Indian Journal of Chemistry Vol. 44A, February 2005, pp. 232-240

Kinetic studies on the reactions of various 9-chloroacridines with some arylsulphonyl hydrazides and antiinflammatory and kinase

inhibition activitiy of the products

Sham M Sandhi 1, Gurudas Bhattachaijee 1*, Rafid K Jameel', Ashok Kumar2 & Kiran Baja/

'Department o f Chemi stry, Indian Institute of Technology Roorkee. Roorkee 247 667, Indi a 2Department of Pharmacology, L.L.R.M. M edica l College, Meerut. M eerut 250 004, India

Email: wordgfcy@ isc .iit r.erner.in

Received 18 Ju11 e 2004: reviser/ 15 Oece111ber 2004

9-Chloro-2,4(un)substituted acri dines ( la-e) have been condensed with benzenesulphony l hydrazide (2a). p­toluenesulphonyl hydrazide (2b), and 4-methoxybenzenesulphonyl-hydrazides (2c) to obtain the corresponding condensed products 3a-o. The structures of all the compounds synthes ized have been confirmed by spectroscopic methods. An tiinflammatory and kinase inhibition acti vities of all the compounds (3a-o) have been investi gated. Compounds 3e,h,i,n ex hibit good and 3a-d,f,gJ-m,o exhibit moderate anti-inllammatory acti vity. Kineti c studi es on the concerned aromatic nucleophili c substituti on (SNAr) have been carried ou t in methanol (MeOH). Another three reactions of la with suphonyl hydrazide 2a-c have been studied in DMSO under the same conditions for compari son. The base cata lysed mechanism (modified heteroconjugate BH+SB, BH+B) has been proposed for the reaction in M eOH . The effect of substituents on the benzene ring of the sulphonyl hydrazide is in the order: MeO>M e>H, retlecting the importance of electron-donating behaviour of the substituent in enhancing the nucleophil city of hydrazide group and al so in stabili zing the zwiuerionic complex T±.

IPC Code: lnt.CI 7 BOIJ

Acridine derivatives possess ing fungicida l' , antiparasitic2

, antiinflammatory and analgesic3

activities have been reported in the literature. A few acridine derivatives (v iz., azacrine, proflavine, mepacrine and aminacrine) al so possess antibacterial and antimalari al activities4

. Another acridine derivative, amsacrine, has been useful as an antitumor drug5

. In view of the wide range of useful biological activities of these derivatives, we continued our search for potential antiinflammatorl·7 and anticancer8

·<J agents and have sy nthesized the title com.pounds. Crampton has recently reviewed the nucleophilic aromatic substitution reactions 10

• The Specific Base-Genera l Acid (SB-GA) mechani sm in dipolar solvents has been proposed 11

-14

. In this type of reactions, the solvent molecule can also act as a base and expulsion of the leaving group is electrophilically catalyzed by conjugate acid of the solvent, SH+. A number. of acridinesulphonyl hydrazide derivatives have been synthesized and screened for their antiinflammatory, analgesic and kinase inhibition activities, the results of which are reported in this

Materials and Methods Chemicals and organic solvents used were of high

purity unless otherwise stated. 9-Chloro-2,4-(un) substituted acridines were sy nthesized as per literature 15

'16 procedure.

Melting points (m.p.) were determined on a JSGW apparatus and are uncorrected. fR spectra were recorded using a Perkin-Elmer 1600Ff spectrometer. Only principal sharply defined IR peaks are reported. 1HNMR spectra were recorded on a Bruker WH-300 Spectrometer in a ca . 5-l 5% (wlv) solution in DMSO­d6 with TMS as internal standard . The MS spectrometer peak meas urements were made on a Jeol SX -120 (FAB) and Micromaas TOF Spec. 2E MALDf TOF MS spectrometer. TLC was performed on silica gel G and spots were visualized by iodine vapour or by irradiation with ultraviolet light (254 nm). Column chromatography was performed usmg Qualigens silica gel (60-120 mesh).

General procedure for synthesis of 3

Condensation of 9-chloroacridine (la-e) with benzenesulphonyl hydrazide (2a-c) and analysis of the

SON DHI eta/.: KINETIC STUDIES ON THE REACTIONS OF VARIOUS 9-CHLOROACRIDI NES 233

mg; 1.2 mmol) and 9-ch loroacridine (256 mg; 1.2 mmol) were di ssolved separately in dry methanol (25 mL for each) by warming. The solutions were then mi xed and a llowed to stand at room temperature for three days. Solvent was removed under reduced pressure and the solid res idue left behind was suspended in 10% sodium carbonate solution (15 mL) and stirred (20 min). It was then filtered, washed with water and air dried to get crude product 3a, which was purified by column chromatography over silica ge l. Elution solvent, yield , m.p. and spectral data for 3a and other compounds prepared (Scheme 1) under similar conditions(3b-o) are reported in Table I .

It may be noted that ElMS spectra of acridinesulphonyl hydrazides (3a-o) did not give M+ ion peaks but gave various fragmentation peaks indicating fragile nature of these acridinesulphony l hydraz ides. In order to confirm the structures of ac ridinesulphonyl hydrazides (3a-o), FABMS of two compounds, i.e., 3a & 3b were obtained. Both these compounds showed correct MH+ ions peaks (Table I) in support of structures assigned to 3a-o.

00¥' + Hf'N HSOz-0-RJ

a) Rl=ll. R2=H h) RI =C H, . R,=H c) R I =H. R2=CH, d) R I =OCH, . R,=H e) R I =H. R,=OCH,

3a

3b

3c

3d

3c

31"

3g

3h

3i

3j

3k

31

3m

3n

3o

2

a) R,=H b) R,=CH,

MeOH c) R1=0CH1

NHNHS02~R3 ~·,

3 R2 R, R, R,

H H H

H H CH,

H H OCH,

CH1 II II

CH, H CH1

CH1 H OCH,

H CH1 II

H CH1 CH1

H CH, OCH,

OCH, H H

OCH1 H CH1

OCH, H OCH,

H OCH, H

H OCH, CH,

H OCH, OCH_,

Scheme I

Kinetic procedure The kinetics of the reactions were fol lowed using a

Shimadzu UV-1601 UV-vis recording spectrophotometer operating in both spec tral and kinetic modes. The spectrophotometer was coupled to a PC that allowed absorbance measure ment vs. time every 20 sec. and the multicell . ho lder was thermostatted to ± 0 . I °C using a 240 A-Shimadzu thermostat. The reactions were fol lowed at 267 nm,

the Amax of the product, which was found to be nearly the same in a ll the solvents used for the kinetic

studi es. The Amax of the product and its observance at an infinite reaction time was constant with the corresponding authentic sample within ±4%. Since a ll the reactions were studied under pseudo-first order conditions, these obeyed the first order kinetics.

Antiinflammatory activity screening Antiinflammatory acti vity screening 17 was carried

out usi ng carrageenin induced paw oedema method in albino rats. Oedema in one of the hind paws was induced by inject ing carrageenin soluti on (0. I mL of 1 %) into planter aponeurosis . The volume of the paw was measured plethysmographyically immed iate ly and also after three hours of injection of the irritant. The difference in vo lume gave the amount of oedema developed. Percent inhibition of the oedema between the control group and compound treated groups was calcul ated and compared with the group receiving a standard drug. Compounds 3a-o at 50 mg/kg p.o . inhibited carrageenin induced hind paw oedema by 20.0 ; 17.5; 21.5; 20.2; 25.4; 18.6; 17 .5 ; 25 .8; 24.3; 19.3 ; 20.4; 16.7 ; 17.3 ; 24.6 and 19.5% respec tively as co mpared to standard drug phenylbutazone whi ch showed 34.6% acti vity at 50 mg/kg p.o.

Kinase inhibition activity evaluation 18"20

The kinase inhibition activity was evaluated as per literature methods 18

-20 using GSK 3~, and CD K 5/p25.

Kinase acti viti es were assayed in Buffer A ( I 0 mM MgC I2, 1 mM EGT A, 1 mM OTT, 25 mM tris-HCI pH 7.5 , 50 )..lg heparin/mL) or C (60 mM ~­

glycerophosphate, 15 mM p-nitrophenylphosphate, 25 mM Mops (pH 7.2), 5 mM EGTA, 15 mM MgCb, I mM DIT, I mM sodium vanadate, and I 00 11M benzamidine) (unless otherwise stated) at 30°C, at a final ATP concentration of 15 )lM. Blank va lues were subtracted and activities calculated as pmoles of phosphate incorporated for a I 0 min incubation. The acti:'ities are expressed in %of the maximal activity, i.e ., in the absence of inhibitors. Controls were perfo rmed with appropriate dilutions of DMSO. In a

234 INDIAN J CHEM, SEC A, FEBRUARY 2005

Tab le I - Phys ical constants and spec tra l data I(IR (K13r) cm-1,

1HNMR (DMSO-d6 +CDCIJ, 300 Ml-l z) 8, J (liz); FABMS or ElMS (111/z ; relt. Int. %) 1 of ac ri cl inesuphonyl hydrazide deri vati ves. 3a-o

Sr. No. Solvent or lll .p. oc

Yield Spec tra l Data

3a

3h

3d

3c

3f

3g

3h

crys talli za ti on/ elution

CA:EtOH (4 I )

MeOH

Me OI-l

M e OI-l

MeOH

EtOH

EtOH

E.A

170

U:iO

184

180

176

172

160

172

o/o

36 IR 3444 & 3 165 (N H): 1575 (Ar); 1 11 NMR 8 7.3 1-7.45 (t, 211 , Ar): 75'2-7.59 (t. 21-L Ar): 7.60-7.70 (q, 2H, one 1-1 exch + 11-1 , A r): 7.79-7.Po2 (cl . 21-1 . A r). 7.9 1 (bel. 51-1. one 1-1 cxch. + 4H. Ar): 8.80 (bs, 21-1 , A r). FABM S 350 (MW. 40'Yc•): 273 (MW-Cr,Ho; 8%)

36 IR 3447 & 3335( H): 1579 (A r): 11-1 MR (DMSO-d6 +D20) 8 2.30 (s, 311 , C l-11) : 7.27 (t , 21-1 . A r), 7.37-7.50 (t, 21-1. A r). 7.55-7.58 (d, 2 1-1 , A r): 7.73-7.76 (cl . 2H. A r): 7.88 (d. 21-1 . Ar); 8.7 1 (d. 21-1 . A r). FABM S 364 (MI-l+; 100 %)

54 IR 3407(N H). 1629 & 1466(Ar); 1!-INMR (DMSO-clr,+D20) 8 3.76 (s, 31-1 , OCHJ). 6.93 -6.96 (d. 21-1 , Ar): 7.45-7.50 (q. 21-1. Ar); 7.59-7.61 (cl, 21-1 . A r); 7.66-7.78(cl. 21-1. Ar);

46

45

49

44

5 1

H S02~c · t-~ ·+ 7.8Po-7.93 (l. 21-1 . Ar); 8.73 (bs, 21-1 , Ar): El MS 179 ( 100 %).

172( ©00' ... 11 .3%), 77(C, H; 11 .5%).

IR 3442(NH), 1576 & 1459 (Ar), 11-INMR 8 2.45 (s, 31-1 , C l-11), 7. 11 -8.87(m, 101-1 , Ar) ; 8_54-8.87 (cl , 2H, A r); 11 .25 (bs, I 1-1 , NI-l); 14.46(bs, I H, NH). ElMS 333 (M +- N2H2;

0.8%). 77 (C61-1 5 +; 40.6%)

IR 3444(N H); 1586 (Ar); 11-lNMR 8 2.36 (s , 31-1 , C l-1 ,), 2.42(s, 31-1 , CH1): 7.12-7 70(m. 7H,Ar); 8. 15-8_25 (del , 21-1 , Ar); 8.46 (s, I H, Ar); 8.80-8.82 (cl , I H. Ar) ; I 0.30- 10.5 (bel. r:QIQ©rCilJ 21-1 , NHNH ; exeh.) .EIMS 193 ( N 46.2 %); 156

HS02--©--c~l]·+ ( ; L I %); 77 (C6H,+; I U %).

IR 3446(N H); 1590 & 1460 (Ar); 1HNMR 8 2.43 (s, 31-1, CH 1); 3.82 (s, 3H, OCH,), 6.79-6.82 (cl , 21-1. Ar); 7.27 - 7.32 (1 , lH, Ar); 7.51 - 7.57 (d, I H, Ar), 7.66-7.75 (del , 3H, Ar), 8. 13-8.23 (clcl , 2H, A r), 8.52 (s, l H, Ar) ; 8.86-8.89 (d. I H, Ar): I 0 50- I 0.70(cl, 21-1 .

c~ ·+ ~ ~+ HS00 OCH ~

NHNH: exch_ ). ElMS 193 ( ; 100%); 172 ( -' :l., C HI.. ;l'

L2%) 108 (H,CO-C6H> : 3.9%) 78 ( 6 c, ; 2.6'Yo); 77 (Cr.l-ls ; 7.4%).

IR 3387 (N H); 1585 & 1469 (Ar), 1HNMR 8 2.85 (s, 3H, CH,); 7.36-7.49 (m, 41-1, A r); 7.58 - 7.63 (1, !H. Ar), 7.74-7.79 (t, 3H. Ar) ; 7.86-7.91{t,IH, Ar); 8.56-8 .59 (d , !H. Ar); 8.7 l -8 .74(d, I H, Ar); 9.04-9.07 (cl , l H, A r); l L05(bs, l H, NH; exch. ); 12.50 (bs. l H,

CHI ' NH: exch.). ElMS 333 (M+ -N 2H2 ; 4.2%); 78 ( 6 6 ; 2 L4%); 77 (C6H5+; 44.6%).

IR 342 1 (NH), l594(Ar), 1 HNMR 8 2.4 (s, 31-1, Cl-1 ;~), 2.88 (s, 31-1 , Cl-1 3); 7. 18- 7.20 {d, 21-1 , Ar); 7.33-7.41 (q, 21-1, Ar); 7.62-7.65(t, 21-1, Ar) 7.69-7 .71 (cl , IH, Ar); 7.79-7.84 (t, !H , Ar); 8.68-8.71 (d, 21-1, Ar); 9_01-9_03 (d, IH , Ar); l LOO (bs, IH, NH, exeh_). !2_70

~~-+ ~y~ HS02~H]+

CHJ , !6%) !56( ~. (bs, l H, NH, exeh.).EIMS.208 (

Co11td

SONDHI eta/.: KINETIC STUDIES ON THE REACTIONS OF VARIOUS 9-CHLOROACRIDINES

Table I- Physical constants and spectral data [(IR (KBr) cnf 1,

1HNMR (DMSO-d6 +CDCI3, 300 MHz) o, J (Hz); FABMS or ElMS (111/z ; relt. Int. %)] of acridinesuphonyl hydrazide derivatives, 3a-o-Crmtd

235

Sr. No. Solvent of crystal! izat ion/

elution

m.p. oc

Yield Spectral Data

3i

3j

3k

31

3m

3n

EA:McOH 4: 1

EA:MeOH 4: 1

Ethy l acetate

Ethy l acetate

Ethy l acetate

EA:MeOH (9: I)

175

182

184

In

166

170

%

58

47

33

33

64

IR 3444 (NH), 1592- 1477 (Ar). 1 HNMR.o 2.86 (s, 3H, CH 3); 3.86 (s, 3H. OCH.1l; 6.84-6.86 (d, 2H. Ar); 7.35-7.47 (m, 2H . Ar) ; 7.65-7 .68 (d, 2H. Ar); 7.72-7.74 (cl. IH. Ar): 7.84-7 .89 (t, IH . Ar); 8.6 1-8.64 (cl. IH. Ar); 8.7 1 (d, I H. Ar); 9.04 (cl . IH . Ar); 10.90

©lOO (bs; IH,NH;exch.) ; 12.70 (bs, IH , NH,exch). ElMS 193 (

;0 2~C11 1 '

113 ; 100%); 171

( ; 15.0%); 77 (C6H5+; 23.3%).

IR 3452 (NH) 1582 & 1488 (Ar); H1NMR o 3.92 (S, 3H, OCH3); 7.4 1-7.62 ( 111 , 51-l . Ar); 7.77 -7.87 (m, 3H. Ar), 8.1 3-8. 17 (del. 3H, Ar) ; 9.03-9.06 (cl , !H. Ar); 10.92 (bs. 2H. NHNH, exch). ElMS. 349 (M+ -N ~H2 ; 0.7%)

:l ' or (M+-CH 20; 0.7%); 78 (Cr,Hr, ; 29.8%); 77 (C6H5+ ; 44.1 %).

IR 3448 (NH), 1582 & 1487 (Ar); H 1NMR o 2.40 (s, 3H, CH3); 3.94 (s, 31-l , OCH3 ) ;

7.1 7-7.20 (cl , 2H, Ar) ; 7.43-7.53 (q, IH, Ar); 7.60-7.63 (del. 3H, Ar); 7.85 (q. II-I. Ar);

~·,

©00'"'()( " 11 :~

(q, I H, Ar). ElMS 209 ( 8.08-8. 16 (m, 3H. Ar) ; 9 00-9.03

100%) 156 ( ; 10.8%)

IR 3464 (NI-l); 1590 & 1535 (Ar). H1NMR o 3.85 (s, 3H, OCH3); 3.93 (s. 31-l , OCH 3) ;

6.89-6.92 (cl, 2H, Ar); 7.46-7. 57 (q, IH, Ar); 7.6 1-7.67 (t, 3H, Ar); 7.88-7.90 ( 111 , !H. Ar); 8.04-8.08 (del, 2H, Ar); 8. I 7 (s, I H, Ar). 9.05-9.08(cl , I H, Ar); I 0.82 (bs, 21-l .

C H1 • NHNH. exch). ElMS 347 (M+ -(OCH3+0CH 3) ; I .7%) 77 ( fi 5 ; 22 .8%).

IR 3406 (NH) I 583 & 1483 (Ar) ; H 1NMR o 4. I 3 (s, 31-l, OCH1); 7. I 5-7 .1 8 (cl , I H, Ar): 7.27-7.35 (q , 2H. Ar); 7.45-7.54 (t, 2H.Ar); 7.59-7.64 (t, !H . Ar) 7.72-7.77(t. I H. Ar) 7.85-7.88(cl, 2H. Ar) ; 8.39-8.42 (cl , 2H. Ar); 8.99 (d. I H, Ar); I 1.00 (bs, I H, NH. exch);

~· 13.00 (bs, IH, NH, exch). ElMS 209 OCH3 ; 93.6%); 142

\i+ Hso-r\Q> cHI'

( - ; 15.8%) 78 ( fi 6 , 38 7%), 77 (C6H_,+ ; 100.00%)

59 IR 3440 (NH) 15!15 & 1488 (Ar), H 1NMR o 2.4 1 (s, 3H, CH3); 4.1 8 (s, 3H, OCH3) ;

7.21-7.24 (cl, 2H, Ar) ; 7.35-7.49 (m, 3H, Ar) ; 7.64-7.67 (d, 2H, Ar); 7.84-7.89 (t, 1H. Ar) 8.33-8.36 (cl , 1 H, Ar); 8.44 (m, 1 H, Ar); 8.99 (m, I H, Ar); I 1.00 (bs, I H, NI-l , cxch);

~· 13.00 (bs, IH, NH, exch). ElMS. 224 OCit3; 14.5%) 156

H SO~H3 ' ( 9.6%) 92 (CH3C6H{ ; 51.5%); 77 (C6H)+; 35.3%).

Contd

236 INDI AN J CHEM , SEC A, FEBRUARY 2005

Tab le I - Physical constants and spectral data r(IR (KBr) cm·1,

1HNMR (DMSO-r/6 +CDCI,, 300 MH z) 8, J (Hz); FABM S or ElMS (111/z ; relt. Int. % )] of acridinesuphonyl hydrazide deri vat ives. 3a-o- Contd

Sr. No. Solvent of m.p. Yield Spectral Data crys talli zat ion/ °C %

elution

3o EA: MeOH 176 (9: I )

57 IR 3477 (NH), 1589 & 1490 (Ar) H 1NM R 8 3.86 (s, 3H, OCH,); 4.15 (s, 3H. OCH1);

6.89-6.92 (cl, 2H, Ar); 7.20-7.23 (d , I H, Ar), 7.3 1-7.40 (q , 2H, Ar); 7.75 -7 .80 (t, JH. A r): 8.4 1-8.44 (cl , 2H, Ar). 9.03(m, IH, Ar): 10.90 (bs. !H . NH exch); 13.00 (bs. !H . NH

exch). ElMS 347 (M+ -(OCH,+OCH,); 8.6%) 108 (C6HsOcH"_l' ; 14.7'Ya ) 77 (C1,H,+: 26. 1%)

few cases phosphorylation of the substrate was assessed by autoradiography after SDS-PAGE.

Results and Discussion Kinet ic studies for nucleophi I ic aromatic

substituti on reactions (SNA r) of BSH, TSH and M BSH (2a-c) with 9-CAC, (la-e) in MeOH and 2a-c with la have been carried out in DMSO for co mpari son. The electroni c spectra showed a pronounced isosbestic point at 402 nm and showed A111ax at 430 nm in the visibl e part of the spectrum. The appearance of isosbesti c point clearl y indicates that no stab le intermediate(s) ts formed during the transformati on.

The values of pseudo first order rate constant, ko and the second order rate constant , k", in MeOH at I6°C are given in Table 2. The table also gives the va lues of ko and k" for the compounds 3a-c in DMSO (under similar conditions as in MeOH).

Effect of solvent and nucleophilc

Due to difference in donor number (ON) and acceptor number (AN) of the two so lvents , DMSO and MeOH, so lva tion of the zwitterioni c complex in these two med ia wou ld be different. Donor number and the acceptor number of DMSO respecti ve ly are 29.8 and 19.3 kcal/mol respecti vely, whereas those fo r MeOH are 19 and 4 1.5 kcal/mole respectivel/ 1

•

The properties in a DMSO solution are dominated by its intrinsic structures, whereas those in methanol so lution are assumed to reflect both its intrinsic molecular characteristic and so lvation. Shinkai et a/.

22

reported that the rate of cis-trans isomerisation of azobenzene was somewhat smaller in protic solvent than in a dipolar aprot ic solvent. This result is not compatibl e with our observation. S Ar reactions siUd ied in this ex periment were faster in MeOH th an in DMSO. The rates of enhancement were 17, 2 and 8 times for BSH , TSH and MBSH , respectively, for 3a-

c in MeOH as compared to those in DMSO (Table 2). As the rate of the reac ti ons for the subst ituted 9-chloroacridines are very slow, the reactions of 9-CAC were, therefore studied in DMSO.

Plots of ko versus [SH] at I6°C in MeOH and DMSO were linear and in some cases other shapes, such as upward curvature and paraboli c toward X-axi s were also observed . For further informati on on the SNAr reaction path , kA values were plotted against [SH] . The plots were of the following type: (i) upward curve linear (+ve slope), for 3a, 3b, 3f and 3j in MeOH, (i i) parabolic toward X-ax is, for 3c-e and 3m in MeOH, (iii) curve linear (-ve slope), fo r 3g-i , 3k, and 3n in MeOH , and for 3b, 3c in DMSO and (iv) linear with zero slope, for 31, 3o, in MeOl-1 , 3a in DMSO. The upward curve linear with +ve slope is indicative of base catalysis. Also, ·apparently thi s difference has given ri se to bi-functional nature of methanol , i.e., HBA and HBD abilities. Also seen from Table 2, order in amine is more than one (found to be three on further analys is). Banj oko et at."' reported thi s trend to be contrary to that expected on the basis of the dimer mechani sm which predi cts an initi al diminution in rate fo ll owed by an increase in the rate at hi gher methanol concentrat ion (above 30%). The SNAr reacti ons of piperidi ne in methanol. acetonitrile, chloroform and nitromethane were not catalyzed by base2~. Upward curvature was reported in aprotic solvents25 for the reactions of 2,4-dinitrofluorobenzene with different primary and secondary amines and showed dimer mechani sm. In the case of methanol , being a protic solvent, no se lf­association of amine occurs to form BH+B; also HBD ability of MeOH wou ld oppose the formati on of BH+B. As BH+B cannot ex ist in pure methanol, the formation of modified heteroconjugate BI-I+SB is envisaged, which involves two amine molecules to account for the unex pected but ex perimenta ll y observed behav iour. The formation of BH+S B is quite

SONDHI eta/ .: KIN ETIC STUDIES ON THE REACTIONS OF VARIOUS 9-CHLOROACRIDINES 237

Table 2 - Values of pseudo-first order rate constant (k.,) and second order rate constant (kA) for the reactions of 9-CAC and its derivati ves with some benzenesul phony l hydrazide (2a-c) in M eOH and in DMSO. [9-CACl = I.Sx i O··'mol/dn? and ISH]= 20-60x lo·"' mol/dnY1

u. Prod. No. C I C2 C3 C4 cs 297 K 305 K 3 13 K

In MeOI-1 3a

3b

3c

3d

3e

31"

3g

3h

3i

3j

3k

31

3m

3n

3o

In DMSO

13SH

TSH

MBH

BS H

TSH

MBH

BSH

TSH

MBH

BSH

TSH

MBH

BSH

TSH

MBH

6.4 (0.32)

32 ( 1.62)

14 (0.71 )

3 2 (0. 16)

7.3 (0.36)

10.1 (0.5 1) 32 .9

( 1.64) 26.7

( 1.33) 27.8

( 1.39) 8.2

(0.41) 8.75

(0.44) 4.60

(0.23) 5.30

(0.26) 12. 1

(0.6 1) 6.20

(0.3 1)

22.7 (0.75) 53.6

( 1.78) 56.8

( 1.89) 15.6

(0.52) 16

(0.52) 15.1 (0.5) 47.9

( 1.59) 39.6

( 1.32) 32.9

( 1.09) 10.8

(0.36) 9.9

(0.33) 7.83

(0.26) 19.1

(0.64) 15.2

(0.5 1) 9.40

(0.3 1)

61 .7 ( I 54) 80. 1

(2 00) 85.2

(2. 13) 26

(0.86) 22

(0.56) 24.4

(0.61 ) 54.5

( 1.36) 49

( 1.22) 38.4

(0.96) 16.3

(0.4 1) 12.6

(0.32) 9.90

(0.33) 24.8

(0.62) 17.9

(0.45) I 1.5

(0.29)

13 1 (2 62) Ill

(2 .22) 103

(2.07) 37 .3

(0.93) 24.8

(0.49) 33.6

(0.67) 69

( 1.38) 5 1.1

( 1.02) 45.8

(0.92) 2 1.1

(0.42) 14.0

(0.28) 11.7

(0.23) 27.8

(0.56) 19.3

(0.39) 14.7

(0.29)

159 (2.65)

137 (2 .29)

11 8 ( 1.97) 26.4

(0.44) 12.6

(0.2 1) 45. 1

(0.75) 86.3

( 1.43) 68.9

(0.96) 55.7

(0.93) 28.7

(0.48) 11.7

(0.20) 14.9

(0.25) 18.8

(0.3 1) 23 .0

(0.38) 18.6

(0.3 1)

229 (4.58)

172 (3.44)

132 (2 .64)

77 ( 1.54) 42.5

(0.85) 57.5

( I. 15) 120

(2.4) 88.2

( 1.76) 70

( 1.4) 53. 1

( 1.06) 27.4

(0.55) 17.5

(0.35) 55.5

(I. II ) 35.9

(0.72) 27. 1

(0.54)

309 (6. 18) 225 (4.5) 1.72

(3.44) 110

(2.2) 63.3

( 1.27) 75.3

( 1.5 1) 185

(3.7) 120

(2.4) 9 1

(1.82) 82

( 1.64) 4 1.2

(0.82) 30.8

(0.62) 89. 1

( 1.78) 51.1

( 1.02) 39. 1

(0.78)

85 (7.7) 282

(5 .64) 2 18

(4 36) 136

(2.72) 75. 7

( 1.5 I ) 96. 7

( 1.93) 228

(4.56) 135

(2.7) 11 3

(2.26) 101

(2.02) 52 .7

( 1.00) 39.8

(0.79) Ill

(2 .22) 67 .9

( 1.36) 46.0

(0.92)

3a BSH 4.8 6.9 I 0.5 12.6 11.0 28.7 37.3 (0.57) 27.4

(0.44) 23.9

(0.48)

52.5 (0.72 36.3

(0.24) (0.23) (0.26) (0.22) (0.21) (0.46) 3b TS H 8.2 8.2 9.9 11.9 14.2 17.9

(0.4 1) (0.27) (0.25) (0.24) (0.24) (0.24) (0.56) 28.5

(0.57) 3c MBH 12.6 10.3 11.2 11.5 14.1 14.7

(0.63) (0.35) (0.28) (0.23) (0.24) (0.29) CJC5 = [B) = 2060x l04 molldm3

; [B] = 50x 104 mol/dm3 in the case in temperalllre effect studies

logical because methanol possesses hydrogen bond acceptor (~=0 . 62) and donor (a=0.93) abilities21

. The structure of BH+SB is believed to be:

Bl-rt----0 -H- -- - B

I CJi3

Such modified heteroconjugate is not expected in DMSO due to non-availability of HBD ability (a=O) and therefore, the order in amine for the compounds 3a is three and for 3b, 3f and 3j, it is two. Thus, to

explain the results which involves base catalysis by modified heteroconjugate, BH+SB and [BWBJ, Scheme 2 is proposed.

However, compounds 31 and 3o (plot kA vs. [SH]) show linear curve with zero slope indicating that the concerned reactions were independent of base concentration, therefore the SNAr reaction proceeds through the un-catalytic route (Scheme 3).

The likely mechanism for the k2 step involves intermolecular proton transfer from nitrogen to oxygen (solvent MeOH) m the zwitterion T±, compiled with carbon-chlorine bond breaking.

238 INDIAN J CHEM, SEC A, FEBRUARY 2005

NHNHS02-o-R3 + HCI ==k=1

="' k_,

R, R, p

BH' II fast, B

fj ~

N~ ~ NHNHS02-o-R3 k. 1[BH' B]

ko(BH' SB]

R,

Scheme 2

T+ fast

Scheme 3

The second order coefficient, kA vs. [SH] for the compounds 3c, 3d, 3e and 3m in MeOH shows a parabolic dependence on amine concentration, which indicates a third order dependence in amine. Similar observations for the reactions of 1-chloro-2,4-dinitrobenzene with ani line were reported in toluene, acetone, DMSO, toluene-acetone mixtures26

. In dipolar aprotic sol vents the dependence was linear. All these results are well explained within the frame of the "dimer nucleophile" mechanism27

·28

• The intercept on X-axis proves the appearance of base catalysis along with the un-catalytic route. In this

mechanism, the formation of the cr-adduct (T) from zwitterion ic complex T±, (nucleophilic attack) is rate lim iting (k 1 slow). If proton transfer steps were rate limiting (k2B slow), the reaction would have shown a second order behaviour. Scheme 4 shows the reaction route .

The plots of kA vs. [SH] for the compounds 3g-i, 3k and 3n in MeOH and 3b and 3c in DMSO were curvilinear (- ve slope) proving that the proton transfer step, k2[B] was slow (Scheme 4) and partially rate limiting. However, the rate constants were unaffected by increase in amine concentration. Similar observations were reported2

'J for the reactions of pyrrolidine with phenylary l sulphides .

Substituent effect

From Table 2, it is clear that the order of reactivity of various acridine derivatives is : H>4-Me>2-Me>4-0Me>2-0Me, which can be explained on the basis of e lectroph ilic nature of the reaction site in acridine30

.

The following two aspects are taken into consideration: (i) factors facilitating attack, and (ii) the stabi li zation of the transition state/zwitterion. The effect of substituents on the benzene ring of sulphonyl hydrazide is in the order: MeO>Me>H, reflecting the importance of electron donating behaviour of the substituent in enhancing the nucleophilicity of hydrazyl group and a lso in stabi li zing the zwitterionic complex T±.

Temperature effect The reactions of various derivatives of 9-CAC

(la-e) have been carried out with BSH, TSH and MBSH separately at different temperatures in MeOH (Table 2) . The reactions of 9-CAC (2a ) have been carried out with BSH, TSH and MBSH separately at different temperatures in DMSO also (Table 2) . In both the solvents k0 increases with rise in temperature, i.e., the reaction proceeding through a mechanism which involves strong species or entities not affected by temperature enhancement. This indicates that the base catalyzed mechanism may proceed through heteroconjugate base-solvent mechani sm [BH+SB]3 1

.

All the reactions obeyed the Arrheniu s relationship. The activation parameters have been calcul ated and the results are summarized in Table 3. In each case large negative value of entropy of activation has been obtai ned, indicating formation of highly charged , crowded and ordered transition state. A lso seen that

SONDHI et al.: KINETIC STUDIES ON THE REACTIONS OF VARIOUS 9-CHLOROACRIDINES 239

N/' ~ Cl + H2NHN02S-o-R3 slow

R, R,

k '3 , last zwitterionic complex

fast

k2 [BW] II slow, k2 [B]

( ~

R, T '

a - adduct

k '3 = uncatalytic route, k"3 = base catalytic route

Scheme4

Table 3- Thermodynamic parameters and frequency factors for the reactions of 9-CAC and its derivatives with sulphony l hydrazide in MeOH and in DMSO

Camp. No Ea (kJ/mol) Log A (min-1)

!11 MeOH 3a 32.965 4. 1047 3b 2.8.527 3.2074 3c 22.813 2.0359 3d 38 .887 4.6559 3e 34.520 3.6649 3f 31.631 3.2750 3g 36.978 4.5507 3h 29.760 3.1298 3i 25 .890 2.357 1 3j 47.39 5.9642 3k 40.390 4.4875 3I 38.990 4. 1142

3m 42.717 5.2075 3n 37.955 4.1800 3o 34.960 3.5300

li1 DMSO 3a 46.24 5.4663 3b 34.865 3.3773 3c 26.639 2.4048

Ea val ues are positive and are in normal pattern, i.e ., faster reaction rate with low Ea. Further, it is seen that 6.Fr values depend on the substituent on the nucleophile moiety in one series . The low values indicate that the k2 step depends on base or solvents for the formation of the aminolysis product. The lowest value for 6.Fr is seen for the faster product formation 3c and the highest 6.1-r value was for the

!':,G~ (kJ/mo l) -/',S~ (J/mo l. K) Mf' (kJ/mol)

72 .71± 1. 1 140±0.5 30.57±0. 1 73.39±1.2 157±0.3 26.02±0.2 73.93±1.3 178±0. 1 20.35±0. 1 75.47±0.9 130±0.9 36.49±0.1 76.82± 1. 1 148±0.6 3 1.78±0.4 76.18± 1.2 156±0.4 29.29±0.1 74.04±1. 1 131±0.5 34.46±0.2 75.1 5± 1.2 158± 1.4 27.66±0.3 75 .65±1.3 173±0.3 23 .51±0.1 76.70±0.7 105±2. 1 44.88±0.1 77.94±1.0 133±0.7 38.06±0.1 78.69± 1.0 140±0.4 36.63±0.1 76.11±0.9 119±0.8 40.30±0. 1 77.28±1.0 139±0.5 35 .59±0.1 78.04±1.1 151±0.75 32.58±0. 1

78.12±0.9 114±1.05 43 .80±0.1 78.81± 1. 1 154±0.4 32.45±0.1 79. 19± 1.2 173±0.4 27 .27±0. 1

compound 3j. Moderately good isokinetic relationships, i.e., log k0 [313] vs . log k0 [289] and 6.1-F vs. 6.S± were obtained. Ti so equal to 326.29 K was estimated from the plot of 6.Fr vs . 6.~, which is not very different from the reaction temperature, i.e., Tiso::..Tex p (infinite and positive). It also indicates that Tiso refers to a real compensation effect, which might try to reduce the activation barrier as seen from T able

240 IND I/\ N J CI-IEM, SEC/\, FEBRUARY 2005

3 by means of base or so lvent. Also, thi s is a good ev idence for the low value of£.,, whi ch is lost in pre­ex ponential facto r of the entropic part31

. Linear relati onshi p is expressed by the equation t:..ft = 326.29 tJSf. + 79.25: R2=0.93 19, indicat ing that above 326.29 K, an in crease in f'..S± results in decrease f'..G± and below this an increase in f'..G±. No compound probably deviates from the compensation to give an unusual kinet ic behaviour with thi s reaction tem perature.

Antiinrlammatory activ ity 17 eva lu ati on of compounds 3a-o was carri ed out at 50 mg/kg p.o. in rats using carragccntn induced paw oedema. Compounds 3a-o showed 20.0; 17.5; 2 1.5; 20.2; 25.4; 18.6; 17.5; 25.8; 24.3; 19.5; 20.4; 16.7; 17.3; 24.6; and 19.5% activity, respec ti vely, as compared to phenylbutazo ne wh ich ex hibited 34.6% act ivity at 50mg/kg p. Kinase inhibition act ivityn-34 of 3a-o for CDK-5 and GSK-3 was determined and 1C50 values were calcul ated. In all the cases, IC50 va lues were fo und to be > I OJ1M and hence all the compounds were found to be inac tive.

A look at activity data of 3a-o indicates that substitution of -CH3 group at 2 or 4 position and -OCH3 group at 4 positi on of acridine and substitution of -CH3 group at para-posttton of sulphonyl hydrazide group, i.e., R3 = -CH3, increases the anti­inflammatory activity as compared to unsubstituted acridine or sulphonyl hydrazide.

Acknowledgement Our thanks are due to the Heads of RSIC at

Lucknow and Chandigarh for providing spectral facilities and to Dr. Laurent Meijer (CNRS, UPS, Molecules and Cibles Therapeutics) Station Biologique, 29680-Roscoff, Bretagne, France, for kinase inhibition studies. Financial help from ICCR, New Delhi, to one of the authors (RKJ) is gratefully acknowledged.

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