Temperature dependent reversal of stereochemistry in enantioselective conjugate amine additions

Enoates derived from 4,4-disubstituted-2-oxazolidinones undergo enantioselective conjugate amine addition when mediated by a chiral Lewis acid derived from magnesium bromide and a bisoxazoline. The face selectivity in these amine additions is temperature dependent. They show an unusual reversal at two different temperatures.