Formation of Five- and Six-Membered Carbocycles with Nitrogenated Tetrasubstituted Carbons by Radical Addition-Carbocyclization of Alkynyl Ketoxime Ethers
摘要:
C3-Ketoxime ethers bearing alkynes with terminal delta-yne or internal gamma-yne functions were prepared in five or six steps and similar to 20% overall yield from commercial glucofuranose derivatives. Their thiyl-, stannyl-, or carbon radical-promoted addition-carbocyclization gave five- or six-membered carbocycles nitrogenated at one of the bridgehead positions. For internal gamma-yne ethers the tandem process was strongly dependent on both the alkyne substituent and the radical-promoting species and could be directed toward either the five- or the six-membered carbocycle. These results are presented and discussed in the context of studies working toward (-)-tetrodotoxin.
Formation of Five- and Six-Membered Carbocycles with Nitrogenated Tetrasubstituted Carbons by Radical Addition-Carbocyclization of Alkynyl Ketoxime Ethers
作者:Marta Fernández-González、Ricardo Alonso
DOI:10.1021/jo060883y
日期:2006.9.1
C3-Ketoxime ethers bearing alkynes with terminal delta-yne or internal gamma-yne functions were prepared in five or six steps and similar to 20% overall yield from commercial glucofuranose derivatives. Their thiyl-, stannyl-, or carbon radical-promoted addition-carbocyclization gave five- or six-membered carbocycles nitrogenated at one of the bridgehead positions. For internal gamma-yne ethers the tandem process was strongly dependent on both the alkyne substituent and the radical-promoting species and could be directed toward either the five- or the six-membered carbocycle. These results are presented and discussed in the context of studies working toward (-)-tetrodotoxin.