Synthesis of Digitoxigenin from 3.beta.-Acetoxyandrost-5-en-17-one. Construction of a Suitably Functionalized Pregnane Side Chain via Presumed Allene Oxide Intermediate
摘要:
The synthesis of digitoxigenin (1) from 3 beta-acetoxyandrost-5-en-17-one (2) involves construction of the 21-hydroxy-20-keto pregnane side chain from 1-bromo-1-(trimethylsilyl)ethylene via presumed intermediate allene oxide 11. The key intermediate alcohol 10 is obtained by addition of 1-lithio-1-(trimethylsilyl)ethylene to the carbonyl group of 4 followed by selective epoxidations of the double bonds in 5. Reaction of trifluoroacetate 8 with aqueous tetra-n-butylammonium fluoride affords 15 beta,21-dihydroxypregn-16-en-20-one 12. After hydrogenation of the C-16,17 double bond, the butenolide ring is formed using (triphenylphosphoranylidene)ketene to give 15 beta-hydroxycardenolide 14, which has previously been converted to digitoxigenin (1).
Synthesis of Digitoxigenin from 3.beta.-Acetoxyandrost-5-en-17-one. Construction of a Suitably Functionalized Pregnane Side Chain via Presumed Allene Oxide Intermediate
摘要:
The synthesis of digitoxigenin (1) from 3 beta-acetoxyandrost-5-en-17-one (2) involves construction of the 21-hydroxy-20-keto pregnane side chain from 1-bromo-1-(trimethylsilyl)ethylene via presumed intermediate allene oxide 11. The key intermediate alcohol 10 is obtained by addition of 1-lithio-1-(trimethylsilyl)ethylene to the carbonyl group of 4 followed by selective epoxidations of the double bonds in 5. Reaction of trifluoroacetate 8 with aqueous tetra-n-butylammonium fluoride affords 15 beta,21-dihydroxypregn-16-en-20-one 12. After hydrogenation of the C-16,17 double bond, the butenolide ring is formed using (triphenylphosphoranylidene)ketene to give 15 beta-hydroxycardenolide 14, which has previously been converted to digitoxigenin (1).
Synthesis of Digitoxigenin from 3.beta.-Acetoxyandrost-5-en-17-one. Construction of a Suitably Functionalized Pregnane Side Chain via Presumed Allene Oxide Intermediate
作者:Marek M. Kabat
DOI:10.1021/jo00111a046
日期:1995.3
The synthesis of digitoxigenin (1) from 3 beta-acetoxyandrost-5-en-17-one (2) involves construction of the 21-hydroxy-20-keto pregnane side chain from 1-bromo-1-(trimethylsilyl)ethylene via presumed intermediate allene oxide 11. The key intermediate alcohol 10 is obtained by addition of 1-lithio-1-(trimethylsilyl)ethylene to the carbonyl group of 4 followed by selective epoxidations of the double bonds in 5. Reaction of trifluoroacetate 8 with aqueous tetra-n-butylammonium fluoride affords 15 beta,21-dihydroxypregn-16-en-20-one 12. After hydrogenation of the C-16,17 double bond, the butenolide ring is formed using (triphenylphosphoranylidene)ketene to give 15 beta-hydroxycardenolide 14, which has previously been converted to digitoxigenin (1).