Synthesis and anticonvulsant activity of new 6-methyl-1-substituted-4,6- diazaspiro[2.4]heptane-5,7-diones

DOI: 10.1016/j.ejmech.2010.05.034

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European Journal of Medicinal Chemistry p. 3818 - 3830 (2010)

Update date:2022-08-03

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Authors:

He, Xianran

Qiu, Guanpeng

Yang, Jin

Xiao, Yuling

Wu, Zhongyuan

Qiu, Guofu

Hu, Xianming

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Article abstract of DOI:10.1016/j.ejmech.2010.05.034

In the present study on the development of new anticonvulsants, twenty new 6-methyl-1-substituted-4,6-diazaspiro[2.4]heptane-5,7-diones were synthesized and tested for anticonvulsant activity using the maximal electroshock (MES) and subcutaneous pentylene

Full text of DOI:10.1016/j.ejmech.2010.05.034

European Journal of Medicinal Chemistry 45 (2010) 3818e3830

Contents lists available at ScienceDirect

European Journal of Medicinal Chemistry

journal homepage: h ttp://www.elsevier.com/locate/ejmech

Original article

Synthesis and anticonvulsant activity of new 6-methyl-1-substituted-4,

6-diazaspiro[2.4]heptane-5,7-diones

Xianran He, Guanpeng Qiu, Jin Yang, Yuling Xiao, Zhongyuan Wu, Guofu Qiu, Xianming Hu

State Key Laboratory of Virology, College of Pharmacy, Wuhan University, Luojiashan Road, Wuhan 430072, China

a r t i c l e i n f o

a b s t r a c t

Article history:

In the present study on the development of new anticonvulsants, twenty new 6-methyl-1-substituted-

4,6-diazaspiro[2.4]heptane-5,7-diones were synthesized and tested for anticonvulsant activity using the

maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) screens. Their neurotoxicity

was determined by the rotorod test. In this series, all of the alkyl- and aryl-substituted 5,5-cyclo-

propanespirohydantoins showed more or less protection against MES and/or scPTZ models. The most

active of the series was 6-methyl-1-(4-(methylsulfonyl)phenyl)-4,6-diazaspiro[2.4]heptane-5,7-dione

(6t), which showed a MES ED₅₀value of 12.5 mg/kg in mice. The median toxic dose (TD₅₀) was 310 mg/kg,

providing compound 6t with a protection index (PI ¼ TD₅₀/ED₅₀) of 24.8 in the MES test which is better than

phenytoin.

Received 11 December 2009

Received in revised form

14 May 2010

Accepted 14 May 2010

Available online 24 May 2010

Keywords:

6-Methyl-1-substituted-4,6-diazaspiro[2.4]

heptane-5,7-diones

Anticonvulsant activity

MES test

scPTZ test

1. Introduction

cyclooctanespirohydantoins (compound IV) [17] have been

synthesized and shown to have anticonvulsant activity (Fig. 1).

Epilepsy affects approximately 1% of the world’s population

according to epidemiological studies, and often, therapeutic regi-

mens for epileptic patients will involve a change of ﬁrstline and/or

add-on antiepileptic drugs [1]. Despite the increasing under-

standing of the pathogenesis of seizures, about one third of

epilepsies are poorly treated with the available antiepileptic drugs

(AEDs) [2]. In recent times, a large number of new AEDs have

emerged to treat epilepsy, such as topiramate [3], lamotrigine [4],

tiagabine [5], felbamate [6], vigabatrin [7], and zonisamide [8].

Unfortunately, most of the currently utilized AEDs have side effects,

which are sometimes severe and in some cases even fatal [9e11].

Thus, there is an enormous need for the development of novel

anticonvulsant drugs with greater efﬁcacy and fewer side effects.

The SAR studies of clinically available AEDs indicated that

most of the compounds contain a cyclic imides system showed

Following these ﬁndings, in the course of ﬁnding new anti-

convulsants, our attention has been focused on 5,5-cyclo-

propanespirohydantoin with different substituents at N-3 atom.

Compound 1,1,6-trimethyl-4,6-diazaspiro[2.4]-heptane-5,7-dione

(compound V) exhibited more anticonvulsant activity than

other alky substituted derivatives at N-3 atom in the MES

screen (Fig. 1) [18].

In line with the above ﬁndings, in the present study, we report

the synthesis and anticonvulsant activities of 6-methyl-1-

substituted-4,6-diazaspiro[2.4]heptane-5,7- diones derivatives

(compounds VI) to investigate the contribution of different alkyl-

and aryl-substituted 5,5-cyclopropanespirohydantoins to the anti-

convulsant activity. Their chemical structures were characterized

using IR, ¹H NMR, ¹³C NMR, MS and elemental analysis techniques.

In additional, their anticonvulsant activity was evaluated by using

experimental epilepsy models, i.e., maximal electroshock (MES)

and subcutaneous pentylenetetrazole (scPTZ) in mice. The rotorod

assay was performed in mice to evaluate the neurotoxicity of the

compounds. The pharmacological activity of this series can help to

better understand their structureeactivity relationship (SAR).

anticonvulsant activity [12]. Hydantoins,

a class of cyclic

imides, have been demonstrated to possess good anticonvul-

sant property [13,14]. Many hydantoin and spirohydantoin

analogs such as 5,5-cyclopentanespirohydantoins (compound I)

[15], 5,5-cyclohexanespirohydantoins (compound II) [16], 5,5-

cycloheptanespirohydantoins (compound III) [17] and 5,5-

2. Chemistry

The synthesis of target compounds 6aet was accomplished as

presented in Scheme 1. The starting materials 1aet were prepared

* Corresponding author. Tel.: þ86 27 68753532; fax: þ86 27 68754629.

E-mail address: hexianran@yahoo.com.cn (X. Hu).

doi:10.1016/j.ejmech.2010.05.034

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

3819

Compound I

Compound III

Compound IV

Compound II

Compound V

Compound VI

Fig. 1. Structure of compounds I, II, III, IV, V and VI.

by condensation of diethyl malonate with different alkyl or aryl

aldehydes. These compounds underwent cyclopropane formation

with trimethylsulphoxonium ylide to afford the compounds 2aet.

Then monoesters 3aet were obtained after monosaponiﬁcation in

a 1 N NaOH/ethanol (1.1 equiv) solution at room temperature for

12 h [19,20]. This was then converted to corresponding acyl azide

by using ethyl chloroformate in the presence of N-methyl mor-

pholine (NMM) followed by reaction with sodium azide in a one-

3. Pharmacology results and discussion

The anticonvulsant activity and neurotoxicity of the synthesized

compounds were evaluated following the standard procedures

proposed by the NIH anticonvulsant drug development (ADD)

program, via the anticonvulsant screening project (ASP) [21]. The

initial evaluation (Phase I) included the maximal electroshock

seizure (MES), the subcutaneous pentylenetetrazole (scPTZ) and

neurotoxicity.

pot synthesis.

a-Carboethoxy isocyanate 4 was successfully

generated by a Curtius reaction in situ on heating the acyl azide in

anhydrous toluene solution at 75 ^ꢀC. Isocyanate 4 was allowed to

react directly with methylamine (aqueous solution, 30%) without

The MES test is associated with the electrical induction of the

seizure, whereas PTZ test involves a chemical induction to generate

the convulsion. Neurotoxicity is primary determined in the

minimal motor impairment-rotorod screen.

isolation. The desired

a-carboethoxy ureas 5aet were readily

obtained. Finally, compounds 5aet cyclized on treatment with Na

(1.1 equiv) in EtOH and provided 6aet in good yields

(yield ꢁ 93%).

The compounds 6aet were administrated intraperitoneally (ip)

into the mice using dose of 30, 100 and 300 mg/kg and the obser-

vations were taken at two different time intervals (0.5 h and 4.0 h).

Neurotoxicity was measured by the rotorod test. The results are

shown in Table 1.

The initial anticonvulsant evaluation showed that all

compounds 6aet, with different substituents at cyclopropane ring

of 5,5-cyclopropanespirohydantoin, were effective in ip MES and/or

scPTZ screens.

The chemical structures of the compounds synthesized were

elucidated on the basis of IR, ¹H NMR, ¹³C NMR, MS and elemental

analysis. The detailed physical and analytical data are listed in

Section 5.

All of these compounds were prepared as racemic mixtures and

no attempt was made to resolve the enantiomers.

Scheme 1. General method for the synthesis of compounds 6aet.

3820

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

Table 1

Anticonvulsant activity and neurotoxocity of compounds 6a-t administered intraperitoneally to mice.

Compound

Dose (mg/kg)

Intraperitoneal injection in mice^a

MES^b

scPTZ^c

NT^d

0.5 h

4.0 h

0.5 h

4.0 h

0.5 h

4.0 h

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

100

300

1/4

2/4

0/4

1/3

2/4

0/4

2/4

3/4

2/4

1/4

2/4

0/4

1/3

2/4

1/4

2/4

0/4

1/4

2/4

1/4

2/4

1/4

2/4

1/4

2/4

0/4

1/4

0/4

2/4

3/4

0/4

2/4

0/4

1/4

2/4

0/4

2/4

0/4

2/4

3/4

30^e

1/4

3/4

0/4

0/3

1/4

0/4

1/4

2/4

1/4

2/4

1/4

0/4

1/4

0/4

0/3

1/4

2/4

1/4

0/4

1/4

0/4

2/4

0/4

2/4

0/4

1/4

2/4

0/4

1/4

2/4

0/4

2/4

0/4

2/4

1/4

2/4

0/4

1/4

0/4

2/4

0/4

2/4

0/4

0/3

0/4

0/3

0/4

0/3

0/4

1/4

1/3

2/4

1/4

0/3

2/4

0/4

0/3

0/4

0/3

0/4

0/3

2/4

0/4

0/3

2/4

0/4

0/3

0/4

0/3

1/4

0/4

2/3

3/4

0/4

2/4

1/4

0/4

2/4

1/4

2/4

0/4

0/3

1/4

0/4

0/3

0/4

0/3

0/4

0/3

0/4

1/4

2/4

e^f

0/4

0/3

0/4

0/3

2/4

0/4

0/3

0/4

0/3

1/4

0/4

0/3

0/4

0/3

2/4

0/4

0/3

0/4

0/3

1/4

0/4

0/3

0/4

0/3

0/4

0/3

2/4

0/4

0/3

1/4

0/4

1/4

0/4

1/4

0/4

1/4

2/4

0/4

0/3

0/4

0/3

0/4

0/3

0/4

0/3

0/4

1/4

2/4

0/4

0/3

0/4

0/3

0/4

1/4

0/3

2/4

0/4

0/3

0/4

1/4

0/3

2/4

0/4

0/3

0/4

0/3

2/4

0/4

0/3

2/4

0/4

0/3

0/4

0/3

1/4

0/4

0/3

1/4

0/4

0/3

2/4

0/4

0/3

0/4

0/3

0/4

0/3

0/4

2/4

3/4

0/4

1/4

2/4

0/4

1/4

0/4

2/4

3/4

0/4

0/3

2/4

100

0/4

0/3

2/4

0/4

0/3

2/4

0/4

0/3

2/4

0/4

0/3

0/4

0/3

0/4

0/3

0/4

0/3

1/4

0/4

0/3

0/4

0/3

0/4

0/3

2/4

0/4

0/3

2/4

0/4

0/3

0/4

0/3

0/4

0/3

0/4

0/3

0/4

2/4

0/4

2/4

0/4

2/4

0/4

1/4

2/4

0/4

0/3

0/4

100

300

100

300

100

300

100

300

Phenytoin^g

Ethosuximide^h

100

300

30, 100, and 300 mg/kg of doses were administered ip. in mice. The animals were examined at 0.5 h and 4.0 h after injection were administered.

Number of animals protected/number of animals tested in the MES test.

Number of animals protected/number of animals tested in the scPTZ test.

Number of animals exhibiting toxicity/number of animals tested in the rotorod test.

The data in the reference drug entries indicate the minimal dose whereby biological activity was demonstrated in half or more of the tested mice.

A dash indicates the absence of anticonvulsant activity and neurotoxicity at the maximum dose administered (300 mg/kg).

Data from Ref. [31].

Data from Ref. [32].

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

3821

Table 3

In the MES test, compounds 6a, 6d, 6e, 6g, 6h, 6j, 6k, 6l, 6o and

Anticonvulsant evaluation (scPTZ) of compounds after oral administration in rats.

6t were active against MES test at 30 mg/kg. The most active of

these compounds were 6d, 6g, 6o and 6t, which presented 50% of

protection at dose of 30 mg/kg at 0.5 h. Interestingly, compound 6t

continued to protect from the seizures at the same dose at 4.0 h

also. It indicates that 6t have rapid onset and long duration of

anticonvulsant at lower dose. Compounds 6d, 6g and 6o were also

active at 4.0 h but at the higher dose of 100 mg/kg.

Compounds that were active at a dose of 100 mg/kg at 0.5 h in

MES screen included 6a, 6c, 6e, 6h, 6j, 6k, 6l, 6n and 6p, whereas

compounds 6b, 6f, 6i, 6q, 6r and 6s were active at a dose of 300 mg/

kg. The majority of these compounds were active in the MES test

both at 0.5 h and 4.0 h. This showed that they have quick onset and

long duration of anticonvulsant at higher dose. From these series

6b, 6e, 6f, 6h, 6p and 6q were active only at 0.5 h, indicating that

they have rapid onset and short duration of anticonvulsant activity.

Compounds 6a, 6c, 6i, 6k, 6l, 6m, 6n and 6r were active at 4.0 h at

a dose of 300 mg/kg, among these compounds 6m showed only

activity at 4.0 h.

Compounds

Oral administration to rats^a

scPTZ screening

NT screening

0.25 h 0.5 h 1 h 2 h 4 h 0.25 h 0.5 h 1 h 2 h 4 h

Ethosuximide^b

ND ND ND

ND, not determined.

The compounds were administered in a dose of 50 mg/kg. The date in the table

indicate the number of rats of four, which were protect.

Reference drug, date from Ref. [34].

tested animals at the time of 0.5 h (6g, 6o), 2 h (6o). Compound 6d

protected 25% of rats at the time of 0.25 h and showed the peak of

50% protection at 1.0 h. The neurotoxicity screen showed that they

were non-toxic when given orally.

In the scPTZ screen, compounds 6d, 6e, 6o and 6t were active

against scPTZ test at 30 mg/kg, compounds that showed protection

at 0.5 h were 6d, 6e, 6h, 6i, 6l, 6m, 6n, 6o and 6t. Among these

compounds 6o and 6t showed anti-scPTZ activity at the dose of

100 mg/kg and 300 mg/kg at time periods 0.5 and 4.0 h that was

equivalent to ethosuximide used as reference anticonvulsant drug.

Compounds 6b and 6k were active only at 4.0 h at a dose of 300 mg/

kg indicative of the long duration of action of these compounds.

In the neurotoxicity screen, compounds that did not show any

neurotoxicityatthe highestdose(300 mg/kg)included6d, 6f, 6i, 6m,

6n and 6o. These compounds did not cause any motor impairment at

the three doses at the two time periods. Compounds 6c, 6e and 6s

were found neurotoxicity at the minimal dose (30 mg/kg).

Compounds 6c, 6e, 6g, 6h, 6l and 6q were less neurotoxic than

phenytoin and exhibited motor impairmentat the doseof 300 mg/kg

at 0.5 h and also 4.0 h (6c, 6q). Compound 6p revealed neurotoxicity

at a dose of 100 mg/kg. Compound 6s showed neurotoxicity at the

minimum dose administered.

After the initial ip mouse screen, compounds 6d, 6g, 6o and 6t

were selected and examined for future oral evaluation in rats

(according to the Antiepileptic Drug Development (ADD) Program).

The anti-MES activity and neurotoxicity determined in rats treaded

with 30 mg/kg (po) of the compounds under investigation are

presented in Table 2.

As shown in Table 2, the most active compound 6t was active in

all time periods except at the time of 0.25 h, it provided 50%

protection at the time of 0.5 h and 1.0 h and 75% protection at the

time of 2.0 h and 4.0 h which showed long duration of anticon-

vulsant as well as phenytoin. Compounds 6g and 6o were moder-

ately effective in rat MES oral screen and protected only 25% of

Compounds 6l, 6m, 6o and 6t which were active in the ip scPTZ

screen after 0.5 h at a dose of 100 mg/kg in mice, were selected to

investigate the subcutaneous pentylenetetrazole test after oral

administration into rats. The results are presented in Table 3.

The results showed that compounds 6l, 6o and 6t protected only

25% of tested animals at time of 0.5 h (6l), 1.0 h (6o, 6t). Compounds

6m showed no activity at any time periods. All the compounds

selected were less active than ethosuximide which is the model

substance effective in this screen. All the compounds were found

inactive devoid of neurotoxicity.

In the Phase-II anticonvulsant screen, the most active

compound 6t was quantitatively evaluated for its anticonvulsant

activity (ED₅₀) and neurotoxicity (TD₅₀). The results are shown in

Table 4. The compound displayed encouraging activities, which was

comparable to standard drug. In the mice ip MES and scPTZ screens

compound 6t revealed ED₅₀values of 12.5 (42.5 mmol) and 427

(1452.4 mmol) mg/kg respectively. The TD₅₀was 310 mg/kg

(1054.4 mmol/kg), providing compound 6t with protective index

(TD₅₀/ED₅₀) of 24.8 in the MES test and 0.73 in the scPTZ test. The

time to peak effect (TPE) for this molecule was 0.5 h.

In the preliminary anticonvulsant screen, all of the alkyl- and

aryl-substituted 5,5-cyclopropanespirohydantoins showed better

protection against ip MES test but less response toward scPTZ test.

Compounds with straight chain propyl (6c) and butyl (6d)

substituents at propane ring have shown more active than other

alkyl-substituted derivatives, the introduction of the shorter or

branch alkyl chain (6b, 6e, 6f) resulted in decreased anticonvulsant

activity.

When the alkyl groups were replaced by a phenyl ring, substi-

tution of a small lipophilic group like ﬂuorine (6o) or chlorine (6p)

at the para position of phenyl ring resulted in increased anticon-

vulsant activity. On the other hand, the ﬂuoro substituent was more

potent and less neurotoxic than the chloro and bromo derivatives.

The anticonvulsant properties depended also on the location of the

substituents at the phenyl ring. The chlorine substituted at 2-

position of phenyl ring was less active than 4-position. Substitution

with electron-donating groups like methyl (6h) and methoxy (6i) at

the 4-position of the phenyl ring of (6g) exhibited decrease in

anticonvulsant activity compared to (6g) in MES test. The inclusion

of more methoxy groups (6je6n) to phenyl ring of 6g caused less

activity and neurotoxic than the methyl- and single methoxy-

derived compounds. Compound with 2-furan ring at cyclopropane

ring (6s) resulted in the loss of protection activity, it seems that

phenyl ring is especially important for anti-MES protection [22]. It

is also noteworthy that 6-methyl-1-(4-(methylsulfonyl)phenyl)-

4,6-diazaspiro[2.4]heptane-5,7-dione (6t) was found to exhibit

Table 2

Anticonvulsant evaluation (MES) of compounds after oral administration in rats.

Compounds Oral administration to rats^a

MES screening

NT screening

0.25 h 0.5 h 1 h 2 h 4 h 0.25 h 0.5 h 1 h 2 h 4 h

Phenytoin^b

ND ND ND

ND, not determined.

The compounds were administered in a dose of 30 mg/kg. The date in the table

indicate the number of rats of four, which were protect.

Reference drug, date from Ref. [33].

3822

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

Table 4

Phase-II quantitative anticonvulsant evaluation in mice (test drug administered i.p.).

PI^c

TPE^d

Compounds

ED₅₀

MES

TD₅₀

scPTZ

MES

scPTZ

12.5 (11.3e16.7)^e

9.5 (8.1e10.4)

427 (413e441)

>300

310 (285.2e352.4)

65.5 (52.5e72.9)

24.8

6.9

0.73

<0.22

0.5 h

2.0 h

Phenytoin^f

Number of animals used: 10; solvent used: 0.5% Carboxymethyl cellulose-0.9% saline standard (0.1 ml, i.p.).

Dose in milligrams per kilogram body mass.

Minimal toxicity which was determined by rotorod test 30 min after the test drug was administered.

Protection index (TD₅₀/ED₅₀).

The time to peak effect (TPE) in h.

Date in parentheses are the 95% conﬁdence limits.

Date from Ref. [35].

more promising activity than other phenyl-substituted in MES test,

which showed equivalent activity to phenytoin used as reference

anticonvulsant drug. It may be proved sulfonyl group displayed

a better activity proﬁle compared to other groups in MES test [23].

6H, J ¼ 4.23 Hz, 2ꢃ CH₃), 1.13(m, 1H, HCH), 1.28(2t, 6H, J ¼ 7.12 Hz,

2ꢃ CH₃), 1.36(m, 1H, HCH), 1.72(m, 1H, CH), 4.13(q, 2H, CH₂,

J ¼ 7.12 Hz), 4.23(q, 2H, CH₂, J ¼ 7.12 Hz). ¹³C NMR (150 MHz, CDCl₃):

13.89, 14.11, 20.28, 21.70, 22.37, 28.55, 34.86, 36.04, 61.16, 61.22,

168.36, 170.45. Anal. Calcd for C₁₂H₂₀O₄: C, 63.14; H, 8.83; found: C,

63.33; H, 8.65%.

4. Conclusions

In conclusion, the series of new 6-methyl-1-substituted-4,6-

diazaspiro[2.4]heptane-5,7-diones were synthesized and tested for

their anticonvulsant activity as shown by MES and scPTZ models in

comparison with standard drugs. In neurotoxicity studies some of

the active compounds were devoid of toxicity. The most potent

compound was 6-methyl-1-(4-(methylsulfonyl)phenyl)-4,6-dia-

zaspiro[2.4] heptane-5,7-dione (6t) with ED₅₀value of 12.5 mg/kg,

this compound showed lower neurotoxicity (TD₅₀¼ 310 mg/kg)

and higher protective index (PI ¼ 24.8) than phenytoin.

5.1.1.2. Diethyl 2-ethylcyclopropane-1,1-dicarboxylate (2b). Color-

less oil. Yield: 94%; IR (KBr, cm^ꢂ1): 2974(CH), 1726(C]O). ¹H NMR

(400 MHz, CDCl₃):

d 0.86(1H, m, CH), 1.07(m, 3H, CH₃), 1.21(t, 3H,

CH₃, J ¼ 7.12 Hz), 1.27(t, 3H, CH₃, J ¼ 7.12 Hz), 1.39(m, 2H, HCH), 1.76

(2H, m, CH₂), 4.17(q, 2H, CH₂, J ¼ 7.12 Hz), 4.21(q, 2H, CH₂,

J ¼ 7.12 Hz). ¹³C NMR (150 MHz, CDCl₃):

d 13.88, 14.12, 14.25, 21.26,

28.32, 32.96, 34.11, 61.52, 61.75, 168.13, 170.26. Anal. Calcd for

C₁₁H₁₈O₄: C, 61.66; H, 8.47; found: C, 61.93; H, 8.62%.

5.1.1.3. Diethyl 2-propylcyclopropane-1,1-dicarboxylate (2c). Color-

less oil. Yield: 96%; IR (KBr, cm^ꢂ1): 2959(CH), 1742(C]O). ¹H NMR

5. Experimental protocols

(400 MHz, CDCl₃):

d 0.89(m, 3H, CH₃), 1.00(m, 2H, CH₂), 1.21(t, 3H,

5.1. Chemistry

CH₃, J ¼ 7.14 Hz), 1.24(t, 3H, CH₃, J ¼ 7.14 Hz), 1.29e1.54 and

1.88e2.12(m, 5H, CH₂, and Cpr-CHCH₂), 4.12(q, 2H, CH₂, J ¼ 7.14 Hz),

All the chemicals and solvent were purchased from commercial

sources. Solvents and reagents were dried and puriﬁed according to

the literature methods. Melting points were uncorrected and

measured on an XT-4 apparatus. IR spectra were recorded from KBr

pellets at a range of 400e4000 cm^ꢂ1on a PerkineElmer (Spectrum

One) spectrometer. ¹H and ¹³C NMR spectra were obtained on

a Varian Mercury VX400 apparatus in DMSO-d₆and CDCl₃with

TMS as internal standard. The elemental analysis (C, H, N) data were

obtained from a VarioEL III (German) elemental analyzer. The mass

spectra (MS) were recorded on AMD-604 Mass Spectrometer

operating at 70 eV.

4.27(q, 2H, CH₂, J ¼ 7.14 Hz). ¹³C NMR (150 MHz, CDCl₃):

d 13.72,

14.02, 14.13, 21.09, 22.05, 28.00, 32.69, 34.07, 61.20, 61.28, 168.32,

170.57. Anal. Calcd for C₁₂H₂₀O₄: C, 63.14; H, 8.83; found: C, 62.97;

H, 8.98%.

5.1.1.4. Diethyl 2-butylcyclopropane-1,1-dicarboxylate (2d). Color-

less oil. Yield: 94%; IR (KBr, cm^ꢂ1): 2992(CH), 1732(C]O). ¹H NMR

(400 MHz, CDCl₃):

d 0.88(m, 3H, CH₃), 1.09e2.16(overlapping m,

15H, 3ꢃ CH₂, Cpr-CHCH₂, and 2ꢃ CH₃), 4.13(q, 2H, CH₂, J ¼ 7.12 Hz),

4.25(q, 2H, CH₂, J ¼ 7.12 Hz). ¹³C NMR (150 MHz, CDCl₃):

d 13.92,

14.03, 14.14, 21.08, 22.31, 28.25, 28.34, 31.02, 34.16, 61.21, 61.29,

168.32, 170.58. Anal. Calcd for C₁₃H₂₂O₄: C, 64.44; H, 9.15; found: C,

63.21; H, 9.45%.

5.1.1. General procedure for the synthesis of compounds 2aet

To a stirred suspension of sodium hydride (2.12 g, 0.044 mol,

57% in oil dispersion) in dry dimethyl sulfoxide (DMSO) (100 ml)

under nitrogen was added of trimethylsulfoxonium iodide (TMSI)

(9.6 g, 0.044 mol) in a single portion [24]. After frothing ceased, the

grey-white suspension was cooled to 15 ^ꢀC, and to this mixture was

added with stirring a solution of 7.4 g (0.04 mol) of 1 in 25 ml of

DMSO in one portion. The stirring was continued for 10 min at

15 ^ꢀC, overnight at room temperature and 4 h at 50e60 ^ꢀC. After it

was cooled and 400 ml of ice-water was added to it, the mixture

was extracted with ether, and the combined ether fractions were

washed with brine, dried over anhydrous sodium sulfate (Na₂SO₄),

5.1.1.5. Diethyl

Colorless oil. Yield: 94%; IR (KBr, cm^ꢂ1): 3095 and 2987(CH), 1726

(C]O). ¹H NMR (400 MHz, CDCl₃):

2-isobutylcyclopropane-1,1-dicarboxylate

(2e).

0.93(d, 3H, CH₃, J ¼ 5.92 Hz),

0.95(d, 3H, CH₃, J ¼ 5.92 Hz), 0.98e1.01(m, 1H, HCH), 1.27(t, 3H,

CH₃, J ¼ 7.12 Hz), 1.29(t, 3H, CH₃, J ¼ 7.12 Hz), 1.33e1.52(m, 3H, CH₂,

and HCH), 1.64e1.74(m, 1H, CH), 1.88e1.93(m, 1H, CH), 4.08(q, 2H,

CH₂, J ¼ 7.12 Hz), 4.22(q, 2H, CH₂, J ¼ 7.12 Hz). ¹³C NMR (150 MHz,

CDCl₃): d 14.06, 14.18, 21.42, 22.27, 22.59, 26.78, 28.10, 33.79, 37.42,

61.25, 61.35, 168.38, 170.65. Anal. Calcd for C₁₃H₂₂O₄: C, 64.44; H,

9.15; found: C, 63.56; H, 9.33%.

and evaporated to give

a pale yellow oil without further

puriﬁcation.

5.1.1.6. Diethyl 2-(pentan-3-yl)cyclopropane-1,1-dicarboxylate (2f).

Colorless oil. Yield: 94%; IR (KBr, cm^ꢂ1): 2966(CH), 1726 and 1685

5.1.1.1. Diethyl 2-isopropylcyclopropane-1,1-dicarboxylate (2a).

(C]O). ¹H NMR (400 MHz, CDCl₃):

0.88(t, 3H, CH₃, J ¼ 6.98 Hz), 1.25(t, 3H, CH₃, J ¼ 7.12 Hz), 1.28(t, 3H,

0.84(t, 3H, CH₃, J ¼ 6.98 Hz),

Colorless oil. Yield: 95%; IR (KBr, cm^ꢂ1): 3088 and 2987(CH), 1728

(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.87(m, 1H, Cpr-CH), 1.01(2d,

CH₃, J ¼ 7.12 Hz),1.19e1.98(overlapping m, 7H, 2ꢃ CH₂, CH, and Cpr-

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

3823

HCH), 2.87(m, 1H, CH, Cpr-H), 4.07(q, 2H, CH₂, J ¼ 7.12 Hz), 4.13(q,

(m,1H, HCH), 2.29e2.31(m, 1H, HCH), 3.25e3.30(m,1H, CH), 3.78(s,

3H, OCH₃), 3.81(s, 3H, OCH₃), 3.94(q, 2H, CH₂, J ¼ 7.12 Hz), 4.28(q,

2H, CH₂, J ¼ 7.12 Hz), 6.72e6.74(m, 1H, C₄-ArH), 6.80e6.83(m, 1H,

C₅-ArH), 6.94e6.96(m, 1H, C₆-ArH). ¹³C NMR (150 MHz, CDCl₃):

2H, eCH₂, J ¼ 7.12 Hz). ¹³C NMR (150 MHz, CDCl₃):

d 10.50, 10.85,

14.05, 14.13, 20.73, 25.58, 25.80, 33.38, 33.78, 39.55, 61.23, 61.28,

168.87, 170.58. Anal. Calcd for C₁₄H₂₄O₄: C, 65.60; H, 9.44; found: C,

63.23; H, 9.78%.

13.03, 14.07, 20.92, 31.26, 36.73, 55.34, 60.62, 62.12, 62.48, 112.45,

121.93, 123.79, 128.93, 147.66, 153.42, 169.59, 170.43. Anal. Calcd for

C₁₇H₂₂O₆: C, 63.34; H, 6.88; found: C, 63.63; H, 6.97%.

5.1.1.7. Diethyl 2-phenylcyclopropane-1,1-dicarboxylate (2g). Color-

less oil. Yield: 95%; IR (KBr, cm^ꢂ1): 3065 and 2980(CH), 1726 (C]O)

and 1645 (C]C). ¹H NMR (400 MHz, CDCl₃):

0.84(t, 3H, CH₃,

5.1.1.13. Diethyl 2-(2,3,4-trimethoxyphenyl)cyclopropane-1,1-dicar-

boxylate (2m). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3034 and

2978(CH), 1742 (C]O) and 1648 (C]C). ¹H NMR (400 MHz, CDCl₃):

J ¼ 7.12 Hz), 1.27(t, 3H, CH₃, J ¼ 7.12 Hz), 1.66e1.73(m, 1H, HCH),

2.16e2.19(m, 1H, HCH), 3.11e3.20(m, 1H, CH), 3.81(q, 2H, CH₂,

J ¼ 7.12 Hz), 4.12(q, 2H, CH₂, J ¼ 7.12 Hz), 7.19e7.31(m, 5H, ArH). ¹³

0.93(t, 3H, CH₃, J ¼ 7.12 Hz), 1.29(t, 3H, CH₃, J ¼ 7.12 Hz), 1.68e1.71

NMR (150 MHz, CDCl₃):

13.44, 14.12, 18.87, 32.32, 37.43, 61.12,

(m, 1H, HCH), 2.27e2.31(m, 1H, HCH), 3.21e3.25(m, 1H, CH), 3.82(s,

3H, OCH₃), 3.84(s, 3H, OCH₃), 3.85(s, 3H, OCH₃), 3.94(q, 2H, CH₂,

J ¼ 7.12 Hz), 4.16(q, 2H, CH₂, J ¼ 7.12 Hz), 6.59(d, 1H, J ¼ 8.64 Hz, C₅-

ArH), 6.84(d, 1H, J ¼ 8.64, C₆-ArH). ¹³C NMR (150 MHz, CDCl₃):

61.89, 127.33, 128.09, 128.63, 134.87, 166.86, 169.99. Anal. Calcd for

C₁₅H₁₈O₄: C, 68.68; H, 6.92; found: C, 68.89; H, 7.03%.

5.1.1.8. Diethyl 2-p-tolylcyclopropane-1,1-dicarboxylate (2h). Color-

less oil. Yield: 92%; IR (KBr, cm^ꢂ1): 3054 and 2983(CH), 1722 (C]O)

d 13.24, 14.12, 22.02, 32.89, 38.34, 56.67, 60.98, 61.03, 62.22, 62.75,

107.12, 120.23, 124.37, 141.97, 154.23, 154.76, 169.18, 170.52. Anal.

Calcd for C₁₈H₂₄O₇: C, 61.35; H, 6.86; found: C, 61.55; H, 7.15%.

and 1643 (C]C). ¹H NMR (400 MHz, CDCl₃):

d 0.72(t, 3H, CH₃,

J ¼ 7.12 Hz), 1.12(t, 3H, CH₃, J ¼ 7.12 Hz), 2.24e2.27(m, 1H, HCH),

2.32(s, 3H, Ar-CH₃), 2.36e2.38(m, 1H, HCH), 3.34e3.38(m, 1H, CH),

3.83(q, 2H, CH₂, J ¼ 7.12 Hz), 4.02(q, 2H, CH₂, J ¼ 7.12 Hz), 7.10e7.16

5.1.1.14. Diethyl 2-(3,4,5-trimethoxyphenyl)cyclopropane-1,1-dicar-

boxylate (2n). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3054 and

2980(CH), 1732 (C]O) and 1655 (C]C). ¹H NMR (400 MHz, CDCl₃):

(m, 4H, ArH). ¹³C NMR (150 MHz, CDCl₃):

d 13.33, 14.04, 19.56, 22.11,

33.89, 39.62, 62.07, 62.89, 129.41, 129.89, 133.12, 138.43, 167.87,

169.76. Anal. Calcd for C₁₆H₂₀O₄: C, 69.54; H, 7.30; found: C, 69.84;

H, 7.47%.

0.92(t, 3H, CH₃, J ¼ 7.12 Hz), 1.28(t, 3H, CH₃, J ¼ 7.12 Hz), 1.66e1.69

(m,1H, HCH), 2.22e2.25(m,1H, HCH), 3.34e3.36(m,1H, CH), 3.81(s,

3H, C₄-ArOCH₃), 3.83(s, 6H, C_3,5-ArOCH₃), 3.89(q, 2H, CH₂,

J ¼ 7.12 Hz), 4.13(q, 2H, CH₂, J ¼ 7.12 Hz), 6.43(s, 2H, ArH). ¹³C NMR

5.1.1.9. Diethyl 2-(4-methoxyphenyl)cyclopropane-1,1-dicarboxylate

(150 MHz, CDCl₃): d 13.23, 14.12, 21.56, 33.89, 40.76, 56.67, 60.87,

(2i). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3054 and 2980(CH),

62.32, 62.78, 106.65, 130.23, 138.21, 154.31, 169.76, 170.23. Anal.

Calcd for C₁₈H₂₄O₇: C, 61.35; H, 6.86; found: C, 61.67; H, 7.02%.

1732 (C]O) and 1655 (C]C). ¹H NMR (400 MHz, CDCl₃):

d 0.72(t,

3H, CH₃, J ¼ 7.12 Hz), 1.11(t, 3H, CH₃, J ¼ 7.12 Hz), 2.24e2.27(m, 1H,

HCH), 2.29e2.32(m, 1H, HCH), 3.33e3.37(m, 1H, CH), 3.72(s, 3H,

OCH₃), 3.87(q, 2H, CH₂, J ¼ 7.12 Hz), 4.04(q, 2H, CH₂, J ¼ 7.12 Hz),

6.79(d, 2H, J ¼ 8.64 Hz, C_3,5-ArH), 7.14(d, 2H, J ¼ 8.64 Hz, C_2,6-ArH).

5.1.1.15. Diethyl 2-(4-ﬂuorophenyl)cyclopropane-1,1-dicarboxylate

(2o). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3034 and 2986(CH),

1749 (C]O) and 1653 (C]C). ¹H NMR (400 MHz, CDCl₃):

d 0.89(t,

¹³C NMR (150 MHz, CDCl₃):

13.34, 14.03, 21.83, 32.98, 40.76, 55.33,

3H, CH₃, J ¼ 7.12 Hz), 1.27(t, 3H, CH₃, J ¼ 7.12 Hz), 1.68e1.71(m, 1H,

HCH), 2.11e2.14(m, 1H, HCH), 3.16e3.20(m, 1H, CH), 3.88(q, 2H,

CH₂, J ¼ 7.12 Hz), 4.26(q, 2H, CH₂, J ¼ 7.12 Hz), 6.93e6.97(m, 2H,

C_3,5-ArH), 7.16e7.17(m, 2H, C_2,6-ArH). ¹³C NMR (150 MHz, CDCl₃):

62.69, 62.90, 113.94, 125.73, 130.68, 159.98, 169.82, 170.03. Anal.

Calcd for C₁₆H₂₀O₅: C, 69.74; H, 6.90; found: C, 69.92; H, 7.11%.

5.1.1.10. Diethyl 2-(2,5-dimethoxyphenyl)cyclopropane-1,1-dicarbox-

ylate (2j). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3034 and 2982

(CH), 1738 (C]O) and 1656 (C]C). ¹H NMR (400 MHz, CDCl₃):

d 13.66, 13.99, 18.73, 31.22, 37.24, 61.11, 61.65, 114.82, 130.17, 160.83,

163.27, 166.45, 169.62. Anal. Calcd for C₁₅H₁₇FO₄: C, 64.28; H, 6.11;

found: C, 64.68; H, 6.46%.

0.92(t, 3H, CH₃, J ¼ 7.12 Hz), 1.27(t, 3H, CH₃, J ¼ 7.12 Hz), 1.15e1.17

(m, 1H, HCH), 2.14e2.16(m, 1H, HCH), 3.19e3.24(m, 1H, CH), 3.71(s,

3H, OCH₃), 3.75(s, 3H, OCH₃), 3.82(q, 2H, CH₂, J ¼ 7.12 Hz), 4.27(q,

2H, CH₂, J ¼ 7.12 Hz), 6.69e6.72(m, 2H, C_3,4-ArH), 6.74e6.78(m, 1H,

5.1.1.16. Diethyl 2-(4-chlorophenyl)cyclopropane-1,1-dicarboxylate

(2p). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3040 and 2978(CH),

1752 (C]O) and 1658 (C]C). ¹H NMR (400 MHz, CDCl₃):

d 0.87(t,

C₆-ArH). ¹³C NMR (150 MHz, CDCl₃):

12.13, 13.32, 21.83, 30.77,

3H, CH₃, J ¼ 7.12 Hz), 1.28(t, 3H, CH₃, J ¼ 7.12 Hz), 1.69e1.72(m, 1H,

HCH), 2.09e2.12(m, 1H, HCH), 3.18e3.22(m, 1H, CH), 3.86(q, 2H,

CH₂, J ¼ 7.12 Hz), 4.19(q, 2H, CH₂, J ¼ 7.12 Hz), 7.22(d, 2H, C_2,6-ArH,

J ¼ 8.36 Hz), 7.35(d, 2H, C_3,5-ArH, J ¼ 8.36 Hz). ¹³C NMR (150 MHz,

36.75, 54.52, 54.78, 61.34, 62.23, 109.55, 112.34, 115.73, 124.33,

151.89, 152.42, 169.48, 170.87. Anal. Calcd for C₁₇H₂₂O₆: C, 63.34; H,

6.88; found: C, 63.66; H, 6.96%.

CDCl₃):

d 13.43, 14.03, 19.89, 32.75, 38.52, 61.46, 61.87, 128.88,

5.1.1.11. Diethyl 2-(3,4-dimethoxyphenyl)cyclopropane-1,1-dicarbox-

ylate (2k). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3042 and 2989

(CH), 1747 (C]O) and 1648 (C]C). ¹H NMR (400 MHz, CDCl₃):

130.75, 132.64, 134.84, 166.85, 169.93. Anal. Calcd for C₁₅H₁₇ClO₄: C,

60.71; H, 5.77; found: C, 60.88; H, 5.48%.

0.93(t, 3H, CH₃, J ¼ 7.12 Hz), 1.29(t, 3H, CH₃, J ¼ 7.12 Hz), 1.66e1.71

5.1.1.17. Diethyl 2-(2-chlorophenyl)cyclopropane-1,1-dicarboxylate

(m, 1H, HCH), 2.11e2.14(m, 1H, HCH), 3.16e3.21(m, 1H, CH), 3.84(s,

3H, OCH₃), 3.86(s, 3H, OCH₃), 3.88(q, 2H, CH₂, J ¼ 7.12 Hz), 4.26(q,

2H, CH₂, J ¼ 7.12 Hz), 6.72e6.77(m, 3H, ArH). ¹³C NMR (150 MHz,

(2q). Colorless oil. Yield: 94%; IR (KBr, cm^ꢂ1): 3034 and 2988(CH),

1743 (C]O) and 1664 (C]C).¹H NMR (400 MHz, CDCl₃):

d 0.86(t, 3H,

CH₃, J ¼ 7.12 Hz), 1.26(t, 3H, CH₃, J ¼ 7.12 Hz), 1.67e1.71(m,1H, HCH),

CDCl₃): d 13.13, 14.44, 21.66, 32.74, 39.86, 55.58, 55.92, 62.48, 62.79,

2.07e2.09(m, 1H, HCH), 3.19e3.22(m, 1H, CH), 3.76(q, 2H, CH₂,

109.77, 112.48, 121.75, 127.37, 149.86, 149.92, 169.78, 170.43. Anal.

Calcd for C₁₇H₂₂O₆: C, 63.34; H, 6.88; found: C, 63.27; H, 6.93%.

J ¼ 7.12 Hz), 4.14(q, 2H, CH₂, J ¼ 7.12 Hz), 7.17e7.33(m, 4H, ArH). ¹³

NMR (150 MHz, CDCl₃):

d 13.23, 14.03, 20.16, 32.74, 39.78, 61.44,

62.08, 126.34, 129.00, 129.95, 131.33, 132.47, 137.82, 166.85, 169.43.

Anal. CalcdforC₁₅H₁₇ClO₄: C, 60.71; H, 5.77; found:C, 60.85;H, 5.42%.

5.1.1.12. Diethyl 2-(2,3-dimethoxyphenyl)cyclopropane-1,1-dicarbox-

ylate (2l). Colorless oil. Yield: 96%; IR (KBr, cm^ꢂ1): 3030 and 2988

(CH), 1744 (C]O) and 1653 (C]C). ¹H NMR (400 MHz, CDCl₃):

5.1.1.18. Diethyl 2-(4-bromophenyl)cyclopropane-1,1-dicarboxylate

0.93(t, 3H, CH₃, J ¼ 7.12 Hz), 1.30(t, 3H, CH₃, J ¼ 7.12 Hz), 1.64e1.67

(2r). Colorless oil. Yield: 93%; IR (KBr, cm^ꢂ1): 3052 and 2982(CH),

3824

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

1756 (C]O) and 1661 (C]C). ¹H NMR (400 MHz, CDCl₃):

0.90(t,

J ¼ 6.66 Hz), 1.39(t, 3H, CH₃, J ¼ 7.16 Hz), 1.41e1.45(m, 2H, CH₂),

1.52e1.55(m, 2H, CH₂), 1.67e2.05(m, 3H, Cpr-HCH₂), 4.27(q, 2H,

CH₂, J ¼ 7.16 Hz), 9.22(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

3H, CH₃, J ¼ 7.16 Hz), 1.27(t, 3H, CH₃, J ¼ 7.16 Hz), 1.66e1.70(m, 1H,

HCH), 2.08e2.12(m, 1H, HCH), 3.11e3.15(m, 1H, CH), 3.86(q, 2H,

CH₂, J ¼ 7.16 Hz), 4.23(q, 2H, CH₂, J ¼ 7.16 Hz), 7.06(d, 2H, C_2,6-ArH,

J ¼ 8.40 Hz), 7.36(d, 2H, C_3,5-ArH, J ¼ 8.40 Hz). ¹³C NMR (150 MHz,

13.86, 13.92, 22.01, 24.06, 29.98, 31.52, 36.81, 62.43, 172.30, 172.84.

Anal. Calcd for C₁₀H₁₆O₄: C, 59.98; H, 8.05; found: C, 60.33; H, 7.96%.

CDCl₃):

d 13.74, 14.07, 29.68, 31.34, 37.36, 61.25, 61.76, 121.27,

130.29, 131.19, 133.80, 166.36, 169.53. Anal. Calcd for C₁₅H₁₇BrO₄: C,

52.80; H, 5.02; found: C, 52.93; H, 5.04%.

5.1.2.4. 2-Butyl-1-(ethoxycarbonyl)cyclopropanecarboxylic acid (3d).

Colorless oil. Yield: 82%; IR (KBr, cm^ꢂ1): 2988(O-H), 1741(C]O),

1692(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.91(m, 3H, CH₃),

5.1.1.19. Diethyl 2-(furan-2-yl)cyclopropane-1,1-dicarboxylate (2s).

1.21e2.22(overlapping m, 12H, 3ꢃ CH₂, Cpr-CHCH₂, and CH₃), 4.25

(m, 2H, CH₂), 10.23(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃): 13.56,

13.88, 22.52, 24.31, 26.59, 29.91, 32.06, 37.04, 62.88, 172.56, 172.62.

Anal. Calcd for C₁₁H₁₈O₄: C, 61.66; H, 8.47; found: C, 61.82; H, 8.33%.

Colorless oil. Yield: 93%; IR (KBr, cm^ꢂ1): 3039 and 2997(CH), 1755

(C]O), 1326(O]S]O). ¹H NMR (400 MHz, CDCl₃):

d 1.05(t, 3H,

eCH₃, J ¼ 7.12 Hz), 1.28(t, 3H, CH₃, J ¼ 7.12 Hz), 1.73e1.76(m, 1H,

HCH), 2.04e2.07(m, 1H, HCH), 3.06e3.10(m, 1H, CH), 4.02(q, 2H,

CH₂, J ¼ 7.12 Hz), 4.24(q, 2H, CH₃, J ¼ 7.12 Hz), 6.11e6.12(m, 1H, C₄-

ArH), 6.27e6.28(m,1H, C₅-ArH), 7.27e7.29(m,1H, C₅-ArH). ¹³C NMR

5.1.2.5. 1-(ethoxycarbonyl)-2-isobutylcyclopropanecarboxylic acid

(3e). Colorless oil. Yield: 82%; IR (KBr, cm^ꢂ1): 2995(O-H), 1743(C]

(150 MHz, CDCl₃):

14.12, 14.32, 30.12, 47.32, 62.33, 73.42, 73.87,

O), 1689(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.87(d, 3H, CH₃,

111.37, 143.28, 149.67, 149.89, 167.43, 169.72. Anal. Calcd for

C₁₃H₁₆O₅: C, 61.90; H, 6.39; found: C, 61.76; H, 6.47%.

J ¼ 5.92 Hz), 0.91(d, 3H, CH₃, J ¼ 5.92 Hz), 1.31(t, 3H, CH₃,

J ¼ 7.16 Hz), 1.34(m, 1H, HCH), 1.52e1.54(m, 1H, HCH), 1.61e1.64(m,

2H, CH₂), 1.85e1.88(m, 1H, CH), 2.07(m, 1H, CH), 4.27(d, 2H,

J ¼ 7.16 Hz), 9.66(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃): 13.72,

22.13, 22.51, 23.82, 27.41, 31.51, 34.98, 36.83, 62.53, 172.98, 173.01.

Anal. Calcd for C₁₁H₁₈O₄: C, 61.66; H, 8.47; found: C, 61.53; H, 8.41%.

5.1.1.20. Diethyl 2-(4-(methylsulfonyl)phenyl)cyclopropane-1,1-dicar-

boxylate (2t). Colorless oil. Yield: 94%; IR (KBr, cm^ꢂ1): 3041 and

2992(CH), 1324(O]S]O), 1754 (C]O). ¹H NMR (400 MHz, CDCl₃):

0.91(t, 3H, CH₃, J ¼ 7.14 Hz), 1.29(t, 3H, CH₃, J ¼ 7.14 Hz), 1.67e1.71

(m, 1H, HCH), 2.07e2.12(m, 1H, HCH), 3.14e3.19(m, 1H, CH), 3.08(s,

3H, CH₃), 3.92(q, 2H, CH₂, J ¼ 7.14 Hz), 4.26(q, 2H, CH₂, J ¼ 7.14 Hz),

7.26(d, 2H, C_2,6-ArH, J ¼ 8.16 Hz), 7.89(d, 2H, C_3,5-ArH, J ¼ 8.16 Hz).

5.1.2.6. 1-(ethoxycarbonyl)-2-(phentan-3-yl)cyclopropanecarboxylic

acid (3f). Colorless oil. Yield: 85%; IR (KBr, cm^ꢂ1): 3001(O-H), 1742

(C]O), 1699(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.81(t, 3H, CH₃,

¹³C NMR (150 MHz, CDCl₃):

13.88, 13.92, 22.56, 33.83, 39.43,

J ¼ 7.44 Hz), 0.97(t, 3H, CH₃, J ¼ 7.44 Hz), 1.32(t, 3H, CH₃,

J ¼ 7.08 Hz), 1.25e2.13(overlapping m, 8H, 2ꢃ CH₂, CH, and Cpr-

CHCH₂), 4.31(q, 2H, CH₂, J ¼ 7.08 Hz), 9.48(br s, 1H, OH). ¹³C NMR

44.56, 62.38, 62.97, 127.65, 130.66, 140.14, 141.69, 166.88, 169.73.

Anal. Calcd for C₁₆H₂₀O₆S: C, 56.46; H, 5.92; found: C, 56.56; H,

6.13%.

(150 MHz, CDCl₃):

d 10.66, 11.27, 14.03, 24.63, 26.35, 26.63, 30.16,

39.67, 43.57, 62.75,171.79,175.07. Anal. Calcd for C₁₂H₂₀O₄: C, 63.14;

H, 8.83; found: C, 63.23; H, 8.93%.

5.1.2. General procedure for the synthesis of compounds 3a-t

To a solution of compound 2 (10 mmol) in anhydrous ethanol

(50 ml) was added 1 N sodium hydroxide (25 ml, 1.1 equiv,

25 mmol), and the resulting mixture was stirred art room

temperature for 12 h. EtOH was removed under reduced pressure,

water was added to the residue, and the mixture was acidiﬁed by

means of a saturated KHSO₄and extracted with ethyl acetate

(3 ꢃ 30 ml). The combined extracts were dried over Na₂SO₄and

evaporated to give products 3 without further puriﬁcation.

5.1.2.7. 1-(ethoxycarbonyl)-2-phenylcyclopropanecarboxylic acid

(3g). Colorless oil. Yield: 85%; IR (KBr, cm^ꢂ1): 3001(O-H), 1742(C]

O), 1699(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.72(t, 3H, CH₃,

J ¼ 7.16 Hz), 2.30(m, 1H, HCH), 2.41(m, 1H, HCH), 3.44(m, 1H, Cpr-

CH), 3.83(q, 2H, CH₂, J ¼ 7.16 Hz), 7.30e7.32(m, 2H, C_2,6-ArH),

7.46e7.52(m, 1H, C₄-ArH), 7.60e7.64(m, 2H, C_3,5-ArH), 10.63(br s,

1H, OH). ¹³C NMR (150 MHz, CDCl₃):

d 13.10, 21.39, 33.33, 40.36,

62.41, 127.90, 128.31, 129.35, 134.18, 171.18, 172.87. Anal. Calcd for

C₁₃H₁₄O₄: C, 66.66; H, 6.02; found: C, 66.54; H, 6.15%.

5.1.2.1. 1-(ethoxycarbonyl)-2-isopropylcyclopropanecarboxylic acid

(3a). Colorless oil. Yield: 85%; IR (KBr, cm^ꢂ1): 2986(O-H), 1742(C]

O), 1699(C]O). ¹H NMR (400 MHz, CDCl₃):

0.92(d, 3H, CH₃,

5.1.2.8. 1-(ethoxycarbonyl)-2-p-tolylcyclopropanecarboxylic acid

J ¼ 6.64 Hz), 1.07(d, 3H, CH₃, J ¼ 6.60 Hz), 1.25(t, 3H, CH₃,

J ¼ 7.00 Hz), 1.52e1.56(m, 1H, HCH), 1.71e1.75(m, 1H, HCH),

1.82e1.84(m, 1H, Cpr-CH), 1.85e1.89(m, 1H, CH), 4.28(q, 2H, CH₂,

(3h). Colorless oil. Yield: 82%; IR (KBr, cm^ꢂ1): 3005(O-H), 1748

(C]O), 1701(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.72(t, 3H, CH₃,

J ¼ 7.16 Hz), 2.24e2.28(m, 1H, HCH), 2.32(s, 3H, CH₃), 2.36e2.39

J ¼ 7.00 Hz), 10.22(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

d 11.88,

(m, 1H, HCH), 3.35e3.37(m, 1H, Cpr-CH), 3.77(q, 2H, CH₂,

21.25, 21.68, 22.01, 28.25, 30.98, 44.93, 62.32, 172.42, 172.82. Anal.

Calcd for C₁₀H₁₆O₄: C, 59.98; H, 8.05; found: C, 60.06; H, 8.23%.

J ¼ 7.16 Hz), 7.08e7.10(m, 2H, C_2,6-ArH), 7.12e7.14(m, 2H, C_3,5

ArH), 10.55(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

13.16,

19.23, 21.15, 33.79, 62.33, 128.91, 129.16, 131.00, 137.62, 171.57,

172.29. Anal. Calcd for C₁₄H₁₆O₄: C, 67.73; H, 6.50; found: C, 67.94;

H, 6.55%.

5.1.2.2. 2-(ethoxycarbonyl)-2-ethylcyclopropanecarboxylic acid

(3b). Colorless oil. Yield: 82%; IR (KBr, cm^ꢂ1): 2984(O-H), 1738(C]

O), 1696(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.89(t, 3H, CH₃,

J ¼ 7.30 Hz), 1.24(t, 3H, CH₃, J ¼ 7.02 Hz), 1.44e1.72(m, 2H, CH₂),

1.55e1.62(m, 1H, HCH), 1.69e1.75(m, 1H, HCH), 1.93e1.99(m, 1H,

Cpr-CH), 4.31(q, 2H, CH₂, J ¼ 7.02 Hz), 10.35(br s, 1H, OH). ¹³C NMR

(150 MHz, CDCl₃): 12.25, 14.88, 24.32, 28.55, 32.76, 37.21, 62.42,

172.01, 172.22. Anal. Calcd for C₉H₁₄O₄: C, 58.05; H, 7.58; found: C,

58.34; H, 7.92%.

5.1.2.9. 1-(ethoxycarbonyl)-2-(4-methoxyphenyl)cyclopropanecarboxylic

acid (3i). Colorless oil. Yield: 88%; IR (KBr, cm^ꢂ1): 3003(O-H), 1744

(C]O), 1699(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.77(t, 3H, CH₃,

J ¼ 7.16 Hz), 2.28e2.31(m, 1H, HCH), 2.36e2.39(m, 1H, HCH),

3.34e3.39(m, 1H, Cpr-CH), 3.77(s, 3H, CH₃), 3.82(q, 2H, CH₂,

J ¼ 7.16 Hz), 6.83(d, 2H, C_3,5-ArH, J ¼ 8.64 Hz), 7.17(d, 2H, C_2,6-ArH,

J ¼ 8.64 Hz), 11.12(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

d 13.24,

5.1.2.3. 1-(ethoxycarbonyl)-2-propylcyclopropanecarboxylic acid

21.49, 33.45, 40.61, 55.33, 62.42, 113.64, 125.99, 130.53, 159.31,

170.84, 173.23. Anal. Calcd for C₁₄H₁₆O₅: C, 63.63; H, 6.10; found: C,

64.36; H, 6.34%.

(3c). Colorless oil. Yield: 88%; IR (KBr, cm^ꢂ1): 2988(OeH), 1741(C]

O), 1692(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.92(t, 3H, CH₃,

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

3825

5.1.2.10. 2-(2,5-dimethoxyphenyl)-1-(ethoxycarbonyl)cyclo-

propanecarboxylic acid (3j). Colorless oil. Yield: 82%; IR (KBr,

cm^ꢂ1): 3001(O-H), 1742(C]O), 1699(C]O). ¹H NMR (400 MHz,

5.1.2.16. 2-(4-chlorophenyl)-1-(ethoxycarbonyl)cyclopropanecarboxylic

acid (3p). Colorless oil. Yield: 86%; IR (KBr, cm^ꢂ1): 3004(O-H), 1748

(C]O), 1698(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.78(t, 3H, CH₃,

CDCl₃):

0.68(t, 3H, CH₃, J ¼ 7.12 Hz), 2.25e2.28(m, 1H, HCH),

J ¼ 7.16 Hz), 2.28e2.34(m, 1H, HCH), 2.35e2.39(m, 1H, HCH),

3.36e3.41(m, 1H, Cpr-CH), 3.85(q, 2H, CH₂, J ¼ 7.16 Hz), 7.20e7.22

(m, 2H, C_2,6-ArH), 7.29e7.31(m, 2H, C_3,5-ArH), 12.23(br s, 1H, OH).

2.30e2.33(m, 1H, HCH), 3.20e3.25(m, 1H, Cpr-CH), 3.72(s, 3H,

OCH₃), 3.77(s, 3H, OCH₃), 3.82(q, 2H, eCH₂, J ¼ 7.12 Hz) 6.70e6.73

(m, 1H, C₄-ArH), 6.77e6.79(m, 2H, C_3,6-ArH), 13.12(br s, 1H, OH). ¹³

¹³C NMR (150 MHz, CDCl₃):

d 13.24, 21.62, 33.13, 39.62, 62.64,

NMR (150 MHz, CDCl₃):

61.11, 109.42, 112.06, 115.67, 123.33, 151.88, 152.11, 170.05, 173.06.

Anal. Calcd for C₁₅H₁₈O₆: C, 61.22; H, 6.16; found: C, 61.44; H, 6.32%.

12.02, 20.84, 30.98, 36.38, 54.72, 54.81,

128.49, 130.76, 132.76, 133.86, 170.52, 172.95. Anal. Calcd for

C₁₃H₁₃ClO₄: C, 58.11; H, 4.88; found: C, 58.44; H, 4.95%.

5.1.2.17. 2-(2-chlorophenyl)-1-(ethoxycarbonyl)cyclopropanecarboxylic

5.1.2.11. 2-(3,4-dimethoxyphenyl)-1-(ethoxycarbonyl)cyclo-

propanecarboxylic acid (3k). Colorless oil. Yield: 82%; IR (KBr,

cm^ꢂ1): 3005(O-H), 1748(C]O), 1702(C]O). ¹H NMR (400 MHz,

acid (3q). Colorless oil. Yield: 86%; IR (KBr, cm^ꢂ1): 3003(O-H), 1740

(C]O), 1696(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.62(t, 3H, CH₃,

J ¼ 7.20 Hz), 2.28e2.31(m, 1H, HCH), 2.34e2.38(m, 1H, HCH),

3.29e3.34(m, 1H, Cpr-CH), 3.76(q, 2H, CH₂, J ¼ 7.20 Hz), 7.18e7.34

(m, 4H, ArH), 10.21(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

CDCl₃):

0.77(t, 3H, CH3, J ¼ 7.12 Hz), 2.29e2.32(m, 1H, HCH),

2.36e2.40(m, 1H, HCH), 3.36e3.41(m, 1H, Cpr-CH), 3.76(q, 2H, CH₂,

J ¼ 7.12 Hz), 3.83(s, 3H, OCH₃), 3.87(s, 3H, OCH₃), 6.75e6.77(m, 1H,

C₅-ArH), 6.80e6.81(m, 2H, C_2,6-ArH), 12.82(br s, 1H, OH). ¹³C NMR

12.72, 22.68, 32.71, 39.18, 61.21, 126.21, 128.88, 128.94, 130.63,

132.25, 136.71, 170.96, 171.82. Anal. Calcd for C₁₃H₁₃ClO₄: C, 58.11;

H, 4.88; found: C, 58.42; H, 5.17%.

(150 MHz, CDCl₃):

d 13.33, 21.64, 33.40, 40.90, 55.97, 55.99, 62.46,

110.76, 112.44, 121.69, 126.52, 148.70, 148.80, 170.78, 173.31. Anal.

Calcd for C₁₅H₁₈O₆: C, 61.22; H, 6.16; found: C, 62.41; H, 6.26%.

5.1.2.18. 2-(4-bromophenyl)-1-(ethoxycarbonyl)cyclopropanecarboxylic

acid (3r). Colorless oil. Yield: 86%; IR (KBr, cm^ꢂ1): 3002(O-H), 1747

5.1.2.12. 2-(2,3-dimethoxyphenyl)-1-(ethoxycarbonyl)cyclo-

propanecarboxylic acid (3l). Colorless oil. Yield: 85%; IR (KBr,

cm^ꢂ1): 3002(O-H), 1740(C]O), 1695(C]O). ¹H NMR (400 MHz,

(C]O), 1698(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.78(t, 3H, eCH₃,

J ¼ 7.16 Hz), 2.28e2.34(m, 1H, HCH), 2.35e2.39(m, 1H, HCH),

3.36e3.41(m, 1H, CH), 3.85(q, 2H, eCH₂, J ¼ 7.16 Hz), 7.20e7.22(m,

CDCl₃):

0.71(t, 3H, CH₃, J ¼ 7.16 Hz), 2.31e2.33 (m, 2H, HCH),

2H, C_2,6-ArH), 7.29e7.31(m, 2H, C_3,5-ArH), 12.23(br s, 1H, -OH). ¹³

3.30e3.35(m, 1H, Cpr-CH), 3.80(s, 3H, OCH₃), 3.81(s, 3H, OCH₃),

3.84(q, 2H, CH₂, J ¼ 7.16 Hz), 6.79e6.81(m, 1H, C₄-ArH), 6.85e6.87

NMR (150 MHz, CDCl₃): d 13.58, 19.16, 31.58, 38.02, 61.32, 122.15,

130.83, 131.86, 133.41, 170.65, 171.36. Anal. Calcd for C₁₃H₁₃BrO₄: C,

49.86; H, 4.18; found: C, 50.06; H, 4.43%.

(m, 1H, C₅-ArH), 6.97e7.01(m, 1H, C₆-ArH), 12.94(br s, 1H, OH). ¹³

NMR (150 MHz, CDCl₃):

d 13.04, 21.66, 32.52, 36.81, 55.80, 60.53,

62.28, 112.32, 121.77, 123.30, 128.28, 148.81, 152.38, 171.06, 173.68.

Anal. Calcd for C₁₅H₁₈O₆: C, 61.22; H, 6.16; found: C, 61.43; H, 6.32%.

5.1.2.19. 1-(ethoxycarbonyl)-2-(furan-2-yl)cyclopropanecarboxylic acid

(3s). Colorless oil. Yield: 86%; IR (KBr, cm^ꢂ1): 3008(O-H), 1748(C]

O), 1695(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.97(t, 3H, eCH₃,

5.1.2.13. 1-(ethoxycarbonyl)-2-(2,3,4-trimethoxyphenyl)cyclo-

propanecarboxylic acid (3m). Colorless oil. Yield: 86%; IR (KBr,

cm^ꢂ1): 3003(O-H), 1749(C]O), 1692(C]O). ¹H NMR (400 MHz,

J ¼ 7.16 Hz), 2.25e2.29(m, 1H, HCH), 2.33e2.37(m, 1H, HCH),

3.21e3.26(m, 1H, Cpr-CH), 3.98(q, 2H, CH₂, J ¼ 7.16 Hz), 6.25e6.26

(m, 1H, ArH), 6.32e6.33(m, 1H, ArH), 7.32e7.33(m, 1H, ArH), 12.32

CDCl₃):

0.75(t, 3H, CH₃, J ¼ 7.16 Hz), 2.29e2.32(m, 2H, HCH),

(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

d 14.08, 30.41, 47.02,

3.24e3.26(m, 1H, Cpr-CH), 3.81(s, 3H, OCH₃), 3.85(s, 3H, OCH₃),

3.87(s, 3H, OCH₃), 3.90(q, 2H, CH₂, J ¼ 7.16 Hz), 6.59(d, 1H, C₅-ArH,

62.41, 73.25,110.11,110.69,143.82,149.88,167.54,171.22. Anal. Calcd

for C₁₁H₁₂O₅: C, 58.93; H, 5.39; found: C, 59.23; H, 5.64%.

J ¼ 8.60 Hz), 6.87(d, 1H, C₆-ArH, J ¼ 7.76 Hz), 12.92(br s, 1H, OH). ¹³

NMR (150 MHz, CDCl₃):

13.25, 21.61, 32.54, 37.58, 56.08, 60.80,

5.1.2.20. 1-(ethoxycarbonyl)-2-(4-(methylsulfonyl)phenyl)cyclo-

propanecarboxylic acid (3t). Colorless oil. Yield: 82%; IR (KBr,

cm^ꢂ1): 3002(O-H), 1747(C]O), 1698(C]O), 1324(O]S]O). ¹H

60.91, 62.30, 106.16, 120.48, 124.44, 141.63, 153.31, 153.91, 170.84,

174.00. Anal. Calcd for C₁₆H₂₀O₇: C, 59.25; H, 6.22; found: C, 59.43;

H, 6.38%.

NMR (400 MHz, CDCl₃):

0.71(t, 3H, CH₃, J ¼ 7.16 Hz), 2.33e2.37(m,

1H, HCH), 2.40e2.43(m, 1H, HCH), 3.05(s, 3H, CH₃), 3.45e3.50(m,

1H, Cpr-CH), 3.84(q, 2H, CH₂, J ¼ 7.16 Hz), 7.49(d, 2H, C_2,6-ArH), 7.91

(d, 2H, C_3,5-ArH), 12.87(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

5.1.2.14. 1-(ethoxycarbonyl)-2-(3,4,5-trimethoxyphenyl)cyclo-

propanecarboxylic acid (3n). Colorless oil. Yield: 81%; IR (KBr,

cm^ꢂ1): 3000(O-H), 1741(C]O), 1696(C]O). ¹H NMR (400 MHz,

13.28, 21.66, 33.37, 38.35, 44.46, 62.69, 127.44, 130.41, 140.07,

CDCl₃):

0.78(t, 3H, CH₃, J ¼ 7.16 Hz), 2.23e2.26(m, 1H, HCH),

140.84, 170.43, 171.94. Anal. Calcd for C₁₄H₁₆O₆S: C, 53.84; H, 5.16;

found: C, 54.12; H, 5.45%.

2.34e2.37(m, 1H, HCH), 3.35e3.40(m, 1H, Cpr-CH), 3.81(s, 3H,

OCH₃), 3.84(s, 6H, 2ꢃ OCH₃), 3.87(q, 2H, CH₂, J ¼ 7.16 Hz), 6.47(s,

2H, C_2,6-ArH), 12.96(br s, 1H, OH). ¹³C NMR (150 MHz, CDCl₃):

5.1.3. General procedure for the synthesis of compounds 5a-t

Compound 3 (10 mmol) was dissolved in dry THF (30 ml) and

cooled to ꢂ15 ^ꢀC. After the addition of EtOCOCl (11 mmol) and

NMM (12 mmol), the mixture was stirred for 20 min. A solution of

NaN₃(25 mmol) in H₂O was added and stirred for 1 h at ꢂ10 ^ꢀC. The

solution was then diluted with H₂O and extracted with EtOAc. The

organic layers were washed with brine, dried over Na₂SO₄and

concentrated under reduced pressure to give crude acyl azide. This

crude acyl azide could be further puriﬁed by a ﬂash column chro-

matography (PE-EtOAc, 4:1, Rf ¼ 0.6). Puriﬁed acyl azide was dis-

solved in toluene (30 ml) and the resulting solution was heated to

75 ^ꢀC under stirring. After gas evolution had stopped toluene was

13.31, 21.67, 33.38, 40.52, 56.21, 60.87, 62.42, 106.32, 129.92,

137.71, 153.04, 170.95, 172.80. Anal. Calcd for C₁₅H₁₈O₆: C, 61.22; H,

6.16; found: C, 62.39; H, 6.50%.

5.1.2.15. 1-(ethoxycarbonyl)-2-(4-ﬂuorophenyl)cyclopropanecarboxylic

acid (3o). Colorless oil. Yield: 86%; IR (KBr, cm^ꢂ1): 3006(O-H), 1744

(C]O), 1700(C]O). ¹H NMR (400 MHz, CDCl₃):

d 0.78(t, 3H, CH₃,

J ¼ 7.12 Hz), 2.31e2.35(m, 1H, HCH), 2.37e2.40(m, 1H, HCH),

3.38e3.42(m, 1H, Cpr-CH), 3.85(q, 2H, CH₂, J ¼ 7.12 Hz), 7.00e7.05

(m, 2H, C_3,5-ArH), 7.24e7.27(m, 2H, C_2,6-ArH), 12.33(br s, 1H, OH).

¹³C NMR (150 MHz, CDCl₃):

d 13.23, 21.77, 33.04, 40.02, 62.59,

115.39, 131.13, 161.15, 163.60, 170.40, 173.32. Anal. Calcd for

C₁₃H₁₃FO₄: C, 61.90; H, 5.19; found: C, 62.03; H, 5.47%.

removed under reduced pressure to afford

a-carboethoxy isocya-

nate 4 as clear oil. This -carboethoxy isocyanate 4 was directly

3826

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

used in the next step without further puriﬁcation. Methylamine

(10 mmol, aqueous solution, 30%) was added to a stirred suspension

of isocyanate 3 in dry THF (40 ml) at r.t for 1 h. The solvent was

removed under reduced pressure to give products 5 and were

recrystallized as white solid.

¹H NMR (400 MHz, CDCl₃):0.81(t, 3H, eCH₃, J ¼ 7.36 Hz), 0.90(t, 3H,

CH₃, J ¼ 7.44 Hz), 1.25(t, 3H, CH₃, J ¼ 7.12 Hz), 1.28e1.32(m, 5H, 2ꢃ

CH₂and Cpr-HCH), 1.34e1.40(m, 1H, Cpr-HCH), 1.35e1.40(m, 1H,

Cpr-CH), 1.58e1.59(m, 1H, CH), 2.77(d, 3H, CH₃, J ¼ 4.72 Hz), 4.16(q,

2H, CH2, J ¼ 7.12 Hz), 4.92(br s, 1H, NH), 5.46(br s, 1H, NH). ¹³C NMR

(150 MHz, CDCl₃):

d 11.11, 11.89, 14.36, 22.83, 26.78, 26.99, 27.26,

5.1.3.1. Ethyl 2-isopropyl-1-(3-methylureido)cyclopropanecarboxylate

(5a). White powdery crystals. Yield: 85%; mp: 146e148 ^ꢀC. IR (KBr,

cm^ꢂ1): 3352 (NeH), 1729(C]O), 1672(C]O). ¹H NMR (400 MHz,

37.79, 39.49, 39.72, 62.46, 159.28, 172.53. MS (m/z): 257[M þ 1]^þ.

Anal. Calcd for C₁₃H₂₄N₂O₃: C, 60.91; H, 9.44; N, 10.93; found: C,

71.08; H, 9.23; N, 10.75%.

CDCl₃):

0.93(d, 3H, CH₃, J ¼ 6.56 Hz), 1.02(d, 3H, CH₃, J ¼ 6.72 Hz),

1.25(t, 3H, CH3, J ¼ 7.12 Hz), 1.26e1.28(m, 1H, HCH), 1.50e1.53(m,

1H, HCH), 1.54e1.56(m, 1H, Cpr-CH), 1.71e1.79(m, 1H, CH), 2.79(d,

3H, CH₃, J ¼ 4.76 Hz), 4.19(q, 2H, CH₂, J ¼ 7.12 Hz), 4.77(br s, 1H, NH),

5.1.3.7. Ethyl 1-(3-methylureido)-2-phenylcyclopropanecarboxylate

(5g). White powdery crystals. Yield: 84%; mp: 137e139 ^ꢀC. IR (KBr,

cm^ꢂ1): 3351 (NeH), 1747(C]O), 1669 (C]O). ¹H NMR (400 MHz,

5.21(br s, 1H, NH). ¹³C NMR (150 MHz, CDCl₃):

14.25, 22.07, 22.13,

CDCl₃):

0.82(t, 3H, CH₃, J ¼ 7.08 Hz), 1.65e1.68(m, 1H, HCH),

22.51, 26.94, 27.04, 39.36, 39.64, 61.40, 159.00, 172.05. MS (m/z): 229

[M þ 1]^þ. Anal. Calcd for C₁₁H₂₀N₂O₃: C, 57.83; H, 8.83; N, 12.27;

found: C, 57.43; H, 8.44; N, 12.51%.

2.25e2.31(m, 1H, HCH), 2.89(d, 3H, CH₃, J ¼ 4.54 Hz), 2.92e2.95(m,

1H, CH), 3.84(q, 2H, eCH₂, J ¼ 7.08 Hz), 5.15(br s, 1H, NH), 6.12(br s,

1H, NH), 7.25e7.33(m, 5H, ArH). ¹³C NMR (150 MHz, CDCl₃):

d 13.52,

21.22, 27.14, 35.66, 41.35, 61.27,127.38,128.73,129.18,132.11,159.23,

172.03. MS (m/z): 263[M þ 1]^þ. Anal. Calcd for C₁₄H₁₈N₂O₃: C, 64.10;

H, 6.92; N, 10.68; found: C, 64.43; H, 7.14; N, 10.89%.

5.1.3.2. Ethyl-2-ethyl-1-(3-methylureido)cyclopropanecarboxylate

(5b). White powdery crystals. Yield: 85%; mp: 187e189 ^ꢀC. IR (KBr,

cm^ꢂ1): 3376 (NeH), 1712(C]O), 1664(C]O). ¹H NMR (400 MHz,

CDCl₃):

0.90(t, 3H, CH₃, J ¼ 7.28 Hz), 1.25(t, 3H, CH₃, J ¼ 6.96 Hz),

5.1.3.8. Ethyl 1-(3-methylureido)-2-p-tolylcyclopropanecarboxylate

(5h). White powdery crystals. Yield: 85%; mp: 140e142 ^ꢀC. IR (KBr,

cm^ꢂ1): 3364 (NeH), 1743(C]O), 1686 (C]O). ¹H NMR (400 MHz,

1.34e1.41(m, 3H, Cpr-H), 1.55e1.57(m, 2H, CH₂), 2.76(d, 3H, CH₃,

J ¼ 4.82 Hz), 4.16(q, 2H, eCH₂, J ¼ 7.28 Hz), 4.83(br s, 1H, NH), 5.24

(br s, 1H, NH). ¹³C NMR (150 MHz, CDCl₃):

13.88, 14.12, 22.55,

CDCl₃):

0.84(t, 3H, CH₃, J ¼ 7.08 Hz), 1.80e1.82(m, 1H, HCH),

27.01, 29.78, 32.33, 39.12, 61.43, 160.12, 171.23. MS (m/z): 215

[M þ 1]^þ. Anal. Calcd for C₁₀H₁₈N₂O₃: C, 56.06; H, 8.47; N, 13.07;

found: C, 57.36; H, 8.65; N, 12.88%.

2.11e2.13(m, 1H, HCH), 2.78e2.80(m, 1H, CH), 2.84(d, 3H, eCH₃,

J ¼ 4.56 Hz), 2.98(s, 3H, eCH₃, Ar-CH₃), 3.82(q, 2H, eCH₂,

J ¼ 7.08 Hz), 5.43(br s, 1H, NH), 6.27(br s, 1H, NH), 7.06e7.17(m, 4H,

ArH). ¹³C NMR (150 MHz, CDCl₃):

d 13.25, 19.88, 21.34, 26.72, 35.56,

5.1.3.3. Ethyl 1-(3-methylureido)-2-propylcyclopropanecarboxylate

(5c). White powdery crystals. Yield: 85%; mp: 168e170 ^ꢀC. IR (KBr,

cm^ꢂ1): 3377 (NeH), 1743(C]O), 1672(C]O). ¹H NMR (400 MHz,

43.45, 62.66, 117.26, 128.73, 134.54, 136.79, 160.54, 172.75. MS (m/

z): 277[M þ 1]^þ. Anal. Calcd for C₁₅H₂₀N₂O₃: C, 65.20; H, 7.30; N,

10.14; found: C, 65.44; H, 7.63; N, 9.84%.

CDCl₃):

0.91(t, 3H, CH₃, J ¼ 7.28 Hz), 1.26(t, 3H, CH₃, J ¼ 6.96 Hz),

1.33e1.51(m, 7H, CH₂, CH₂, Cpr-HCH₂), 2.79(d, 3H, CH₃, J ¼ 4.80 Hz),

4.19(q, 2H, CH₂, J ¼ 7.28 Hz), 4.77(br s, 1H, NH), 5.25(br s, 1H, NH).

5.1.3.9. Ethyl

2-(4-methoxyphenyl)-1-(3-methylureido)cyclo-

propanecarboxylate (5i). White powdery crystals. Yield: 85%; mp:

¹³C NMR (150 MHz, CDCl₃):

d 13.79, 14.24, 22.35, 22.85, 26.87, 29.19,

138e140 ^ꢀC. IR (KBr, cm^ꢂ1): 3355 (NeH), 1745(C]O), 1690 (C]O).

31.33, 38.84, 61.28, 159.34, 172.26. MS (m/z): 229[M þ 1]^þ. Anal.

Calcd for C₁₁H₂₀N₂O₃: C, 57.87; H, 8.83; N, 12.27; found: C, 57.56; H,

8.69; N, 12.57%.

¹H NMR (400 MHz, CDCl₃):

0.85(t, 3H, CH₃, J ¼ 7.88 Hz), 1.56e1.60

(m,1H, HCH), 2.18e2.22(m,1H, HCH), 2.76e2.81(m,1H, CH), 2.83(d,

3H, CH3, J ¼ 4.72 Hz), 3.79(s, 3H, OCH₃), 3.83(q, 2H, CH₂,

J ¼ 7.88 Hz), 4.92(br s, 1H, NH), 5.59(br s, 1H, NH), 6.80(d, 2H, C_3,5

5.1.3.4. Ethyl

2-butyl-1-(3-methylureido)cyclopropanecarboxylate

ArH, J ¼ 8.56 Hz), 7.21(d, 2H, C_2,6-ArH, J ¼ 8.52 Hz). ¹³C NMR

(5d). White powdery crystals. Yield: 85%; mp: 173e175 ^ꢀC. IR (KBr,

(150 MHz, CDCl₃): d 13.72, 20.53, 27.00, 34.50, 41.25, 55.24, 61.04,

cm^ꢂ1): 3376 (NeH), 1721(C]O), 1668(C]O). ¹H NMR (400 MHz,

113.39, 127.38, 130.26, 158.61, 159.50, 171.17. MS (m/z): 293[M þ 1]^þ.

Anal. Calcd for C₁₅H₂₀N₂O₄: C, 61.63; H, 6.90; N, 9.58; found: C,

61.42; H, 6.56; N, 9.94%.

CDCl₃):

0.92(m, 3H, CH₃),1.25e2.1(overlapping m,12H, 3ꢃ CH₂, Cpr-

CHCH₂, and CH₃), 2.82(d, 3H, CH₃, J ¼ 4.80 Hz), 4.22(m, 2H, eCH₂),

4.88(br s, 1H, NH), 5.32(br s, 1H, NH). ¹³C NMR (150 MHz, CDCl₃):

13.41, 13.78, 23.12, 24.50, 25.96, 26.71, 30.11, 32.06, 38.24, 61.52,

5.1.3.10. Ethyl

2-(2,5-dimethoxyphenyl)-1-(3-methylureido)cyclo-

157.66,172.36. MS (m/z): 243[M þ 1]^þ. Anal. Calcd for C₁₂H₂₂N₂O₃: C,

propanecarboxy late (5j). White powdery crystals. Yield: 85%; mp:

59.48; H, 9.15; N, 11.56; found: C, 58.58; H, 9.21; N, 11.96%.

170e172 ^ꢀC. IR (KBr, cm^ꢂ1): 3385 (NeH), 1709(C]O), 1609 (C]O).

¹H NMR (400 MHz, CDCl₃):

0.91(t, 3H, CH₃, J ¼ 7.12 Hz), 1.59e1.62

5.1.3.5. Ethyl 2-isobutyl-1-(3-methylureido)cyclopropanecarboxylate

(5e). White powdery crystals. Yield: 84%; mp: 153e155 ^ꢀC. IR (KBr,

cm^ꢂ1): 3374 (NeH), 1712(C]O), 1677(C]O). ¹H NMR (400 MHz,

CDCl₃): 0.86e0.93(m, 6H, 2-CH₃), 1.34(t, 3H, CH₃, J ¼ 7.12 Hz), 1.47

(m, 1H, HCH), 1.51(m, 1H, HCH), 1.64(m, 2H, CH₂), 1.86(m, 1H, Cpr-

CH), 2.05(m, 1H, CH), 2.80(d, 3H, eCH₃, J ¼ 4.76 Hz), 4.27(q, 2H,

eCH₂, J ¼ 7.12 Hz), 4.89(br s, 1H, NH), 5.63(br s, 1H, NH). ¹³C NMR

(m, 1H, HCH), 2.00e2.03(m, 1H, HCH), 2.72e2.77(m, 1H, CH), 2.89

(d, 3H, CH₃, J ¼ 4.60 Hz), 3.76(s, 3H, OCH₃), 3.81(s, 3H, OCH₃), 3.88

(q, 2H, CH₂, J ¼ 7.12 Hz), 5.23(br s, 1H, NH), 6.39(br s, 1H, NH),

6.76e6.79(m, 3H, C_3,4,6-ArH). ¹³C NMR (150 MHz, CDCl₃):

d 13.75,

22.04, 27.05, 31.77, 40.07, 55.67, 55.87, 60.76, 110.51, 112.56, 117.31,

125.23, 152.23, 153.64, 159.51, 170.54. MS (m/z): 323[M þ 1]^þ. Anal.

Calcd for C₁₆H₂₂N₂O₅: C, 59.61; H, 6.88; N, 8.69; found: C, 59.55; H,

6.54; N, 8.93%.

(150 MHz, CDCl₃):

d 12.93, 22.24, 22.75, 24.31, 24.97, 27.22, 28.34,

33.11, 37.52, 64.24, 159.71, 171.98. 243[M þ 1]^þ. Anal. Calcd for

C₁₂H₂₂N₂O₃: C, 59.48; H, 9.15; N, 11.56; found: C, 59.43; H, 9.34; N,

11.88%.

5.1.3.11. Ethyl

2-(3,4-dimethoxyphenyl)-1-(3-methylureido)cyclo-

propanecarboxy late (5k). White powdery crystals. Yield: 85%; mp:

186e187 ^ꢀC. IR (KBr, cm^ꢂ1): 3374 (NeH), 1725(C]O), 1653 (C]O).

5.1.3.6. Ethyl

1-(3-methylureido)-2(pentan-3-yl)cyclo-

¹H NMR (400 MHz, CDCl₃):

0.86(t, 3H, CH₃, J ¼ 7.08 Hz), 1.56e1.60

propanecarboxylate (5f). White powdery crystals. Yield: 85%; mp:

(m, 1H, HCH), 2.17e2.21(m, 1H, HCH), 2.78e2.82 (m, 1H, CH), 2.83

(d, 3H, CH₃, J ¼ 5.48 Hz), 3.82(q, 2H, CH₂, J ¼ 7.08), 3.85(s, 3H,

134e135 ^ꢀC. IR (KBr, cm^ꢂ1): 3371 (NeH), 1708(C]O), 1668 (C]O).

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

3827

OCH₃), 3.86(s, 3H, OCH₃), 4.94(br s, 1H, NH), 5.59(br s, 1H, NH),

6.76e6.86(m, 3H, C_2,5,6-ArH). ¹³C NMR (150 MHz, CDCl₃):

13.80,

NH), 5.68(br s, 1H, NH), 7.09e7.18(m, 2H, C_2,6-ArH), 7.22e7.36(m,

2H, C_3,5-ArH). ¹³C NMR (150 MHz, CDCl₃):

15.83, 22.76, 30.01,

20.65, 27.03, 34.83, 41.23, 55.87, 61.05, 110.66, 112.49, 121.37, 127.99,

148.06, 148.46, 159.50, 171.08. MS (m/z): 323[M þ 1]^þ. Anal. Calcd

for C₁₆H₂₂N₂O₅: C, 59.61; H, 6.88; N, 8.69; found: C, 59.33; H, 6.53;

N, 8.79%.

34.76, 45.88, 61.39, 126.88, 130.13,132.14, 154.55, 166.28, 169.33. MS

(m/z): 297[M þ 1]^þ. Anal. Calcd for C₁₄H₁₇ClN₂O₃: C, 56.66; H, 5.77;

N, 9.44; found: C, 56.85; H, 6.02; N, 9.21%.

5.1.3.17. Ethyl 2-(2-chlorophenyl)-1-(3-methylureido)cyclopro-

panecarboxylate (5q). White powdery crystals. Yield: 85%; mp:

211e213 ^ꢀC. IR (KBr, cm^ꢂ1): 3372 (NeH), 1726(C]O), 1676 (C]O).

5.1.3.12. Ethyl-2-(2,3-dimethoxyphenyl)-1-(3-methylureido)cyclo-

propanecarboxy late (5l). White powdery crystals. Yield: 85%; mp:

179e181 ^ꢀC. IR (KBr, cm^ꢂ1): 3388 (NeH), 1743(C]O), 1689 (C]O).

¹H NMR (400 MHz, CDCl₃):

0.83(t, 3H, CH₃, J ¼ 7.16 Hz), 1.56e1.60

¹H NMR (400 MHz,CDCl₃):

0.93(t, 3H, CH₃, 7.15 Hz), 1.57e1.61(m,

(m, 1H, HCH), 2.15e2.19(m, 1H, HCH), 2.92(d, 3H, CH₃, J ¼ 4.54 Hz),

2.93e2.99(m, 1H, CH), 3.87(q, 2H, CH₂, J ¼ 7.16 Hz), 4.92(br s, 1H,

NH), 5.78(br s, 1H, NH), 7.18e7.34(m, 4H, ArH). ¹³C NMR (150 MHz,

1H, HCH), 2.10e2.13(m,1H, HCH), 2.79e2.83(m,1H, CH), 2.89(d, 3H,

CH₃, J ¼ 4.56 Hz), 3.84(q, 2H, CH₂, J ¼ 7.15 Hz), 3.87(s, 3H, OCH₃),

3.88(s, 3H, OCH₃), 5.26(br s, 1H, NH), 6.39(br s, 1H, NH), 6.79e6.80

(m, 1H, C₄-ArH), 6.86e6.87(m, 1H, C₅-ArH), 7.00e7.04(m, 1H, C₆-

CDCl₃):

d 15.98, 22.81, 30.23, 34.86, 45.92, 61.45, 127.92, 128.89,

128.91, 131.76, 134.48, 135.79, 158.66, 172.89. MS (m/z): 297

[M þ 1]^þ. Anal. Calcd for C₁₄H₁₇ClN₂O₃: C, 56.66; H, 5.77; N, 9.44;

found: C, 56.73; H, 5.96; N, 9.17%.

ArH). ¹³C NMR (150 MHz, CDCl₃):

d 13.72, 21.02, 27.01, 31.60, 40.86,

55.74, 60.67, 60.96, 111.78, 122.34, 123.57, 128.61, 148.29, 151.81,

159.56, 170.26. MS (m/z): 323[M þ 1]^þ. Anal. Calcd for C₁₆H₂₂N₂O₅:

C, 59.61; H, 6.88; N, 8.69; found: C, 59.35; H, 6.43; N, 8.92%.

5.1.3.18. Ethyl 2-(4-bromophenyl)-1-(3-methylureido)cyclopro-

panecarboxylate (5r). White powdery crystals. Yield: 85%; mp:

213e214 ^ꢀC. IR (KBr, cm^ꢂ1): 3373 (NeH), 1735(C]O), 1678 (C]O).

5.1.3.13. ethyl1-(3-methylureido)-2-(2,3,4-trimethoxyphenyl)-cyclo-

propanecarbo xylate (5m). White powdery crystals. Yield: 85%; mp:

122e124 ^ꢀC. IR (KBr, cm^ꢂ1): 3352 (NeH), 1743(C]O), 1692 (C]O).

¹H NMR (400 MHz, DMSO-d₆):

0.85(t, 3H, CH₃, J ¼ 7.16 Hz),

1.59e1.67(m, 1H, HCH), 2.15e2.19(m, 1H, HCH), 2.95(d, 3H, CH₃,

J ¼ 4.56 Hz), 2.97e3.02(m, 1H, CH), 3.84(q, 2H, CH₂, J ¼ 7.16 Hz),

4.80(br s, 1H, NH), 5.53(br s, 1H, NH), 7.13e7.23(m, 2H, C_2,6-ArH),

¹H NMR (400 MHz, CDCl₃):

0.95(t, 3H, eCH₃, J ¼ 7.12 Hz),

1.56e1.59(m, 1H, HCH), 2.07e2.10(m, 1H, HCH), 2.71e2.76 (m, 1H,

CH), 2.89(d, 3H, CH₃, J ¼ 4.56 Hz), 3.83(s, 3H, OCH₃), 3.85(s, 3H,

OCH₃), 3.89(q, 2H, eCH₂, J ¼ 7.12 Hz), 3.94(s, 3H, OCH₃), 5.33(br s,

1H, NH), 6.28(br s, 1H, NH), 6.62(d, 1H, C₅-ArH, J ¼ 8.64 Hz), 6.65(d,

7.39e7.45(m, 2H, C_3,5-ArH). ¹³C NMR (150 MHz, DMSO):

16.39,

24.35, 30.23, 34.34, 45.98, 62.13, 122.78, 129.42, 131.23, 134.75,

154.62, 171.54. MS (m/z): 341[M

1]^þ. Anal. Calcd for

1H, C₆-ArH, J ¼ 8.64 Hz). ¹³C NMR (150 MHz, CDCl₃):

13.84, 21.02,

C₁₄H₁₇BrN₂O₃: C, 49.28; H, 5.02; N, 8.21; found: C, 49.58; H, 5.34; N,

8.53%.

27.02, 31.59, 40.66, 55.92, 60.56, 60.73, 61.08, 106.67, 120.59, 124.83,

141.13, 152.82, 153.23, 159.52, 170.31. MS (m/z): 353[M þ 1]^þ. Anal.

Calcd for C₁₇H₂₄N₂O₆: C, 57.94; H, 6.86; N, 7.95; found: C, 58.12; H,

6.94; N, 8.11%

5.1.3.19. Ethyl 2-(furan-2-yl)-1-(3-methylureido)cyclopropa-

necarboxylate (5s). Yellow powdery crystals. Yield: 85%; mp:

154e156 ^ꢀC. IR (KBr, cm^ꢂ1): 3356 (NeH), 1712(C]O), 1653 (C]

5.1.3.14. Ethyl 1-(3-methylureido)-2-(3,4,5-trimethoxyphenyl)ecyclo-

propanecarb oxylate (5n). White powdery crystals. Yield: 85%; mp:

182e184 ^ꢀC. IR (KBr, cm^ꢂ1): 3354 (NeH), 1732(C]O), 1643 (C]O).

O). ¹H NMR (400 MHz, CDCl₃):

1.00(t, 3H, CH₃, J ¼ 7.12 Hz),

1.67e1.71(m, 1H, HCH), 1.91e2.22(m, 1H, HCH), 2.64e2.69(m, 1H,

CH),2.84(d, 3H, CH₃, J ¼ 4.68 Hz), 3.94(q, 2H, CH₂, J ¼ 7.12 Hz),

5.14(br s, 1H, NH), 5.65(br s, 1H, NH), 6.16(m, 1H, C₃-ArH), 6.30

(m, 1H, C₄-ArH), 7.31(m, 1H, C₅-ArH). ¹³C NMR (150 MHz, CDCl₃):

¹H NMR (400 MHz, CDCl₃):

0.85(t, 3H, eCH₃, J ¼ 7.12 Hz),

1.56e1.60 (m, 1H, HCH), 2.16e2.20(m, 1H, HCH), 2.78e2.80 (m, 1H,

CH), 2.83(d, 3H, eCH₃, J ¼ 4.80 Hz), 3.80(s, 3H, C₄-ArOCH₃), 3.84(s,

6H, C_3,5-ArOCH₃), 3.86(q, 2H, eCH₂, J ¼ 7.12 Hz), 4.91(br s, 1H, NH),

5.55(br s, 1H, NH), 6.55(s, 2H, C_2,6-ArH). ¹³C NMR (150 MHz, CDCl₃):

17.23, 24.44, 27.26, 36.75, 47.38, 64.56, 110.44, 113.87, 144.54,

149.89, 159.32, 172.87. MS (m/z): 253[M þ 1]^þ. Anal. Calcd for

C₁₂H₁₆N₂O₄: C, 57.13; H, 6.39; N, 11.10; found: C, 56.85; H, 6.64;

N, 10.94%.

13.74, 20.67, 27.05, 35.23, 41.23, 56.10, 60.83, 61.02, 106.32, 131.36,

137.07, 143.54, 152.82, 159.32, 170.91. MS (m/z): 353[M þ 1]^þ. Anal.

Calcd for C₁₇H₂₄N₂O₆: C, 57.94; H, 6.86; N, 7.95; found: C, 60.13; H,

7.13; N, 8.07%.

5.1.3.20. Ethyl 2-(4-(methylsulfonyl)phenyl)-1-(3-methylureido)cyclo-

propanecarb oxylate (5t). White powdery crystals. Yield: 88%; mp:

221e223 ^ꢀC. IR (KBr, cm^ꢂ1): 3356 (NeH), 1712(C]O), 1653 (C]O),

5.1.3.15. Ethyl 2-(4-ﬂuorophenyl)-1-(3-methylureido)cyclopro-

panecarboxylate (5o). White powdery crystals. Yield: 85%; mp:

212e214 ^ꢀC. IR (KBr, cm^ꢂ1): 3344 (NeH), 1728(C]O), 1687 (C]O).

1322(O]S]O). ¹H NMR (400 MHz, CDCl₃):

d 0.71(t, 3H, CH₃,

J ¼ 7.16 Hz), 1.61e1.72(m, 1H, HCH), 2.25e2.29(m, 1H, HCH), 2.94(d,

3H, CH₃, J ¼ 4.46 Hz), 3.03(s, 3H, CH₃), 3.45e3.49(m, 1H, CH), 3.83

(q, 2H, eCH₂, J ¼ 7.16 Hz), 4.78(br s, 1H, NH), 5.91(br s, 1H, NH),

7.47e7.49(m, 2H, C_2,6-ArH), 7.88e7.90(m, 2H, C_3,5-ArH). ¹³C NMR

¹H NMR (400 MHz, CDCl₃):

0.82(t, 3H, CH₃, J ¼ 7.16 Hz), 1.59e1.62

(m,1H, HCH), 2.16e2.19(m,1H, HCH), 2.82(d, 3H, eCH₃, J ¼ 4.56 Hz),

2.83e2.89(m, 1H, CH), 3.83(q, 2H, CH₂, J ¼ 7.16 Hz), 4.97(br s, 1H,

NH), 5.75(br s, 1H, NH), 6.94e7.02(m, 2H, C_3,5-ArH), 7.29e7.33(m,

(150 MHz, CDCl₃):

d 17.39, 25.35, 31.23, 35.34, 45.98, 46.87, 63.33,

127.38, 130.22, 138.97, 141.35, 157.63, 172.68. MS (m/z): 341

[M þ 1]^þ. Anal. Calcd for C₁₅H₂₀N₂O₅S: C, 52.93; H, 5.92; N, 8.23;

found: C, 53.13; H, 6.12; N, 8.10%.

2H, C_2,6-ArH). ¹³C NMR (150 MHz, CDCl₃):

d 15.77, 22.54, 29.88,

34.52, 45.55, 61.04, 113.53, 129.82, 153.45, 159.65, 161.30, 170.11. MS

(m/z): 281[M þ 1]^þ. Anal. Calcd for C₁₄H₁₇FN₂O₃: C, 59.99; H, 6.11;

N, 9.99; found: C, 60.22; H, 6.35; N, 10.23%.

5.1.4. General procedure for the synthesis of compounds 6a-t

To a solution of compound 5 (1 mmol) and EtOH (10 ml) was

added sodium (1.2 mmol), and the reaction mixture was stirred

at room temperature for 2 h. EtOH was removed under reduced

pressure. Ethyl acetate and water were added to the residue.

The ethyl acetate layer was dried over anhydrous Na₂SO₄,

concentrated, and recrystallized to give compound 6 as white

solid.

5.1.3.16. Ethyl 2-(4-chlorophenyl)-1-(3-methylureido)cyclopro-

panecarboxylate (5p). White powdery crystals. Yield: 85%; mp:

215e217 ^ꢀC. IR (KBr, cm^ꢂ1): 3365 (NeH), 1722(C]O), 1672 (C]O).

¹H NMR (400 MHz, CDCl₃):

0.84(t, 3H, CH₃, J ¼ 7.16 Hz), 1.57e1.61

(m, 1H, HCH), 2.17e2.20(m, 1H, HCH), 2.89(d, 3H, CH₃, J ¼ 4.54 Hz),

2.91e2.98(m, 1H, CH), 3.84(q, 2H, CH₂, J ¼ 7.16 Hz), 4.89(br s, 1H,

3828

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

5.1.4.1. 1-Isopropyl-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-dione

(6a). White powdery crystals. Yield: 95%; mp: 172e174 ^ꢀC. IR (KBr,

cm^ꢂ1): 3444 (NeH), 1758(C]O), 1714 (C]O). ¹H NMR (400 MHz,

CDCl₃):

CH), 2.98(s, 3H, eCH₃), 6.19(br s, 1H, NH), 7.28e7.30(m, 2H, C_2,6

ArH), 7.31(m, 1H, C₄-ArH), 7.32e7.34(m, 2H, C_3,5-ArH). ¹³C NMR

d 1.81e1.85(m, 1H, HCH), 2.13e2.17(m, 1H, HCH), 2.89(m,1H,

CDCl₃):

0.89e0.90(d, 3H, CH_3,J ¼ 6.56 Hz), 1.00e1.02(d, 3H, CH₃,

(150 MHz, CDCl₃): d 18.06, 24.73, 32.19, 46.24,127.40,128.14,128.74,

J ¼ 6.76 Hz), 1.37e1.50(m, 3H, Cpr-CHCH₂), 1.93e2.00(m, 1H, CH),

133.08, 158.24, 171.45. MS (m/z): 217[M þ 1]^þ. Anal. Calcd for

C₁₂H₁₂N₂O₂: C, 66.65; H, 5.59; N, 12.96; found: C, 66.73; H, 5.47; N,

12.77%.

3.06(s, 3H, CH₃), 6.91(br s, 1H, NH). ¹³C NMR (150 MHz, CDCl₃):

20.50, 21.48, 22.48, 24.69, 25.69, 36.32, 44.53, 158.09, 173.56. MS

(m/z): 183[M þ 1]^þ. Anal. Calcd for C₉H₁₄N₂O₂: C, 59.32; H, 7.74; N,

15.37; found: C, 59.41; H, 7.59; N, 15.21%.

5.1.4.8. 6-Methyl-1-p-tolyl-4,6-diazaspiro[2.4]heptane-5,7-dione (6h).

White powdery crystals. Yield: 95%; mp: 213e215 ^ꢀC. IR (KBr,

cm^ꢂ1): 3452 (NeH), 1735(C]O), 1697(C]O). ¹H NMR (400 MHz,

5.1.4.2. 1-Ehtyl-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-dione (6b).

White powdery crystals. Yield: 98%; mp: 133e136 ^ꢀC. IR (KBr,

cm^ꢂ1): 3442 (NeH), 1748(C]O), 1713(C]O). ¹H NMR (400 MHz,

CDCl₃):d 1.79e1.83(m, 1H, HCH), 2.10e2.14(m, 1H, HCH), 2.31(s, 3H,

C₄-Ar-CH₃), 2.84e2.89(m, 1H, CH), 2.97(s, 3H, eCH₃), 6.41(br s, 1H,

CDCl₃):

0.93e0.99(t, 3H, CH_3,J ¼ 7.36 Hz), 1.37e1.39(m, 1H, HCH),

NH), 7.11e7.13(m, 2H, C_2,6-ArH), 7.15e7.17(m, 2H, C_3,5-ArH). ¹³C

1.45e1.48(m, 1H, HCH), 1.56e1.62(m, 1H, CH), 1.64e1.76(m, 2H,

NMR (150 MHz, CDCl₃): d 18.07, 21.18, 24.73, 31.99, 46.21, 128.58,

CH₂), 3.05(s, 3H, eCH₃), 6.65(br s, 1H, NH). ¹³C NMR (150 MHz,

128.90, 129.95, 137.06, 158.12, 171.49. MS (m/z): 231[M þ 1]^þ. Anal.

Calcd for C₁₃H₁₄N₂O₂: C, 67.81; H, 6.13; N, 12.17; found: C, 67.67; H,

6.47; N, 11.93%.

CDCl₃):

d 13.47, 19.19, 20.49, 24.64, 30.00, 44.22, 158.21, 173.61. MS

(m/z): 169[M þ 1]^þ. Anal. Calcd for C₈H₁₂N₂O₂: C, 57.13; H, 7.19; N,

16.66; found: C, 57.22; H, 7.43; N, 16.37%.

5.1.4.9. 1-(4-methoxyphenyl)-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-

dione (6i). White powdery crystals. Yield: 94%; mp: 208e210 ^ꢀC.

IR (KBr, cm^ꢂ1): 3426 (NeH), 1745(C]O), 1711(C]O). ¹H NMR

5.1.4.3. 6-Methyl-1-propyl-4,6-diazaspiro[2.4]heptane-5,7-dione (6c).

White powdery crystals. Yield: 95%; mp: 101e103 ^ꢀC. IR (KBr,

cm^ꢂ1): 3444 (NeH), 1751(C]O), 1718(C]O). ¹H NMR (400 MHz,

(400 MHz, CDCl₃):d 1.79e1.83(m, 1H, HCH), 2.08e2.12(m, 1H,

CDCl₃):

0.90(t, 3H, eCH₃, J ¼ 7.36 Hz), 1.32e1.72(overlapping m,

HCH), 2.83e2.87(m, 1H, CH), 2.98(s, 3H, eCH₃), 3.78(s, 3H, OCH₃),

6.41(br s, 1H, NH), 6.84e6.86(d, 2H, C_3,5-ArH, J ¼ 8.56 Hz),

7.18e7.20(d, 2H, C_2,6-ArH, J ¼ 8.48 Hz). ¹³C NMR (150 MHz,

7H, 2ꢃ CH₂, and Cpr-HCH₂), 3.07(s, 3H, CH₃), 6.95(br s, 1H, NH). ¹³

NMR (150 MHz, CDCl₃):

d 13.53, 20.43, 22.25, 24.63, 27.55, 28.11,

44.19, 158.27, 173.67. MS (m/z): 183[M þ 1]^þ. Anal. Calcd for

C₉H₁₄N₂O₂: C, 59.32; H, 7.74; N, 15.37; found: C, 59.63; H, 7.93; N,

15.06%.

CDCl₃): d 16.43, 23.00, 29.97, 44.38, 53.45, 111.86, 123.15, 128.02,

157.07, 169.68. MS (m/z): 247[M

1]^þ. Anal. Calcd for

C₁₃H₁₄N₂O₃: C, 63.40; H, 5.73; N, 11.38; found: C, 63.18; H, 5.44; N

11.63%.

5.1.4.4. 1-Butyl-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-dione (6d).

White powdery crystals. Yield: 95%; mp: 87e89 ^ꢀC. IR (KBr, cm^ꢂ1):

3440 (NeH), 1746(C]O), 1712(C]O). ¹H NMR (400 MHz, CDCl₃):

5.1.4.10. 1-(2,5-dimethoxyphenyl)-6-methyl-4,6-diazaspiro[2.4]

heptane-5,7-dione (6j). White powdery crystals. Yield: 94%; mp:

206e208 ^ꢀC. IR (KBr, cm^ꢂ1): 3441 (NeH), 1767(C]O), 1728(C]O).

0.91(t, 3H, CH₃, J ¼ 7.33 Hz),1.31e2.01(overlapping m, 9H, 3ꢃ CH₂,

and Cpr-CHCH₂), 3.15(s, 3H, CH₃), 7.23(br s, 1H, NH). ¹³C NMR

¹H NMR (400 MHz, CDCl₃):

d 1.76e1.80(m, 1H, HCH), 1.93e1.96(m,

(150 MHz, CDCl₃):

13.44, 20.68, 22.53, 23.15, 24.88, 27.96, 29.16,

1H, HCH), 2.69e2.74(m, 1H, CH), 2.99(s, 3H, CH₃), 3.68(s, 3H, OCH₃),

3.76(s, 3H, OCH₃), 6.42(br s, 1H, NH), 6.71e6.75(m, 2H, C_3,4-ArH),

44.21, 158.33, 173.26. MS (m/z): 183[M þ 1]^þ. Anal. Calcd for

C₁₀H₁₆N₂O₂: C, 61.20; H, 8.22; N, 14.27; found: C, 60.96; H, 8.43; N,

14.54%.

6.77e6.79(m, 1H, C₆-ArH). ¹³C NMR (150 MHz, CDCl₃):

d 18.04,

24.59, 27.43, 45.73, 55.66, 110.54, 112.60, 116.25, 123.58, 152.61,

153.34, 158.26, 172.00. MS (m/z): 277[M þ 1]^þ. Anal. Calcd for

C₁₄H₁₆N₂O₄: C, 60.86; H, 5.84; N, 10.14; found: C, 60.66; H, 5.58; N,

10.41%.

5.1.4.5. 1-Isobutyl-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-dione

(6e). White powdery crystals. Yield: 94%; mp: 96e99 ^ꢀC. IR (KBr,

cm^ꢂ1): 3448 (NeH), 1742(C]O), 1708(C]O). ¹H NMR (400 MHz,

CDCl₃):

0.87(d, 3H, CH₃, J ¼ 3.08 Hz), 0.92(d, 3H, CH₃, J ¼ 3.12 Hz),

5.1.4.11. 1-(3,4-dimethoxyphenyl)-6-methyl-4,6-diazaspiro[2.4]

heptane-5,7-dione (6k). White powdery crystals. Yield: 97%; mp:

195e197 ^ꢀC. IR (KBr, cm^ꢂ1): 3433 (NeH), 1743(C]O), 1708(C]O).

1.35e1.38(m, 1H, HCH), 1.46e1.49(m, 1H, HCH), 1.57e1.60(m, 3H,

Cpr-CH, CH₂and CH), 3.05(s, 3H, eCH₃), 6.37(br s, 1H, NH). ¹³C NMR

(150 MHz, CDCl₃):

20.39, 22.01, 22.26, 24.64, 36.83, 28.24, 34.13,

¹H NMR (400 MHz, CDCl₃):

d 1.80e1.85(m, 1H, HCH), 2.09e2.13(m,

44.22, 158.24, 173.69. MS (m/z): 197[M þ 1]^þ. Anal. Calcd for

C₁₀H₁₆N₂O₂: C, 61.20.13; H, 8.22; N, 14.27; found: C, 61.45; H, 8.12;

N, 14.46%.

1H, HCH), 2.83e2.88(m,1H, CH), 2.99(s, 3H, CH₃), 3.85(s, 3H, OCH₃),

3.88(s, 3H, OCH₃), 6.44(br s, 1H, NH), 6.79e6.82(m, 3H, C_2,5,6-ArH).

¹³C NMR (150 MHz, CDCl₃):

d 18.36, 24.73, 32.12, 46.29, 55.78,

55.88, 110.65, 111.95, 120.92, 125.51, 148.25, 148.53, 158.22, 171.61.

MS (m/z): 277[M þ 1]^þ. Anal. Calcd for C₁₄H₁₆N₂O₄: C, 60.86; H,

5.84; N, 10.14; found: C, 60.65; H, 5.72; N, 10.23%.

5.1.4.6. 6-Methyl-1-(pentan-3-yl)4,6-diazaspiro[2.4]heptane-5,7-dione

(6f). White powdery crystals. Yield: 95%; mp: 95e97 ^ꢀC. IR (KBr,

cm^ꢂ1): 3448 (NeH), 1735(C]O), 1712(C]O). ¹H NMR (400 MHz,

CDCl₃):

0.76(t, 3H, CH₃, J ¼ 7.44 Hz), 0.93(t, 3H, CH₃, J ¼ 7.44 Hz),

5.1.4.12. -(2,3-dimethoxyphenyl)-6-methyl-4,6-diazaspiro[2.4]heptane-

5,7-dione (6l). White powdery crystals. Yield: 97%; mp: 189e191 ^ꢀC.

IR (KBr, cm^ꢂ1): 3426 (NeH), 1766(C]O), 1724(C]O). ¹H NMR

1.15e1.22(m, 1H, Cpr-CH), 1.36e1.52(m, 6H, 2ꢃ CH₂and Cpr-CH₂),

1.65e1.69(m, 1H, CH), 3.05(s, 3H, CH₃), 6.83(br s, 1H, NH). ¹³C NMR

(150 MHz, CDCl₃):

10.67, 10.93, 19.90, 24.68, 26.39, 26.74, 33.11,

(400 MHz, CDCl₃):d 1.78e1.82(m,1H, HCH), 2.07e2.07(m,1H, HCH),

36.50, 44.24, 158.21, 173.92. MS (m/z): 211[M þ 1]^þ. Anal. Calcd for

C₁₁H₁₈N₂O₂: C, 62.83; H, 8.63; N, 13.32; found: C, 62.51; H, 8.47; N,

13.14%.

2.89e2.93(m, 1H, CH), 2.97(s, 3H, CH₃), 3.73(s, 3H, OCH₃), 3.83(s,

3H, OCH₃), 6.50(br s, 1H, NH), 6.81e6.86(m, 2H, C_4,5-ArH),

7.02e7.06(m, 1H, C₆-ArH). ¹³C NMR (150 MHz, CDCl₃):

d 17.55,

24.68, 27.41, 46.10, 55.64, 60.26, 111.84, 120.99, 123.49, 127.46,

148.20, 152.18, 158.02, 171.68. MS (m/z): 277[M þ 1]^þ. Anal. Calcd

for C₁₄H₁₆N₂O₄: C, 60.86; H, 5.84; N, 10.14; found: C, 60.56; H, 5.71;

N, 10.43%.

5.1.4.7. 6-Methyl-1-phenyl-4,6-diazaspiro[2.4]heptane-5,7-dione

(6g). White powdery crystals. Yield: 95%; mp: 204e206 ^ꢀC. IR (KBr,

cm^ꢂ1): 3442 (NeH), 1745(C]O), 1706(C]O). ¹H NMR (400 MHz,

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

3829

5.1.4.13. 6-Methyl-1-(2,3,4-triimethoxyphenyl)-4,6-diazaspiro[2.4]

5.1.4.19. 1-(furan-2-yl)-

6-methyl-4,6-diazaspiro[2.4]heptane-5,7-

heptane-5,7-dione (6m). White powdery crystals. Yield: 96%; mp:

dione (6s). White powdery crystals. Yield: 92%; mp: 168e170 ^ꢀC. ¹H

188e190 ^ꢀC. IR (KBr, cm^ꢂ1): 3299 (NeH), 1748(C]O), 1707(C]O).

NMR (400 MHz, CDCl₃):d 1.78e1.81(m, 1H, HCH), 1.96e2.00(m, 1H,

¹H NMR (400 MHz, CDCl₃):

1.76e1.81(m, 1H, HCH), 1.99e2.05(m,

HCH), 2.88e2.92(m, 1H, CH), 3.07(s, 3H, CH₃), 5.96(br s, 1H, NH),

6.25e6.26(m, 1H, C₃-ArH), 6.35e6.36(m, 1H, C₄-ArH), 7.34(m, 1H,

1H, HCH), 2.80e2.85(m,1H, CH), 2.98(s, 3H, CH₃), 3.78(s, 3H, OCH₃),

3.84(s, 3H, OCH_3,), 3.85(s, 3H, OCH₃), 6.56(br s, 1H, NH), 6.64(d, 1H,

C₅-ArH, J ¼ 8.68 Hz), 6.89(d, 1H, C₆-ArH). ¹³C NMR (150 MHz,

C₅-ArH). ¹³C NMR (150 MHz, CDCl₃):

d 16.70, 23.29, 24.86, 46.50,

108.43, 110.90, 142.23, 148.90, 157.24, 172.72.MS (m/z): 295

[M þ 1]^þ. Anal. Calcd for C₁₀H₁₀N₂O₃: C, 58.25; H, 4.89; N, 13.59;

found: C, 58.06; H, 4.69; N, 13.78%.

CDCl₃):

d 17.60, 24.62, 27.36, 45.95, 55.83, 60.60, 60.75, 106.47,

119.55, 123.49, 141.52, 152.75, 153.17, 158.19, 171.94. MS (m/z): 307

[M þ 1]^þ. Anal. Calcd for C₁₅H₁₈N₂O₅: C, 58.82; H, 5.92; N, 9.15;

found: C, 59.13; H, 5.73; N, 9.34%.

5.1.4.20. 6-Methyl-1-(4-(methylsulfonyl)phenyl)-4,6-diazaspiro[2.4]

heptane-5,7-dione(6t). White powdery crystals. Yield: 92%; mp:

230e232 ^ꢀC. IR (KBr, cm^ꢂ1): 3375 (NeH), 1706(C]O), 1669(C]O),

5.1.4.14. 6-Methyl-1-(3,4,5-triimethoxyphenyl)-4,6-diazaspiro[2.4]

heptane-5,7-dione (6n). White powdery crystals. Yield: 98%; mp:

194e196 ^ꢀC IR (KBr, cm^ꢂ1): 3288 (NeH), 1734(C]O), 1698(C]O).

1334(O]S]O). ¹H NMR (400 MHz, DMSO-d₆):

d 1.85e1.89(m, 1H,

HCH), 2.05e2.09(m, 1H, HCH), 2.96e3.01(m, 1H, CH), 3.18(s, 3H,

CH₃), 7.54(d, 2H, C_2,6-ArH, J ¼ 8.32 Hz), 7.81(d, 2H, C_3,5-ArH,

J ¼ 8.32 Hz), 8.64(br s, 1H, NH). ¹³C NMR (150 MHz, DMSO-d₆):

¹H NMR (400 MHz, CDCl₃):

d 1.82e1.86(m, 1H, HCH), 2.08e2.14(m,

1H, HCH), 2.81e2.86(m, 1H, CH), 3.01(s, 3H, CH₃), 3.83(s, 3H, C₄-

ArOCH₃), 3.86(s, 6H, C_3,5-ArOCH₃), 6.50(s, 2H, C_2,6-ArH), 6.65(br s,

d 17.08, 24.17, 30.38, 43.42, 46.05, 126.32, 129.77, 138.81, 140.38,

1H, NH). ¹³C NMR (150 MHz, CDCl₃):

18.61, 24.74, 32.67, 46.44,

156.28, 171.04. MS (m/z): 295[M þ 1]^þ. Anal. Calcd for C₁₃H₁₄N₂O₄S:

56.10, 60.82, 105.82, 128.84, 137.18, 152.83, 158.09, 171.41. MS (m/z):

307[M þ 1]^þ. Anal. Calcd for C₁₅H₁₈N₂O₅: C, 58.82; H, 5.92; N, 9.15;

found: C, 59.01; H, 5.87; N, 9.32%.

C, 53.05; H, 4.79; N, 9.52; found: C, 53.25; H, 4.69; N, 9.89%.

5.2. Anticonvulsant screening

5.1.4.15. 1-(4-ﬂuorophenyl)-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-

dione (6o). White powdery crystals. Yield: 98%; mp: 224e226 ^ꢀC. IR

(KBr, cm^ꢂ1): 3446 (NeH), 1759(C]O), 1727(C]O). ¹H NMR

Anticonvulsant activity assays were carried out by the Antiepi-

leptic Drug Development Program, Epilepsy Branch, National

Institute of Neurological and Communicative Disorders and Stroke,

National Institute of Health in Bethesda, USA [25]. Male Kunming

mice (20 ꢄ 2.0 g) and male Kunming rats (250 ꢄ 5.0 g) were used as

experimental animals in this study. Animals of the same age and

weight have been selected in order to minimize biological. The

animals were approved by the Animal Care Committee of Wuhan

University. All the animals were purchased from Wuhan University

Laboratory Animal Center (Wuhan, China). The tested compounds

were injected intraperitoneally to mice as a suspension in 0.5%

methylcellulose at dose of 30, 100, and 300 mg/kg to one to four

mice. The anticonvulsant activity of the tested compounds were

evaluated by two models namely, MES and scPTZ models.

Phenytoin and ethosuximide were used as the standard drugs for

the comparison. The neurological toxicity was determined in the

rotorod test. Procedures employed for evaluation of anticonvulsant

activity and neurotoxicity were described elsewhere [26].

(400 MHz, CDCl₃):d 1.83e1.87(m, 1H, HCH), 2.08e2.12(m, 1H, HCH),

2.85e2.90(m, 1H, CH), 2.98(s, 3H, CH₃), 6.68(br s, 1H, NH),

6.98e7.03(m, 2H, C_3,5-ArH), 7.22e7.26(m, 2H, C_2,6-ArH). ¹³C NMR

(150 MHz, CDCl₃): d 17.63, 24.61, 30.46, 46.06, 114.85, 115.07, 130.76,

130.79, 131.14, 131.22, 156.74, 160.32, 162.73, 171.66. MS (m/z): 235

[M þ 1]^þ. Anal. Calcd for C₁₂H₁₁FN₂O₂: C, 61.53; H, 4.73; N, 11.96;

found: C, 61.85; H, 4.56; N, 12.10%.

5.1.4.16. 1-(4-chlorophenyl)-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-

dione (6p). White powdery crystals. Yield: 98%; mp: 229e231 ^ꢀC. IR

(KBr, cm^ꢂ1): 3447 (NeH), 1755(C]O), 1716(C]O). ¹H NMR

(400 MHz, CDCl₃):

d 1.83e1.87 (m, 1H, HCH), 2.09e2.13(m, 1H,

HCH), 2.82e2.87(m, 1H, CH), 2.98(s, 3H, CH₃), 6.33(br s, 1H, NH),

7.20(d, 2H, C_2,6-ArH, J ¼ 8.36 Hz), 7.28(d, 2H, C_3,5-ArH, J ¼ 8.36 Hz).

¹³C NMR (150 MHz, CDCl₃):

d 17.45, 24.62, 30.54, 46.20, 128.14,

131.17, 131.68, 133.71, 156.71, 171.58. MS (m/z): 307[M þ 1]^þ. Anal.

Calcd for C₁₂H₁₁ClN₂O₂: C, 57.49; H, 4.42; N, 11.17; found: C, 58.12;

H, 4.25; N, 11.29%.

5.2.1. MES-maximal electroshock seizure pattern test

This activity was tested according to the method of Swinyard

et al. [27]. In experiments with mice, a 60-Hz current of 50-mA

intensity was applied through corneal electrodes for a 0.25 s

duration; with rats, seizure activity was induced by delivery of

a 150-mA current (0.2 s) to the cornea. Both procedures caused

immediate hindlimb tonic extension. After 0.5 h and 4.0 h of drug

administration, electroshocks were via corneal electrodes. Absence

of tonic extension suggests that the tested compound was consid-

ered as positive criteria.

5.1.4.17. 1-(2-chlorophenyl)-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-

dione (6q). White powdery crystals. Yield: 93%; mp: 220e222 ^ꢀC. IR

(KBr, cm^ꢂ1): 3431 (NeH), 1745(C]O), 1702(C]O). ¹H NMR

(400 MHz, CDCl₃): 1.81e1.85(m, 1H, HCH), 1.91e1.94(m, 1H, HCH),

2.78(s, 3H, CH₃), 2.79e2.80(m, 1H, CH), 7.26e7.40(m, 5H, ArH), 8.62

(br s, 1H, NH). ¹³C NMR (150 MHz, CDCl₃):

d 18.32, 22.97, 29.32,

43.16, 127.88, 128.76, 128.81, 131.71, 134.22, 135.68, 158.16, 172.32.

MS (m/z): 307[M þ 1]^þ. Anal. Calcd for C₁₂H₁₁ClN₂O₂: C, 57.49; H,

4.42; N, 11.17; found: C, 57.32; H, 4.51; N, 11.31%.

5.2.2. Pentylenetetrazole (PTZ) induced seizure test

For the chemically induced convulsant test according to the

method of Vamecq et al. [28], pentylenetetrazole was dissolved in

sufﬁcient 0.9% saline to allow subcutaneous injections to mice or

rat. Standard drug in this model was ethosuximide. After 0.5 h and

4.0 h of drug administration the failure to observe even a threshold

seizure (a single episode of clonic spasms of at least 5 s duration) is

deﬁned as protection.

5.1.4.18. 1-(4-bromophenyl)-6-methyl-4,6-diazaspiro[2.4]heptane-5,7-

dione (6r). White powdery crystals. Yield: 98%; mp: 168e170 ^ꢀC. IR

(KBr, cm^ꢂ1): 3475 (NeH), 1765(C]O), 1712(C]O). ¹H NMR

(400 MHz, CDCl₃):d 1.83e1.87(m, 1H, HCH), 2.09e2.13(m, 1H, HCH),

2.80e2.85(m, 1H, CH), 2.98(s, 3H, CH₃), 6.09(br s, 1H, NH), 7.14(d,

2H, C2,6-ArH, J ¼ 8.08 Hz), 7.44(d, 2H, C3,5-ArH, J ¼ 8.16 Hz). ¹³C

NMR (150 MHz, CDCl₃):

d 17.39, 24.63, 30.62, 46.17, 120.22, 131.05,

131.54, 134.13, 156.71, 171.57. MS (m/z): 295[M þ 1]^þ. Anal. Calcd for

C₁₂H₁₁ClN₂O₂: C, 48.84; H, 3.76; N, 9.49; found: C, 48.67; H, 3.62; N,

9.63%.

5.2.3. Neurotoxicity screening

Minimal motor impairment was measured in mice or rats by

using standardized rotorod test [29]. The mouse was placed on a 1

3830

X. He et al. / European Journal of Medicinal Chemistry 45 (2010) 3818e3830

[6] P. Emilio, Epilepsia 40 (Suppl. 9) (1999) S7e13.

[7] J.A. French, Epilepsia 40 (1999) 11e16.

[8] E.S. James, J. Lesley, CNS Drugs 19 (2005) 347e367.

[9] W. Löscher, D. Schmidt, Epilepsy Res. 50 (2002) 3e16.

[10] R.S. Greenwood, Epilepsia 41 (2000) S42e52.

[11] M.J. Brodie, Epilepsy Res. 45 (2001) 3e6.

[12] S.M. Tasso, L.E. Bruno-Blanch, S.C. Moon, G.L. Estiú, J. Mol. Struct. 504 (2000)

229e240.

in. diameter knurled plastic rod rotating at 6 rpm. Trained animals

were given an ip injection of the test compounds in doses of 30,100,

and 300 mg/kg. Neurotoxicity was indicated by the inability of the

animal to maintain equilibrium on the rod for at least 1 min in each

of the four trials.

[13] H.H. Merritt, T.J. Putnam, Arch. Neurol. Psychiatry 39 (1938) 1003e1015.

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44 (2009) 296e302.

5.2.4. Quantiﬁcation studies

Anticonvulsant activity was expressed in terms of the median

effective dose (ED₅₀), that is, the dose of drug required to produce

the biological responses in 50% of animals, neurotoxicity was

expressed as the median toxic dose (TD₅₀). For determination of the

ED₅₀and TD₅₀, groups of 10 mice were given a range of ip doses of

the test drug until at least three points were established in the

range of 10e90% seizure protection or minimal observed neuro-

toxicity [30]. From the plot of these data, the respective ED₅₀and

TD₅₀values, 95% conﬁdence intervals, slope of the regression line,

and standard error of the slope were calculated by means of

a computer program written at NINDS, NIH.

[19] J. Su, J. Xiong, S. Liang, G. Qiu, X. Feng, H. Teng, L. Wu, X. Hu, Synth. Commun.

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223e231.

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G. Estiu, L.E. Bruno-Blanch, J. Med. Chem. 52 (2009) 1592e1601.

[24] W. Fraser, C.J. Sucking, H.C.S. Wood, J. Chem. Soc., Perkin Trans.1 (1990) 3140.

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Acknowledgments

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[27] E.A. Swinyard, Epilepsia 10 (1969) 107e119.

[28] J. Vamecq, D. Lambert, J.H. Poupaert, B. Masereel, J.P. Stables, J. Med. Chem. 41

(1998) 3307e3313.

This investigation was made possible through the ﬁnancial

support of Key Project of Science & Technology of HuBei Province,

China (Grant No. 2008CDA 057) and the Important National Science

& Technology Speciﬁc Projects, China (Grant No. 2009ZX09301-14).

[29] N.W. Dunham, T.A. Miya, J. Am. Pharm. Assoc., Sci. 46 (1957) 206e212.

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J. Balzarini, E. DeClercq, Eur. J. Med. Chem. 30 (1995) 303e314.

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[33] K. Kaminski, J. Obniska, Bioorg. Med. Chem. 16 (2008) 4921e4931.

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