Synthesis of peptides containingcis- ortrans-3- or 4-aminocyclohexane-carboxylic acid residues

摘要

1976 1199Synthesis of Peptides containing cis- or trans-3- or 4-Aminocyclohexane-carboxylic Acid ResiduesBy Vinko SkariC,rsquo; MiCe KovaEeviC, and Djurdja SkariC, Laboratory of Stereochemistry and Natural Products,cis- and trans-3- and 4-Aminocyclohexanecarboxylic acids have been inserted into di- and tri-peptides con-taining L-phenylalanine and L-cysteine. Dipeptide derivatives containing L-phenylalanine and 3(4)-hydroxy-methyl- or 3(4)-chloromethyl-cyclohexylamine are also described.Institute Rugjer Bo5kovi6, 41 001 Zagreb, Croatia, YugoslaviaTHE absolute stereochemistry of 2-aminocyclohexane- methylcyclohexylamines as hydrochlorides. cis-3-Benz-carboxylic acid derivatives has been investigated amidocyclohexanecarboxylate (VII), which was isolatedextensive1y.ls2 cis- and trans-3-Aminocyclohexanecarb-oxylic acids have been prepared by a stereospecificm e t h ~ d .~ Selective coupling methods for the attach-ment of L-valine, glycine, and L-alanine derivatives tocis- or trans-4-aminocyclohexanecarboxylic acid havebeen described re~ently.~ We wished t o prepare di-and tri-peptides containing cis- or trans-3- or amp;amino-cyclohexylcarbonyl, L-phenylalanyl, and L-cysteinylresidues.Ethyl 4-aminocyclohexanecarboxylate has beenshown by t.1.c. and by spinning-band distillation to bea mixture of trans- and cis-isomers, separable onlyas trans- (I) and cis- (11) N-benzoyl derivatives. At-tempted debenzoylation of compounds (I) and (11) bythe reported procedure 59 gave only N-benzoyl-trans-(I1 I) and -cis- (IV) 4-hydroxymethylcyclohexylamine.Hydrolysis of these benzamido-alcohols with hydro-chloric acid afforded trans- (V) and cis- (VI) chloro-W. L.F. Armarego and T. Kabayashi, J . Chew. SOC. (C),1970. 1597.lsquo;H. Nohira, K. Ehara, and A. Miyashita, Bull. Chew. SOC.F. R. Hewgill and P. R. Jefferies, J . Chem. Soc., 1955, 2767.Wen-Yih Chen and R. I. Olsen, J . Org. Chem., 1975,40,350.Japan, 1970, 43, 2230.I . trules- cis- CiS- R1 R2(I) (11) (VII) C0,Et Bz(IX) CH,OH Bz(X) CH,Cl HBoc-Phe(XV) CO,H Boc-Phe(XVII) (SBz1)CysOMe Boc-PheCH20H Boc-Phe(XX) (XXI) (XXII) CH,C1 Boc-Phe(I(II{ 1;;;(XI) (XII) (XIII) C02EtW V )(XVI)(XVIII) (XIX)(XXIII) CHamp;l PheBoc-Phe = t-butoxycarbonyl-L-phenylalanyl ; (SBzl) Cys =in larger amount (see Table) than its trans-isomer(VIII), was used for the preparation of 3-hydroxy-methyl- (IX) and S-chloromethyl- (X) cyclohexylamines.S-benz yl-L-cysteinyl.5 W.Schneider and K. Lehman, Tetrahedron Letters, 1970, 49,6 W. Schneider and A. Hutermann, Arch. Pharm., 1965, 298,4285.2261200 J.C.S. Perkin IThe successful separations of the benzamidocyclo-hexanecarboxylates (I), (11), (VII), and (VIII) en-couraged us to attempt the preparation and separationof stereoisomeric aminocyclohexanecarboxylic acid pep-tides. Thus, ethyl t-but oxycarbonyl-L-phenylalanyl-trans- (XI) and -cis- (XII) 4-aminocyclohexanecarboxyl-ates were easily separated when the N-hydroxy-succinimido-ester of t-butoxycarbonyl-L-phenylalaninewas coupled with a mixture of ethyl 4-aminocyclo-hexanecarboxylates.Similarly, the dipeptide (XIII)was obtained from a mixture of 3-amino-carboxylates.Finally, hydroxysuccinimido-esters of t-butoxycarbonyl-~-phenylalanyl-trans-4-amino- (XIV) and -cis-3-amino-(XV) cyclohexanecarboxylic acids were coupled withmethyl esters of S-benzyl-L-cysteine to give trans-4-(XVI) and cis-3- (XVII) aminocyclohexanecarboxylicacid tripeptides.Reduction of the dipeptides (XI) and (XII) withlithium aluminium hydride gave the correspondingtrans- (XVIII) and cis- (XIX) 4-hydroxymethylcyclo-hexylamine derivatives. The trans-4- (XX) , cis-4-(XXI) , and cis-3- (XXII) chloromethylcyclohexylaminedipeptides were prepared by reactions of the chloro-methylcyclohexylamines (V), (VI), and (X) with theStereoisomeric 3- and 4-aminocyclohexanecarboxylicacids and derivatives *Compd.M.p. ("C) Yield () a= (") (c)(I) 167-168 31.998-99 49.4 a80.091-93 81.070.8 a(VIII) 85-87 6.2 a(IX) 142-144 86.0(XI) 157-159 39.0 a +lS.O (1.2)(11)(IV)(VII) 110-112(111) 153-15668-70 46.1 +14.5 (1.25)65.0 +10.9 (1.28)(XIV) 173-175 84.2 +15.4 (0.52)(XVI) 179-181 60.4(XII)(XV) 131-133 96.7 + 12.2 (0.19)(XIII) 133-136(XVII) 143-145 70.0 -6.25 (0.96) C(XVIII) 144-145 92.0 + 13.0 (1.95)foam 76.0 +12.0 (1.17)(XXI) 105-107 70.0 +l4.0 (0.78)(XXII) 143-145 78.5 +14.8 (0.67)69.7 +17.0 (0.7)( X W(XX) 138-140(XXIII) 87-90 94.0 -39.7 (0.78) e0 Recrystallized from methylene chloride-ether-n-hexane.a Based on total amount of trans-cis aminocarboxylates.Inmethylene chloride. d From ethyl acetate-n-hexane. e Inethyl acetate.* Elemental analyses and i.r. data are available as Supple-mentary Publication No. SUP 21728 (2 pp.); for details ofSupplementary Publications see Notice to Authors No. 7,J.C.S. Perkin I, 1975, Index issue.hydroxysuccinimido-ester of t-butoxycarbonyl-L-phenyl-alanine. N-Deprotection is exemplified by the hydro-lysis with trifluoroacetic acid of the dipeptide (XX) togive L-phenylalan yl-trans-4-chloromet hylcyclohexyl-amine (XXIII).EXPERIMENTALThe same techniques and apparatus were used as des-cribed previ~usly.~ In addition, optical rotations weremeasured for solutions in anhydrous methanol at 21 "C( I = 1 dm) unless otherwise stated.3(4)-Aminocy~Zohexane~arboxyZic Acids.-Hydrogenationof m@)-aminobenzoic acid (1.46 mmol) was carried out in30 ethanol (18 ml) for 5 h, a t 25 "C and 60 lb in-2, withplatinum oxide (50 mg) as catalyst.The cis-trans-mixtureof 3-aminocarboxylic acids, m.p. 260-285", was isolatedin 76.5 yield from the m-isomer and the 4-aminocarboxylicacids, m.p. 300", were obtained in 92 yield from thep-isomer .Ethyl 3(4)-AminocycZohexanecarboxyZates.-The trans-cis-mixture of 3- or 4aminocyclohexanecarboxylic acids (3.65-01) was refluxed in ethanolic 3 hydrochloric acid(25 ml) for 18 h; the solution was evaporated to drynessand the residue dissolved in water (20 ml) and treated withconcentrated ammonia (to pH 10). A chloroform extractafforded a cis-trans-mixture of 3-aminocarboxylates separ-ated (goyo), l i p ca.0.3 and 0.2 (CH2C12-MeOH, 4 : l),v- 1724 cm-l (ester G O ) or a mixture of 4-amino-carboxylates (96), RF ca. 0.2 and 0.3, vmK 1724 cm-1(ester G O ) .Ethyl 3 (4) -BenzamidocycZohexanecarboxyZates .-To the cis-trans-mixture of ethyl 3- or 4-aminocyclohexanecarboxyl-ates (3 mmol) in anhydrous pyridine (8 ml), a solution ofbenzoyl chloride (3.2 mmol) in anhydrous pyridine (7 ml)was added. The mixture was stirred for 24 h at roomtemperature, then evaporated to dryness. The residuewas dissolved in water-methylene chloride (20 and 30 ml),acidified with concentrated hydrochloric acid, and extractedinto methylene chloride. The ethyl trans-cis-4-benzamido-carboxylates were obtained in 87.3 yield; R p ca.0.7(methylene chloride-ether, 4 : 1) ; and the ethyl cis-trans-3-benzamidocarboxylates in 86.3 yield (RF ca. 0.83).Chromatography of the ethyl trans-cis-4-benzamido-carboxylates (720 mg) on a silica gel (40 g) column andelution with a linear gradient (0.1-5) of methanol inmethylene chloride separated the cis-isomer (11), RF ca. 0.4(ten developments in methylene chloride), T 4.21-3.70(1 H, m, NH) and 2.90-2.20 (5 H, m, aromatic); and thetrans-isomer (I), RF ca. 0.3, T 3.68 (1 H, d, NH) and 2.82-2.05 (5 H, m, aromatic). Similarly the cis- (VII), RF ca.0.30, T 3.60 (1 H, d, NH) and 2.83-2.08 (5 H, m, aromatic) ;and the trans- (VIII) 3-benzamido-isorner, R p ca. 0.25,T 4.0-3.32 (1 H, m, NH) and 2.83-2.02 (5 H, m, aromatic),were obtained.N-BenzoyZ-trans- (111) and cis- (IV) 4-hydroxymethyl-cycZohexyZamines.-Ethyl trans- (I) or cis-4-benzamido-cyclohexanecarboxylate (11) (0.24 mmol) in anhydrousether (30 ml) was added dropwise (1.5 h) to a stirredsolution of lithium aluminium hydride (2.4 mmol) inanhydrous ether (30 ml).The mixture was refluxed for20 h (trans-isomer) or 5 h (cis-isomer), then decomposed inthe cold with water and N-sulphuric acid. From anethereal extract a solid separated which was purified bypreparative t.1.c. ; the trans-isomer (111) showed T (CD,OD)6.82-6.48 (2 H, m, CH,O) and 2.80-1.76 (5 H, m, aro-matic) ; and the cis-isomer (IV), T 6.47 (2 H, d, CH20) and2.91-2.08 (5 H, m, aromatic).N-Benzoyl-cis-3-hydroxymethyEcycEohexyZamine (IX) .-Ethyl cis-3-benzamidocyclohexanecarboxylate (VII) ( 1 10mg, 0.4 mmol) in anhydrous tetrahydrofuran (15 ml) wasadded dropwise (1 h) to a suspension of lithium aluminiumhydride (148 mg, 4.0 mmol) in anhydrous tetrahydrofuran7 V.SkariC, V. Turjak-Zebi6, and D. SkariC, J.C.S. Perkin I,1974, 14061976 1201(35 ml) and the mixture was stirred for 3 h at room tem-perature. The product, 7 (CD,),CO 6.61 (2 H, d, CH,O)and 2.72-1.95 (5 H, m, aromatic), was extracted intomethylene chloride and separated as described for (111)and (IV).Hydrochlorides of trans-4- (V), cis-4- (VI), and cis-3- (X)ChZorornethyZcyclohexy1amines.-A solution of N-benzoyl-trans-4- (111), -cis-4- (IV) , or -cis-3- (IX) hydroxymethyl-cyclohexylamine (1.25 mmol) in hydrochloric acid (10 ml)was sealed in a tube and heated for 50 h a t 110-115 "C,then diluted with water (20 ml), and partitioned withmethylene chloride.The evaporated water layer yieldedthe appropriate hydrochloride of trans-4-chloromethylcyclo-hexylavnine (V), m.p. 140-165" (87), v- 3 448, 2 924br,2 532, 2 062, and 1 597 cm-l; cis-4-chZoromethylcycZohexy1-amine (VI), m.p. 125-135' (76), v- 3484, 2924br,2 513, 1 996, and 1 608 cm-1; or cis-3-chlorornethyZcyclo-hexylainine (X), m.p. 150-160" (80), vmx. 3 483, 2 941br,2 532, 2 020, and 1 600 cm-l.Ethyl 2-Butoxycarbonyl-~-phenylalanyl-trans-4- (XI) , cis-4-(XII) , and cis-3- (XIII) Aminocyclohexanecarboxy1ates.-The hydrochlorides of the trans-cis-mixture of 3- or 4-aminocyclohexanecarboxylates (2.7 1 mmol), the hydroxy-succinimido-ester of t-butoxycarbonyl-L-phenylalanine (2.71mmol), and triethylamine (1 ml) were dissolved in an-hydrous 1,2-dimethoxyethane (25 ml).The mixture wasstirred at room temperature for 4 h, diluted with water(80 ml), and partitioned with methylene chloride (20 ml).In the case of the 4-isomers an oil separated from theorganic layer which partly crystallized (79.5), R p ca. 0.53(methylene chloride). Chromatography on a silica gel(50 g) column elution with methylene chloride-ther(97 : 3, 95 : 5, and 90 : lo) separated crystalline and oilyfractions. The crystalline fractions after rechromato-graphy yielded the trans-4-isomer (XI) (39), and the oilyfractions the cis-4-isomer (XII) (45).The fraction of IZF ca.0.53, obtained from the amino-isomers was purified by preparative t.1.c. (87.5) and thenby fractional crystallization to give the cis-3-isomer (XIII)(65), T 8.60 (9 H, s, But) and 2.92-2.73 (5 H, s, aromatic).t-Butoxycarbonyl-~-phenylalanyZ-trans-4-amino- (XIV) andcis-3-amino- (XV) cyclohexanecarboxylic Acids.-A solutionof the trans-4-amino- (XI) or the cis-3-aminocyclohexane-carboxylate (XII) (0.82 mmol) in methanol (3.5 ml) wastreated with methanolic N-potassium hydroxide (3.5 ml) .The mixture was refluxed for 5 h, and then evaporated todryness. The residue was diluted with water (10 ml) andacidified with acetic acid to pH 3. The crystalline pre-ci9itate was filtered off, washed with water, and purified bypreparative t.1.c.t-ButoxycarbonyZ-~-phenyZalanyl-trans-4- (XVI) and cis-4- (XVII) aminocyclohexylcarbonyl-S-benzyl-L-cysteine MethylEsters.-" solution of t-butoxycarbonyl-L-phenylalanyl-trans-4- (XIV) or cis-3-aminocyclohexanecarboxylic acid(XV) (0.26 mmol) and NN'-dicyclohexylcarbodi-imide(0.28 mmol) in anhydrous 1,2-dimethoxyethane (10 ml) waskept for 20 h at 0-5 "C. The precipitate was filtered offand the filtrate treated with S-benzyl-L-cysteine methylester (58 mg, 0.26 mmol) and kept for 16 h at room tem-perature. The mixture was then diluted with water (15ml) and partitioned with methylene chloride. The residuefrom the organic layer was purified by chromatography ona silica gel (7 g) column with methylene chloride-ether(98 : 2, 97 : 3, and 95 : 5) as eluant and then by preparativet.1.c.; the product showed 7 8.60 (9 H, s, But), 6.32 (2 H, s,SCH,), 6.29 (3 H, s, OCH,), and 2.76 and 2.73 (2 x 5 H, s,aromatic).t-Butoxycarbonyl-L-PhenyZaZanyZ-trans- (XVIII) and cis-(XIX) 4-hydroxymethylcyclohexylamines.-A solution of L-phenylalanyl-trans-4- (XV) or -cis-4-aminocyclohexane-carboxylate (XII) (0.24 mmol) in anhydrous tetrahydro-furan or ether (20 ml) was treated with lithium aluminiumhydride (2.4 mmol) and the product was worked up asdescribed for (111), (IV), and (IX); 7 8.60 (9 H, s, But),2.92-2.73 (5 H, s, aromatic), and ca.6.64 (2 H, d, CH,O).t-ButoxycarbonyZ-~-PhenyZaZanyZ-trans-4- (XX), cis-4-(XXI), and cis-3- (XXII) chlorovnethyZcyclohexy1amines.-The hydrochloride of the trans-4- (V), cis-4- (VI), or cis-3-cyclohexylamine (X) (0.28 mmol) , the hydroxysuccinimido-ester of t-butoxycarbonyl-L-phenylalanine (0.32 mmol) ,and triethylamine (0.2 ml) reacted together in anhydrous1,2-dimethoxyethane (8 ml). The product was worked upas described for (XI) and (XII). The crude materials werepurified by preparative t.1.c. ; n.m.r. spectra were similarto those of (XVIII) and (XIX).(XXIII) .-The 4-chloromethylcyclohexylamine (XXII)(100 mg, 0.26 mmol) was dissolved in trifluoroacetic acid(1.1 ml) a t 0 "C, and kept at room temperature for 15 min.The solution was evaporated to dryness, and residuedissolved in methylene chloride. The solution was par-titioned with aqueous 50 potassium carbonate. Fromthe organic layer an oil separated (70 mg, 94), whichcrystallized.~-PhenylalanyZ-trans-4-chloronzethylcycZo hexy lamineWe thank Mrs. L. TomiC: for recording the n.m.r. spectraand Mrs. M. TonkoviC and Mrs. R. Kuliman for the micro-analyses.5/2094 Received, 27th October, 1975