Indian Journal of Chemistry Vol. 38B, September 1999, pp. 1070-1074

Synthesis and antimicrobial activity of some new 2-aminomethyl -S-(4-phenyl-5-mercapto-l,2,4-triazol-3-yl)methoxyindole derivatives

G S Gadaginamath* & SA Patil t

Department of Chemistry, Karnatak Univers ity, Dharwad 580003, Indi a

t lCI India Ltd , Research & Technology Centre, POBox-I 55, Thane Belapur Road , Thane 400 60 I . Ind ia

Received II May 1999; accepted I September 1999

6-Bromo-2-bromometh yl-l-butyl-3-ethoxycarbonyl-5-ethoxycarbonylmethoxyindo le 2 has been prepared from 2-met hylindole derivative 1 using NBS as regioselective brominating agen t in the presence of radical initi ator like dihen7.Uyl peroxide. Compound 2 is then reacted wi th ami nes to yie ld corresponding 2-aminomethylindole diesters 3a-b. Hyd ro lys is o f 3a-b by ethanolic sodium hydroxide gives the corresponding diacids 4a-b. Diesters 3a-b also react chemoselec ti ve ly with excess of hydrazi ne hydrate (99 %) to yield the corresponding monocarbohydrazides Sa-b in stcad o f the cx pected dicarbohydrazides 6a-b. The monocarbohydrazides Sa-b on reaction with phenylisothiocyanate followed by treatmen t with NaOH (4 %) so lution afford the required 2-aminomethyl-5-(4-phenyl-5-mcrcapto-I ,2,4-tri azol- 3-y I )methoxyindole derivatives Sa-b. All the newly synthesised compounds are screened for their antimicrobial activi ties.

Indoles and triazole derivatives have exhibited valuable pharmacological activities like analgesic l.2,

antii nflammatory" anticonvulsant4, antidepressantS,

tuberculostatic6 and fungicidal 7. Indole derivatives8

,9

have gained prominence because of their potential pharmaceutical values, and some indole derivatives reported from our laboratory have shown interest ing antimicrobial activities lO

. Encouraged by the above reports we have embarked on the synthes is of hitherto unreported bisheterocycles and screened them fo r their antibacterial and antifungal acti vities.

The convenient starting material for the synthes is of the title compounds was 5-hydroxyindole which

b . d b d . h N . . II I? was 0 tame y a optlllg t e ellltzescu reactIOn ' -. Bromination of l-butyl-3-ethoxycarbonyl-2-methyl ­indole with bromine in acetic acid 13 produced the corresponding 6-bromo analogue, which was then refluxed with ethyl chloroacetate in the presence of anhyd. K2CO, with catalytic amount of KI in dry acetone to give 6-bromo-l-butyl-3-ethoxycarbonyl-5-ethoxycarbonylmethoxy-2-methylindole 1. Compound 1 was then brominated regioselectively with NBS in the presence of radical initiator such as dibenzoyl peroxide in CCI4 to obtain 6-bromo-2-bromomethyl­J -buty 1-3-ethox ycarbon y 1-5-ethoxycarbony I meth ox y­indole 2. Compound 2 was stirred at room tempe­rature with amines in dry benzene to obtai n the desi red 2-aminomethyl-6-bromo-l-butyl-3 -ethoxy­carbonyl-5-ethoxycarbony lmethoxyindole 3a-b. Com­pounds 3a-b were refluxed with ethanolic NaOH solution to yield the dicarboxylic ac ids 4a-b. The

diesters 3a-b were further treated with hydrazine hydrate (99%) in boiling ethanol to produce exc lusive ly the monocarbohydrazides 5a-b instead of the expected dicarbohydrazides 6a-b. The observed formation of monocarbohydrazides revealed the chemoselec ti vi ty of Cs-ester function over the C,-ester functi on, which is in confo rmity with the earlier report sl6

. Further, these monocarbohydrazides 5a-b were reacted with phenyl isothiocyanate in refluxing eth ano l to get the required thiosemicarbohydrazides, which were gently heated with NaOH (4%) so lution to secure the desi red 2-aminomethyl-6-bromo- l-butyl-3-ethoxycarbonyl-S­(4-phenyl-5-mercapto- J ,2,4-triazol-3-y I )methox yindoles 8a-b (Scheme I). The structures of all these newl y synthesised compounds were confirmed by their spectral and analytical data.

Antimicrobial activity All the newly synthesised compounds ( 100 fl g in

0.1 mL dimethyl formide) were screened for their antibacterial activi ty in vit ro agai nst Gram positi ve bacterium Escherichia coli, and Gram negati ve bactrium Bacillus cirrojlagellosus usin g Norfl oxac in as standard and for thei r antifungal acti vity ill vit ro against fungi Aspergillus niger and Candida a/him ns using Griseofulvin as standard . DMF was used as solvent contro l. The culture media was Ilutrient agar and the method employed was cup-plat meth od 17. I X .

The zones of inhibiti on formed were measured in mm and are represented by (+), (++), and (+++) depending upon the diameter and clarity. orfl oxac in showed a

GADAGINAM ATH el at.: SYNTHESIS & ANTIMICROBIAL ACTIVITY OF INDOLE DERIV ATIVES 107 1

NBS, BZ20 2,

CCl4 •

I ~~:i;ee~e(d ry) stirred for 4-5h

° ° . ~)~ £'... rOC2Hs Alc. NaOH HJLO. ~I ~~;2-R

BrUrr

HSC20 UrrCH2-R .... 4f------ Br ~ I

I n-Bli

4a-b

Sa-b

N2H4.H20 ,

Ethanol, Pyridine,

n-Bli 3a-b

° ~:c3=NHNH 2 H2NHN O,;? I '\:: CHz-R

Br ~ N I

n-BlI

6a-b

t PhNCS, Ethanol , ~

~ ~ :c3=0 OC2Hs

HSC6HNCHNHN O ,;? I '\:: CH2-R NaOH(4%) ..

Br ~ N I

n-Bu

7a-b R

a = -N(CH3)C6HS

b = -N'b '-f

8a-b

Scheme I

zone of in hibiti on of 33 mm agai nst E. coli and 31 mm again st bacterium B. cirrojlagellosus. Gri seo­ful vin exhibited a zone of inh ibi tion of 32 mm against both fu ngi A. niger and C. albicans. Preliminary

screening resul ts have shown that compounds 3a and 7a were weakly act ive against B. cirroj logelloslfs and compounds 8a and 8b were weakl y active agai nst E. coli . Compound Sa was mode rate ly active aga inst

1072 INDI AN 1. C HEM., SEC B, SEPTEMBER 1999

Table 1-Antibacteri al and anti fungal activi ties of the compounds 3a,b-Sa,b, 7a,h and 8a,h

Zone o f inhibition in nm Compd R Anti microbial activity Antifunga l ac ti vit y

E. coli B. cirroflagellosus A. I/iger C. a/him l/ .'

3a -N(CHJ)Cr,Hs 3b - morpholino 4a -N(CH1)Cr, H, 4b - morpho I i no Sa - N(CHJ)Cr,H5

Sb -morpholino 7a -N(CHJ)Cr, H\ 7b - morpho lino 8a -N(CHJ)Cr,Hs 8b - morpho lino

+

+ +

+

+

++

+ +

+ + + + +

+ +

(-)=inactive (less th an 12 mm), (+)=weak ly acti ve ( 12- 16mm), (++ )=moderately acti ve ( 17-2 1 mm), (+++ )=h ighl y acti ve (22-30 mm)

A. niger and weakl y acti ve aga inst C. albicans , while compounds 7a and 7b were weakl y acti ve against both the fungi. Compounds 3a, 3b, 4a and 4b were weakly ac tive against C. albicans. Remaining compounds were inacti ve aga inst both the organisms of bacteria and fungi (Table I) .

Experimental Section

Melting points are uncorrected . IR spectra wer~

recorded on a Perkin-Elmer spec trometer, and tH NMR spectra on a Brucer 250 MHz automatic NMR spectrometer. E lemental analyses were carried out on a Heraus CHN rapid analyser.

6-Bromo-2-bromomethyl-I-butyl-3-ethoxycarbon­yl-S-ethoxycarbonylmethoxyindole 2. A mixture of 2-methylindole deri vati ve I (0 .0 I mole), powdered NBS (0.0 I mole) and benzoy l perox ide (500 mg) in CCI4 (50 mL) was heated at reflu x fo r 5hr. The succinimide formed was filtered off and the solvent was removed under reduced pressure. The res idue was recrystalli sed from benzene-pet. ether (40-60° C) mp 122°C. Ana l. Found fo r C2oH2SNBr20 ,,: C, 46. 10; H, 4.90; N, 2.85. Calcd: C, 46.26; H, 4.85; N, 2.69%; IR (KBr) cm-I; 295 1 (-CH), 1689 (CTC=O), 1739 (C,,­C=O) and 570 (-CBr); IH NMR (CDCb, TMS): 8 1.00 (t, J=7.2 Hz, 3 H, N-CH2-CHz-CHz-CH)), 1.20-1.95 (m, 10 H, C)- and Cs-COO-CH2-CH), N-CHz­CHr CH2-CH )), 4.00-4.52 (m, 6 H, C,- and Cs-COO­CH2CH), N-CH2-CH2CH2C H.\), 4.69 (s, 2H, Cs-O­CH2COOC2Hs), 5.02 (s, 2 H, CHIBr), 7.5 (s, I H Cr H) and 7.65 (s, I H, C4-H).

6-Bromo-I-butyl-3-cthoxycarbonyl-S-ethoxycar ­bonylmethoxy-2-(N-methyl-N-phenylamino)methyl­indole 3a. To a stirred solution of 2-bromomethyl­indole derivative 2 (0.0 1 mole) in dry benzene (30 mL),

N-methyl-N-phenylamine (0 .02 mole) was added dropwise. It was stirred further fo r 5hr and the separated hydrobromide was fil tered ofr. T he fil trate was concentrated at reduced pressure 10 10 Il1L and then triturated with pet. ethe r (40-60°). Separated product was filt ered, washed with pet. ether (40-60°) and recrysta ll ised fro m benzene-pet. e the r (40-60°) ; yie ld 64%, mp 78°C; IR (KBr) cm-I

: 2963 (-C H), 1755 (Cs-C=O) and 1684 (C.\-C=O); IH NM R (CDCI" TMS): 80.84 (t, J=7 .2 Hz, 3H, N-C H1C H2CH2CH.;), 1.15- 1.70 (m, 10H, C.\-COOCH2CH.;, Cs-COOCH1CH.; and N-CH2CH2CH2C H,), 2.75 (s, 3H, N-CH \), 4.00 (t, J=7 .2 Hz, 2H, N-CH2CH2CH1C H ,) , 4 .30 (g, J=7.0 Hz, 2H, Cs-COOCH2CH.\ ), 4.40 (g, ./=7.0 Hz, C ;­COOCH2CH,), 4 .75 (s, 2H, CI-CH2-) , 5.00 (s, 2H, Cs-O-CHI -), 6.70-7 .48 (m, 5H , ArH), 7.55 (s, I H, Cr H) and 7.70 (s, I H, C~-H ); Ana l. Found for C27H13N2B rOs: C, 59.55; H , 6 .1 5; N, 5.05. Calcd: C. 59.45 ; H, 6. 10; N, 5. 14%.

6-Bromo-I-butyl-3-ethoxycarbonyl-5-ethoxyca r­bonylmethoxy-2-morpholinomethylindol e 3b. Yield 60 % ; mp noDc (benzene-pet. ether): IR ( KBr) cm- I: 2980 (-CH ), 1740 (Cs-C=O) and 16150 (C,-C=O):. Anal. Found for C24H.\.\ N2BrO(, : C, 54.95 ; H. 6.25 ; N. 5.45. Ca lcd : C, 54.86; 6.33; N, 5.33 9'0 .

6-Bromo-I-butyl-3-carboxy-2-(N-methyl-N-phenyl­amino)methylindol-5-yloxyacetic acid 4a, A so lut ion of 3a (0.01 mole) and sodium hydrox ide (0. 1 mo le) in ethanol (25 mL) was heated under re fl ux fo r 10hr. The reaction mi xture was coo led, poured into cru shed ice (50 g) and ac idified with Conc. HCI. The prec ipitated di ac id 4a was filtered and rec ryslallised from ethanol; yie ld 6 1 %; mp 2250e; IR(KBr) cm-I :3431 (-OH), 2956 (-C H) and 1690 (Cs and C 1 -

C=O); IH NM R (DMSO-d(" TMS):8 0 .65 (I, ,/=7.2

GADAGINAMATH el al.: SYNTHESIS & ANTIMICROBIAL ACTIVITY OF INDOLE DERIVATIV ES 1073

Hz., 3H, N-CH2CH2CH2CH,), 1. 10-1.48 (m, 4H, N­CH2CH2CH2CH,), 2.68 (s, 3H, N-CH,), 3.9 (t, 1=7.2 Hz, 2H, N-CH2CH2CH2CH,) , 4.2 (s, 2H, C2-CHr ), 5.2 (s, 2H, CS-0-CH2- ), 6.6-7.2 (m, 5H, ArH), 7 .5 (s, I H, Cr H) and 8.0 (s, I H, C.rH) Anal. Found for C2,H2SN2BrOs: C , 56.45 ; H, 5 .20; N; 5.60. Ca\cd: C, 56.45; H , 5.15; N, 5 .72% .

6-Bromo-l- butyl-3-carboxy-2-morpholinometh­ylindol-S-yloxyacetic acid 4b. Yield 81 %; mp 178°C; (Ethanol) ; IR (KBr) cm-I: 3430 (OH) and 1685 (Cs and C, -C=O):Anal found for C2oH2SN2Br06: C, 51.10; H, 5.45 ; N 6.05. Ca\cd: 51.18; H, 5.37, N, 5.27%.

6-Bromo-I-butyl-3-ethoxycarbonyl-2-(N-methyl­N-phenylamino)methylindol-S-yloxyacetic acid hydrazide Sa. A mixture of 3a (0 .0 I mole), hydrazine hydrate (0.02 mole) and pyridine ( I drop) in ethanol (50 mL) was refluxed on a boiling water-bath for 20 hr. concentrated to half of the original volume and left overnight. The separated solid carbohydrazide was filtered, washed with a little e thanol and recrystallised from ethanol; yie ld 56% ; mp 168°C; IR (KBr) cm- I :343 1 and 33 17 (am ide -NH/NH2) and 1703

(amide and Cr C=O) ; IH NMR (COCI" TMS) :8 0.85 (t, 1=7.2 Hz, 3H, N-CH2CH2CH2CH,), 1.45 (t, 1=7.0 Hz, 3H, C,-COOCH 2CH,), 1.10-1.80 (m, 4H, N­CH2CH2CH2CH,), 2.7 1(s, 3H, N-CH,), 4 .00 (t, 1=7.2 Hz, 2H, N-CH2CH2CH2CH" a s igna l due to Cs-carbohydrazide NH2 was found merged in the above triplets at 4.00), 4.43 (q, 1=7.0 Hz, 2H., C, ­COOCH2CH,), 4.70 (s, 2H, Cz-CH2- ) , 4.99 (s , 2H, Cs-O-CHr ), 6.70-7.40 (m, 5H, ArH ), 7 .50 (s, I H, Cr H) and 7.70 (s, I H, C4-H); Anal Found for C25H, IN4Br04: C, 56 .30 ; H , 5.95 ; N; 10.40. Ca\cd: C, 56.50; H, 5 .88; N, 10.54%.

6-Bromo-I-butyl-3-ethoxycarbonyl-2-morpholino­methylindol-S-yloxyacetic acid hydrazides Sb. Yi e ld 70%; mp 208°C (dioxane-water) ; TR (KBr) cm-1 :3302 (br, amide NH/NH2) 2960 (-CH) and 1698 (Cs-and C,-C=O) ; Anal. Found for C22H' IN4BrO.,: C, 51.55 ; H , 6.25; N, 10.80. Calcd: C, 51.67; H, 6.11; N, 10.96%.

6-Bromo-I-butyl-3-ethoxycarbonyl-2-(N-methyl­N-phenyl)aminomethylindol-S-yloxymethylcarbothio­semicarba7ide 7a. To a so luti on of carbohydrazide Sa (0.00 I mole) in ethanol ( 10 mL) was added phenyli sothiocyanate (0. 00 I mole) with stirring . The mixture was heated under reflux for 5hr and part of the solvent was evaporated . The sol id that separated on cooling to r.t. was fi ltered, washed with little amount of ethanol and recrys talli sed from ethanol, yie ld 60%: mp 162°C; IR (KBr) cm-I :3276 (amide

-NH), 1703 (Cs- and C, -C=O) and I 188 (-C=S) ; Anal. Found for C32H,6NsSBr04: C, 57.75 ; H, 5 .35 ; N, 10.60. Ca\cd : C, 57.66; H, 5.44 N, 10.51 %.

6-Bromo-l-butyl-3-ethoxycabonyl-2-morpholino­methylindol -S-yloxymethylcarbothiosemicarbazide 7b. y 'ield 77%; mp 180°C ; (ethan ol-di oxa ne): IR (KBr) cm- I :3364, 33 10 and 3271 (amide HI H2),

1698 (Cs and Cr C=O) and 1202 (-C=S ); Ana l. Found for C29H,6NsSBrOs: C, 53 .75 . H, 5.75 . Ca lcd: C, 53 .87; H, 5.61 ; N, 10.83%.

6-Bromo-I-butyl-3-ethoxycarbonyl-2-(N-methyl­N-phenyl)aminomethyl-S-( 4-phenyl-5-mercapto-J ,2,4-triazol-3-yl)methoxyindole 8a. The suspension of thiosemicarbazide 7a (0 .00 I mo le) in sod iulll hydroxide so luti on (4%, 10 mL) was heated gentl y under reflux for I hr. The reacti on mi xtu re after cooling to r.t. was poured into cru shed ice (20 g) and ac idified carefully with acetic ac id . The prec ipitate thus obtained was filtered, washed with wa te r. dri ed and recrystallised from ethanol, yie ld 6 1 %; mp 2050e: IR (KBr) cm- I :3 11 0 (-NH ), 1693 (C, -C=O) and I 197

(-C=S) ; IH NMR (COCl .I , TMS):8 0.95 (t, .1=7 .2 Hz, 3H, N-CH2CH2CH2CH,), 1.40 (t, .1=7.0 Hz. 3H , C,­COOCH2CH,), 1.20-1.82 (m, 4H, N- CH2CH2CH2CH.,), 2.85 (s, 3H, N-CH,), 4. 13 (t, .1=7.2 Hz, 2H . N­CH2CH2CH2CH, ), 4.45 (C] • .1=7 .0 Hz, 2 H, C,­COOCH2CH.,), 5.12 (s, 2H , C2-CHr ), 5.20 (s , 2 H, C ,­O-CHr ), 6.80-7.90 (m, 12 H, ArH) ami 11 .65 (br, IH, NH, di sappeared on 0 20 exc hange); Anal. Found for C'2H' 4NsSBr0.1 : C, 59.35 ; H, 5.40: N, 10 .65. Calcd : C, 59.26 ; H,5 .28; N, 10.80%.

6-Bromo-I-butyl-3-ethoxycarbonyl-2-morpholi no­methyl-S-( 4-phenyl-S-mercapto-I,2,4-triazol-3-y J)­methoxyindole 8b. Yield 56%; mp 248°C (eth anol­dioxane); IR (KBr) cm-I: 3 110 (-NH), 1683 (C-C=O) and 1186 (-C=S); IH NMR (DMSO-dr" TMS ): o 0.90 (t, .1=7 .2 Hz, 3H, N-CH 1C H2CH 2CH,). 1.40 (t, 1=7.0Hz, 3H, C,-COOCH 1CH ,). 1.20- 1.75 (Ill . 4 H. -CH2CH2CH2CH, ), 2. 10 (t, .1=7.0 Hz, 4 H, 2CH1

adjacen t to N of morpholine), 3.30 (t, .1=7 .0 Hz, 4 H. 2CH2 adjacent to 0 of Illorph oline), 4 .20 (I. .1=7.2 Hz, 2H, N-CH2CH2CH2CH,), 4 .30 (C] , 1=7.0 Hz, 2H, C,­COOCH2CH, ), 4 .75 (s, 2H, C2-CH2) , S.05 (s. 2H, CS-0-CH2), 6.85-7 .95 (m, 12H , ArH ), 14 .1 (br. s. I H. NH di sappeared on 0 20 cxc hange):Anal. Found for C29H'4NsSBrO~ : C , 99.30 ; H, 5 .50; N, 11.20. Ca lcd : C, 55.4 1; H, 5.45; N, 11.1 4%.

Acknowledgement The authours thank Dr L R Subraman ian,

University of Tubin gen, Ge rmany, RS IC, Mad ras ail e!

1074 INDIAN J. CHEM ., SEC B, SEPTEMBER 1999

RSIC, Bangalore for spectral and elemental analyses and also Mr Raju, Research scholar, Dept. of Botany, K. U. Dharwad, for his help in antimicrobial screening. One of the authors (SAP) thanks CSIR, New Delhi, for the award of SRF.

References 1 Shen T Y, Windhulz T B, Rosegay A, Witzel B E, Wilson A

N, Willett J 0 , Holtz W J, Elli s R L, Matzuk A R, Lukas S, Stamme, C H, Holly F W, Sarett L H, Ri sley E A, Nuss G W & Winter C A, f Am chem Soc, 85, 1963, 488.

2 (a) Glennon R A, f madill Chem , 30, 1987, I . (b) Glennon R A, f mednl Chem , 31 , 1985, 5.

3 Fauran C, Ddouzan C, Raynaud G & Pourris B, Fr Demand, 1975,2269938; Chem Abstr, 84, 1976, I 64289z .

4 (a) Prasad A R, Raw A N, Ramalingam T & Sattur P B, Indian Drugs, 25, 1988. 257. (b) Prasad A R, Raw A N, Ramalingam T & Sattur P B, Illdian Drugs, 25 , 1988, 301.

5 Kadry A M, Badawy M A & Hanna H R, Pharmazie, 41 , 1986, 558.

6 Meenakshi S, Dixit K S & Barthwal J P, f III dian Chem Soc, 68, 1992, 8, 466.

7 Amir M & Srivastav J , Pharll1akeuitke, 9, 1996, 79 ; Chem, Abstr, 126, 1997, 89317z.

8 Medne K, Grinsteins V & Cipens G. Lat l'ijas RSR Zinallll re Akad Vestis, 1961 , 85 ; Chelll Abstr, 56, 1962. 13506.

9 Tomari M. Tsuji N, Sakuma 0 , Ooto H, Mast lli H, Na!!aoka K & Nakamura T, ff/n Kokoi Tok/.:)'o Kuho .lP, OR325243, 1996, 39; Chem Abstr, 126, 1997, I 1798 1.

10 (a) Joshi R G, Gadaginamalh G S & Plij ar B G . .I In diall

11

12

13

14

15

16

17

18

Chem Soc, 71 , 1994, 175 . (b) Shyadligeri A S & Gadaginaillath G S, Illdiall .I Chelll, 34B , 1995, 1059. Nenitzescu C 0 , 8/1/1 Soc ChillI ROIIIII , I I. 1929. 37: Chelll Abstr, 64 ( 1966) 966ge. Grinev A N, Shvedov V I & Pani shev E K. Z/I Orgall Khilll , I , 1965,2051 ; Chell! Abstr, 64, 1966, 966ge. BelI M R, OSlernlin R, Beyler A L, Harding H R & POllS G 0, f.Med dI em , 10, 1967,264. Gadaginamath G S & Joshi R G, 'lldiall .I Chelll. 34. 1995, 120. Gadaginamath G S & Palil S A. Polish .I Chelll . 7 1. 1997. 923. Joshi R G, Kamath A G & Gadaginamalh G S. R eI' R Ol l/II

Chem, 40, 1995, 475 . Seeley W & Demark P, f Microbes ill actioll:A ul/Jo/'{/tor\' Manual of Microbiology , (0 .B . Taraporevala So ns and Cl;. Pvt. Ltd, Bombay), 1975, pp 55, 80. Kavanagh F, Analytical Microbi%g.\', (Acadcmi c Press, New York), 1963, 125.