NOTES
Jiily 1969
705
with stirring. The aqueous phase was extracted (CHC18, three The reactions employed for the preparation of I (iso10-ml portions) and the combined CHC13 phases were t,horoughly lated as the salt, VIII) are outlined in Scheme I. The washed (H20) to remove p-nitrophenol, dried (MgSO,), and tetracyclic ltetorie I1 (prepared by procedures preevaporated. The residual g u m was trit,iir:it,edfirst, wit,h PhSle, viously reportedj) wax converted via the glyoxalate 111 then with Et20, to give a solid which was recrystallized from EtOH to give 1.5 g (45CG)of colorless needles, mp 153..S155°. to corresponding @-ketoester IV. Bromination of II' =Inal. (C,,HIIN,O~.O..~H~O) C, H, N. gave the pyridopheriothiazir~iumsalt T',6which was not Dipotassium 6-[~1~-cu-(5-Tetrazolyl)phenylacetamidojpenicilisolated but was converted directly to its conjugate lanate (IV).-To a cold (0-5") solution of 1.62 g (7.5 mmoles) base, the unsaturated @-keto ester VI. It was later of 6-aminopenicillanic acid and 1,515 g (15 mmoles) of discovered that VI could be obtained in greater over-all Et3N in 25 nil of dry CH2C12was added with stirring 2.439 g (7.5 mmoles) of p-nitrophenyl DL-a-(.itetrazolyl)phenylacetate. yield by ketone cleavage of the unsaturated glyoxalate The mixture was stirred for '2 hr a t 0-5" and for 17 hr a t room VI1 using KaOEt. Compound YII was obtained from temperahre and was then added to 25 ml of ice-water with I11 by bromination followed by neutralization with vigorous stirring. The aqueous phase was ext,racted (CHC13, triethylamine. two 20-ml portions) and acidified to pH 4.5 and reextracted (EtOAc, three 20-ml portions) t o remove p-nitrophenol. The The unsaturated p-keto ester VI proved to be surpH was t,hen lowered to 2.0 with 42Cc H,PO, and the penicillin prisingly resistant to alkaline hydrolysis; treatment of was extract.ed into EtOhc (three 20-ml port.ions). gft,er t,he VI with ethanolic KOH a t reflux temperatures for 18 hr extracts had been washed ( H 2 0 )and dried (AIgS04),1 5 mmoles failed to yield I. Unchanged starting material was of a 50% solution of potassium 2-et,hylhexanoate (KEH) in also obtained when 5% HC1 or 72% H?S04were used as n-BuOH was added and the solvent' x a s evaporated to halfvolume under reduced pressure at 33 '. The product, precipitated catalysts. Finally, the procedure employed for the on t'he walls of the flask from which it' was recovered by trituration hydrolysis of mesitoic ester7 using coiiceiitrated H,SOI with dry Et20, filtration, and drying over PZO, in vacuo. This was successfully carried out to give YIII! the conjugate yielded 2.5 g of hygroscopic material for which a satisfactory acid of I.8 Attempts to obtain I by ketone cleavage of analysis could not be obtained; the pririty of the penicillin was estimated from ir and nmr spectra t o be 9 0 7 . VI1 with KOH a t 2.5" gave an uncharacterizable
Acknowledgment.-The microbiological data were kindly supplied by Dr. I NaOH solution. The c6&%-as yellow crystals, mp 287". Anal. (C,8€I,3XO$3)C, H, N , S. twiprr:it ed and the wireacted ketone was recovered. The comMethod B. Bromination of 1V.---A solut,ion of 2.0 g ( 6 . 2 aOH .solution was acidified with 10% HC1 to yield a mmoles) of I V in 300 ml of CCI, was cooled t o 0" and 5 nil o r i,etltlish precaipitate which, after filtering and recrystallizing from CC1, containing 1.0 g (6.3 mnioles) of Br,! was added. A41miia1 95f'; I5TOI1, gave 50 g ( 6 2 p ; ) of reddish needles, mp 162'. immediately a brown solid was formed. A small sample of t h r .lnu/. (c,,€rlJo,s) c:, 13, x, s. latter, after recrystallization from dioxane, gave ir bands (KBr) at Ethyl 1,2-Dihydro-3-keto-3H-pyrido[3,2,l-~Z]phenothiazine3030 (OH) and 1692 cni-I (ester carbonyl). The remaining mu2-carboxylate iIV).-Compoiind I11 (15 g, 0.043 mole) and 15 g lerial was stirred for 15 niin with 10 ml of Et3N, which was theii of pciwderrd glass were mixed irr a dry flask in a bath preheated removed. The resulting solid x a a collected on a filter a r i d I O 170". Gas evoliition began t o ocxur at 157", then the teniwashed (H20). After recrystallization from dioxane 1.2 g ( 6 0 5 [1eratrti'ca w a s ahJWed t o increase to 162'. The mixt,ure was of VI, mp 282-283', was obtained. This substance was ident.icd heatrtl fat, 2,.5 h r . The reddish residiie was extracted with
NOTES
July 1909 with the product obtained from method A by comparison of uv and ir spectra. 2-Carboxy-3-hydroxy-3H-pyrido [ 3,2,1-IC4 phenothiazinium Bisulfate (X).-A solution of 2.4 g (7.4 mmoles) of VI in 50 ml of concentrated H,SOd wab heated on water bath for 20 hr. The mixture m-ab porved onto ice water aiid a yellow precipitate wab formed. A ctude yield of 2.9 g i99.8'7h) of brown solid was obobtained and recrystallihed from t-BitOlT and distilled H20. The firbt crop wai reciystalliLed from a mixtiire of t-BriOH and deioniAed distilled HLO to which a few drop5 of concentrated HlSO, had been added. Bronn cryatals were obtained, mp 300". Anal. (C16H11~0&)C, H, N, S.
Acknowledgment.-The authors thank S. C. Jong for assistance in the microbiological testing.
The Bacteriostatic Effectiveness of 1-Acyl-3-(3,4-dichlorophenyl)ureas ~IONEE H.BZ.4K.4RI.4 .1HD DAVIDTABER
Armour-Dial, Inc., Chicago, Illinois 60609
707 RNHCONH
I1
c1
Synthesis of the desired materials involved treating 3,4-dichlorophenyl isocyanate with aliphatic amides, halogenated benzamides, and nicotinamide under anhydrous conditions. Relevant data, including minimum inhibitory concentrations (111C's) in soap for Staphylococcus aureus ATCC 6538 are shown in Table I. I n the aliphatic series maximum activity (1-5 pg/ml) was observed when R was Pr, Bu, or 9-decenyl. I n the series derived from benzamides, 1IIC's of 0.1-0.5 pg/ml were observed when R was 2,4-dichlorophenyl, and 1-5 pg/ml when R was 3,4-dichlorophenyl. Interestingly, in the carbanilide series, a structurally related group of compounds, maximum activity is observed with the 3,4-dichloro isomer and not the 2,4 deri~ative.~
Received February 10, 1969
I n continuation of our search for antibacterial compounds, a number of 1-acyl-3-(3,4-dichlorophenyl)ureas (I) were prepared. 1-Acylureas have been reported,'
qcl
RCONHCONH
I
c1
but not as bacteriostats. A recent communication2 from this laboratory described the synthesis and bacteriostatic properties of a similar series of compounds, the 1-alkyl-3-(3,4-dichlorophenyl)ureas(11). The ac-
Experimental Section Since one of the reactants is 3,4-dichlorophenyl isocyanate, which readily forms 3,3',4,4'-tetrachlorocarbanilidein the presence of water, the reaction must be carried out under extremely anhydrous conditions. The first few members of the series were prepared by first heating the amide in C6H6 for 2 hr and azeotroping moisture through a Dean-Stark trap, then adding 1 equiv of 3,4-dichlorophenyl isocyanate in dry o-dichlorobenzene. The mixture was heated to 130-140" and C& was collected. Finally, the reaction was continued under reflux for 10 hr. At the end of this period, most of the solvent, was distilled off and the residue was cooled and trit'urated with C6H6,causing a crude product. to precipitate. The solid was filtered off and air dried. In most cases it. was found to be a mixture of 3,3',4,4'-tetrachloro-
TABLE I 1-ACYL-3-(3,4-DICHLOROPHENYL)URQ*S
~,~-CISCF,H~NHCONHCOR No.
R
Mp, o c a
Yield,
RIIC,
70
rg/mib
Formula'
Reorystn solvent
173 C2H5 CioHioC12N20 EtOH 78 20 n-C8H7 155-156 CiiHizClzNz02 PhH 38 1-5 n-CdH8 159 Ci2Hi4CLNz02 PhH 97 1-5 4 n-CA1 130-1 31 86 20 Ci3Hi~ChN202 PhH 5 n-Cdh 128-129 82 20 CiJLoC12Nz02 EtOH 6 n-C& 114-115 78 20 Ci6H22C12Y202 EtOH 7 n-Cl1H23 105-106 Ci9H28CLX~202 EtOH 70 20 8 9-Decenyl 100 CisHzrC12N202 EtOH 69 5 9 %C13H27 99-100 52 20 Ci8H32CLNz02 EtOH 10 3-Pyridyl 272-273 Ci3HgCltS302 d 94 20 11 O-C1CsHd 208 70 20 CiiH~C13N202 lIe2C0 12 p-ClC6Hr 273 87 20 Ci~H~Cl3Nz0~ d 13 2,4-ClzC& 222 65 0.1-0.5 CiaHaCLN202 1\Ie2C0 14 3,4-C12CeH3 235-236 96 1-5 Ci4HsClrN202 31e2C0 a All melting points were taken on a Fischer-Johns melting point apparatus and are uncorrected. 3Iinimiim inhibitory concentratioii against 8. aweus ATCC 6538. All compounds were analyzed for C and H, and the results were within 0.47, of the theoretical val1ie.i except for 13 where the C variance was 0.5%. d Triturated with Me2C0. 1 2 3
tivity was found t o increase with chain length, reaching a maximum with the n-octyl derivative, then decreasing as the was lengthened A series Of N-acylureas were Prepared to determine whether these also are antibacterial and, if so, the chain length of R at which optimum activity occurs. (1) P. F. Wiley, J . Am. Chem. Soc., 71, 1310 (1949). (2) T. A. Schenach, J. Brown, Jr., A. J. Wpsocki, and F. Yackovich, J. M e d . Chem., 9, 426 (1966).
carbanilide and the desired material. Separation was achieved by boiling the mixture in C6&, filtering while hot, and cooling the filtrate, whereupon the acylurea precipitated. The method of choice, which avoids formation of tetrachlorocarbanilide, was t o run the reaction in dry PhMe for 24 hr according to the procedure of Wiley.1 Yields were generally in excess of 707, and ranged from 38 to 977& The following preparation is representative. ( 3 ) D. J. Beaver, D. P. Roman, and P. J. Stoffel. J . A m . Chem S a c , 79, 1236 (1957).
