Untersuchungen über asymmetrische Synthesen III. Über die Anwendung der asymmetrischen Synthese zur Konfigurationsbestimmung bei Triterpenen und Steroiden
作者:W. G. Dauben、D. F. Dickel、O. Jeger、V. Prelog
DOI:10.1002/hlca.19530360142
日期:——
angeführten Triterpene und Steroide die Konfigurationen I–III und XII–XV abgeleitet. Daraus folgt, dass die erwähnten Triterpene und Steroide mit 30 Kohlenstoffatomen die gleiche Konfiguration und Konstellation im Ringe A besitzen, wie die Abkömmlinge des Cholestanols-(3β), dessen absolute Konfiguration mit Hilfe der asymmetrischen Synthese indirekt bestimmt wurde.
Replacement of a carbonyl group of cyclic ketones by an oxygen atom: A four-step transformation of cyclic ketones into cyclic ethers
作者:Hiroshi Suginome、Shinji Yamada
DOI:10.1016/0040-4039(84)80049-0
日期:——
We describe a new and versatile method for transforming cyclic ketones into cyclic ethers with the same ring size in which the chirality adjacent to the carbonylgroup of the ketones is retained.
The results of the photolysis of five steroidal 6-membered cyclic α-nitro ketones in ethanol are described. Irradiation with a Pyrex-filtered light of 2-nitro-5α-cholestan-3-one in ethanol, which exists exclusively in the enol form in the solvent, resulted in a new photorearrangement and gave 5α-cholestane-2,3-dione 3-oxime with the accompanying formation of the corresponding α-diketone. We propose
Hydroxy-steroids. Part XI. The preparation and infrared spectra of vicinal cholestanediols
作者:C. W. Davey、E. L. McGinnis、J. M. McKeown (née Chancellor)、G. D. Meakins、M. W. Pemberton、R. N. Young
DOI:10.1039/j39680002674
日期:——
Twenty-eight vicinal cholestanediols (positions 1,2; 2,3; 3,4; 4,5; 5,6; 6,7; and 7,8) have been prepared by unambiguous routes starting from the corresponding olefins. The O–H stretching bands of dilute solutions of these diols and of seven reference compounds have been examined under high dispersion. Characteristic differences between ax,ax, ax,eq, and eq,eq compounds were observed. It was concluded
The vicinal effect between the keto groups of the two cholestane-4,7-diones epimeric at C-5 is small for the 5α-compound 3, but appreciable for the 5β-isomer 2. The synthesis and chiroptical properties of some lactones and lactames of 5-carboxy-5α-cholestane are described.