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
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.