Stereoselective intramolecular [4 + 3] cycloadditions of nitrogen-stabilized chiral oxyallyl cations via epoxidation of N-tethered allenamides.
The first intramolecular [4 + 3] cycloaddition reaction using nitrogen-stabilized chiral oxyallyl cations that are tethered to furan or diene through the nitrogen atom is described here. Formation of these nitrogen-stabilized chiral oxyallyl cations is achieved by a chemoselective epoxidation of chiral allenamides via syringe pump addition of dimethyl dioxirane. The ensuing cycloaddition can be carried out with a range of different lengths for the tether, and high diastereoselectivities can be obtained when using chiral allenamides with shorter tethers.
Xiong
Hui
H
Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Huang
Jian
J
Ghosh
Sunil K
SK
Hsung
Richard P
RP