Darstellung und Konstitution zweier Pentaacetyl‐saccharosen

Die Mikroanalysen wurden in verdankenswerter Weise im analytischen Laboratorium desZurchcr Institutes unter der Leitung von Herrn H. FROHOPER ausgefiihrt : die DEBYE-SCHERRER-Diagramme wurden von Herrn Dr. R. MULLER und die 1R.-Spektren von Herrn Dr. E. GANZ in den Physik-Laboratorien der CIBA ,4G. aufgenommen, wofur wir auch an dicser Stellc bestens danken mochten. SUMMARYCyclisation of active esters3) of the racemic tripeptides glycyl-glycyl-nL-phenylalanine and glycyl-DL-phenylalanyl-glycine as well as of the hexapeptide glycylglycyl-DL-phenylalanyl-glycyl-glycyl-DL-phenylalanine (unidentified mixture of diastereoisomers) has yielded as main product the meso-cyclohexapeptide, cyclo-glycyl-L-phenylalanyl-glycyl-glycyl-D-phenylalanyl-g~ycyl (IV) 5). This is proven by comparison of the X-ray powder diagram of the said product with those of the corresponding meso, L-L, D-D, and racemic cyclohexapeptides (Fig.1). The synthesis of these isomers by the azide pioceduree) is described. The hydrazide function was introduced in a protected form') early in the synthesis (as -NHNH*CO*OC(CH,),) and the blocking group (t-butoxy-carbonyl) removed in one of the last steps (schemes 2 and 3).The reported reactions constitute the fiist observation of stereospecific cyclisation in the peptide field. Obviously, in our case, a D-tripeptide reacts preferentially with an I,-tripeptide, and vice versa.Models for the conformation of cyclohexapeptides are discussed: that proposed by SCHWYZER (Fig.3)Is) allows construction of the optically active as well as of the meso-cyclohexapeptides on the same basic ring structure, and is supported by IR. data.

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Die Konstitution der isomeren Acetyldigitoxine. 48. Mitteilung über Herzglykoside

Kühn

Lichti

Wartburg

1962

Helvetica Chimica Acta

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Volumen XLV, Fasciculus 111 (1962) -No. 102-103 881 Smp. 84-88" lieferte. Nach mehrmaliger Umkristallisation wurde ein einheitliches Praparat vom Smp. 87-88" erhalten; [ C C ]~ = -33,8O (c = 1,82 in Wasser). Die Identitat mit dem durch NaBH, gewonnenen Reduktionsprodukt wurde durch Mischprobe, Vergleich der Rf-Werte und 1R.-Spektren bewiesen. C,H,,04 (150,18) Ber. C 48.0 H 9,4 0 42,6% Gef. C 47,7 H 9,l 0 42.2% Di-0,O-benzyliden-D-digitoxit. 234 mg D-Digitoxit wurden nach der Vorschrift von WINDAUS & S C H W A R T E~~) mit 0.5 ml Benzaldehyd und 1.5 ml50-proz. Schwefelsaure umgcsetzt. Es resultierten 528 mg hellgelber Sirup, die aus Methylenchlorid-Ather-Pentan 283 mg Kristalle vom Smp. 110-111" ergaben, nach Umkristallisieren aus Methanol 182 mg Kristalle vom Smp. 139-141" 44). [ a ] g = +67,3" (c = 0,79 in Chloroform), +64,7" (c = 0.94 in 95-proz. Pyridin). C,,H,,O, (326,40) Ber. C 73,6 H 6,8 0 19,6% Gef. C 73,7 H 6,7 0 19.4% SUMMARYIn order to elucidate the structure of its sugar moiety, digitoxin (I) has been permethylated. Since it was not possible to isolate a homogeneous 0-methyl derivative of (I) the mixture of permethylation products was degraded by hydrolysis. As parts of the sugar moiety, 3,4-di-O-methyl-~-digitoxose (111) and D-cymarose (IV) could be isolated in a 1 : 2 ratio. The reaction of digitoxin (I) with phenylisocyanate gave homogeneous and crystalline digitoxin-tetraphenylurethane (VIII) which was cleaved by methanolysis into digitoxigenin and the methylglycosides of both ~-digitoxose-3-phenylurethane (XV) and ~-digitoxose-3,4-bis-phenylurethane (IX, X). Characterization and quantitative determination of the glycosidic fragments proved the linear arrangement of the three digitoxose units in digitoxin (I) as well as their 1,Clinkages.From the constitution of digitoxin (I), the structures of the sugar moiety of both lanatosides and deacetyl-lanatosides follow. In all these Digitalis glycosides, the tetrasaccharide part must form a straight, 1,Clinked chain.Pharmazeutisch-chemische Forschungslaboratorien SANDOZ A. G., Base1 41) In der Literatur2s) ist der Smp. mit 142' (aus Methanol) angegeben. 103. Die Konstitution der isomeren Acetyldigitoxine 48. Mitteilung uber Herzglykoside') von M a x Kuhn, Heinz Lichti und Albert von Wartburg (6. 111. 62) Die genuinen Hauptglykoside der Digitalis lalzata EHRH., die Lanatoside A, B und C 2), spalten bei der Einwirkung spezifischer Enzyme wie Digilanidase, Digipuipidase u. a. 3, leicht 1 Mol. D-Glucose ab und gehen in die entsprechenden Desgluco-Derivate Acetyldigitoxin, Acetylgitoxin und Acetyldigoxin uber4). Diese glucosel) 47. 56 882 HELVETICA CHIMICA ACTA Formelschema 7 R, = H; R, = H: Lanatosid A R, = H; & = OH: Lanatosid B R, = OH; Rz = H: Lanatosid C Digilanidase Digipurpidase /-"\I" OH /-"\r' Acetyldigitoxin-cc R l = = H ; R 2 = H Acetyldigitoxin-B Acetylgitoxin-cc R, = H ; R, = OH Acetylgitoxin-,!? Acetyldigoxin-a R , = OH; R 2 = H Acetyldigoxin-/3 freien Abbauprodukte konnen in zwei isomeren Formen (u und ,B) auftreten, die sich reversibel ineina...

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Darstellung und Konstitution zweier Pentaacetyl‐saccharosen

Abstract: Durch Tritylieren der Saccharose konnte K. JOSEPH SON^) eine -nicht kristallisierte -Tritrityl-saccharose darstellen, die er durch Acetylieren in ihr ebenfalls

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Zur Struktur der Zuckerkomponente des Digitoxins. 47. Mitteilung über Herzglykoside

Die Konstitution der isomeren Acetyldigitoxine. 48. Mitteilung über Herzglykoside

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