Stereoselective Synthesis of Polysubstituted Tetrahydropyrans by Radical Cyclization of Epoxides using a Transition-Metal Radical Source
作者:Biplab Banerjee、Subhas Chandra Roy
DOI:10.1002/ejoc.200500424
日期:2006.1
Epoxyalkyl propargyl ethers 3a–f and allyl epoxyalkyl ethers 6a–c smoothly undergo radical cyclization reactions using a titanium(III) species (Cp2TiCl) as the radical initiator to form polysubstituted tetrahydropyrans 4a–f and 7a–c in good yields and with high diastreoselectivity. The titanium(III) species was prepared in situ from commercially available titanocene dichloride and Zn dust in THF. On the other