Auxiliary induced asymmetric Michael-aldol reaction under kinetic and thermodynamic conditions

Asymmetric intramolecular Michael-aldol reaction of (−)-phenylmenthyl enoates 1 affords tricyclic cyclobutanes 2 in excellent diastereoselectivity. It is made clear that Michael-aldol reaction is reversible under conditions using trimethylsilyl iodide (TMSI) in the presence of hexamethyldisilazane (HMDS) at ambient temperature. The difference of stereoselectivity under kinetic or thermodynamic conditions are reported.