Bufadienolides—19 : 3β-acetoxy-15-oxo-5β,14β-bufa-8,20,22-trienolide

Reaction of 3β - hydroxy - 14α,15α - epoxy - 5β - bufa - 20,22 - dienolide (1a) with 72% perchloric acid was found to yield 14β - artebufogenin (2a), 14α - artebufogenin (2b), 15α - hydroxy-bufalin (3a), and a new substance 3β,15ξ - dihydroxy - 5β,14ξ - bufa - 8,20,22 - trienolide (4a). Similar results were realized by antimony (III) chloride and an iron(III) chloride catalyzed ring opening of epoxide 1a. Selective acetylation of the new bufadienolide (4a) followed by oxidation completed a route to the title substance.     

Studies on steroidal plant-growth regulator: VII. Synthesis of 2α, 3α-dihydroxy-7-oxa-6-oxo-23, 24-dinor-B-homo-5α-cholanic acid and 2α, 3α-dihydroxy-7-oxa-6-oxo-24-nor-B-homo-5α-cholanic acid

Two brassinolide analogues, (2) and (3), have been synthesized from hyodeoxycholic acid (4) through a sequence of reactions as shown in Scheme 1 and 2 of the text.     

Synthese von diastereo- und enantio-selektiv deuterierten β,ε-, β,β-, β,γ- und γ,γ-Carotinen

Synthesis of Diastereo- and Enantioselectively Deuterated β,ε-, β,β-, β,γ- and γ,γ-Carotenes We describe the synthesis of (1′R, 6′S)-[16′, 16′, 16′-²H₃]-β, εcarotene, (1R, 1′R)-[16, 16, 16, 16′, 16′, 16′-²H₆]-β, β-carotene, (1′R, 6′S)-[16′, 16′, 16′-²H₃]-γ, γ-carotene and (1R, 1′R, 6S, 6′S)-[16, 16, 16, 16′, 16′, 16′-²H₆]-γ, γ-carotene by a multistep degradation of (4R, 5S, 10S)-[18, 18, 18-²H₃]-didehydroabietane to optically active deuterated β-, ε- and γ-C₁₁-endgroups and subsequent building up according to schemes \documentclass{article}\pagestyle{empty}\begin{document}${\rm C}_{11} \to {\rm C}_{14}^{C_{\mathop {26}\limits_ \to }} \to {\rm C}_{40} $\end{document} and C₁₁ → C₁₄; C₁₄+C₁₂+C₁₄→C₄₀. NMR.- and chiroptical data allow the identification of the geminal methyl groups in all these compounds. The optical activity of all-(E)-[²H₆]-β,β-carotene, which is solely due to the isotopically different substituent not directly attached to the chiral centres, is demonstrated by a significant CD.-effect at low temperature. Therefore, if an enzymatic cyclization of [17, 17, 17, 17′, 17′, 17′-²H₆]lycopine can be achieved, the steric course of the cyclization step would be derivable from NMR.- and CD.-spectra with very small samples of the isolated cyclic carotenes. A general scheme for the possible course of the cyclization steps is presented.     

Umwandlung von Cardenoliden durch Mikroorganismen VI. 7β, 11α-Dihydroxydigitoxigenin und Abbau von 7β-Hydroxy-digitoxigenin zum 3β, 7β-Diacetoxy-14-hydroxy-5β, 14β, 17αH-ätiansäure-methylester. Mitteilung über Reaktionen mit Mikroorganismen [1]

Digitoxigenin ( 3 ) was transformed by a Fusarium spec. to 7β-hydroxydigitoxigenin ( 1 ) 1β, 7β-dihydroxydigitoxigenin ( 4 ) and to the hitherto unknown 7β, 11α-dihydroxydigitoxigenin ( 9 ). 7β-acetoxy-digitoxigenin ( 2 ) was degraded to methyl 3β, 7β-diacetoxy-14-hydroxy-5β, 14β, 17αH-etianate ( 11 ).