An Unexpected Reversal of Diastereoselectivity in the [4+3]-Cycloaddition Reaction of Nitrogen-Stabilized Oxyallyl Cations with Methyl 2-Furoate

Abstract

An unexpected reversal of diastereoselectivity in the [4+3] cycloaddition of methyl 2-fuorate with nitrogen-stabilized oxyallyl cations derived from epoxidation of chiral allenamides is described here. This intriguing reversal in favor of the endo-II cycloaddition pathway is likely a result of minimizing the dipole interaction between the oxyallyl cation and ester carbonyl of methyl 2-fuorate.