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COMMUNICATIONS TO THE: EDITOR
VOl. 80
followed by hydrogenation over palladium on strontium carbonate produced X, m.p. 162-164' (Found: C, 80.36; H, 8.74). Conversion of X to the A4-3-ketone v i a Birch reduction followed by reoxidation a t C I ~with chromic acid-sulfuric acid in acetone gave d18,19-bisnorprogesterone XI, m.p. 136-140', X2zoH 240 mp, E 17,000, 5.89, 6.02, after purification by paper chromatography and recrystallization from aqueous methanol. The rotatory dispersion was closely similar to that of A:3-chole~tenone.~It may be of some interest that
Carbobenz~xyserylmethionylglutamine~ was decarbobenzoxylated to give serylmethionylglutamine, dec. 228', [ ( Y ] ~ ' D -13.3' (in water), Rr = 0.39 (Partridge), migrates faster than his in the 2-butanol-ammonia system. Anal. Calcd. for C,13H?4CsN&3.H20:C, 40.8; H, 6.9; N, 14.6; S, 8.4. Found: C, 40.6; H, 7.2; N, 14.9; S, 7.8. Completely digestible by leucine aminopeptidase (LAP), amino acid ratios in digest serlmetl.6 The interaction of this tripeptide with the azide of carbobenzoxyseryltyrosine6 afforded carbobenzoxyseryltyrosylserylmethionylglutamine, m.p. 167171'. [ c Y ] ' ~ ~-D15.3' (in glacial acetic acid). A n d . Calcd. for C33H44012NdS.H20: C, 51.7; H, 6.0; N, 11.0. Found: C, 51.4; H, 3.9; N, 11.5. The acylated pentapeptide was converted into its azide (subunit A) via the methyl ester and hydrazide.? Carbobenzoxyhistidylphenylalanylnitroarginyltryptophylglycine benzyl esterS was saponified and the ensuing acylated pentapeptide coupled with e-tosyllysylprolylvalinea~nide~to give carboCHo benzoxyhistidylphenylalanyhit r o a r g in y 1t r y p t oI phylglycyl- e- tosyllysylprolylvalineam i de. c=o The presence of the C-terminal glycine residue precluded racemization in this N,N'-dicyclohexylCarbodiimidelO induced reaction. Hydrogenation of the acylated octapeptide afforded histidylphenylIX I X XI alanylarginyltryptophylglycyl - E - tosyllysylprolylbisnorprogesterone shows no progestational activ- valine amide (subunit B) which was purified ity a t twice the effective dose of progesterone.6 by countercurrent distribution, l 1 and isolated as (4) Showing the essentially symmetric environment around Cn the diacetate dihydrate, [ a I z 5 D -40.0' (in 0.3N caused by removal of t h e methyl group a t Cu. I-ICI), homogeneous on paper in the Partridge (5) A totd synthesis of a dl-18,19-bisnorprogesterone,also essensystem, Rt = 0.72. Anal. Calcd. for C e l H ~ o O d l s S : tially inactive, has been reported by N. A. Nelson and R. B. Garland, TEISJOURNAL, 79,6133 (1957). C, 54.9; H, 6.8; N, 16.8. Found: C, 55.2; H, CHEMICAL LABORATORIES GILBERTSTORK 7.0; N, 16.2. Completely digestible by LAP, COLUMBIA UNIVERSITY H. 3.KHASTCIR amino acid comp. of digest : hislphelargltrylglylA . J. SOLO c-toslyslvall. Proline present but not determined. NEW Yo= 27, NEWYORK RECEIVEDOCTOBER 22, 1958 Tryptophan, calcd. 15.3; found: 15.1.12 The interaction of subunits A and B in dimethylformamide and triethylamine a t p H S afforded STUDIES ON POLYPEPTIDES. XI1 carbobenzoxyseryltyro sy l s e r y l m e t h i on y lglu t aT H E SYNTHESIS OF A PHYSIOLOGICALLY minylhistidylphenylalanylarginyltryptophylg 1y c y 1 ACTIVE BLOCKED TRIDECAPEPTIDE AMIDE POSSESSING THE AMINO ACID e-tosyllysylprolylvalineamide. After countercurSEQUENCE OF a-MSH' rent distribution single spot on paper, Rr = 0.90 Sir: (Partridge) ninhydrin negative, positive color with The corticotropins2 and the melanocyte expand- the Pauly, Ehrlich, Sakaguchi and methionine ing principle a-MSHa embody within their struc- reagents. Composition of acid hydrolysate serz.1tures the amino acid sequence ser.tyr.ser.met.glu. Hofmann, T. A. Thompson and E. T. Schwartz, THIS his.phe.arg.try.gly.lys.pro.va1. . . . In the cortico- J O U(4)R NK. A L , 79, 6087 (1957). tropins the amino group of the terminal serine is (5) Because of pyrrolidonecarboxylic acid formation glutamine free, whereas in a - M S H it is acylated, presumably cannot be determined by the uinhydrin technique. ( 0 ) K . ilufmann, A. Johl, A. E. Furlenmeier and H , Rappeler, THIS by an acetyl group. We wish to record a t this time 79, 1636 (1957). a synthesis and the physiological activity of the JOLRNAL, (7) Decarbobenzoxylation of the acylated pentapeptide g a r e serylblocked tridecapeptideamide carbobenzoxyserylty- tyrosylserylmethionylglutamine ( P ] = D - 19.4" (in 2 N HCl), Rr = rosylserylmethionylglu t a m i n y 1h i s t i d y Ip h e n y 1- 0.48 (Partridge). Completely digestible by L A P , amino acid ratios in alanylarginyltryptophylglycyl - e - tosyllysylprolyl- digest serr.rtyri.ometi.i." Anal. Calcd. for Cz~HsaOieN~S.1.5HzO: H , 6 . 4 ; N , 13.1. Found: Z,46.8; H,6.3; N , 13.8. valineamide which contains the entire amino acid C,46.8; (8) K. Hofmann, M. E. Woolner. G. Sptihler and E. T . Schwartz, sequence of a-MSH. THISJ O U R N A L , 80, 1456 (1955). ~
(1) Supported by grants from t h e U. S. Public Health Service, T h e National Science Foundation, T h e American Cancer Society, Armour and Company and Eli Lilly and Company, (2) (a) P.H. Bell, THISJOURNAL, 76, 5565 (1954); (b) W. F. White and W. A. Landmann, i b i d . , 77, 1711 (1955); (c) C . H.Li,I.I. Geschwind, R . D . Cole, I. D. Raake. J. I. Harris and J, S. Dixon, Naturr, 176, 687 (1955); (d) R. G. Shepherd. S. D. Willson. K. S. Howard, P. H Bell, D . S. Davits, S. B. Davis, E. A . Eigner and N . E. Shakespeare, TIUS JOURNAL, 78, 5067 (1956); (e) C. H. I i , J . S. Dixon and D. Chung, ibid., 80, 2587 (1958). (3) J. I. Harrir and A. B. l x r n e r , Nature, 179. 1346 (1957).
(9) Prepared from a-carbobenzoxy-c-tosyllysincand prolylvalineamide followed by decarbobenzoxylation: hydrochloride laIUD -52.5" (in water), Ry = 0.77 (Partridge), migrates faster than etosyls in the 2-butanol-ammonia system; completely digestible by L A P , molar amino acid ratios in digest e-tosylsivali. Anal. Calcd. for C,iHiaOsNsSCl: N, 13.2; CI, 6.6; S, 6.0. Found: N, 13.0: CI, 6 . 3 ; s. 3.9. (10) J. C Sheehan and G. P. Hess, THIS J O U R N A L , 77, 1067 (1955). (11) Solvent system l-butanot-lO% acetic acid. (12) T. W. Goodwin and R . A. Merton, Biochctn. J . , 40, 628 (1946).
COMMUNICATIONS TO THE EDITOR
Dec. 5, 1958
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The infrared spectrum of the trichloromethyl compound shows two C-H stretching frequencies, a t 3.25 p and 3.45 p. Similar frequencies are observed in compounds containing a cyclopentadienyl ring u bonded to a metaL3 Cyclopentadienyl rings that are n bonded are known to have only one C-H stretching frequency, in the region 3.20-3.25 The weak absorption a t 6.2 p characteristic of u bonded cyclopentadienyl rings is also present. The infrared spectrum indicates that a t least one ring in the trichloromethyl compound is u bonded to the cobalt. I n this case, the formation of the compound involves a rearrangement from n to u bonding. Other indications for u bonding are that (13) K. Shirume, A. B . Lerner and T. B. Fitzpatrick, Endocrinol., the compound reacts with maleic anhydride in 64, 553 (1954). (14) We wish to express our gratitude to Drs. A. B. Lerner and M. R. warm benzene and also reacts with ferrous chloride Wright of the Department of Medicine, Yale University School of in tetrahydrofuran to form small amounts (about Medicine, for these assays. one per cent. yield) of bis-cyclopentadienyliron(I1). KLAUSHOFMANN BIOCHEMISTRY DEPARTMENT MIRIAME. WOOLNER The other products of these reactions were not UNIVERSITY OF PITTSBURGH HARUAKI YAJIMA identified. Piper and Wilkinson2 have shown that SCHOOL OF MEDICINE GERTRUDE S P ~ H L E Rthese two reactions can be used as qualitative THOMAS A. THOMPSON PITTSBURGH, PENNSYLVANIA tests for a u bonded cyclopentadienyl group. ELEANORE T. SCHWARTZ Assuming u bonding for one ring, the reaction RECEIVED OCTOBER 10, 1958 with ethanol-water involves a second rearrangement, from u bonding back to n bonding. Herwig and Zeiss4have postulated a similar rearrangement REACTION OF BISCYCLOPENTADIENYLCOBALT(I1) WITH involving (CaHs)&r. The possibility that the triORGANIC HALIDES chloromethyl group is bonded to one of the rings : has been considered but discarded as incompatible Wilkinsonl has reported that bis-cyclopenta- with this reaction. dienylcobalt(I1) reacts with ethyl bromide to form Another possible explanation is the formation of bis-cyclopentadienylcobalt (111)bromide. We have a u bond between the trichloromethyl group and observed that with certain halogenated hydro- the cobalt, the rings retaining their n character, carbons, new covalent cyclopentadienylcobalt com- but sufficiently distorted by the large u bonded pounds are formed as well as the bis-cyclopenta- group to account for the infrared spectrum and dienylcobalt(II1) halides. The formation of these the chemical reactivity. This would eliminate the new compounds may involve a rearrangement from necessity for ir to u and u to n rearrangements. n bonded cyclopentadienyl rings to u bonded rings. Further work is a t present being carried out to We wish t o report some preliminary work on the establish the structure and bonding in this comreaction of bis-cyclopentadienylcobalt(I1) with pound and in the products of similar reactions with carbon tetrachloride. other organic halides. A detailed account of this On the addition of bis-cyclopentadienylcobalt(11) work will be published in the near future. to carbon tetrachloride in an inert atmosphere, bis(2) T. S. Piper and G. Wilkinson, i b i d . , 3, 104 (1956). cyclopentadienylcobalt(II1) chloride precipitates (3) T.S. Piper. F. A. Cotton and G. Wilkinson, ibid., 1, 165 (1955). (4) W. Herwig and H. H. Zeiss, THISJOURNAL, 1 9 , 0501 (1957). leaving a cyclopentadienylcobalt compound in No. 672 FROM THE INSTITUTEFOR ATOMIC solution. Removal of the carbon tetrachloride by CONTRIBUTION AND DEPARTMENT OF CHEMISTRY vacuum distillation leaves a residue which after RESEARCH LABORATORY SEYMOUR KATZ sublimation and fractional crystallization from AMES IOWASTATECOLLEGE JAMESF. WEIHER hexane has the composition (C5H&CoCCls. Calcd. AYES, IOWA ADOLFF. VOIGT RECEIVED SEPTEMBER 26, 1958 for (C5H6)2CoCC13:C, 42.96; H, 3.28; Co, 19.17; C1, 34.59. Found: C, 42.94; H, 3.46; Co, 19.34; C1, 33.04. Molecular weight calcd. : 307.5. Found: S-BIS-( 2-CHLOROETHYL)-AMINOURACIL, 315. The yields of the trichloromethyl compound A NEW ANTITUMOR AGENT and the bis-cyclopentadienylcobalt(II1) chloride Sir: are 90% and loo%, respectively, based on the Since the discovery of the pharmacological equation properties of methyl-bis-(2-chlaroethyl)-aminel 2( CrHr)iCo CClr +(C‘Hr)zCoCClr (CrHs)iCoCl HN2l and its therapeutic use in human maligThe trichloromethyl compound, m.p. 79-80’, nancies,l a number of analogs and related alkylatis orange to red depending on crystal size, de- ing agents have been developed which have clinical composes over a period of hours above 40°, and is va1ue.l Nevertheless, the need for compounds soluble in organic solvents and insoluble in water. (1) A. Gilman and F. S. Philipr, Science, 108,408 (1046). In ethanol-water solutions i t reacts slowly t o form (2) L. S. Goodman, M. M. Wintrobe, W. Domeahek, M. J. Goodthe bis-cyclopentadienylcobalt (111) cation in man, A. Gilman and M. J. McLennon. J . Am. Mird. AJSOC..lSS, 126 (1940). greater than 70% yield. (3) S. Farber, R. Toch, E. M. Sears and D. Pinkel. in “Advsncu In
tyrl.lglul.lhiso.Bphel.oargo.oglyl.oe-tosy1sl.o. Met, val and pro present but not determined. The final product and a number of intermediates were assayed for melanocyte expanding ability, l S . l 4 with the following results which are expressed in MSH units per gram : his.phe.arg.try.gly 1.5 X 1O4; his.phe. arg.try .gly.- e- tos1ys.pro.va1. amide 0.5 x lo6; cbzoser.tyr.ser.met.gluta .his.phe .arg.try. gly .-E- tosly s.pro .Val. amide 0.8 x 108. From these results i t is apparent that our blocked tridecapeptideamide possesses essentially the same MSH activity as the corticotropins, and that it is one per cent. as active as a-MSH.
sir
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(1) G. Wilkinson, F. A. Cotton and J. M. Birmingham, J . Iaorp. and Nuclear Chrm., II, 95 (1955).
Cancer Research.” J. P. Greenstein and A. Haddoa, editorr, Academie Press, Inc.. New York, N. Y., Vol. IV,1956, pp. 20-33.
