0Hz, H-3 furan), 6.86 (2H,
Anal. Calcd for C25H29N3O6 (467.51): C, 64.23; H, 6.25; N, d, J=11.4Hz, H-3′,5′ Ar), 7.18 (2H, d, J=11.7Hz, H-2′,6′ Ar),
8.99. Found: C, 64.37; H, 6.22; N, 9.17.
7.46 (1H, d, J=2.1Hz, H-2 furan), 11.80 (1H, s, OH, exch.
4-Methoxy-7-(morpholin-4-ylmethyl)-5-[5-(3,4,5-trime- D2O). IR (KBr) cm−1: 3431 (OH), 3066 (CH Ar), 2933, 2835
thoxyphenyl)-4,5-dihydro-1H-pyrazol-3-yl]benzofuran-6-ol (CH aliphatic), 1664 (C=O), 1618, 1514 (C=C). MS (m/z) %:
(4d) Yield 70%. mp 114–117°C. 1H-NMR (CDCl3) δ: 478 (M+−1) 0.51%. Anal. Calcd for C26H29N3O6 (479.52): C,
2.50–2.63 (4H, m, morpholine H), 3.11–3.40 (4H, m, morpho- 65.12; H, 6.10; N, 8.76. Found: C, 65.17; H, 6.17; N, 8.90.
line H), 3.82 (1H, dd, J=14.1, 7.8Hz, CH2 pyrazoline), 3.87
5-[1-Acetyl-5-(3,4-dimethoxyphenyl)-4,5-dihydro-1H-pyr-
(9H, s, 3×OCH3), 3.95 (3H, s, OCH3), 4.03 (2H, s, CH2), 4.33 azol-3-yl]-4-methoxy-7-(morpholin-4-ylmethyl)benzofuran-
(1H, dd, J=14.4, 8.2Hz, CH2 pyrazoline), 4.86 (1H, t, CH 6-ol (5c) Yield 67%. mp 131–132°C. 1H-NMR (CDCl3)
pyrazoline), 6.66 (2H, s, H-2′,6′ Ar), 6.80 (1H, d, J=2.3Hz, δ: 2.06 (3H, s, COCH3), 2.34–2.43 (4H, m, morpholine H),
H-3 furan), 7.50 (1H, d, J=2.1Hz, H-2 furan), 10.10 (1H, s, 3.47–3.77 (6H, m, morpholine H, CH2 pyrazoline), 3.84 (6H,
NH, exch. D2O), 12.40 (1H, s, OH, exch. D2O). IR (KBr) s, 2×OCH3), 3.97 (3H, s, OCH3), 4.21 (2H, s, CH2), 5.41 (1H,
cm−1: 3446 (OH), 3260 (NH), 3100 (CH Ar), 2916, 2848 (CH t, CH pyrazoline), 6.78–6.97 (4H, m, H-3 furan, H-2′,5′,6′
aliphatic), 1618, 1593, 1560, 1540, 1508 (NH, C=C). MS (m/z) Ar), 7.48 (1H, d, J=2.1Hz, H-2 furan), 11.73 (1H, s, OH,
%: 499 (M++2) 0.42%. Anal. Calcd for C26H31N3O7 (497.54): exch. D2O). IR (KBr) cm−1: 3423 (OH), 3072 (CH Ar), 2924,
C, 62.76; H, 6.28; N, 8.45. Found: C, 62.79; H, 6.31; N, 8.52.
2850 (CH aliphatic), 1662 (C=O), 1620, 1544, 1517 (C=C).
5-[5-(4-Hydroxy-3-methoxyphenyl)-4,5-dihydro-1H-pyr- MS (m/z) %: 508 (M+−1) 1.14%. Anal. Calcd for C27H31N3O7
azol-3-yl]-4-methoxy-7-(morpholin-4-ylmethyl)benzofuran- (509.55): C, 63.64; H, 6.13; N, 8.25. Found: C, 63.70; H, 6.18;
6-ol (4e) Yield 55%. mp 88–89°C. 1H-NMR (CDCl3) δ: N, 8.38.
2.40–2.65 (4H, m, morpholine H), 3.20–3.80 (5H, m, morpho-
5-[1-Acetyl-5-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-
line H, CH2 pyrazoline), 4.00 (1H, dd, J=14.1, 7.8Hz, CH2 pyrazol-3-yl]-4-methoxy-7-(morpholin-4-ylmethyl)benzofuran-
pyrazoline), 4.06 (3H, s, OCH3), 4.12 (3H, s, OCH3), 4.20 (2H, 6-ol (5d) Yield 70%. mp 116–117°C. 1H-NMR (CDCl3)
s, CH2), 4.85 (1H, t, CH pyrazoline), 6.75–6.90 (4H, m, H-3 δ: 2.08 (3H, s, COCH3), 2.30–2.56 (4H, m, morpholine H),
furan, H-2′,5′,6′ Ar), 7.45 (1H, d, J=2.1Hz, H-2 furan), 12.00 3.81 (9H, s, 3×OCH3), 3.83–3.89 (6H, m, morpholine H,
(1H, s, NH, exch. D2O), 13.00 (2H, s, 2×OH, exch. D2O). IR CH2 pyrazoline), 3.90 (3H, s, OCH3), 4.10 (2H, s, CH2), 5.40
(KBr) cm−1: 3392 (OH), 3296 (NH), 3066 (CH Ar), 2922, 2850 (1H, t, CH pyrazoline), 6.45 (2H, s, H-2′,6′ Ar), 6.86 (1H, d,
(CH aliphatic), 1618, 1560, 1540, 1520 (NH, C=C). MS (m/z) J=2.4Hz, H-3 furan), 7.45 (1H, d, J=2.4Hz, H-2 furan), 11.70
%: 457 (M++4) 0.19%. Anal. Calcd for C24H27N3O6 (453.49): (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3421 (OH), 3066
C, 63.56; H, 6.00; N, 9.27. Found: 63.64; H, 6.04; N, 9.39.
(CH Ar), 2935, 2839 (CH aliphatic), 1660 (C=O), 1618, 1593,
General Procedure for Synthesis of 5-[1-Acetyl-5-((un)- 1543, 1508 (C=C). MS (m/z) %: 539 (M+) 0.88%. Anal. Calcd
substituted)phenyl-4,5-dihydro-1H-pyrazol-3-yl]-4-me- for C28H33N3O8 (539.58): C, 62.33; H, 6.16; N, 7.79. Found: C,
thoxy-7-(morpholin-4-ylmethyl)benzofuran-6-ol (5a–e)
A
62.41; H, 6.13; N, 7.88.
mixture of the appropriate Mannich base compound 3a–e
5-[1-Acetyl-5-(4-hydroxy-3-methoxyphenyl)-4,5-di-
(10mmol), hydrazine hydrate 98% (0.55g, 0.55mL, 11mmol) hydro-1H-pyrazol-3-yl]-4-methoxy-7-(morpholin-4-ylmethyl)-
1
in glacial acetic acid (5mL) was heated under reflux for 6h. benzofuran-6-ol (5e) Yield 55%. mp 101–104°C. H-NMR
The resulting solution was cooled and poured onto ice water. (CDCl3) δ: 2.12 (3H, s, COCH3), 2.71–2.78 (4H, m, morpholine
The solid obtained was filtered off, washed with water and H), 3.80–4.18 (6H, m, morpholine H, CH2 pyrazoline), 4.19

December 2014
1247
(3H, s, OCH3), 4.25 (3H, s, OCH3), 4.28 (2H, s, CH2), 5.40
3-[6-Hydroxy-4-methoxy-7-(morpholin-4-ylmethyl)benzofu-
(1H, t, CH pyrazoline), 6.76 (1H, s, H-2′ Ar), 6.88 (2H, d, ran-5-yl]-5-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-pyrazole-
J=9.9Hz, H-5′,6′ Ar), 6.92 (1H, d, J=2.4Hz, H-3 furan), 7.48 1-carboxamide (6d) Yield 72%. mp 197–199°C. 1H-NMR
(1H, d, J=2.4Hz, H-2 furan), 13.15 (1H, s, OH, exch. D2O), (CDCl3) δ: 2.54–2.80 (4H, m, morpholine H), 3.74–3.86 (6H,
13.26 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3400 (OH), m, morpholine H, CH2 pyrazoline), 3.90 (9H, s, 3×OCH3),
3080 (CH Ar), 2924, 2850 (CH aliphatic), 1680 (C=O), 1620, 3.93 (3H, s, OCH3), 4.05 (2H, s, CH2), 4.30 (2H, s, NH2, exch.
1589, 1548, 1517 (C=C). MS (m/z) %: 493 (M+−2) 1.82%. D2O), 4.60 (1H, t, CH pyrazoline), 6.88 (1H, d, J=2.4Hz, H-3
Anal. Calcd for C26H29N3O7 (495.52): C, 63.02; H, 5.90; N, furan), 6.94 (2H, s, H-2′,6′ Ar), 7.75 (1H, d, J=2.2Hz, H-2
8.48. Found: C, 63.16; H, 5.96; N, 8.63.
furan), 13.25 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3462
General Procedure for Synthesis of 3-[6-Hydroxy-4-me- (OH), 3392, 3365 (NH2), 3060 (CH Ar), 2926, 2852 (CH ali-
thoxy-7-(morpholin-4-ylmethyl)benzofuran-5-yl]-5-((un)- phatic), 1683 (C=O), 1616, 1593, 1581,1544, 1506 (NH, C=C).
substituted)phenyl-4,5-dihydro-1H-pyrazole-1-carbox- MS (m/z) %: 541 (M++1) 0.03%. Anal. Calcd for C27H32N4O8
amide (or Carbothioamide) (6a–j) A mixture of the appro- (540.56): C, 59.99; H, 5.97; N, 10.36. Found: C, 60.11; H, 6.04;
priate Mannich base compound 3a–e (10mmol), semicarbazide N, 10.43.
or thiosemicarbazide (10mmol) in ethanol (20mL) in presence
5-(4-Hydroxy-3-methoxyphenyl)-3-[6-hydroxy-4-methoxy-
of few drops glacial acetic acid was heated under reflux for 7-(morpholin-4-ylmethyl)benzofuran-5-yl]-4,5-dihydro-1H-
8h. The solvent was concentrated under reduced pressure and pyrazole-1-carboxamide (6e) Yield 55%. mp 90–93°C.
the residue was crystallized from methanol (Chart 1).
1H-NMR (CDCl3) δ: 2.67–2.74 (4H, m, morpholine H),
3-[6-Hydroxy-4-methoxy-7-(morpholin-4-ylmethyl)benzo- 3.75–3.84 (6H, m, morpholine H, CH2 pyrazoline), 4.11 (3H,
furan-5-yl]-5-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamide s, OCH3), 4.20 (2H, s, NH2, exch. D2O), 4.22 (3H, s, OCH3),
(6a) Yield 60%. mp 176–178°C. 1H-NMR (CDCl3) δ: 4.23 (2H, s, CH2), 4.45 (1H, t, CH pyrazoline), 6.79 (1H, s,
2.80–3.20 (4H, m, morpholine H), 3.60–4.00 (6H, m, mor- H-2′ Ar), 6.90 (1H, d, J=2.4Hz, H-3 furan), 6.94 (2H, d,
pholine H, CH2 pyrazoline), 4.03 (3H, s, OCH3), 4.16 (2H, s, J=9.4Hz, H-5′,6′ Ar), 7.45 (1H, d, J=2.4Hz, H-2 furan),
CH2), 4.50 (2H, s, NH2, exch. D2O), 5.10 (1H, t, CH pyrazo- 13.12 (2H, s, 2×OH, exch. D2O). IR (KBr) cm−1: 3433 (OH),
line), 6.95 (1H, d, J=2.4Hz, H-3 furan), 7.43–7.64 (3H, m, 3311, 3253 (NH2), 3068 (CH Ar), 2918, 2848 (CH aliphatic),
H-3′,4′,5′ Ar), 7.64 (2H, d, J=7.8Hz, H-2′,6′ Ar), 7.86 (1H, 1685 (C=O), 1620, 1585, 1560 (NH, C=C). MS (m/z) %: 497
d, J=2.4Hz, H-2 furan), 12.80 (1H, s, OH, exch. D2O). IR (M++1) 0.23%. Anal. Calcd for C25H28N4O7 (496.51): C, 60.48;
(KBr) cm−1: 3462 (OH), 3388, 3342 (NH2), 3059 (CH Ar), H, 5.68; N, 11.28. Found: C, 60.53; H, 5.73; N, 11.49.
2924, 2852 (CH aliphatic), 1685 (C=O), 1618, 1570, 1543
3-[6-Hydroxy-4-methoxy-7-(morpholin-4-ylmethyl)benzofu-
(NH, C=C). MS (m/z) %: 449 (M+−1) 6.16%. Anal. Calcd for ran-5-yl]-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbothioamide
C24H26N4O5 (450.49): C, 63.99; H, 5.82; N, 12.44. Found: C, (6f) Yield 65%. mp 150–152°C. 1H-NMR (CDCl3) δ:
64.03; H, 5.89; N, 12.53.
2.66–2.80 (4H, m, morpholine H), 3.50 (1H, dd, J=12.0,
3-[6-Hydroxy-4-methoxy-7-(morpholin-4-ylmethyl)ben- 4.2Hz, CH2 pyrazoline), 3.75–3.86 (4H, m, morpholine H),
zofuran-5-yl)]-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyr- 4.06 (3H, s, OCH3), 4.07 (2H, s, CH2), 4.17 (1H, dd, J=12.0,
azole-1-carboxamide (6b) Yield 60%. mp 164–166°C. 3.9Hz, CH2 pyrazoline), 4.60 (2H, s, NH2, exch. D2O), 5.45
1H-NMR (CDCl3) δ: 2.80–3.00 (4H, m, morpholine H), 3.47 (1H, t, CH pyrazoline), 6.55 (1H, d, J=2.4Hz, H-3 furan),
(1H, dd, J=18.9, 5.4Hz, CH2 pyrazoline), 3.71–3.82 (4H, m, 6.80–7.20 (3H, m, H-3′,4′,5′ Ar), 7.40–7.65 (2H, m, H-2′,6′ Ar),
morpholine H), 3.84 (3H, s, OCH3), 3.97 (3H, s, OCH3), 4.11 7.85 (1H, d, J=2.4Hz, H-2 furan), 12.80 (1H, s, OH, exch.
(1H, dd, J=17.7, 4.8Hz, CH2 pyrazoline), 4.18 (2H, s, CH2), D2O). IR (KBr) cm−1: 3421 (OH), 3327, 3253 (NH2), 3032 (CH
4.54 (2H, s, NH2, exch. D2O), 5.40 (1H, t, CH pyrazoline), Ar), 2926, 2854 (CH aliphatic), 1620, 1597, 1560, 1541 (NH,
6.43 (1H, d, J=2.2Hz, H-3 furan), 6.80–6.94 (2H, m, H-3′,5′ C=C), 1278 (C=S). MS (m/z) %: 466 (M+) 1.07%. Anal. Calcd
Ar), 7.31–7.62 (2H, m, H-2′,6′ Ar), 7.83 (1H, d, J=2.2Hz, for C24H26N4O4S (466.55): C, 61.78; H, 5.62; N, 12.01. Found:
H-2 furan), 13.00 (1H, s, OH, exch. D2O). IR (KBr) cm−1: C, 61.82; H, 5.67; N, 12.08.
3462 (OH), 3340, 3219 (NH2), 3032 (CH Ar), 2924, 2852
3-[6-Hydroxy-4-methoxy-7-(morpholin-4-ylmethyl)ben-
(CH aliphatic), 1681 (C=O), 1620, 1604, 1583, 1543, 1512 zofuran-5-yl]-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyr-
(NH, C=C). MS (m/z) %: 483 (M++3) 1.45%. Anal. Calcd for azole-1-carbothioamide (6g) Yield 61%. mp 105–107°C.
C25H28N4O6 (480.51): C, 62.49; H, 5.87; N, 11.66. Found: C, 1H-NMR (CDCl3) δ: 2.60–2.95 (4H, m, morpholine H),
62.54; H, 5.94; N, 11.72.
3.40–3.60 (4H, m, morpholine H), 3.76 (1H, dd, J=19.8,
5-(3,4-Dimethoxyphenyl)-3-[6-hydroxy-4-methoxy- 7.5Hz, CH2 pyrazoline), 3.87 (3H, s, OCH3), 4.07 (1H, dd,
7-(morpholin-4-ylmethyl)benzofuran-5-yl]-4,5-dihydro-1H- J=20.1, 7.9Hz, CH2 pyrazoline), 4.14 (3H, s, OCH3), 4.26
pyrazole-1-carboxamide (6c) Yield 66%. mp 206–208°C. (2H, s, CH2), 4.60 (1H, t, CH pyrazoline), 4.65 (2H, s, NH2,
1H-NMR (CDCl3) δ: 2.45–2.65 (4H, m, morpholine H), exch. D2O), 6.82 (1H, d, J=2.2Hz, H-3 furan), 6.95 (2H, d,
3.50–3.85 (6H, m, morpholine H, CH2 pyrazoline), 3.90 (6H, s, J=8.1Hz, H-3′,5′ Ar), 7.48 (2H, d, J=8.2Hz, H-2′,6′ Ar), 7.82
2×OCH3), 3.95 (3H, s, OCH3), 4.04 (2H, s, CH2), 4.40 (2H, br (1H, d, J=2.2Hz, H-2 furan), 13.80 (1H, s, OH, exch. D2O).
s, NH2, exch. D2O), 5.17 (1H, t, CH pyrazoline), 6.93–7.15 (4H, IR (KBr) cm−1: 3421 (OH), 3340, 3280 (NH2), 3020 (CH Ar),
m, H-3 furan, H-2′,5′,6′ Ar), 7.60 (1H, d, J=2.0Hz, H-2 furan), 2916, 2848 (CH aliphatic), 1620, 1602, 1560, 1540, 1510 (NH,
12.20 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3470 (OH), C=C), 1249 (C=S). MS (m/z) %: 498 (M++2) 0.69%. Anal.
3380, 3340 (NH2), 3100 (CH Ar), 2924, 2852 (CH aliphatic), Calcd for C25H28N4O5S (496.58): C, 60.47; H, 5.68; N, 11.28.
1690 (C=O), 1620, 1600, 1590, 1560, 1514 (NH, C=C). MS Found: C, 60.51; H, 5.74; N, 11.34.
(m/z) %: 510 (M+) 0.01%. Anal. Calcd for C26H30N4O7 (510.54):
C, 61.17; H, 5.92; N, 10.97. Found: C, 61.29; H, 5.97; N, 11.09. 7-(morpholin-4-ylmethyl)benzofuran-5-yl]-4,5-dihydro-1H-
5-(3,4-Dimethoxyphenyl)-3-[6-hydroxy-4-methoxy-

1248
Vol. 62, No. 12
pyrazole-1-carbothioamide (6h) Yield 68%. mp 135–138°C. 3308 (NH), 3100 (CH Ar), 2947, 2848 (CH aliphatic), 1606,
1H-NMR (CDCl3) δ: 2.69–2.96 (4H, m, morpholine H), 1575, 1540, 1508 (NH, C=C). MS (m/z) %: 369 (M++1) 100%.
3.42–3.57 (4H, m, morpholine H), 3.65 (1H, dd, J=13.5, 7.2Hz, Anal. Calcd for C20H20N2O5 (368.38): C, 65.21; H, 5.47; N,
CH2 pyrazoline), 3.88 (3H, s, OCH3), 3.95 (6H, s, 2×OCH3), 7.60. Found: C, 65.29; H, 5.51; N, 7.76.
4.05 (1H, dd, J=15.3, 7.2Hz, CH2 pyrazoline), 4.11 (2H, s,
4-Methoxy-5-[5-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-
(7d) Yield 72%. mp
CH2), 4.61 (2H, s, NH2, exch. D2O), 4.82 (1H, t, CH pyrazo- pyrazol-3-yl]benzofuran-6-ol
1
line), 6.80 (1H, d, J=2.0Hz, H-3 furan), 6.92 (1H, d, J=7.8Hz, 154–156°C. H-NMR (CDCl3) δ: 3.33 (1H, dd, J=17.1, 9.3Hz,
H-5′ Ar), 7.16 (1H, s, H-2′ Ar), 7.68 (1H, d, J=7.8Hz, H-6′ CH2 pyrazoline), 3.81 (1H, dd, J=15.3, 9.3Hz, CH2 pyr-
Ar), 7.85 (1H, d, J=2.0Hz, H-2 furan), 13.14 (1H, s, OH, exch. azoline), 3.90 (9H, s, 3×OCH3), 4.04 (3H, s, OCH3), 4.80
D2O). IR (KBr) cm−1: 3423 (OH), 3315, 3250 (NH2), 3040 (CH (1H, t, CH pyrazoline), 6.65 (2H, s, H-2′,6′ Ar), 6.81 (1H, d,
Ar), 2926, 2852 (CH aliphatic), 1618, 1598, 1544, 1512 (NH, J=2.1Hz, H-3 furan), 6.86 (1H, s, H-7 benzofuran), 7.43 (1H,
C=C), 1263 (C=S). MS (m/z) %: 526 (M+) 0.15%. Anal. Calcd d, J=2.1Hz, H-2 furan), 11.60 (1H, s, NH, exch. D2O), 12.80
for C26H30N4O6S (526.60): C, 59.30; H, 5.74; N, 10.64. Found: (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3431 (OH), 3323
C, 59.38; H, 5.78; N, 10.78.
(NH), 3072 (CH Ar), 2939, 2831 (CH aliphatic), 1600, 1560,
3-[6-Hydroxy-4-methoxy-7-(Morpholin-4-ylmethyl)- 1543, 1508 (NH, C=C). MS (m/z) %: 398 (M+) 100%. Anal.
benzofuran-5-yl]-5-(3,4,5-trimethoxyphenyl)-4,5-di- Calcd for C21H22N2O6 (398.41): C, 63.31; H, 5.57; N, 7.03.
hydro-1H-pyrazole-1-carbothioamide (6i) Yield 68%. mp Found: C, 63.37; H, 5.61; N, 7.17.
1
130–132°C. H-NMR (CDCl3) δ: 2.60–3.00 (4H, m, morpho-
5-[5-(4-Hydroxy-3-methoxyphenyl)-4,5-dihydro-1H-pyr-
line H), 3.60–3.80 (4H, m, morpholine H), 3.78 (3H, s, OCH3), azol-3-yl]-4-methoxy-benzofuran-6-ol (7e) Yield 62%; mp
1
3.92 (9H, s, 3×OCH3), 4.03 (1H, dd, J=15.9, 9.3, Hz, CH2 166–168°C. H-NMR (CDCl3) δ: 2.66 (1H, dd, J=15.6, 8.6Hz,
pyrazoline), 4.12 (2H, s, CH2), 4.16 (1H, dd, J=16.2, 9.6Hz, CH2 pyrazoline), 3.75 (1H, dd, J=15.8, 8.6Hz, CH2 pyrazo-
CH2 pyrazoline), 4.30 (2H, s, NH2, exch. D2O), 4.80 (1H, t, line), 4.12 (6H, s, 2×OCH3), 4.38 (1H, t, CH pyrazoline), 6.80
CH pyrazoline), 6.60 (1H, d, J=2.2Hz, H-3 furan), 6.88 (2H, (1H, s, H-7 benzofuran), 6.84 (2H, d, J=7.7Hz, H-5′,6′ Ar),
s, H-2′,6′ Ar), 7.80 (1H, d, J=2.4Hz, H-2 furan), 13.25 (1H, 6.87 (1H, d, J=2.1Hz, H-3 furan), 7.00 (1H, s, H-2′ Ar), 7.46
s, OH, exch. D2O). IR (KBr) cm−1: 3421 (OH), 3336, 3307 (1H, d, J=2.1Hz, H-2 furan), 11.20 (1H, s, NH, exch. D2O),
(NH2), 3080 (CH Ar), 2916, 2848 (CH aliphatic), 1620, 1593, 13.20 (2H, s, 2×OH, exch. D2O). IR (KBr) cm−1: 3446 (OH),
1581, 1558, 1541, 1506 (NH, C=C), 1284 (C=S). MS (m/z) %: 3396 (NH), 3000 (CH Ar), 2918, 2848 (CH aliphatic), 1622,
558 (M++2) 21.13%. Anal. Calcd for C27H32N4O7S (556.63): C, 1591, 1558, 1544 (NH, C=C). MS (m/z) %: 355 (M++1) 5.05%.
58.26; H, 5.79; N, 10.07. Found: C, 58.34; H, 5.83; N, 10.19.
Anal. Calcd for C19H18N2O5 (354.36): C, 64.40; H, 5.12; N,
5-(4-Hydroxy-3-methoxyphenyl)-3-[6-hydroxy-4-methoxy- 7.91. Found: C, 64.47; H, 5.15; N, 7.98.
7-(morpholin-4-ylmethyl)benzofuran-5-yl]-4,5-dihydro-1H-
General Procedure for Synthesis of 4-Methoxy-5-[1-
pyrazole-1-carbothioamide (6j) Yield 60%. mp 110–113°C. (morpholin-4-ylmethyl)-5-((un)substituted)phenyl-4,5-di-
1H-NMR (CDCl3) δ: 2.65–2.78 (4H, m, morpholine H), hydro-1H-pyrazol-3-yl]benzofuran-6-ol (8a–e) To a solu-
4.15–4.21 (6H, m, morpholine H, CH2 pyrazoline), 4.22 (6H, tion of the appropriate compound 7a–e (10mmol) in ethanol
s, 2×OCH3), 4.30 (2H, s, CH2), 4.40 (2H, s, NH2, exch. D2O), (20mL), morpholine hydrochloride (1.36g, 11mmol) and para-
4.80 (1H, t, CH pyrazoline), 6.72 (1H, d, J=2.4Hz, H-3 furan), formaldehyde (0.6g, 20mmol) were added. The mixture was
6.73 (1H, s, H-2′ Ar), 6.89 (2H, d, J=9.4Hz, H-5′,6′ Ar), 7.45 refluxed for 24h. Excess solvent was removed under vacuum
(1H, d, J=2.4Hz, H-2 furan), 13.11 (2H, s, 2×OH, exch. D2O). then cooled and water was added. The mixture was neutral-
IR (KBr) cm−1: 3442 (OH), 3151, 3124 (NH2), 3070 (CH Ar), ized with dilute ammonia and extracted with chloroform.
2920, 2850 (CH aliphatic), 1620, 1612, 1585, 1545 (NH, C=C), Chloroform extract was dried over anhydrous sodium sulfate
1263 (C=S). MS (m/z) %: 514 (M++2) 19.51%. Anal. Calcd for and evaporated under vacuum. The residue was purified using
C25H28N4O6S (512.58): C, 58.58; H, 5.51; N, 10.93. Found: C, preparative thin layer chromatography (TLC) (Chart 2).
58.67; H, 5.48; N, 11.18.
Preparative TLC TLC was prepared by mixing the
General Procedure for Synthesis of 4-Methoxy-5-[5-((un)- adsorbent, silica gel, with a small amount of inert binder,
substituted)phenyl-4,5-dihydro-1H-pyrazol-3-yl]benzofu- calcium sulfate (gypsum) and water. This mixture is
ran-6-ol (7a–e) Hydrazine hydrate 98% (0.55g, 0.55mL, spread as thick slurry on an unreactive carrier sheet, glass
11mmol) was added to a solution of the appropriate propenone (20cm×20cm). The resultant plate was dried and activated by
derivative 2a–e (10mmol) in ethanol (20mL) and the reaction heating in an oven for thirty minutes at 110°C.
mixture was refluxed for 3h. The solvent was concentrated
under reduced pressure and the residue was crystallized from chloroform) were applied to the plate as a thin even layer
methanol (Chart 2).
horizontally, 2cm far from the bottom. When developed
5-[5-(3,4-Dimethoxyphenyl)-4,5-dihydro-1H-pyrazol-3- with the solvent (chloroform/methanol 9:1), the compounds
yl]-4-methoxybenzofuran-6-ol (7c) Yield 65%; mp separated in horizontal bands with yellow color (λmax 366,
The compounds to be separated (about 0.5g dissolved in
1
141–142°C. H-NMR (CDCl3) δ: 3.34 (1H, dd, J=17.4, 9.6Hz, 254nm by UV Vilber Lourmat 77202 were used to determine
CH2 pyrazoline), 3.77 (1H, dd, J=17.4, 9.9Hz, CH2 pyrazo- the compound bands). The lower band (Rf is 0.16–0.32) and
line), 3.89 (6H, s, 2×OCH3), 4.03 (3H, s, OCH3), 4.76 (1H, the upper band (Rf is 0.82–0.95) were scrapped of the baking
t, CH pyrazoline), 6.81 (1H, s, H-7 benzofuran), 6.82 (1H, material. The baking material was extracted with chloroform
d, J=2.1Hz, H-3 furan), 6.86 (1H, s, H-2′ Ar), 6.93 (1H, d, and filtered to give the isolated compound upon evaporating
J=10.2Hz, H-5′ Ar), 6.98 (1H, d, J=9.9Hz, H-6′ Ar), 7.45 solvent. Lower bands yielded compounds 4a–e (with yield
(1H, d, J=2.4Hz, H-2 furan), 11.60 (1H, s, NH, exch. D2O), 60–70%) while upper bands yielded compounds 8a–e (with
11.80 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3440 (OH), yield 30–40%).

December 2014
1249
4-Methoxy-5-[1-(morpholin-4-ylmethyl)-5-phenyl-4,5-di- line), 4.18 (3H, s, OCH3), 4.22 (2H, s, CH2), 4.70 (1H, t, CH
hydro-1H-pyrazol-3-yl]benzofuran-6-ol (8a) Yield 32%. mp pyrazoline), 6.70 (1H, s, H-7 benzofuran), 6.80–6.90 (4H, m,
157–159°C. 1H-NMR (CDCl3) δ: 3.20–3.44 (4H, m, mor- H-3 furan, H-2′,5′,6′ Ar), 7.45 (1H, d, J=2.0Hz, H-2 furan),
pholine H), 3.69–3.74 (4H, m, morpholine H), 3.90 (1H, dd, 11.40 (2H, s, 2×OH, exch. D2O). IR (KBr) cm−1: 3408 (OH),
J=14.7, 6.3Hz, CH2 pyrazoline), 3.98 (3H, s, OCH3), 4.09 3060 (CH Ar), 2918, 2848 (CH aliphatic), 1618, 1560, 1541,
(2H, s, CH2), 4.42 (1H, dd, J=15.0, 6.6Hz, CH2 pyrazoline), 1510 (C=C). MS (m/z) %: 454 (M++1) 1.63%. Anal. Calcd
5.43 (1H, t, CH pyrazoline), 6.74 (1H, d, J=2.1Hz, H-3 furan), for C24H27N3O6 (453.49): C, 63.56; H, 6.00; N, 9.27. Found: C,
6.79 (1H, s, H-7 benzofuran), 7.29–7.55 (6H, m, H-2 furan, 63.69; H, 6.04 ; N, 9.33.
H-2′,3′,4′,5′,6′ Ar), 11.60 (1H, s, OH, exch. D2O). IR (KBr)
In Vitro Vasodilatation Activity Screening The study
cm−1: 3440 (OH), 3059 (CH Ar), 2941, 2841 (CH aliphatic), was performed at the Pharmacology Department, National
1622, 1558, 1541 (C=C). MS (m/z) %: 409 (M++2) 9.47%. Research Centre, Dokki, Egypt, after approval from the Ethics
Anal. Calcd for C23H25N3O4 (407.46): C, 67.80; H, 6.18; N, committee of the centre and in accordance with the recom-
10.31. Found: C, 67.92; H, 6.22; N, 10.42. mendations of the proper care and use of laboratory animals
4-Methoxy-5-[5-(4-methoxyphenyl)-1-(morpholin-4- (NIH publication No. 85–23, revised 1985).
ylmethyl)-4,5-dihydro-1H-pyrazol-3-yl]benzofuran-6-ol (8b)
The vasodilatation activity screening procedures were car-
1
Yield 30%. mp 145–147°C. H-NMR (CDCl3) δ: 3.20–3.35 ried out according to the standard reported techniques46–48) by
(4H, m, morpholine H), 3.50–3.70 (4H, m, morpholine H), testing the effects of the synthesized compounds 3a–e, 4a–e,
3.76 (1H, dd, J=18.0, 6.6Hz, CH2 pyrazoline), 3.84 (3H, s, 5a–e, 6a–j and 8a–e on isolated thoracic aortic rings of male
OCH3), 3.90 (1H, dd, J=16.2, 6.6Hz, CH2 pyrazoline), 3.98 Wister rats (250–350g). Aorta was cut in 3–5mm long rings
(3H, s, OCH3), 4.10 (2H, s, CH2), 5.40 (1H, t, CH pyrazoline), and placed in a vertical chamber “10mL jacketed automatic
6.64 (2H, d, J=6.6Hz, H-3′,5′ Ar), 6.88 (1H, s, H-7 benzofu- multi-chamber organ bath system (model no. ML870B6/C,
ran), 6.85 (1H, d, J=2.1Hz, H-3 furan), 7.30 (2H, d, J=7.1Hz, Panlab, Spain)” filled with modified Krebse Henseleit solu-
H-2′,6′ Ar), 7.45 (1H, d, J=2.1Hz, H-2 furan), 11.40 (1H, s, tion composed of (in mM): NaCl, 118.0; KCl, 4.7; NaHCO3,
OH, exch. D2O). IR (KBr) cm−1: 3415 (OH), 3032 (CH Ar), 25.0; CaCl2, 1.8; NaH2PO4, 1.2; MgSO4, 1.2; glucose, 11.0 and
2931, 2835 (CH aliphatic), 1616, 1560, 1512 (C=C). MS (m/z) oxygenated with carbogen gas (95% O2/5% CO2) at 37 0.5°C.
%: 437 (M+) 1.10%. Anal. Calcd for C24H27N3O5 (437.49): C, Each aorta ring was mounted between two stainless steel
65.89; H, 6.22; N, 9.60. Found: C, 65.96; H, 6.22; N, 9.73.
hooks passed through its lumen. The lower hook was fixed be-
5-[5-(3,4-Dimethoxyphenyl)-1-(morpholin-4-ylmethyl)-4,5- tween two plates, while the upper one was attached to a force
dihydro-1H-pyrazol-3-yl]-4-methoxybenzofuran-6-ol
(8c) displacement transducer (Model no. MLT0201/ Panlab, Spain)
Yield 40%. mp 167–169°C. 1H-NMR (CDCl3) δ: 3.16–3.26 connected to an amplifier (powerLab, AD Instruments Pty.,
(4H, m, morpholine H), 3.49–3.72 (4H, m, morpholine H), Ltd.) which is connected to a computer. The Chart for win-
3.80 (1H, dd, J=20.7, 5.7Hz, CH2 pyrazoline), 3.89 (6H, s, dows (v 3.4) software was used to record and elaborate data.
2×OCH3), 3.93 (3H, s, OCH3), 4.05 (1H, dd, J=20.1, 6.9Hz,
Preparations were stabilized fewer than 2g resting tension
CH2 pyrazoline), 4.21 (2H, s, CH2), 5.70 (1H, t, CH pyrazo- during 2h. The lack of endothelium was confirmed by the
line), 6.73 (1H, s, H-7 benzofuran), 6.80–6.93 (3H, m, H-3 absence of acetylcholine (1µM) vasorelaxent action in aortic
furan, H-5′,6′ Ar), 7.09 (1H, s, H-2′ Ar), 7.49 (1H, d, J=2.0Hz, rings precontracted by noradrenalin (0.1µM). The contractile
H-2 furan), 11.40 (1H, s, OH, exch. D2O). IR (KBr) cm−1: 3433 response to norepinephrine hydrochloride (10−6 M) was mea-
(OH), 3060 (CH Ar), 2935, 2833 (CH aliphatic), 1620, 1560, sured before and after exposure to increasing concentrations
1520, 1516 (C=C). MS (m/z) %: 467 (M+) 0.27%. Anal. Calcd of the tested compounds. The tested compounds as well as
for C25H29N3O6 (467.51): C, 64.23; H, 6.25; N, 8.99. Found: C, prazosin (as reference standard) were dissolved in dimethyl
64.30; H, 6.29; N, 9.14.
sulfoxide (DMSO) as stock solution (10mL of 0.01M). Control
4-Methoxy-5-[1-(morpholin-4-ylmethyl)-5-(3,4,5-trime- experiments were performed in the presence of DMSO alone,
thoxyphenyl)-4,5-dihydro-1H-pyrazol-3-yl]benzofuran-6-ol at the same concentrations as those used with the derivatives
(8d) Yield 40%. mp 175–178°C. 1H-NMR (CDCl3) δ: tested, which demonstrated that the solvent did not affect the
2.85–3.00 (4H, m, morpholine H), 3.40–3.60 (4H, m, mor- contractile response of isolated aorta. The observed vasodi-
pholine H), 3.75 (9H, s, 3×OCH3), 3.84 (1H, dd, J=12.0, latation activity data are reported (Table 1, Fig. 2) and the
6.9Hz, CH2 pyrazoline), 3.95 (3H, s, OCH3), 4.02 (1H, dd, potency (IC50, concentration necessary for 50% reduction of
J=12.0, 6.3Hz, CH2 pyrazoline), 4.11 (2H, s, CH2), 5.72 (1H, maximal norepinephrine hydrochloride induced contracture)
t, CH pyrazoline), 6.50 (1H, s, H-7 benzofuran), 6.62 (1H, d, was determined by the best fit line technique.
J=2.4Hz, H-3 furan), 6.86 (2H, s, H-2′,6′ Ar), 7.14 (1H, d,
QSAR Computational Method All the computational
J=2.4Hz, H-2 furan), 11.40 (1H, s, OH, exch. D2O). IR (KBr) works were performed on Molecular Operating Environment
cm−1: 3442 (OH), 3080 (CH Ar), 2937, 2837 (CH aliphatic), software (MOE version 2008.10.2).52) The structures of 30
1622, 1593, 1560, 1540, 1508 (C=C). MS (m/z) %: 497 (M+) compounds used as training set were sketched using molecular
0.23%. Anal. Calcd for C26H31N3O7 (497.54): C, 62.76; H, 6.28; builder of MOE and each structure was subjected to energy
N, 8.45. Found: C, 62.88; H, 6.35; N, 8.59.
minimization up to 0.01 kcal/mol Å using the MMFF94x force
5-[5-(4-Hydroxy-3-methoxyphenyl)-1-(morpholin- field. Optimization methods were used followed by conforma-
4-ylmethyl)-4,5-dihydro-1H-pyrazol-3-yl]-4-methoxybenzofu- tional search of each energy-minimized structure. The most
1
ran-6-ol (8e) Yield 34%. mp 117–120°C. H-NMR (CDCl3) stable conformer of each structure was selected and saved into
δ: 2.60–2.72 (4H, m, morpholine H), 3.00–3.40 (4H, m, the database to generate the common descriptors. QuaSAR
morpholine H), 3.74 (1H, dd, J=14.7, 7.2Hz, CH2 pyrazoline), descriptor module of MOE was used to calculate descriptors
3.97 (3H, s, OCH3), 4.14 (1H, dd, J=14.4, 6.6Hz, CH2 pyrazo- for each molecule. The probability density functions used are

1250
Vol. 62, No. 12
B., Broberg C. S., Int. J. Cardiol., 171, 351–360 (2014).
Gaussian. The RMSD tolerance was set to 0.5Å. Regression
analysis was performed using vasodilator IC50 as dependent
factor and the calculated descriptors as predictable variables.
In this study, the pool of descriptors was optimized using
principal components analysis (PCA). The optimization start-
ed with the reduction in the number of molecular descriptors
by the determination of the highly inter-correlated descrip-
tor pairs and only one from each pair was selected; then the
descriptors with insignificant variance through the data set
were also rejected. QSAR model was then constructed after
ensuring reasonable correlation of vasodilator activity with the
individual descriptors and minimum inter-correlation among
the descriptors used in the derived model. The quality of the
model was assessed using the statistical parameter r2 and q2.
Molecular Descriptors LogS: Log of the aqueous solubil-
ity (mol/L). This property was calculated from an atom contri-
bution linear atom type model with r2=0.90.
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