Transformation of Hydroxycycloalkanones to Oxabicycloalkenes
摘要:
Oxabicycloalkenes, which represent anti-Bredt enol ethers, can be generated by catalytic dehydration of the hemiacetals of hydroxycycloalkanones (Method I). Another option is provided by the transformation of hydroxycycloalkanones to the corresponding 1,2,3-selenadiazoles and their thermal fragmentation on Cu powder (Method II). The intermediate hydroxycycloalkynes show a transannular addition of the OH group to the triple bond. Altogether seven new oxabicycloalk-1-enes were obtained by this methods.
Transformation of Hydroxycycloalkanones to Oxabicycloalkenes
作者:Herbert Meier、Guido Krämer、Heiner Detert
DOI:10.3987/com-09-11728
日期:——
Oxabicycloalkenes, which represent anti-Bredt enol ethers, can be generated by catalytic dehydration of the hemiacetals of hydroxycycloalkanones (Method I). Another option is provided by the transformation of hydroxycycloalkanones to the corresponding 1,2,3-selenadiazoles and their thermal fragmentation on Cu powder (Method II). The intermediate hydroxycycloalkynes show a transannular addition of the OH group to the triple bond. Altogether seven new oxabicycloalk-1-enes were obtained by this methods.
The first total synthesis of (-)-lepistine has been accomplished in 11 steps from (S)-glycidol. The synthesis features construction of the 10-membered ring via an intramolecular epoxide opening by nosylamide, regioselective dehydration to form an enol ether, and construction of the aminal moiety induced by cleavage of the nosyl groups.