Stereochemistry of Radical Cyclizations to Side-Chain Olefinic Bonds. An Approach to Control of the C-9 Center of Morphine
摘要:
Styrenes of general structure 5 undergo tandem radical cyclization to cis,cis-hydrophenanthrofurans 9, products which contain the carbocyclic skeleton of the morphine alkaloids. Vinylurethane 5E-NHCO(2)Et cyclizes to 9 alpha via the intermediate radical 7E-NHCO(2)Et in the chair-chair conformation. Cyclization of 5Z-NHCO(2)Et also gives predominantly 9 alpha instead of the expected 9 beta. This anomaly is attributed to the isomerization of 5Z to 5E at a rate competitive with that of cyclization.
Stereochemistry of Radical Cyclizations to Side-Chain Olefinic Bonds. An Approach to Control of the C-9 Center of Morphine
摘要:
Styrenes of general structure 5 undergo tandem radical cyclization to cis,cis-hydrophenanthrofurans 9, products which contain the carbocyclic skeleton of the morphine alkaloids. Vinylurethane 5E-NHCO(2)Et cyclizes to 9 alpha via the intermediate radical 7E-NHCO(2)Et in the chair-chair conformation. Cyclization of 5Z-NHCO(2)Et also gives predominantly 9 alpha instead of the expected 9 beta. This anomaly is attributed to the isomerization of 5Z to 5E at a rate competitive with that of cyclization.
Stereochemistry of Radical Cyclizations to Side-Chain Olefinic Bonds. An Approach to Control of the C-9 Center of Morphine
作者:Kathlyn A. Parker、Demosthenes Fokas
DOI:10.1021/jo00093a026
日期:1994.7
Styrenes of general structure 5 undergo tandem radical cyclization to cis,cis-hydrophenanthrofurans 9, products which contain the carbocyclic skeleton of the morphine alkaloids. Vinylurethane 5E-NHCO(2)Et cyclizes to 9 alpha via the intermediate radical 7E-NHCO(2)Et in the chair-chair conformation. Cyclization of 5Z-NHCO(2)Et also gives predominantly 9 alpha instead of the expected 9 beta. This anomaly is attributed to the isomerization of 5Z to 5E at a rate competitive with that of cyclization.