Tetracyclic triterpenes. Part 16. Synthesis of 31-norcucurbitane and fusidane derivatives in the skeletal rearrangements of 9,11-epoxy-4β-demethyl-5α-lanostanes
摘要:
The BF3 . Et(2)O-catalysed rearrangement of 9 beta,11 beta-epoxy-4 beta-demethyl-5 alpha-lanostan-7-one derivatives 11 and 12 in acetic anhydride resulted in formation of 19(10-->9 beta)abeo compounds (31-norcucurbitanes) 20-22 or 23 and 24, respectively. The extent of a rearrangement was dependent on the substituent at position 3 of the steroid. Reaction of the 9 alpha,11 alpha-epoxide 17 under similar conditions gave fusidenone 25 (31-norprotostane) in high yield which had the carbon skeleton characteristic of the steroidal antibiotic, fusidic acid.
Tetracyclic triterpenes. Part 16. Synthesis of 31-norcucurbitane and fusidane derivatives in the skeletal rearrangements of 9,11-epoxy-4β-demethyl-5α-lanostanes
作者:Zdzisław Paryzek、Jacek Martynow
DOI:10.1039/p19960000201
日期:——
The BF3 . Et(2)O-catalysed rearrangement of 9 beta,11 beta-epoxy-4 beta-demethyl-5 alpha-lanostan-7-one derivatives 11 and 12 in acetic anhydride resulted in formation of 19(10-->9 beta)abeo compounds (31-norcucurbitanes) 20-22 or 23 and 24, respectively. The extent of a rearrangement was dependent on the substituent at position 3 of the steroid. Reaction of the 9 alpha,11 alpha-epoxide 17 under similar conditions gave fusidenone 25 (31-norprotostane) in high yield which had the carbon skeleton characteristic of the steroidal antibiotic, fusidic acid.
High-field1H and13C NMR spectra of synthetic protostane derivatives: Total assignment by 2D NMR
作者:Zdzislaw Paryzek、Jacek Martynow、Tetsuro Shimo
DOI:10.1002/mrc.1260300703
日期:1992.7
two‐dimensional high‐field 1H and 13CNMR spectroscopy. Complete assignments of the proton and carbon signals of 11α‐acetoxy‐3β‐benzoyloxy‐5α.9β‐protost‐13(17)‐ene (4) and of 11α‐acetoxy‐31‐nor‐5α,9β‐protost‐13(17)‐en‐3‐one (5) are presented. The assignments were largely determined using substituentchemicalshift and conformationaleffects and by a combination of DEPT, 1H‐‐1H COSY, 1H‐‐13C HETCOR and XCORFE spectra