Bottromycin A1 benzylamide was prepared similarly using benzylamine crystallized from EtOAc; mp 160-168", [ a ]25D -.56O (c 1, Otji'% EtOII). Anal. Calcd for C48TI67N90&.1120: C, 62.9; H , 7.5; N, 13.7; S, 3.5. Found: C, 83.0, H, 7.6; N, 13.4; S, 3.5. Bottromycin AI Ethyl Ester.-A 10-mg/ml solution of bottromycin -41 free base in anhydrous EtOH containing l5YO E t & was heated a t 50" in a sealed tube for 20 hr. The res:ultant mixture of bot,tromycin A1 and the ethyl ester of bottromyciri A1 was separated by partition chromatography. A nul. Calcd for C ~ Z H ~ ~ N ~ O M C, . H60.4; ~ O ; IT, 7 . 5 ; N, 13.1; R, 3.7. Found: C, 60.1; H, 7.4; N, 12.7; S,3.4. Bottromycin t-Butylamide.-Bottromyrin carboxylate16 (480 mg) was dissolved in 5 ml of anhydrous IIMF and was treated successively a t 0" with 219 mg of bis(2,4-diriitrophenyl) carbonate and 0.14 ml of Eta?;. The solution was stirred at 0" for 75 min (16) J. A I . Waisvisz and 11. G. van der H o r r r n , J . A m . C h ~ mS. O C . 80, , 383 (1958).
and then at room temperature for 10 min. T o this mixture was added 2 ml of t-BuNHz. A precipitate formed in a few minut,es. The mixture was heated at 5(1-60° for 30 min, diluted with 20 ml of CHCl3, and filtered to remove the yellow by-product. The filtrate was concentrated to near dryness under reduced pressure. The residue was dissolved in CHCl, and then washed (saturated until the aqueous layer was colorless. NaCl containing 570"3) The organic solution was dried (Na2S04)and concentrated to dryness. A yellow glass (390 mg) was obtained. Tlc ( 1 0 5 MeOH in CHC13, silica gel) gave two zones when sprayed with bromophenol blue. The desired amide was located at Iff 0 . 7 0 , and a slower moving subst,ance IZf 0.13 was observed. These components were separated by preparative tlc yielding 107 mg of the t-butylamide as an off-white glass. This general procedure was used to prepare the derivatives listed in Table 111. In some cases the thin layer chromatograms were developed with XIeOH-CHC13 of different composition to improve resolution of the components. The zones were sometimes developed by staining with iodine vapor or located l)y spraying the dried plate with H20.
S,S-Diarylpenta-2,4-c2ienoicAcid Amides as Potential Antimalarial Agents' \vILLIA1I
T. C O L W E L L , JUDY H.
LrlNGE, .4ND DAVID
\v. HEXRY
Department of Pharmnceictzcal Chantistry, Stanford Research Institute, Menlo Park, Calqornia 94025 Received February 10, 1968
A series of 5,5-diarylpenta-2,4-dienoicacids and their amides have been synthesized and evalriated as antimalarial agents. The acids were prepared from the corresponding diary1 ketones either directly by a Reformatsky procedure or through acetylenic alcohol and acrolein intermediates. The preparation of a series of 3,sbis(4-chloropheny1)acrylic acid amides is also reported. One compound, IVjPi-diethyl-5,5-bis( 4-chloropheny1)penta-2,4-dienoic acid amide, provided significant antiplasmodial activity.
Among the more novel compounds revealed by the World War I1 malaria program to have interesting antiplasmodial action was KDj-isopropy1-5-(p-chlorophenyl)penta-2,4-dienoic acid amide (1).2 This compound was four times more active than quinine in the chick Plasmodium gallinaceum assay employed in that work and had a therapeutic index of 12.5. Two other amides, obtained by coupling the same acid with guanidine and cyanoguanidine, were inactive. Because of the development of resistance to chloroquine in many parts of the world by Plasmodium falciparum, there is an increasing need for new antimalarial drugs of novel structural t ~ p e . ~ This J need suggested that examination of additional chemical structures related to 1 for antiplasmodial properties would be of value. I n addition to antimalarial activity, other biological properties have been associated with pentadienoic acid derivatives. The hydrazide of 5-phenylpenta-2,4-dienoic acid has in vitro antituberculous activity,6and a series of the free acids shows inhibitory action against bacteria, yeast, and fungi.' Sorbic acid (2,4-hexadienoic acid) is widely used for its antifungal properties8 (1) This work was supported by t h e U. S. Army Medical Research and Development Command under Contract No. DA-49-193-MO-2150. This contribution is no. 331 from t h e Army Research Program on hlalaria. (2) G. R. Coatney, W. C. Cooper, N. B. E d d y , a n d J. Greenberg, "Survey of Antimalarial Agents," Public Health Service Publication No. 193, Washington, D. C., 1953, p 139. ( 3 ) Reference 2, p 131. (4) World Health Organ. Tech. R e p t . Ser., No. 296, 1 (1965). ( 5 ) P. J. Bartelloni, F. W. Sheely, and W. D. Tigertt, J. Amer. ,]fed. Ass., 199, 141 (1961), a n d references cited therein. (6) S. Kakimoto, I. Sekikawa, and K . Yamamoto, .I. Pharm. Sac. .Japan, 76, 353 (1955); Chem. Abstr., SO, 1663e (1956). (1) K. Takeichi, Hahho K O ~ QZasshi, ~ U 38, 99, 224. 313, 431, 539, 602 (1960); Chem. Abstr.. 66, 2791b (1961); 57, 2669 (1962).
C1 e C H -- - C H C H = C H C O S H - i - F r
2
/8'
C=CHC=CHCON
c1
I
n N-
W
CH:
CH3 3
and piperine (2, the pungent element of pepper) has insecticidal proper tie^.^ The use of derivatives of 5- (5-nitro-2-furyl)penta-2,4-dienoic acid as antibacterial agents has been patented.'O Of more pertinence to parasitic disease chemotherapy, it has been reported that a series of 5,s-diarylpenta2,4-dienoic acid derivatives of piperazine (e.g., 3) possess marked act'ivity against Dicrocoelium dendriticum, a liver fluke of considerable vet'erinary importance."*12 The closely related fluke, Fasciola hepatica, which infests both animals and man, is affected by these (8) Chemicals Used in Food Processing, Publication 1274, National Academy of Science, National Research Council, Washington, D. C . . 1965, P 5. (9) E. K. Haevill, A . Hartsell, and J. 31. Arthur, Contrib. Boyce Thompson Inst., 19, 81 (1943). (10) H. Saikachi and S. Ogawa, Japanese Patent 11,981 (1962); Chem. Abstr., 59, P11426c (1963). (11) M. Schorr, H. Loewe, E. JUrgens, H . Weber, a n d G. Lammler, Arzneim-Forsch., 14, 1151 (1964). (12) G. Lammler, 2. Tropenmed. Parasitol., 16, 164 (1964).
I),2
0.4 11. .i
I).1 ,
..
-5/.ij
iI.2
compounds to 3 lesser extent.'? Malaria and liver flukc chemotherapy have previously been correlated through the drug 1,4-his(trichIoromethyl)henzeiie. This compound iy curative for Plasnzodiunz beryhei infected miceL3arid has had successful veterinary14 and human clinica11b~16 w e wgaiiist several liver flukes. Hecause n-e xere aware of iiiterest in monoarylpentadieiioic acid amides in another laboratory, we chose to concentrate our development of this lead OIL 3,.5-diarylpeiita-2,~-dieiioicacid amides, thus expanding oil the possible malaria-liver fluke chemotherapy correlation. A series of five diary1 acids were prepared arid converted to various amides. A short series of ainides from a Ion-er vinylog, 3,3-bis(4-chlorophenyl):icrylic acid, was also prepared.
During the c o i m e of this study the lead coinpouiid (1) was found to bc iiixtivc againit 1'. berghei in the niouw qiieiitly Werhel. Heudeii, alid E1d:ger h of nineteen cloiely rekited .;-j)hciiyll)eiita-2,~-dieiioicacid ;imide. h:iriIig :L v:irietj. of substituents on the 1)Iimj1 :ind aniidc fuiictioiis. '' .llthough no 1iunieric:il result< were provided, ~ i o i of i~ thehe conil)ourid< :ilq)cwed t o providc iiiterc~+tiiig :rntiinalurial CI: tivitj. :ig:iinst Z'. bcrghei. Ii, I h Chemistry. Thr. clienoic acidy have h e n prepared l q several procrdurei. Initial a i tempt> t o preparc the diphenyl derivative (21, Table I) by the direct base-catal>zetl concleniatiori of benzophenone u it h methyl crotoiiate ill ( h i e t h y l sulfoxide solution did not jield the de>ircd :icid. This procedure has provcii effective in the .yiitlie-ii of ctiaryldienoic acids nheri $-methylcrotoiiie (>.fer \\ :IS cmiployed :IS thc act I11rthJ 1 .uh-tr:ktc, iTrct
13) Information riven in separate presentations b y D. P. Jacobus and I;. F. Elslager a t the Symposium on Drug-Refractory Malaria, 153rd S a tional Xleeting of tlie .American Chemical Society, 3Iiami Beach, F.a., April I
10. 1967. (14) J . C. Boray, F. A . Happicli, and J. C . .\ndren.s. I'd. H e c . . 8 0 , 213 ( l g f i i ) , and references cited therein. (15) IV,Sheng-miao, et nl., Chinese M e d . J . , 84, 548 (1965). (16) C . Huei-Ian. K. Hsiai-ying, F. LLei-cIii, and H. Chih-piao, ibid., 84. 756 f 1 0 6 5 ) .
(1;) 111 .'f b e r y b e i hioassayr reported in this paper xvere performed b y Ilr. Leo Rane of t h e 1:nicersity of Miami b y a published procedure IT. S. Osdene, P. B. Russell, and I,. Rane, .I. Jfed. Ciiem., 10, 431 (1967)l. T e s t i n g results vere supplied tlirouph t h e courtesy of Dr. David P. Jacolms of t h r Walter Reed Army Institute of Research. CIS) I,. 31. Werbel, N. Headen, and E. F. Elslager, ibid., 10, 366 (1967).
7.51
July 1968 TABLEI1 3.3-BlS(~CHLOROPHENYL)ACRYLICACIDAND
DERIVED AMIDES
Yield.
x
NO.
36 37
-N --N
n
7% 60
141-145
nO*H,O
67
7n
NCH3 U
Mp,
O C
---,\ntimalariaI 40 160
.4nalyses“
C,
...
..
96-99
C, H, r\;
n i
n i
84-85 148-140 139-142 136-138 174-1 76
C, H, N C, H, S C, H, ?i
n 3
0 3
0 5
0 5
act!--
640
Toxicity deathsd
5/5
W
38 NEti 39 IL’hIe2 40 NCH(CTT?)l 41 2“ 42 OHc a See Table I, footnote a. * See Table I, Whitehead, J . Bio/. Chem., 175, 771 (1948).
71
on
5/ 5 2/5
n5 nn .i/R 63 n i n i 5/ 5 68 . . .. .. 0. K. Behrens, J. Corse, TI. E. Huff, R. G. Jones, Q. F. Soper, and C. W. footnote b. d Deaths a t the 640-mg/kg dose level. 65
The Reformatsky addition of methyl y-bromocrotonate to the corresponding diaryl ketones gave 30-50% over-all yields of the diphenyl, fluorenyl, and bis(4chloropheny1)dienoic acids (21, 28, 14). Acrylic acid 42 (Table 11) was obtained in 68% yield via the Reformatsky addition of a-bromoacetate. The three-step Reformatsky procedure involved the initial Reformatsky addition to give a diarylcarbinol, acidcatalyzed dehydration to a dienoic ester, and hydrolysis of the ester. These steps were generally conducted without purification of the intermediate alcohol and ester. This reaction sequence gave only 10% of bis(4-fluoropheny1)pentadienoic acid (35) despite considerable manipulation of the reaction conditions. The addition of 4-phosphonocrotonic ester anion to bis(4-chlorophenyl) ketone gave a lower yield of the desired acid product (14) than was obtained by the Reformatsky sequence. This phosphono ester reagent mas reported by Werbel, et al., to give excellent results in the formation of monoaryldienoic acids from benzaldehydes. The identity of the products obtained by the two procedures, along with uv absorption data, is considered as evidence in the present case against the possible occurrence of “abnormal” reactions on the a-carbon atom of the Reformatsky reagent.Ig The use of the triphenylphosphorus ylide from methyl y-bromocrotonate gave only very poor yields of dienoic esters in several cases when treated with diaryl ketones. Preparation of bis(4-anisy1)pentadienoic acid (32) proved the most difficult of the dienoic acid syntheses reported. The Reformatsky procedure gave the desired acid in, at best, 5% yield although a variety of experimental conditions were employed. This reaction had been previously reported to fail entirely.20 The ylide synthesis also failed in this case. Two successful preparations of acid 32 are illustrated in Scheme I. Reduction and subsequent reoxidation of acrylic ester 5, obtained from Reformatsky addition of methyl bromoacetate t o ketone 4, according to a reported general synthesis,21gave a very poor yield of the intermediate acrolein 6. The reduction of the ester to the intermediate allyl alcohol even under mild conditions produced a major portion of hydrocarbon. (19) F. Bohlmann, Chem. Ber., SO, 1519 (1957). (20) L. H. Klemm a n d G. M. Bower, J . O w . Chem., 23, 344 (1958). (21) R . Heilman a n d R. Glenat, Bull. SOC.Chim. France, 1586 (1955).
SCHEME I (p-hIeOC6H&CO
+ BrZnCH&OOhIe L
4
L
I
LiCcCH
(p-lIeOCoHa)&=CHCOOhIe
I
5
I
(p-lLeOC~1T4)2&C-CFI
Ha0
+
+
7
J.
1. 2.
(p->leOC6H&C=CHCHO 6
.1 p-hIeOC6H4)2C=CHCH=CHCOOH 1.
2.
(
LAH MnO? or Pb(0Ac)a
(C6Hs)3P=CHCOOMe OH-
32
The intermediate acrolein could be converted to dienoic ester via an ylide reaction in good yield. Bis(p-anisyl) ketone (4) was converted to the corresponding acrolein in much better yield by route 4 -t 7 + 6. Acetylenic carbinol 7, prepared from the ketone and lithium acetylide, rearranged readily to 6 in ethanolic sulfuric acid. Aldehyde 6 was rather sensitive and was converted without purification to dienoic acid 32. Before applying this acetylene-acrolein sequence to bis(p-anisyl) ketone, benzophenone was employed as a model. Results were equally good. Again, identity of products obtained by these two procedures with that from the Reformatsky method ruled against an “abnormal” Reformatsky reaction. The amides have been conveniently prepared from the acids by the mixed anhydride method. S o advantage was noted in either yield or ease of work-up of the reactions when isobutyl chloroformate was substituted for methyl chloroformate. Biological Activity.-The compounds were assayed against lethal, blood-induced P. berghei infections in mice“ as part of the Walter Reed Army Institute of Research malaria program. It can be seen from Tables I and I1 that the majority of the amides did not significantly increase the survival time of infected mice. The one interesting compound, 5,5-bis(4-chlorophenyl)penta-2,3-dienoic acid diethylamide (lo), shows both an appreciable activity and a distinct dose-response effect. Kone of the acrylic acid amides were active and all were toxic at the 640-mg/kg dose level. Compounds 12,19, 26, and 36-40 did not inhibit the growth of Staphylococcus albus, Escherichia coli, Serratia marcescens, Klebsiella aerobacter, Saccharomyces cerevis-
