Glykoside von Marsdenia erecta R. Br. 2. Mitteilung: Versuche zur Strukturbestimmung der Genine. Glykoside und Aglykone, 330. Mitteilung

Structures for the genins of the ester glycosides of Marsdenia erecta are suggested. They are based on the behaviour in alkaline hydrolysis of these ester glycosides, their NMR. and mass spectra and ORD. data. All genins are derived from three acyl-free pregnane derivatives, i.e. drevogenin-P ( 1 ), 17 β-marsdenin ( 3 ) and marsectohexol ( 7 ). The structure of 1 is known, 3 and 7 are new compounds, i.e. 3 = 3β,8β,11α,12β,14β-pentahydroxy-Δ⁵-pregnen-20-one and 7 = 3β,8β,11α,12β,14β,20ξ-hexahydroxy-Δ⁵-pregnene. Formulae 13–17 were attributed to the acyl-genins A-1, A-2, A-3, A-4 and A-5, but only two of them were pure compounds, i.e. acyl-genin A-3 = 11,12-di-O-tiglyl-17β-marsdenin ( 15 ) and acyl-genin A-5 = 11,12-di-O-acetyl-marsectohexoi ( 17 ). Acyl-genin A-1 is a mixture of the two esters 13a + 13b derived from drevogenin-P, and similarly acyl-genin A-2 is a mixture of the esters 14a + 14b derived from 17β-marsdenin. The poorly characterised acyl-genin A-4 is most probably a mixture of the esters 16a + 16b , also derived from 17β-marsdenin.     

Stapelogenin,vermutliche Struktur. Glykoside und Aglykone, 276. Mitteilung

Stapelogenin, C₂₁H₃₀O₄, shows a double bond and two hydroxyl groups which can be acetylated. On the grounds of UV.-, IR.-, and NMR-spectra as well as mass spectra, the probable structure is that of a 3β, 12β-dihydroxy-(18, 20β), (14β, 20α)-diepoxy-Δ⁵-pregnene ( 1 ). The exact position of the hydroxyl group, assumed to be 12β, is particularly unsure, as it could also be situated 11α- or 12α-position.     

Synthese von 3-Oxacholestanen

Successive treatment of 5α-cholestan-3-one ( 1 ) with O₂ under basic conditions and then NaBH₄ led to 5α-3-oxa-cholestan-2-one ( 5 ). Analogous reactions with 5β-cholestan-3-one ( 6 ) yielded 5α-4-oxa-cholestan-3-one ( 7 ) and 5 ξ-3-oxa-cholestan-4-one ( 8 ). 4-Cholesten-2-one ( 10 ), which was prepared starting from 4-cholesten-3-one, was isomerized by methanolic KOH to give a mixture of 5α-cholest-3-en-2-one ( 11 ) and 5β-cholest-3-en-2-one ( 12 ). 5β-Cholestane-2,3-dione ( 17 ) was synthesized from 4β-bromo-5β-cholestan-3-one ( 13 ). Ozonolysis of the dione 17 and subsequent NaBH₄ reduction of the oxidation product gave both 5β-2-oxa-cholestan-3-one ( 18 ) and 5β-3-oxa-cholestan-2-one ( 19 ).     

Oxetane from A-nor-steroides: 2-alpha, 5-oxido-A-nor-5-alpha-cholestane, 2-beta, 5-oxido-A-nor-5-beta-cholestane and 2-alpha-ethyl-2-beta,2'-oxido-A-nor-5-alpha-cholestane

Treatment of 2β-tosyloxy-A-nor-5α-cholestane-5-ol ( 2 ) with t-butoxide in t-butanol gave 2α, 5-epoxy-A-nor-5α-cholestane ( 3 ) in quantitative yield. When A-nor-5β-cholestane-2α, 5-diol ( 4 ) was treated with tosyl chloride in pyridine 2β-chloro-A-nor-5β-cholestane-5-ol ( 7 ) and 2α-tosyloxy-A-nor-5β-cholestane-5-ol ( 8 ) were obtained. Whereas the chloride 7 was resistant to t-butoxide the tosylate 8 was transformed into an 1 : 1 mixture of 2α, 5-epoxy-5β-cholestane ( 10 ) and 2ξ-t-butoxy-A-nor-5β-cholestane-5-ol ( 11 ). In 2α-tosyloxy-A-nor-5α-cholestane-5-ol ( 12 ) substitution occurred as the only reaction. Both oxetanes 3 and 10 isomerize after heating above 50° and in polar or protic solvents to form A-nor-Δ³⁽⁵⁾-cholestene-2α-ol ( 6 ) and -2β-ol ( 14 ) respectively. Also, 2, 5-diols are encountered. 2α-Ethyl-2β, 2′-epoxy-A-nor-5α-cholestane ( 23 ) was synthesized starting from A-nor-5α-cholestane-2-one ( 17 ). The intermediates were the ester 16 , the diol 18 , the hydroxy-tosylate 19 and the chlorhydrin 20 . The spirocyclic oxetane 23 was reduced by LiAlH₄ in dioxane (not in ether). By chromatography on silica gel 23 was isomerized to the homoallylic alcohol 21 and transformed into 2-methylene-A-nor-5α-cholestane ( 24 ) by fragmentation. The IR. and NMR. spectra of the new oxetanes were compared with those of a series of known oxetanes.     

New Steroids and a New Alkaloid from the Gorgonian Isis minorbrachyblasta: Structures,Cytotoxicity, and Antilarval Activity

Two new polyoxygenated steroids, (1α,3β,7α,11α,12β)‐gorgost‐5‐ene‐1,3,7,11,12‐pentol 12‐acetate ( 1 ) and 11‐O‐acetyl‐22‐epihippuristanol ( 2 ), and a new alkaloid, 2,3,5,6,11,11b‐hexahydro‐2‐hydroxy‐1H‐indolizino[8,7‐b]indole‐2‐carboxylic acid ( 3 ), together with three known compounds, 22‐epihippuristanol ( 4 ), hippuristanol ( 5 ), and tryptamine ( 6 ), were isolated from the EtOH/CH₂Cl₂ extracts of the South China Sea gorgonian Isis minorbrachyblasta. The structures of the new compounds were determined by spectroscopic methods. Compound 1 showed weak cytotoxicity against A549, HONE1, and HeLa cancer cell lines and strong antilarval activity towards Bugula neritina larvae with an EC₅₀ value of 5.8 μg/ml. Compound 5 showed moderate cytotoxicity against A549, HONE1, and HeLa cell lines, and the epimer mixture 4 / 5 (weight ratio 3 : 2) exhibited potent cytotoxicity against A549 and HONE1 cell lines with IC₅₀ values of 4.2 and 4.8 μg/ml, which indicated that epimers 4 and 5 might have a synergistic effect on their cytotoxicity against A549 and HONE1 cell lines.     

Microbiological transformation of bicyclic monoterpenes by Absidia orchidis (Vuill.) Hagem. 2. Hydroxylation of fenchone and isofenchone. 18. Section on reactions with microorganisms

(+)-Fenchone ( 3a ) was transformed to 6-exo-hydroxy-fenchone (6β-hydroxy-1, 3, 3-trimethyl-nor-bornan-2-one) ( 1a ) and to 5-exo-hydroxy-fenchone 5β-hydroxy-1, 3, 3-trimethyl-nor-bornan-2-one ( 4a ) by the mycelium of Absidia orchidis (Vuill.) Hagem. The structure of the two products was proven by a detailed analysis of the NMR. spectra of the corresponding acetyl derivatives 2a and 5a respectively, and by CrO₃-oxidation. 1a yielded the β-diketone 6a , and 4a the diketone 8a. Whereas 8a was stable to alkali 6a was cleaved to the cyclopentane carboxylic acids 7 and 9 . — Incubation of (—)-fenchone ( 3b ) yielded the enantiomeric hydroxylation products 1b and 4b in the same ratio. - (—)-Isofenchone ( 11a ) was transformed by Absidia orchidis into the two epimers 6-endo-hydroxy-isofenchone (6β-hydroxy-1, 5, 5-trimethyl-nor-bornan-2-one) ( 12a ) and 6-exo-hydroxy-isofenchone (6β-hydroxy-1, 5, 5-trimethyl-nor-bornan-2-one) ( 10a. ) CrO₃-oxidation of both 10a and 12a gave the same β-diketone 6a. - (+)-Isofenchone gave the corresponding enantiomeric hydroxy derivatives 10b and 12b on incubation with Absidia orchidis.     

β-Loop, γ-loop,and helical peptide conformations in cyclopeptides containing a steroidal pseudo-amino acid

The steroidal pseudo-amino acids 3ã-amino-5β-cholan-24-oic acid ( 2a ), 12ã-acetoxy-3ã-ammonia-5β-cholan-24-oic acid ( 2b ), and 7ã,12ã-diacetoxy-3ã-amino-5β-cholan-24-oic acid ( 2c ) are used as rigid spacers in the backbone of the cyclic peptides cyclo(– 2a –Phe-Phe–)₂ ( 1a ), cyclo(– 2b –Phe-Phe–)₂ ( 1b ), and cyclo(–2c-Phe-Phe–)₂ ( 1c ). A homogeneous β-loop conformation is found in the peptide chains of 1a and 1b , while 1c exists as a mixture of ã-helical and γ-loop conformations. The structure and homogeneity of the conformations are established by several NMR techniques and are supported by molecular-dynamics calculations. The peptide conformations depend on the distance and attraction of the two large and lipophilic steroidal parts of the cyclic molecules.     

Chemical content of Margaretta rosea Oliv. roots. 323. Glycosides and aglycones

The roots of Margaretta rosea Oliv., subsp. rosea Bullock contain cardenolides mixed with Kedde negative ester glycosides. 6 Cardenolides were identified by paper chromatography (PC) and thin layer chromatography (TLC). Three of them were free aglycones (uzarigenin ( 1 ), corotoxigenin ( 3 ) and coroglaucigenin ( 5 ), the other three their corresponding 6-deoxy-β-D -allo-pyranosides (ascleposide ( 2 ), gofruside ( 4 ) and frugoside ( 6 ). Only two cardenolides ( 1 and 5 ) were isolated in crystalline form. The behaviour of the more polar portion of the glycoside mixture shows that D -gluco derivatives of at least 5 of the 6 cardenolides mentioned were also present. The Kedde. negative glycosides were a complicated mixture containing mainly 2,6-dideoxysugars linked to esterified polyhydroxy-pregnanes. After mild acid hydrolysis cymarose, oleandrose and digitoxose could be identified by PC and TLC. From the crude aglycone portion only one cristalline genin (M) could be isolated. This was still a mixture, but its main component according to the mass spectrum was a monobenzoyl derivative C₂₈H₃₈O₇. - A small amount of cristalline O-acetyl-β-amyrin was isolated from the least polar components.     

Synthesis of the 2,5-dioles of A-nor-5-alpha-cholestanes and A-nor-5-beta-cholestanes

Treatment of A-nor-Δ³⁽⁵⁾-cholestene-2-one ( 1 ) with alkaline hydrogen peroxide gave 3β,5-epoxy-A-nor-cholestane-2-one ( 2 ) and the epoxylactone 3 (BAEYER -VILLIGER reaction). LiAlH₄-reduction of 2 yielded A-nor-5β-cholestane-2β,5-diol( 4 ) (main product) and A-nor-5β-cholestane-2α,5-diol ( 5 ). LiAlH₄-reduction of 1 led mainly to A-nor-Δ³⁽⁵⁾-cholestene-2α-ol ( 8 ). Catalytic hydrogenation of 8 gave the known A-nor-5α-cholestane-2α-01 ( 10 ), A-nor-5β-cholestane-2α-01 ( 11 ) (main product), A-nor-5β-cholestane ( 9 ) and A-nor-5β-cholestane-2-one ( 12 ). By LiAlH₄-reduction of the ketones 12 and 13 the two additional alcohols 14 and 15 were obtained.     

Major terpenoids from Telekia speciosa flowers and their cytotoxic activity in vitro

In addition to known constituents of Telekia speciosa, an acetone extract from ray florets of the plant yielded: 5,5?-dibutoxy-2,2?-bifuran (1), 5,5?-diisobutoxy-2,2?-bifuran (2), α-tocopherol (3), β-tocopherol (4), loliolide palmitate (5), a mixture of calenduladiol esters - 16β-hydroxylupeol-3-O-palmitate (7) and 16β-hydroxylupeol-3-O-myristate (8), 1-epiinuviscolide (12), inuviscolide (13), 3-epiisotelekin (16), 4α-hydroxy-9β,10β-epoxy-1β(H)-11(13)-guaien-8α,12-olide (17), 4α-hydroxy-1β(H)-9(10),11(13)-guaiadien-8α,12-olide (18), loliolide (19) and 4β,10β-dihydroxy-1α(H),5α(H)-11(13)-guaien-8α,12-olide (20). Calenduladiol esters and asperilin (14) were the major constituents of the extract. Their cytotoxic effect on human normal prostate epithelial cells (PNT-2), human prostate carcinoma cell lines, human skin fibroblasts (HSF) and human melanoma cell lines was examined in vitro. Triterpene esters showed no cytotoxicity against nearly all cell lines tested, except for Du145 prostate carcinoma cells (IC₅₀ – 62.0 μΜ). Asperilin displayed activity against the cell lines under study, especially against three tested lines of melanomas (A375, IC₅₀ – 17.6 μΜ, WM793, IC₅₀ – 28.2 μΜ and Hs 294T, IC₅₀ – 29.5 μΜ).     

Ringschlussreaktionen mit 2-(β-Styryl)benzylaminen 5-Phenyl-1H-2-benzazepine. 23. Mitteilung über siebengliedrige Heterocyclen

Cyclization reactions with 2-(β-styryl)benzylamines 5-Phenyl-1H-2-benzazepines Cyclization of the urea derivative 3 with POCl₃ to give 2-(4-methyl-1-piperazinyl)-4-phenylquinoline ( 4 ) was carried out in analogy to the quinoline synthesis of Foulds & Robinson. This reaction was used for the preparation of 2-benzazepines. The trisubstituted ureas 6 and 8 , derived from the 2-(β-styryl)-benzylamines 5 , were cyclized with POCl₃ to yield the 3-amino-5-phenyl-1H-2-benzazepines 7 and 9 , respectively. Similarly, cyclization of the corresponding acetyl-derivatives 10 gave the 3-methyl-5-phenyl-1H-2-benzazepines 12 . On the other hand, the disubstituted urea 15 , cyclized under the same conditions to the 1-methyl-1-phenylisoindoline derivative 16 , and 2-(β-styryl)benzylamine ( 5a ) on treatment with phosgene gave the isoindoline 17 in an analogous manner.     

A Novel Asymmetric Synthesis of 3‐(1H‐Pyrrol‐1‐yl)‐Substituted β‐Lactams via a Bismuth Nitrate‐Catalyzed Reaction

The reaction of racemic α‐keto β‐lactams 5a – 5c with the commercially available chiral compound trans‐4‐hydroxy‐L ‐proline ( 6 ) in the presence of a catalytic amount of Bi(NO₃)₃?5 H₂O in EtOH gave a diastereoisomer mixture of β‐lactams with a pyrrole ring at C(3) ( 7 to 12 ). This is the first enantioselective synthesis of optically active β‐lactams (=azetidin‐2‐ones) that possess a pyrrolyl residue at C(3), in a single step.     

Hydrolytic Reaction of Plant Extracts to Generate Molecular Diversity: New Dammarane Glycosides from the Mild Acid Hydrolysate of Root Saponins of Panax notoginseng

Molecular diversity was generated by hydrolyzing the crude root saponins of Panax notoginseng (Burk .) F. H. Chen under mild acidic condition (AcOH/EtOH 1 : 1). From the acid hydrolysate, five new dammarane glycosides, named notoginsenoside T₁ (=(3β,6α,12β,20E,23RS)‐24,25‐epoxy‐6‐[(β‐D ‐glucopyranosyl)oxy]‐dammar‐20(22)‐ene‐3,12,23‐triol; 1 ), notoginsenoside T₂ (=(3β,6α,12β,20E,23RS)‐24,25‐epoxy‐6‐[(β‐D ‐glucopyranosyl)oxy]‐23‐methoxydammar‐20(22)‐ene‐3,12‐diol; 2 ), notoginsenoside T₃ (=(3β,6α,12β,20S)‐6‐[(β‐D ‐glucopyranosyl)oxy]‐20‐ethoxydammar‐24‐ene‐3,12‐diol; 3 ), notoginsenoside T₄ (=(3β,6α,12β,20S,22E,24RS)‐6‐[(β‐D ‐glucopyranosyl)oxy]dammar‐22‐ene‐3,12,20,24,25‐pentol; 4 ), and notoginsenoside T₅ (=(3β,6α,12β, 24E)‐6‐[(β‐D ‐xylopyranosyl‐(1→2)‐β‐D ‐glucopyranosyl)oxy]dammara‐20(21),24‐diene‐3,12‐diol; 5 ), were isolated, together with 15 known dammarane glycosides, and their structures were elucidated on the basis of spectroscopic evidence. Among the known compounds, ginsenosides Rg₃ and Rh₁ were isolated as major constituents, in addition to ginsenosides Rg₅, Rh₄, and a mixture of (20R)‐ and (20S)‐25‐hydroxyginsenoside Rh₁, all of which were obtained from P. notoginseng for the first time.     

Konkurrenz von Endoperoxid- und Hydroperoxid-Bildung bei der Umsetzung von Singulett-Sauerstoff mit cyclischen,konjugierten Dienen. Teil I

Competition of Endoperoxide and Hydroperoxide Formation in the Reaction of Singlet Oxygen with Cyclic, Conjugated Dienes Rose-bengal-sensitized photooxygenation of (?)-(R)-α-phellandrene ( 1 ) in MeOH at room temperature yielded a complex mixture of products, contrary to previous reports describing cis-(3S, 6R)-epidioxy-p-menthene ( 2 ) and trans-(3R, 6S)-epidioxy-p-menthene ( 3 ) as the only products. The mixture was separated by prep. HPLC (silica gel, pentane/Et₂O 9:1). Besides the known endoperoxides 2 (yield 39%) and 3 (26%), all those hydroper-oxides, which can be deduced from an ene reaction of ¹O₂ with 1 , were isolated, i.e. 4β-p-mentha-2,5-dien-1β-yl hydroperoxide ( 4 ) (14%), 4β-p-mentha-2,5-dien-1α-yl hydroperoxide ( 5 ) (9%), (2R, 4R)-p-mentha-1(7), 5-dien-2-yl hydroperoxide ( 6 ) (2,1%), (2S, 4R)-p-mentha-1(7),5-dien-2-yl hydroperoxide ( 7 ) (1,5%) and (1R)-p-mentha-3,6-dien-yl hydroperoxide ( 8 ; 1,5%; Scheme 1). Furthermore, the constant cis/trans ratio for all diastereoisomeric pairs ( 2 / 2 , 4 / 2 , 6 / 2 ) was striking. With the help of the two possible conformers 1a and 1b of the starting material a model of a common first step for endoperoxide as well as for hydroperoxide formation is developed. A photooxygenation at ?50° supports this model. The absolute value of the cis/trans ratio changes in the same way for the endoperoxides and the hydroperoxides.     

Diterpenoide Drüsenfarbstoffe aus Labiaten: Coleone U,V, W und 14-O-Formyl-coleon-V sowie 2 Royleanone aus Plectranthus myrianthus BRIQ.; cis- und trans-A/B-6, 7-Dioxoroyleanon

Leaf-gland Pigments: Coleons U, V, W, 14- O -Formyl-coleon-V, and two Royleanones from Plectranthus myrianthus BRIQ. ; cis - and trans -A/B-6,7-Dioxoroyleanones From leaf-glands of the South-African P. myrianthus (Labiatae) the following diterpenoids have been isolated and their structures established: coleon U, C₂₀H₂₆O₅ (6, 11, 12, 14-tetrahydroxy-abieta-5, 8, 11, 13-tetraene-7-one, 2a ); coleon V, C₂₀H₂₆O₅ (11, 12, 14-trihydroxy-abieta-8, 11, 13-triene-6, 7-dione, 4a ); coleon W, C₂₂H₂₈O₈ (16(or 17)-acetoxy-6, 11, 12, 14, 17 (or 16)-pentahydroxy-abieta-5, 8, 11, 13-tetraene-7-one, 6 ); 14-O-formyl-coleon-V, C₂₁H₂₆O₆ (14-formyloxy-11, 12-dihydroxy-abieta-8, 11, 13-triene-6, 7-dione, 4b ); 7α-formyloxy-6β-hydroxyroyleanone, C₂₁H₂₈O₆ (7α-formyloxy-6β, 12-dihydroxy-abieta-8, 12-diene-11, 14-dione, 1a ); the already known 6β, 7α-dihydroxyroyleanone ( 1c ) and a dimeric abietane derivative whose structure is not yet elucidated. This is the first record of a co-occurrence of coleons and royleanones in the same plant. In the course of chemical investigations of 4a and 4b the highly oxidized trans- and cis-A/B-6,7-dioxoroyleanones ( 5a and 5b ) were obtained.     

Nucleoside und Nucleotide. Teil 15. Synthese von Desoxyribonucleosid-monophosphaten und -triphosphaten mit 2(1H)-Pyrimidinon, 2(1H)-Pyridinon und 4-Amino-2(1H)-pyridinon als Basen

Nucleosides and Nucleotide. Part 15. Synthesis of Deoxyribonucleoside Monophosphates and Triphosphates with 2(1H)-Pyrimidinone, 2(1H)-Pyridinone and 4-Amino-2(1H)-pyridinone as the Bases The phosphorylation of the modified nucleosides 1-(2′-deoxy-β-D -ribofuranosyl)-2(1 H)-pyrimidinone (M_d, 4 ), 4-amino-1-(2′-deoxy-β-D -ribofuranosyl)-2(1 H)-pyridinone (Z_d, 6 ) and the synthesis of 1–2′-deoxy-β-D -ribofuranosyl-2(1 H)-pyrimidinone-5′-O-triphosphate (pppM_d, 1 ), 1-(2′-deoxy-β-D ribofuranosyl)-2(1 H)-pyridinone-5′-O-triphosphate (pppII_d, 2 ), and 4-amino-1-(2′-deoxy-βD -ribofuranosyl)-2(1 H)-pyridinone-5′-O-triphosphate (pppZ_d, 3 ) are described. The nucleoside-5′-monophosphates pM_d (5) and pZ_d (7) were obtained by selective phosphorylation of M_d (4) and Z_d (6) , respectively, using phosphorylchloride in triethyl phosphate or in acetonitril. The reaction of pM_d (5) pII _d (8) or pZ_d (7) with morpholine in the presence of DCC led to the phosphoric amides 9, 10 and 11 , respectively, which were converted with tributylammonium pyrophosphate in dried dimethylsulfoxide to the nucleoside-5′triphosphates 1, 2 and 3 , respectively.     

Opposid,vermutliche Struktur. Glykoside und Aglykone, 302. Mitt.

The hypothetical structure 1 is proposed for opposide (C₂₉H₄₄O₁₁), a new glycoside from the seeds of Acokanthera oppositifolia (LAM.) CODD. Opposide is derived from the new aglycone gratogenin, which is most probably the 1β, 3β, 5β, 11α, 14β-pentahydroxy-card-20:22-enolide ( 8 ) (C₂₃H₃₄O₇) and which is bound glycosidically through position 3 to the α-pyranosidic form of 6-desoxy-L-talose. The hydrolysis of opposide by HCl in acetone gave an anhydrogenin (C₂₃H₃₂O₆) instead of the intact aglycone. In analogy to the reaction sequence observed by VOLPP and TAMM for ouabagenin, the structure of the anhydrogenin is deduced to be that of a 3β, 5β, 14β-trihydroxy-1α, 11α-epoxy-card-20:22-enolide ( 6 ). The above mentioned structures are based on the course of acetylation and especially on NMR.-spectra.     

Deoxy-nitrosugars. 16th Communication. Synthesis of N-acetyl-4-deoxyneuraminic acid

The synthesis of 5-acetamido-4-deoxyneuraminic acid ( 1 ) is described. Acetylation of a mixture of the epimeric triols 4 and 5 gave the tetraacetates 7 and 8 (Scheme 1). Ozonolysis of a mixture of these acetates followed by base-promoted β-elimination led to the (E) -configurated α,β-unsaturated keto ester 10 , which was hydrogenated to give the saturated keto ester 11 . Saponification of 11 and hydrolytic removal of the benzylidene group followed by anion-exchange chromatography gave the 5-acetamido-4-deoxyneuraminic acid ( 1 , Scheme 1 and 2). De-O-acetylation (NaOMe/MeOH) of the keto ester 11 gave a mixture of the tert-butyl ester 12 and the methyl ester 13 , which were converted to tert-butyl N-acetyl-4-deoxyneuraminate ( 14 ) and to methyl N-acetyl-4-deoxyneuraminate ( 15 ), respectively. Hydrogenolysis of the benzylidene acetal 11 followed by de-O-acetylation gave the pentahydroxy ester 16 .     

The glycosides of Marsdenia erecta R. Br. I. Isolation, glycoside and aglycone. 325

Dried leaves of Marsdenia erecta R. Br. gave over 6% of a crude glycoside mixture, the main portion of which consisted of weakly polar material, soluble in ether or chloroform. By mild acid hydrolysis it yielded crude sugars and aglycones. The following four crist. sugars were isolated: D -cymarose, D -oleandrose and two bioses: pachybiose and marsectobiose (C₁₄H₂₄O₈, new). By PC. and TLC. the presence of digitoxose, canarose, thevetose and 3-O-methyl-6-deoxyallose could be demonstrated. The crude acyl-genin mixture contained β-sitosteryl-β-D -glucopyranoside and three highly hydroxylated pregnane derivatives: drevogenin-P, 17 β-marsdenin (C₂₁H₃₂O₆, new) and marsectohexol (C₂₁H₃₄O₆, new), all partly esterified with acetic, tiglic and benzoic acid. Five crist. acyl-genins (A1–A5) were isolated by chromatography, but most of them still were mixtures. After alkaline hydrolysis of the crude acyl-genins 6 acyl-free compounds were obtained. 4 of them were identical with the above mentioned substances, the other two: 17-iso-drevogenin-P and marsdenin (17 α-marsdenin) are formed from drevogenin-P and 17 β-marsdenin by isomerisation.     

Alkaloide aus Cortex Condurango

From the CH₂Cl₂ extract of the bark of Marsdenia cundurango Reichenb. fil. (Cortex Condurango) a mixture of basic compounds could be isolated. Repeated thin layer and column chromatography yealded two alkaloids in pure form. For Kondurangamin A, which would be the mayor alkaloid with a content of 0.0007%, the structure was determined as 3β, 14β,20-trihydroxy-11 α-nicotinoyloxy-12β-acetoxy-5α,14β-pregnane and for Kondurangamin B as 3β,11α,12β,14β-tetrahydroxy-20-nicotinoyloxy-5α,14β-pregnane.