July 1967
NALEAMIC ACIDSAND EXCRETION PROCESSES
For chromatographic purposes, two 10-ml portions of a strong anion-exchange resin (aniberlite IRA 400) were each washed with 100 nil of 1 S carbonate-free NaOH to be certain the resin was in the OH form of the cycle and then wit,h 200 ml of water until the washes were neutral. Two-milliliter volumes (containing approximately 13 mg of protein with attached boron hydride anions) were passed through the resin columns, and volumes of 23-100 ml were collected. Aliquots were analyzed for boron content. Acute toxicity studies in CD1 male (Swiss Albino) mice were carried out by a physiological saline. For rabbit toxicity studies, male and female Kew Zealand white rabbits weighing bet'ween 2.1 and 3.1 kg were used. The cesium salt of the BI2HIISH2-anion was converted to its sodium salt, by ion-exchange resins and a n isotonic solution of this compound a t p H 7.2 was sterilized by passage through a Millipore
717
filter (pore size: 0.43 p ) prior to its injection into the ear vein of the rabbit. A dose of 40 mg of boron/kg was administered daily for 5 successive days and then the animals were observed for 30 days following the last injection.
Acknowledgments.-The authors wish to thank Dr. William H . Sweet, Professor of Surgery a t the Harvard Medical School and Chief of the Neurosurgical Service of the Massachusetts General Hospital for his great interest and support of this work. The invaluable technical assistance of A h . Janette R. llesser and her collaborators, Misses Beverly Whitman, Mary Hagney, and Barbara Greene, is gratefully acknowledged.
Maleamic Acids That Affect Plasma Cholesterol and Penicillin Excretion EVERETT 11. SCHULTZ,WILLIAM A. BOLHOFER, ALBERTAUGENBLICK, JOHN B. BICKING, CHARLES N. HABECKER, J. KENNETH HORNER,SARA F. KWOXG, AND ADOLPH 11. PIETRUSZKIEWICZ Xerck Sharp & Dohme Research Lcboratories, Davision of Merck & Co., Inc., West Poznt, Pennsylvania Received January 16, 196'7 A number of maleamic acids have been prepared by the reaction of maleic anhydride with an appropriate amine. In general, the amines are of the di- and triphenyl-substituted alkyl type for which synthetic procedures are given. Some of these have two asymmetric centers and in most instances both of the racemates were obtained in pure form. Compounds were prepared to show the biological effect of (a) the degree of substitution on the amide nitrogen atom, (b) systematic variation of substituents on the carbon atom a to it, and (c) variation in the positions of the aryl groups on the alkyl chain of the amine. For comparison purposes, the fumaramic acid analog of one of the most active maleamic acids and the succinamic acid analog of another were prepared. The hypocholesterolemic activity in rats and/or the inhibitory effect on penicillin excretion in dogs is reported. Structureactivity relationships are developed and biological effects of the major structural variations are emphasized. One of the maleamic acids, N-[2,3-bis(p-chlorophenyl)-l-methylpropyl] maleamic acid (benzmalecene) has been t'he subject of clinical investigation.
The effect of a maleamic acid, benzmalecene,2 on penicillin excretion, uric acid transport, and plasma cholesterol in the dog, plasma cholesterol in the rat, and on t'he in. vitro synthesis of cholest,erol from mevalonic acid in rat liver homogenates has been reported from these laboratories. 3 , 4 The act'ion of benzmalecene on microbiological systems has been reported by -4aronson, et ~ 1 . ~and 5 by Holz, et ale6 Inhibition of the active transport of bile acids across t'he int,est,inal mucosa by a number of maleamic acids has been studied by Lack and Weiner.7 Clinical evaluation in man has shown that' benzmalecene has a hypocholesterolemic action,8 inhibits (1) T o whom inquiries should be addressed. (2) Denzmalecene is the generic name f o r pi- [2,3-bis(p-chlorophenyl)-lmethylpropyljrnaleamic acid ( a isomer): E. 41. Schulte, J. B. Bicking, and V. D. Wiebelhaus. British Patent 901,438(July 18,1962). (3) J. E. Haer, If. F. Russo, A. V. h o o k s , and K. H. Beyer, Pharmacologzst, 1, s o . 2, 53 (1959). (4) J. I V . IlulT and J. L. Gilfillan, Proc. SGC.E x p t l . B i d . N e d . . 103, 41 (1960). (5) S. Saronson, B. Bensky, and h1. Shifrine, ibid., 109, 130 (1962): S.Aaronson, J . Gen. Microbial., 37, 225 (1964): 39, 367 (1965): Xature, 202, 1355 (1964). (6) G. G . Holz. Jr., L. Rasrnussen, and E. Zeuthen, Compt. Rend. Trav. Lab. Carlaberg, 88, 290 (1963). (7) L. Lack a n d I. M. Weiner, J . Pharmacal. Ezptl. Therap., 139, 248 (1963); Federation Proc., 21,258 (1962). (8) S. S. Bergen, Jr., T. B. Van Itallie, and W. H. Sebrell. Proc. Soc. E z p t l . B i d . Med., 103, 39 (1960); 9. S. Bergen, Jr., and T. B. Van Itallie, Ann. Internal M e d . , 58, 355 (1963); E. E. Cooper, Circulation, 20, 681 (1959); R. H.Furrnan, R. P. Howard. L. N. Norcia. and C. W.Robinson, Jr., Proc. Soc. E x p t l . Biol. .\fed.. 103, 302 (1960); J . Lab. Clin. ,\fed., 54, 817 (1959); I. H.Page a n d R. E. Schneckloth, Circulation, 20, 1075 (1959); B. A. Sacks, E. Danielson, and R. J. Sperber, Metab. Clin. Ezptl., 9, 783 (1960); Circulation. 20,762 (1959).
the excretion of peni~illin,~ and has a uricosuric effect,9t10 which, however, is not reflected in a decrease of blood uric acid levels. Benzmalecene (1, Table 11) is a representative member of a series of related maleamic acids. The synthesis of other members of the series along with data for their inhibitory action on penicillin excretion in dogs and/or the hypocholesterolemic activity in rats comprise the subject matter of the present report. All of the maleamic acids were prepared by the reaction of an amine with maleic anhydride. The appropriate amines mere obtained from various precursors by procedures such as (1) the Leuckart reaction on an appropriate ketone, (2) catalytic hydrogenation of a corresponding ketoxime, (3) reduction of a nitrile, and (4) hydrogenation of a corresponding ketimine. These transformations are depicted diagramatically in Scheme I. The intermediate ketones, ketoximes (1)
SCHEME I
>=o
( 3 ) >-CN (4) >=NH
I
+-CNHCO
-
COOH
' CHI= Hd
(Table I), nitriles, and ketimines were prepared by standard procedures, the details of which are set forth in the Experimental Section. Known amines were pre(9) P. E. Siegler, J. R. Rosenfeld. D. Naide, J. DilLlarco. and J. H. Nadine, Current Therap. Res., 2,448 (1960); C l m . Ezptl. Res., 8 , 290 (1960) (10) J. H. Talbot, J . Bone J o z d Surg., 40A, 994 (1958).
T 18
SCHULTZ, et al. TABLE
I (~rys1n
OxImP
Ketone I ,2-Dipiieri~l-3-pentanuri~" 1,X,4-Triphenyl-2-butanoneh :~-Benz~l-3-pIienyi-2-prntanoiie 1,2,3-TriphenyI-l-propanone< 3-Denzyl-3.4-diphenyl-Z-butsnoned 3,4,4-Triplrenyl-2-1~utanon~ 3,3,4-Triphenyl-2-butanonef 3,4-T3is(p-rhlorophenyl)-2-h~itanotie
1.01. 1 0
Alp,
'265". Anal. Calcd for C I ~ H I , C ~ ~ ? : . H CC, ~ : 58.11; H, 5 5 0 ; ?;, 4.24. Found: C, 58.32; H, 5.53; N, 4.22. p Isomer.-The oily filtrate ( F ) from the isomer was diluted with water until the oil dissolved and then extracted nTith ether. The ether was discarded. The aqueous layer was made basic with 207, KaOH and again extracted with ether. After the ether extract had been dried (K2C03),it was acidified by the addition of alcoholic HCl (6 LY). The precipitated hydrochloride of the isomer was collected and crystallized from 2-propanol. The yield was 65 g ( 4 1 q ) , mp 184-186". Anal. Calcd for C16Hl;C12X.HC1: C, 58.11; H, 5.50; X, 4.24. Found: C, 58.18; H, 5.91; N, 3.93. 2-(p-Chlorophenyl)-l-methyl-3-phenylpropylamineHydroreaction mixture from a Leuckart chloride. a Isomer.-The reaction on 3-(p-chlorophenyl)-4-phenyl-2-butanone (80 g) was added, with stirring, to water (250 ml). A purple oil, a mixture of the hydrochlorides of the a and p forms of the amines, separated. This material has the peculiar property of being almost insoluble in cold water but soluble in ether. The oil was extracted with ether. The ether solution, which now contained all of the product, was extracted 25-30 times with 250-ml portions of water. Each water extract was made basic (20Tc NaOH) and serially extracted with two 250-ml portions of ether. There was thus obtained, on combining the two portions of ether extracts, about 500 ml of ether containing all of the basic products. This ether soliltion was dried ( K P C O ~and ) acidified with alcoholic HC1 (6 AV). After chilling a t 5" for 16 hr, the a form (7 g ) separated and was collected. The filtrate (F) was reserved for isolation of the p isomer. The solid was crystallized from water to obtain pure a isomer HCl (4.8 g), mp 2,50°. d n a l . Calcd for Cl~H&lN.HCl: C, 64.87; H, 6.46; N, 4.73. Found: C, 65.20; H, 6.50; N, 4.71. p Isomer.-The ether filtrate (F)from the a isomer was evaporated. The residue (51 g) was crystallized from benzene-hexane (3:2) t o obtain the p isomer (39 g), m p 196-198'. Anal. Calcd for C16H18ClN.HCl: C, 64.87; H, 6.46; N, 4.73. Found: C, 64.63; H, 6.46: N, 4.70. 3-(p-Chlorophenyl)-l-methyl-2-phenylpropylamine Hydrochloride. a Isomer.-The hydrolysis mixture of a Leuckart reaction on 4(p-chlorophenyl)-3-phenyl-2-butanone (113 g, 0.435 mole) was added to water (ca. 200 ml). A water-insoluble precipitate remained undissolved. This solid was collected and washed with water. The filtrate and washings (F) containing the 0 isomer were reserved. The crude solid was crystallized from water to obtain the pure a isomer hydrorhloride, mp 290292". Anal. Calcd for C16H&lN.HCl: C, 64.87; H, 6.46; N, 4.73. Found: C, 64.93: H, 6.56; N, 4.70. p Isomer.-The aqueous filtrate (F) from the crude a isomer was extracted with ether and made basic (2094 NaOH). The oil that separated was extracted with ether. The ether extract was dried ( K z C O ~and ) acidified with alcoholic HC1 ( 6 N ) . The precipitate was collected and crystallized from isopropyl alcohol to obtain the pure p isomer, mp 179-180'. Anal. Calcd for ClsH18C1N.HCl: C, 64.87; H, 6.46; N, 4.73. Found: C, 64.92; H, 6.56; E,4.76. 2,3-Diphenyl-l-methylpropylamineHydrochloride. a Isomer. -The hydrolysis mixture of the formamido intermediate obtained from the Leuckart reaction on 3,4-diphenyl-2-butanone18 was made basic by addition of 20% NaOH and extracted with ether. The dried ether solution was evaporated and the residue was distilled to obtain the mixture of isomeric amines, bp 120122" (0.3 mm). The distillate, 137 g, was suspended in water (200 ml) and concentrated HCl was added at 15" until a lasting
f23
precipitate just formed. The mixture was heated to 80" and then cooled to 20". A critde solid (31 g, mp 210-228"), designated a isomer, separated and was collected. The filtrate was reserved for isolation of the fl isomer. The crude a isomer was crystallized from water to obtain 32 g of pure a isomer hydrochloride,20mp 247-248". Anal. Calcd for C16H19N.HC1: N, 5.35; C1, 13.55. Found: N, 5.33; C1, 13.56. p Isomer.-The filtrate which was reserved for isolation of the p isomer was kept at 20" while concentrated HCl (ca. 20 ml) was added until a lasting precipitate formed. The mixture was heated a t 80" and then cooled t o 5". The solid that separated was collected and crystallized from 2-propanol to obtain the pure p isomer hydrochloride, rnp 161-162'. Anal. Calcd for C16H19N.HCl: C, 73.40; H, 7.70: N, 3.35. Found: C, 73.28; H, 7.18; N, 5.31. 1-( 2,2-Diphenylethyl)butylamine.-l ,l-Diphenyl-3-hexanone was submitted to a Leuckart reaction in the manner described by the general procedure. After hydrolysis of the intermediate formamido derivative with HC1, the reaction mixture was made basic (20Yc NaOH) and extracted with ether. The dried ether solution was evaporated and the residue was distilled to obtain the desired amine, bp 145-150" (0.3 mm). I n a similar manner, using the designated ketone, the following amines were prepared. 2,2-Dimethyl-1-(2,2-diphenylethyl)propylamine,bp 128-130" (0.2 mm), mp 78-80' (from hexane), from 1,l-diphenyl-4,4dimethyl-3-pentanone.19 Anal. Calcd for C11H?,N: C , 85.34; H , 9.42; N, 5.25. Found: C, 85.40; H, 9.51; X, 5.21. l-Cyclohex~l-3,3-diphenylpropylamine, bp 180-181" (0.5 mm), from l-cyclohexyl-3,3-diphenyl-l-propanone. 1-(2-Phenethyl)butyIamine,bp 142" (25 mm), from l-phenyl-3hexanone.21 1-(1-Naphthyl)pentylamine,bp 119-123" (0.1 mm), from 1-(1naphthyl)-1-pen tanone. 2 2 2-Benzyl-l-methyl-3-phenylpropylamine,bp 193-198" (15 Neither the hydromm), from 3 benzyl-4-phenyl-2-b~tanone.~~ chloride, benzamide, nor phenylthiourea of this amine could be obtained in crystalline form. 2 4 p-Butoxyphenyl)-1,3-dimethylbutylamineHydrochloride,The amine (bp 125-130" (0.3 mm)) obtained from 3-(p-butoxypheny1)-4-methyl-2-pentanone by the Leuckart reaction was dissolved in ether and precipitated as the hydrochloride by addition of alcoholic HC1. After repeated crystallizations from acetone, a pure isomer melting a t 174-175" was obtained as the hydrochloride. Although two racemic modifications are possible, no other well-defined isomer was obtained. Anal. Calcd for C16H27KO: C, 67.22; H, 9.87: N, 4.90. Found: C, 67.36: H, 9.78; N, 4.89. 2,3-Diphenyl-l -methylpropylmethylamine.-3,4-Diphenyl-2butanone18 (0.38 mole) and N-methylformamide (1.5 moles) reacted under Leuckart conditions to yield 55 g (61%) of the amine, bp 120-122" (0.2 mm). The base (54 g) was converted to the hydrochloride by dissolving it in ether (250 ml) and acidifying with 3 -V ethanolic HC1. The solid hydrochloride (.56 g), mp 163-169", was crystallized repeatedly from methanol to obtain a hydrochloride (16 g), mp 191-192", which appeared to be a pure isomer. The second of the two possible isomers was not isolated. Anal. Calcd for Cl?H?lN.HCl: C, 74.03; H, 8.04; C1, 12.86. Found: C, 74.18: H, 8.07; C1, 12.76. 2,2-Diphenyl-l-methylhexylamine.-By the method of Pick, ~ ~ was treated with methylard, et ~ l . 2,2-diphenylhexanenitrileP5 magnesium bromide to yield the crude ketimine of 3,3-diphenyl2-heptanone. This was hydrogenated in methanol over prereduced Adams catalyst to yield product, bp 115-120" (0.2 mm). The phenylthiourea derivative melted at 191-192". (20) E. Ishiwata and K . Suzuki [ J . Pharm. Soc J a p a n , 11, 1272 (1951); Chem. Abstr., 46, 5.5912 (1952j1 prepared the amine by reduction of t h e corresponding oxime (Na-EtOHj b u t report only a hydrochloride salt, m p 2490. (21) C. Harries and P. Bromberger, Chem. Ber.. 35, 3089 (1902), reduced l-phenyl-2-hexen-3-one with NaHg. T h e present authors used catalytic hydrogenation over P d in ethanol. ( 2 2 ) L. G. Nnnn and H. R. Heme, J . Oro. Chem., 12, 540 (1947). (23) H . Leuchs, A . Heller, and A . Hoffmann, Chem. Ber., 62, 87 (1929). (24) ( a ) P. L. Pickard and D. J. Vaughn, J . A m . Chem. Soc., 72, 876 (19501; (b) P. L. Pickard and E . F. Engles, zbzd., 76, 2148 (1953). ( 2 5 ) J. Hoch and M ,Lecocq, Compt. Rend., 246, 7 3 (1957); Chem. Abstr., 62, 19678 (1958).
