,January 1968
ASTIINFLAMMATORY 5-(2-ANILINOPHENYL)TETRAZOLES
n Z 41.4800, ~ X::a:EtoH 260 mp ( E 4300). A4multiplet centered at 5.8 ppm was assigned to the fotir vinyl protons in the nmr spectrum of 16. d n a l . (ClaH,;N) C, 11, N. Its methiodide crystallized from Ne2CO-Et20 as white iieedles, rnp 17!)-180°. d n a / . (C,H?,IN) C, H, I, N. Compound 16 Was rediiced as described for 12 to give 2-dimethylami~ioethylcyclohexaiie. The methiodide of the reduced product was recrystallized from 1\Ie2CO-Et20 to furnish white needles, mp 223" (lit.16mp 224'). 1-Methyl-5-oxo-cis-octahydroindole(17).-A solution of 5indole (1 g ) in 20 ml of MeOH was hydrogenated a t (initial pressure, 119.4 kg,lcmz) with 3 g of liariey iiickel for 1 hr. The rooled couteiits were filtered and evaporated to afford 1.0 g of a colorlesb >yrup. CrOs (0.3 g, 0.0033 mole eqiiiv) i n 0.2 ml of 1 1 2 0 and 2 nil of HOAc was added dropwise to a solution of O..il g (0.0033 mole) of the reduced indole in 10 ml of HOAc a t 60-65". The mixture was stirred at 60-6.i0 initil the solution was completely green. Most of the HOAc was removed, and the residue was made strougly basic with NaOH soliition and extracted with three 20-ml portions of EtPO. The EtrO extracts were combined, dried (AIgSOa), arid filtered. Removal of solvent at reduced pressure afforded a colorless liquid. Tlc of the liqiiid on neutral alumina usirig 1: 1 EtOHSkelly B showed spots for starting material and product 17. The mixtiire was chromatographed on an aliimina coliimn made i i i Skelly B (Woelm, activity grade 111, 40 g) iising 5c; EtOAc i i i Skelly B1 and 20-ml fractioiis were collected. The ketone 17 (0.1.; g, 30';;) had an unresolved triplet a t 3.05 ppm (baiid half-width 1.5 cps) assigned to the equat,orial C-ia proton. 1-Methyl-5-oximino-cis-octahydroindole(18).-The ketone 17 (0.1s g, 0.0012 mole) was heated on a steam bath for 3 hr with a solutioii of 0.4 g of T\;H20H.IIClin 5 ml of I&O. The solution was neutralized with S a z C 0 3solution and heated on a steam bath for 3 0 mill. Cooling of the solution did not precipitate the oxime. It was evaporated to dryness by codistillation with two 100-ml portions of absolute EtOH, and the dry residue was extracted with two 10-ml portions of boiling EtOAc. The extracts were concentrated to a small volume. The solution, on cooling, afforded 0.14 g ( 7 0 % ) of 18 as white crystals (EtOAcSkelly B), mp 134.5-1.j6..io. d n a l . (CsH16N,0) C, H, N. 1-Methyl-5-syn-dimethylamino-cis-octahydroindole (15). A. From 18.-A solutioii of 0.50 g (0.003 mole) of 18 in 8 ml of absolute EtOH was heated to boiling; the heating was disrontinued, mid temperature was maintained by introducing pieces of S a ( 1 g ) through the condenser. After the solution was refluxed for 30 mill and cooled, it was diluted with an equal volume O
111
of H20, acidified with HCl, and evaporated. The residue was made strongly alkaline with S a O H solution and extracted with CHC13. The extraxts were dried aiid filtered. Solvent was removed under reduced pressure to give 0.17 g (377,) of a thick colorless liquid. To this was added 0.25 g of 377, CHzO and 0.26 g of 88% HCOOH, and the mixture was heated on the steam bath for 2 hr. The solution was treated with 5 ml of dilute HC1 and excess CH20 and HCOzH were removed by evaporation to dryness. The residue was made alkaline with NaOH solution and extracted with Et2O. The solvent was evaporated to give 0.16 g of a liquid which was identical with 1-methyl-5-syn-dimethylamino-cis-octahydroindole (15)by infrared and tlc. The amino ketone 17 (0.23 g, 0.0015 mole) was heated a t 160170" for 3 hr with 0.44 g (0.006 mole) of 1 I N F and 0.41 g (0.008 mole) of 88% HC02H. The cooled solution was treated with 3 ml of 4 S HC1 and evaporated to dryness. The residue was made alkaline with S a O H solution and extracted with EtZO. The extract was dried (MgSO,) and evaporated to afford 0.21 g of a yellowish liqiiid which was identical with 15 by infrared and tlc. Catalytic Reduction of 1-Methyl-5-oximino-cis-octahydroindole (18).-A solution of 0.23 g of 18 in 10 ml of HOAc was hydrogenated overnight a t 2.1 kg/cmz (room temperature) with i.i mg of PtO?. After filtering, the soliition was evaporated to remove most of the HOAc. The residue was made alkaline with S a O H solution and extracted with Et,O to give (after drying and evaporation) 0.19 g of a thick liquid. The liquid was heated 011 the steam bath for 3 hr with 0.26 g of 37Yc H,CO and 0.28 g of 88C:; HCOOH, treated with 5 ml of 4 S IIC1, and evaporated to drylieus. The residue was made strongly alkaline with NaOII solution, extracted with Et,O, and dried (MgSOd), aiid the solvent was removed to afford 0.18 g of a colorless liquid which was identical with 15 by ir and tlc. Biological Testing.-The contractioiis of the isolated ileum were obtained by treatment with ganglionic stimulants, and the percentage reduction in the size of these contractions brought about by the antagonists was used as a measure of their effect. Each compound was examined three times on fresh ileum preparations. The normal control contractions of the guinea pig ileum were obtained by the addition of 2-, 10 , and 20-pg doses of nicotine, acetylcholine, arid histamine, respectively, in the bath in which the ileum was suspended. Then, the contractions were obtained with the same drugs after the previous addition (90 sec before) of the antagonist to the bath. The doses of the antagonists used were 100, .50, 23, 12..i, 6.25, 3.12, 1.36, and 0.78 pg.
Preparation and Antiinflammatory Properties of Some 5-(2-Anilinophenyl)tetrazoles1 P. F. JUBY, T . 147. HUDYMA, AND 11. BROWN Research Diuision, Bristol Laboratories, Division of Bristol-Myers Company, Syracuse, New York 13201 Received J u l y 27, 1967 Tetrazole analogs of a series of known N-phenylanthranilic acid antiinflammatory agents were prepared. Some of these 5-(2-anilinophenyl)tetrazoles showed antiinflammatory activity comparable to the corresponding carboxylic acids when tested orally in rats.
The knowledge that %substituted tetrazoles and their carboxylic acid analogs have comparable acidic dissociation c ~ n s t a n t shas ~ ~led ~ a number of chemists to replace the carboxyl group in biologically active compounds with the 5-tetrazolyl group (-CS4H). Hopes of maintaining or improving upon biological activity have been realized in some cases.
Tetrazole analogs of plant growth regulators such as 3-indolylacetic acid and 2,4-dichlorophenoxyacetic acid retained some a c t i ~ i t y . ~Two , ~ out of three tetrazole analogs of glutamic acid acted as substrates for beef liver L-glutamic dehydrogenase,6 whereas 5-(Paminophenyl) tetrazole, an analog of p-aminobenzoic acid, was found t o be inactive against Staphylococcus aureus
(1) Some of these compounds have been described b y P. F. J u b y , U . S. P a t e n t 3,294.813 (1966). (2) F. R. Benaon, Chen,. Reo., 41, 1 (1947). ( 3 ) R. hI. Herhst. "Essays in Biochemistry," J o h n Wiley and Sons, Inc., New York, N. Y.,1958, p 141.
(4) C . van d e Westerinyh and H. Veldstra, Rec. Trau. Chim., 77, 1107 (1958). ( 5 ) J . hl. McManus and R. M. Herbst, J . Org. Chem., 24, 1464 (1959). (6) .J. K. Elwood, R. M. Herbst, a n d G. L. Kilpour, J . B i d . Chem., 240, 2073 (1965).
:tnd Escherichia The tetrnzole t~niilogof the antituberculous p-aminosalicylic acid prci~wlto he iii:ictive when tested in ~ ' i t r o . ~The tetmzole :malog of nicotiriic mid \vas effective in high coricentr:~ticin~: t i :I gron th factor for Lactobacillus arnbinosz~s~ and \Y:E fouiid to t i ? three t o four times more potrnt thuii iiicotiiiicb :wid 111 lowering serum cholesterol in i i i n ~ i . ~ part of :t program to provitlc non+teroid:il aiitiiiiflurnmatory agerit.: \rithout the c oft'crt.: of presentlj av:LiLibk c*onipou 1)rel):ired tctrazcile :tiialogs of ;I w i c 5 of S-plicnj 1:uithraiiilic acids \\ hich h:iv(> h e r i reported to p o w b i antiinflammatory :tctivity in both pli:irrnnc.ologicaly and clinicallo tests. Thiz paper describes the prepnration, some physical properties. arid the pre1imiii:iry pharmacology of these ~-(2-~1iiliriopheii~I) tetrazolcs. Chemistry.-All of the 5-(2-:~iiiliiio~~Iieii~l)t et r:izolc (T:tble I) were prepared from 1hc c-orresporiding 1 ~1~eiir.l:~rithrariilic :tcids hy t h e ~ ) r o c ~ c I i i rteh~a t ~ i r ~
0
1 KaN,. NH,CI
DMF
0
2. Hi
VI ( 7 ) 11. 13rouwer-van Stratten, D. Solinger, C'. Tan de \Vesterindl, a n d 11. Veldstra, Hec. Tmu. Ciiim.. 77, 1129 (1958). (8) (a) Reported by G. F. Holland a t t h e Tenth Xntional Aledicinal Chemistry Symposium of t h e .imerican Chemiral Society, Uloomington, Ind., J u n e 1966; (h) 0 . F. IIolland and J. N. Pereira, J . M e d . Chem., 10, 149 ( l 9 6 i ) . (9) (a) CI-583; see R. A. Scherrer. C. V. \\'inder, a n d F. \V. Short, Abstracts, Ninth Kational Medicinal Chemistrh- Symposium of t h e American Chemical Society, hlinneapolis, Minn,, J u n e 1966, p l l a ; (b) C. \Tinder, J. \vas. L. Scotti, R. A. Schemer, E. hl. Jones, and F. \V. Short, J . Pharmaeol. Erptl. Therap., 138, 405 (1962); ( e ) C. V. Winder, J. W a s , 1%. Serrano, E. h f . Junes. a n d &I.L. hIcPhee, Arthritzs Rheumat., 6, 36 (1963); (d) C. V. JVinder, .J. Wax. and AI. \\-elford, J . Pharmacol. Ezptl. Y'hernp., 148, 422 (1965); (e) F. Delbarre, N . P. Buu-HUT, 4.Kahan, P. Jacquignon, H . Ilrouilhet, h l . h l a r t y , and F. Perin, .Wed. E x p t l . , 11, 389 (1064). (10) (a) L. J. Cam a n d \IS. -. Frederik, J . Phormacol. Ezptl. T h e r a p . . 139, 172 (1963); (12) P. Young, Arthritis Rheumat., 6 , 307 (1963); (c) E. L. Coodley, lITratern .lfed,, 4 , 228 (1963): (d) D. E, liarnardo, 11. L. F. Currev. 11. I I . .\labon, \V. 11. Fox, and AI, \Yeatherall, Rrd. .\IPc/. J . , 2 , :342 (106iil.
\'.
SCHEME I1
7'
of the latter compound with diazomethane in ether. Structural assignments were made from the nmr qpectra.17 One of the derivatives s h o w a chemical shift of 4.18 ppm for the K-methyl protons and was assigned structure XVIII. Structure X I X was assigned to the other isomer with a chemical shift of 4.39 ppm for the S-methyl protons.
-
C1
NaH,DMF
N'
N
\N
N
N1 N'
CH,
C+Cl
P XVIII
XI1
XI
SCHEME I11
c1 \
dl
CH3 XI11
kH3 XIV
SCHEME IT'
xv
XVI
N'
N \N
XVII
As might have been predicted,3 the 5-(2-anilinopheny1)tetrazoles (Table I) would appear t o be slightly stronger acids than the corresponding S-phenylanthranilic acids. 5- [2-(3-Trifluoromethylanilino) phenylltetrazole (4) and 5- [2-(2,6-dichloro-3-methylanilino)phenyl]tetrazole (14) have pKa values of 5.31 and 5.66, respectively, compared with values of 6.28 and 6.88 for K-(3-trifluoromethylphenyl)anthranilic acid (21) and N-(2,6-dichloro-3-methylphenyl)anthranilic acid (31), respectively. All pK, titrations were carried out in 2-methoxyethanol-mater ( 2 :1) solutions. The ultraviolet spectra of the tetrazole compounds are similar to those of the corresponding carboxylic a ~ i d s . 9 ~ Both of the possible S-methyltetrazole derivatives (XVIII and XIX) of 5- [2-(3-trifluoromethylanilino)phenylltetrazole (XVII) were obtained after treatment
XIX
Pharmacology.-.ill of the 5-(2-anilinophenyl) tetrazoles (1-17), as well as the corresponding S-phenylanthranilic acids (18-34), were evaluated orally for antiinflammatory activity in the carrageenin-induced rat foot edema test.18 The results, expressed as the percentage inhibition of edema, are recorded in Table I. Any result of more than 30yGinhibition is greater than three times the standard deviation of the result in control animals and is considered to indicate significant activity. The two most active 5-(2-anilinophenyl)tetrazoles in the dose range of 100-130 mg/kg are 4 and 14, which are the tetrazole analogs of the two most active Sphenylanthranilic acidy 21 (flufenamic acid) and 31 ,9a There is also reasonable correlation in structure and antiinflammatory activity between moct of the other tetrazole-acid pairs. Compound 4, 5- [2-(3-trifluoromethylanilino)phenyl]tetrazole,l9 had a minimal eff ective dose (29% inhibition of edema) of 16 mg/kg, with an oral LDjoof 455 mg/kg in rats. Both of the nonacidic S-methyltetrazole derivatives (XVIII and XIX in the Chemistry section) of 4 showed insignificant activity in the foot edema test. This suggests that both the 5-(2-anilinophenyl)tetrazoles and the S-phenylanthranilic acids owe their activity, in part, to their ability to provide an anionic center for a hypothetical cationic receptor site.Qa In summarl, it may be stated that the 5-tetrazolyl group is an effective substitute for the carboxyl group for the retention of antiinflammatory activity in the series of S-phenylanthranilic acid agents studied. Experimental Section*O N-Phenylanthranilic Acids.-K-Pheiiylanthrarlilic acid (18) (Aldrich Chemical Co., Iric.) was purified by recryptallizatiori from 1 l e C S . N-(8-Trifluoromet~hylpheriyl)anthranilicacidz1 (21) arid S-iZ,3-dimethylpheripl)aiithrariilic acidz2 (25) were prepared by a method similar t o that described for S-pherij-1( l i ) J. H. Markgraf and W. T. Baclimann [.I. Org. Chem., SO, 347 (196511 reported t h a t t h e signal from t h e S-methyl protons of 1,5-dimethl-Itetrazole appears upfield from t h e signal from t h e K-methyl protons of 2,5dimethyltetrazole. (18) C. .i.tvinter. E. -1.Risley, and G. iV. Nuss, Proc. SOC.Bzptl. B i d . X e d . , 111, 541 (1962). (19) h more detailed account of t h e pharmacology of 5-[2-(3-trifluoromethylanilinojplienylltetrazole (BL-RI91) will be reported elsewhere. (20) Melting points were determined in a Rlel-Temp apparatus and are uncorrected. N m r spectra (CDC18) were obtained using a Varian Associates hlodel A-60 spectrometer. Chemical shifts ( 6 ) were measured donnfield from T l I S . (21) J. H. \Vilkinson and I. L. Finar, J. Chem. SOC.,32 (1948). (22) R. A . Schemer, French Patent 1,315,030 (1963); Chem. .4bntr., 69, 1538 (1963).
13
AIiTIINFLAlfllATOItT 5-(2-r\NILINOPHENTL)TF,TRAZOLES
115
STEROIDS.CCCX. HYPXOTIC AGEKTS
January 196s
benzamide (48) (14.0 g, 0.0475 mole) in redistilled POCl, (100 ml), arid the mixture was heated under reflux for 0.5 hr. T h e excess POCl, was removed under reduced pressure. il CHCl, solution of the residue was washed (aqueoiis K2C03, H20). The solution was dried (NanS04)arid the CHCL was removed. The residue was exharistively extracted with boiling Skellysolve B. The combined extracts were reduced in volume and cooled to yield 10.5 g (80.2(';,) of 65 as pale yellow needles, mp 129,3-132°. 5-(2-Anilinophenyl)tetrazoles.-All of the tetrazoles in Table I were prepared from the corresponding nitriles by the general procedure of Fiiiriegan, et al.," as illustrated for 5-[2-(2,6dichloro-3-methylaiiilino)phenyl]tetrazole (14) as follows. A mixture of 2-(2,6-dichloro-3-methyla1iilino)benzoriitrile (9.0 g, 0.0325 mole), Sax3(2.54 g, 0.039 mole), arid NH&l (2.09 g, 0.039 mole) in DlLF (63 ml) was heated, with stirring, at an oil bath temperatiire of 157" for 17 hr. The 1 I N F was removed under reduced pressure aiid the residiie was suspeiided iri cold 1120 (300 nil) which was acidified to pH 2 with concentrated IICl (beware of any liberated HN,). The solid product was collected aiid recrystallized from aqueoiis l I e O H (Sorit) to give 14 (8.6 g, 82.77,) as yellow needles: mp 207-208.5' dec; LIV maxima (9.55; EtOH, 0.01 in HCl), 280 mp (e 7.510), 329 mp (e 7360). .5-[2-(3-Trifluoromethylaniliiio)pheiiyl] tetrazole (4), mp 20520io,had iiv maxima (95('; EtOH, 0.01 -Y iii HCl), 287 mp ( E 16j200)j 336 mp ( e i300). Alternative Preparation of 5-[2-(3-Trifluoromethylanilino)phenyl] tetrazole (4).--A solution of 5-( 2-bromophenyl)tetrazole27 (3.0 g, 0.0222 mole) in dry hexamethylphosphoramide (20 ml) was added slowly to a cooled (ice-water), stirred suspension of S a H (1.80 g of a 5 9 . 4 5 S a H dispersion in mineral oil, 0.0446 mole of N a H ) in hesamethylphosphoramide (20 ml). When the vigorous evolution of H, had ceased, 3-trifluoromethylaniline (3.58 g, 0.022% mole) was added to the reaction mixture. The temperature of the mixture was dowly raised under N2. At aboiit 120' a further gaseoiis evolution occurred. When this reaction had subsided, the mixture was then heated a t 185" for l..i hr. The cooled reaction mixture was diluted (cold H&, 400 rnl). The resulting solution was acidified to pH 2 with colicelitrated HC1. The acidified mixture was extracted (CHC13, f o i i r 100-ml portions). The combined extracts were washed (cold € 1 2 0 , 100 ml). The CHC1, soliition was then extracted with 10:; aqueoiis S a O f I (two 30-ml portioiis). The combiiied NaOII A\-
(27) R. A I . Herbst a n d
IC. R. JYilson, J. Oyg. Chem.,
22, 1142 ( 1 9 5 i )
117
extracts were acidified to pH 2 with colicelitrated HC1. The resulting mixture was extracted (CHCI,, four 30-ml portions). The combiiied CIIC13 extracts were washed (HZO, 30 ml), dried (NaZSO,), and filtered, aiid the filtrate was reduced to dryness. The brown oily residue (8.0 g) was purified by chromatography on silicic acid (900 g). The crude product was iiitrodiiced onto the columii in a mixtiire of hIeBCO ( 3 ml) and C ~ H G ( 2 5 ml). The coliimii was eluted with lIe~CO-CsH6 (1 : 20). After the first 400-1nl fraction, the eluate was collected in 300-ml fractions. A buff, cryFtalliiie solid (1.9 g, 28"; yield) was obtained after the removal of the solvent from fractions 2 4 , inclusive. The solid had nip l98-%Wo, with mmp 202-205O wit,h authentic 5-[2-(3trifliioroniethylariilirio)pheiiyl] tetrazole (4). The solid was recrystallized from aqueous EtOH to give b\iU crystals, mp 203-207° (ir spectrum identical with aiitheiitic 4). -4 repeat of the above reaction using 3-(2-~hloropheiiyl)tetraxole27 in place of the 5-(2-bromopheriyl)tetrazole gave 4 iii 34.5"; yield. -2 repeat using .5-(2-chloropheiiyl jtetrazole (0.0222 mole), S a H (0.0666 mole), arid 3-trifluoromethylariiliiie (0.0444 mole) gave 4 iii 46% yield. 1-Methyl-5- [2-(3-trifluoromethylanilino)phenyl] tetrazole (XVIII) and 2-Methyl-5-[2-(3-trifluoromethylanilino)phenyl] tetrazole (XIX).-A cooled (ice-water bath) suspension of 5-[2(3-trifluoromethylanilirio)phe1iyl]tetrazole (10.0 g ) in E t & ( 100 mlj was treated with aii ethereal solution of excess CH2NB. Excess CH2N2 and E t & were removed. Fractional recrystallization of the residue from 3IeOH gave two products. The first product (9.4 g) was recrystallized from NeOH to give colorless crystals of SIX, mp ll9.3-121", iimr peak (CL)cl,) a t 6 4.3Y (3 H singlet, CH&
