Journal of Medicinal Chemistry, 1970, Vol. IS, N o . 6 997
l;OTCS
250 ml of HzO. A gummy precipitate was produced when the pH of the aq solution was carefully adjusted t o 4. The mixture was allowed to stand for 2 hr a t room temperature, the supernatant liquid was decanted, and the residual gum was triturated with abs EtOH t o give 1.2 g (187,) of Ia, mp 204-207' dec. The product was recryst,alliaed from a large volume of H 2 0 and dried in vacuo a t 1%' t o yield analytically pure product: nip 235-237' dec; '.::A 288 mp ( E 27,800); xF1 245 mp ( e 12,400); 290 mp ( e 29,100). Anal. ( C I ~ H ~ ~ SC, ~ H, O EN.) Method B.-A solut,ion of i.4 g (0.025 mole) of dimethyl p aminobenzoyl-~-glutamate,~~ 3.0 g (0.0125mole) of I I b and a few crystals of K I in 230 ml of abs EtOH was refluxed for 16 hr. The result,ing solution was evaporated under reduced pressure and the residue was dissolved in 250 nil of HIO. The pH of the aq solution was adjusted t o 8-9 with XaHC03 which caused the precipitatioii of a gummy substance. Y o attempt was made t o isolate the diwter iiiterrnediate. The aq layer was decanted and t o the i~esidualgiim was added 200 nil of 1 S SaOH. The mixture was allowed to stir at. room temperature for 2 hr. The pH of the solutiori was carefully adjusted t o 4 with 6 9 HCl at which point the product precipihted. I t was purified by recrystallization from HzOt o give 1.1 g (17Yc) of Ia. The product was found t,obe identical with that prepared by method -1. Method C.-To a solution of 3.1 g (0.007 mole) of p-( [(2,6diacetamid0-8-purinyl)methyl]-~Y-acet~amido} benzoic acid in 250 nil of DhIF cooled at 0" was added 0.7 g (0.007 mole) of Et3N followed by 0.8 ml (0.007 mole) of ethyl chloroformate. The mixture was stirred a t 0" for 1 hr. A solution of 1.5 g (0.007 mole) of dimethyl L-glutamate.HC1 and 0.7 g (0.007 mole) of EtzN in 50 ml of DMF was then added to the mixture. The resulting suspension was stirred for 20 hr at room temperature. Excess solvent was evaporated under reduced pressure a t ca. 45'. To the residue was added 200 ml of 1 S NaOH. The resulting dark solution was refluxed for 30 min, purified with charcoal, and filtered. The filtrate -'as acidified with 6 -1' HC1 to give a light yellow solid, which was recrystallized twice from H2O t o give 1 g (33y0)of Ia. The product was found t o be identical with that prepared by method A. p - ( [ (2,6-Diamino-8-purinyl)methyl] -N-methylamino } benzoyl-L-glutamic Acid (Ib).-A solution of 34 g (0.1 mole) of diethyl p-methylaminobenzoyl-L-glutamatej16 €7g (0.075 mole) of IIb, and a few crystals of KI in 500 ml of abs EtOH was refluxed for 48 hr. The reaction mixture was evaporated under reduced pressure and the diester intermediate was saponified by stirring t'he residue with 200 ml of 1 N NaOH a t room temperature for 2 hr. The solution was then acidified t o pH 4 with 6 N HC1 and a gummy substance was formed. ilfter decantation of the supernatant liquid, the residual gum was triturated with absolute EtOH. The resulting yellow solid %-ascollected by filtration to give 10 g of crude product. Recrystallization from H20 gave, after being dried a t 135' in vucuo, 4..5 g (1270)of analytically pure Ib: 292 mp ( E 29,200);::A 249 mw ( E 13,200); mp 216-218'; : : : A ':::A 295 mp ( e 32,800). Anal. ( C I ~ H Z ~ XC~, H, O ~S. )
Acknowledgment.-The authors wish to t,hank Mrs. Margaret L. Rounds and hlr. John R. Gravatt for the analytical and instrumental measurements. (1.5) R. lioeliler. 1,. Goodman, J. DeGraw, and B. R . Raker, J . Amer. Chem. Yoc.. 8 0 , S i 7 9 (19.58). (16) S.-C. J. Fu and RI. lteiner, J . O r g . Chem.. 30, 1277 (1965).
the bile and collected in the gallbladder. We wish to report that sodium 3-butyramido-a-ethy1-2,4,G-triiodohydrocinnamate, sodium tyropanoate' (5), showed favorable characteristics in laboratory studies as an oral cholecystographic agent. CH
l2
I&C02H
2,COH 3, COCH3 4, COCZH5 5,CO(CHz)2CH3(Na salt)
I
Sodium tyropanoate (5) is a derivative of iopanoic acid (1) and was found to excel iopanoic acid and other oral agents3-10 in one or more laboratory studies. Table I compares the acute toxicities in mice and the average cholecystographic indexes" (ACI) in cats of Na tyropanoate and other agents. Both iv and oral toxicities are given in Table I although there are shortcomings in the comparison of compounds by each method. Since only oral administration is used in the clinic for these agents, there is not necessarily a direct relationship between the acute iv toxicity and the adverse effects observed in the clinic. The acute oral toxicities may be ineffective for comparison purposes because of the difficulty of giving a massive dose which is required to produce mortality in animals in a manner which corresponds to the clinical administration. The method of Hoppe and Archer" was used for determining the acute oral toxicities reported in Table I. This consisted of administering the materials as a powder suspended in HzO with gum tragacanth in a volume of 0.5 f 0.35 ml by stomach tube. I n the clinic iopanoic acid is administered in tablets and Na tyropanoate in capsules. Large variations in the acute oral toxicity can exist from sample to sample for some agents. For iopanoic acid the toxicities varied from 6.6 to 15.8 g/kg (24 hr) and 5.9 to 13.9 g/kg (7 days) for a series of more than 10 samples. Most 7-day values were between 6 and 10 g. The reason for this broad range mas not readily determined. It is speculated that the cause is a combination of differences in particle size and crystalline habit. Other workers reported acute oral LD60 values of 5.1212and 3.8713g/kg in mice for iopanoic acid but did not describe their methods. With samples of Na tyropanoate (5) values in the acute oral LD60toxicities ranged from 4.8 to 16.3 g/kg. This variation is believed to be due to different methods of crystallization which produced crystals with different
Sodium Tyropanoate,' a New Oral Cholecystographic Agent .I. 0. llorrb:,2H,J. IT.
h ( ' K l ~ : l t h t . \ X , 2 'A. '
A.
f , \ I < S k , N > ..AN!)
J. LIoSS
Sterling- IL-inlhrop Research Inslittcte, Kensselaer, Xew York 1.3146 Rrceived May 11, 1970
Cholecystography is the roentgenographic visualization of the gallbladder after an administered radioopaque substance or its metabolite has been secreted in (1) IJilopaque.
(21 (a) Deceased; (b) author t o whom inquiries should be addressed.
(3) E. A. Graham and IT. H. Cote, J . Amer. M e d . A s s . , 88, 613 (1924). (4) hi. Dohrn and P, Diedrick, Deut. M e d . Wochenschr., 66, 1133 (1940): X. Rleiber, ibid., 66, 1134 (1940); K . Junkmann, Klin. Wochenschr., 80, 125 (1941). ( 5 ) T. R . Lewis and S. Archer, J . Amsr. Chem. Soc., 71, 3763 (1949). (6) D . Papa, H. F. Ginsberg, I. Lederman, and V. Decamp, ibid., 75, 1107 (1953). I. and P-C. H u , Hua Hsfieh Hsaeh Pao, 83, 361 (1957); Chem. (7) &Chao Abstr., 68, 154670 (1958). (8) H . Priewe and A. Poljak, Chem. Ber., 93, 2347 (1960). (9) British Patent 876,321; Chem. Abstr., 55, 246831 (1961). (10) J. A. Korver, R e d . TTQU. Chim. Pay-Bas, 87, 308 (1968). (11) J. 0. Hoppe and S. Archer, Amer. J . Roentgcnol. Radium Ther Nucl. M e d . , 69, 630 (1953). (12) R . Shauiro, Radiology, 66, 687 (1953). (13) K. Winser, H. Langecker, and K . Junkmann, Aertxl. Wochenschr., 9, 950 (1954).
rtlttls of solution. The inherent difficultit niitiing acute oral toxicities by the admin 5olid~could be avoided by the iibe of aqueous solution+, but ive belicve thi. rvould correcpoiid even less t o clinical procrdure t h m t h e method used here. In addition, :in ~ g ~ ilike i t iopunoic acid would h a w to be converted firit to :t water-soluble halt. Deipite the\? l)roblei11.. t l l c h actit? o r d and intravenous toxicitiei : u t ' t h e u-ual ni:tiii1er for obtaining L: preliniiiiqd e t ) of oral cholecystographic agent+. Sodiiini tyropanoate (5) i q the S a halt of the but) 1 . ~ 1 clciiv:itivt> of ioparioic wid ( 1 ) . Other acyl derivativr. 1 \\ hwli coiitain 1 to (ic' atom- 111 the i~cylgroup \ w i t ' ~ ~ i : t d:i1ltl t , T:iblt. I1 \ho\t tli(3 :iclltt' I V IADo[lva1ut.s 111 i i i i w aiid thr .IC1 valur.; 111 ciit* of thi+ vrie- of coiiipoiiiicl. .ill of thrw compoiiritls +ho\\14good to ('\crlleiit g:illbl:iddt~r viwiiliz:itiori i n c:it- r w q ) t f o r tlrcl f o m i y l tlerivatiw, :tiid t l i P touutit>\ i i i c i w w l n l t l i iiicr~~it\itig h e of t h e itcj I groui) ~ ~ ( ~ l u dthis ~ i iI'orm> g I tlcrivativc. 3 - =Icetumido - CY - t,th>1- 2,4)[j-triiodohj di.( ciiiriainic acitl14 (N-~icetyhopnnic:icid, 3), i+ the 1ea.t t oxir iiicniber of t h i h Yeric:, a i i t l M LL. previouslj- invertigatcd i t 1 the clir~ic.'~I t hac1 :I iiinrlted reduction I I I ob,twrrrl d c . cff w t \ i l l c.omI):ii 1-011 to iopittioic :icitl, but uriforturiatel~, thew \v: I (ltw-tliL\e in the efficirric> of g:tllbladder viwa1iz:itioii : ~ i i d it did riot appear to h:ivc any advantage The poor vi\ualizatioiI found i i i the clinic with 3 is attributed to too niucli low of materid b j urinary excretion. Sa tyropanoate, which ha2 niorc methylene- on tlir acyl group than N-acetylioi):iri(~ic acid, \vas prepared with t h e expectation that it \\ oiiltl Iiavtl It+ urinary arid r r t o r ~biliary excretion than )-
Journal of Medicinal Chemistry, 1970, Vol. 13, N o . 5 994
the gallbladder with the salt than with the free acid. The side effects observed with N a tyropanoate in the clinic were less than those seen with iopanoic acid.18,20-22 A crossover study in man by 1IcChesney and Banks showed that 50% of a 4.5-g dose of Na tyropanoate is excreted in the urine in 108 hr while 37y0 of a 3-g dose of iopanoic acid was in the urine.23 AIcChesney and Hoppe reported that iopanoic acid and Na tyropanoate are metabolized in the cat arid man and that the biliary excretion is mostly as the glucuronic acid conjugates. 24-77 The suggested metabolite of S a tyropanoate is shown in 8.
%fl
0
Experimental Section *s
~~-Ethyl-3-formamido-2,4,6-triiodohydrocinnamic Acid (2),Na 3-Acetamido-~~-ethyl-2,4,6-triiodohydrocinnamate (3, Na Salt), (4, and Na or-Ethyl-2,4,6-triiodo-3-propionamidohydrocinnamate Na Salt).-The preparation of the first two of these compounds by the acylation of iopanoic acid5 is described elsewhere.'* The acid 4 corresponding to the last of the above compounds is also described.l4 The Na salt of 4 was prepared by the method employed for Na tyropanoate and was obtained as colorless crystals, mp 199-210". Anal. (CIrHl&NNaOa) C, H ; I: calcd, 58.66; found, 58.06. Tyropanoic Acid, 3-Butyramido-a-ethyl-2,4,6-triiodohydrocinnamic Acid ( 5 , Acid).-A mixture of 50.0 g (0.0875 mole) of iopanoic acid5 ( I ) , 28.6 ml (0.175 mole) of butyric anhydride, 310 ml of PrCO*H, and 5 drops of H2SOa was heated on a water bath a t 70-80" for 2 hr. A solution formed and was poured int,o H20. The solid which separated was collected and dried, 47.0 g (84y0) of tan solid, neutralization equiv, 637; calcd for ClbHl&?rTO3: neutralizat,ion equiv, 641. Recrystallization from EtOAc gave very pale t,anprisms, mp 182-184" (reported mp 172185.5Ol4); neutralization equiv 640; uv max (9570 EtOH) 237 mp (e 33,900); ir (3/4% KBr disc) 1660 (CONH), 1690 (COOH), 2500-2670 (broad H bonding), 2940 (CH), and 3220 cm-' (NH). Na Tyropanoate, [Na 3-Butyramido-a-ethyI-2,4,6-triiodohydrocinnamate ( 5 ) ].-Tyropanoic acid ( 5 , acid) was converted into its Na salt by the addition of a slight excess of methanolic NaOH to a suspension of 5 (acid) in MeOH. A solution was otitained and a gumnij- material separated when E t 2 0was added. The addition of fresh Et20 t o t,he residue aft,er the liquid layer W'HS decanted arid tritiiratioii produced a solid which was collected and dried. There was obtained a colorless solid, mp 208-210". dnal. (Cl:H171&NaO~)C, H ; I : calcd, 57.42; found, ,56.6. Other samples of S a tyropanoate were recrystallized from HzOand aq i-PrOH. Na a-Ethyl-2,4,6-triiodo-3-valeramidohydrocinnamate (6, Na Salt).-The reaction of iopanoic acidj with valeric anhydride in the presence of valeric acid and H2S04 in the manner described for tyropanoic acid ( 5 , acid) gave a-ethyl-2,4,6-triiodo-3-valeritmidohydrocirinamic acid (6). Recrystallization (EtOH) gave (23) E. \V, JIcChesnej- and \\-, F. I3anks, Jr., Proc. Soc. E x p . Biol. M e d . ,
119,1027 (1905). (24) E. W. hIcChesnes and J. 0. Hoppe, Arch. Intn. Phar?nacodyn., 99,127 (1954). ( 2 5 ) E. W. McChesney a n d J. 0. Hoppe, ibid.. 105, 306 (1956). (26) E. W. McChesney a n d J. 0. Hoppe, i b i d . , 142, 562 (1963). (27) E. W. RlcChesney, Biochem. Pharnacol.. 15, 1366 (1964). ( 2 8 ) When analyses are indicated only b y symbols of elements, analytical results obtained for those elements were within &0.4Y0 of t h e theoretical i nliics. Melting points \yere taken in a Hernhberg-type apparatus anti :ire rurrwted. T h e spectra Tverr determined on a Cary 1 3 ultraviolet spect r o i i l i o t w i e t e r and on a I'erkin-Elmer 21 inirared spectrophotometer.
colorless prisms, mp 189-190.5'. Anal. (C16H2013N03)neutralization equiv: calcd., 655; found 652. The Na salt of 6 was obtained as colorless solid, mp 212-217' dec, from 6 in the manner described for Na tyropanoate. Anal. ( C I ~ H I & N N ~ O ~ ) C , H ; I : calcd, 56.23, found, 56.75. Na ~-Ethyl-3-hexanamido-2,4,6-triiodohydrocinnamate (7).The reaction of iopanoic acid5with hexanoyl anhydride and H2SO( gave a-ethyl-3-hexanamido-2,4,6-triiodohydrocinnamicacid (7) a- colorless prisms (EtOH), mp 196-198'. Anal. (C1~H2J3K03) C, H : I : calcd, 56.90; found, 56.01. The Na salt of 7 was prepared from the acid in the manner described for X a tyropanoate ( 5 ) and was obtained as a colorless solid, mp 170-190". Anal. (CnH&NKaOd C,H, I.
Acknowledgments.-Appreciation is expressed to 1Ir. John Romano, Mr. Chester Sapino, and Mr. Arnold Ludke for technical assistance. The authors wish to thank the Analytical and Physical Chemistry Departments a t Sterling-Winthrop Research Institute for the analytical and spectral data. We also wish to thank Dr. H. 1'. Drobeck and A h . L. Duprey for the acute toxicity studies.
Isoquinolines. 2. 3-(Dialkylaminoalkylamino)isoquinolines as Potential Antimalarial Drugs'sZ JOHN L.
?jEUMEYER3 -4ND
KLAUSK.
WEIh.H.IRDT
Arthur D . Little, Inc., Acorn Park, Cambridge, Massachusetts 02140 Received March I S , 1970
Because quinolines have played such an important role in malaria chemotherapy, we believed that the heretofore unexplored class of 3-aminoisoquinolines deserved further investigation. I n our previous report1 we presented the synthesis and biological activity of a number of 3-aminoisoquinolines which do not contain the usual dialkylaminoalkylamino side chain, a common feature of the active quinoline antimalarials such as chloroquine (Ia) or pamaquine (Ib). Q--NHCHCH&H~CH&"C~H~)Z AH3
Ia, Q Ib, Q
= =
4-(i-chloroqr1inoline) 8-(6-niethoxyquirioline)
This report will present the synthesis and biological activitjr of such isoquinoline derivatives. Chemistry.-The synthesis of the diamines (VI) was carried out by the sequence of reactions shon-n in Scheme I from the appropriately substituted aminoisoquinoline' (11). The attempted alkylation of the 3chloropropionamide 27 with N-methylaniline yielded only the elimination product, N-(3-isoquinolyl)acrylamide.4a Such an elimination also occurred when the ( 1 ) Paper 1: J . I.. Seumeyer and K. K. Weinhardt, J . M e d . Chem., l S , 613 (1970). (2) This work was supported b y t h e U. S. Army Medical Research and Development Command under Contract DA-49-193-AID-3023. Titis is Contribution No. 783 from the Army Research Program on Malaria. Presented in part a t t h e 155th National Meeting of the American Chemical Society, hliami, Florida, 1968, S-28. (3) T o whom inquiries should be addressed a t t h e Department of Medicinal Chemistry, College of Pharmacy, Northeastern Oniversity, Boston, Mass. 02115. ( 4 ) ( a ) This compound was described in t h e previous paper (ref 1 ) and \vas desinnated as compound 14; (b) This compound x a s described in t h e Previous payer (ref I ) and ma8 deaignateri a s compound 15.
