Enantiocontrol with a Hydrogen-bond Directing Pyrrolidinylsilanol Catalyst

A new bifunctional catalyst containing a silanol group has been designed and synthesized with high enantioselectivity in three steps. The hydrogen-bonding properties of this pyrrolidinylsilanol have been investigated using NMR binding studies and electrospray ionization mass spectrometry (ESI-MS) analysis. The ability of the silanol group to activate an electrophile and afford enantiocontrol through hydrogen-bond directing effects has been demonstrated using an enantioselective aldol reaction with isatin and acetaldehyde, affording up to 88% ee.