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.

本研究设计并通过三步反应合成了一种含硅醇基团的新型双功能催化剂，该催化剂具备优异的对映选择性。通过核磁共振结合实验与电喷雾电离质谱（ESI-MS）分析，本研究对该吡咯烷基硅醇的氢键结合特性展开了系统探究。进一步利用靛红与乙醛参与的对映选择性羟醛缩合反应，验证了硅醇基团可通过氢键导向作用活化亲电试剂并实现对映体控制的能力，该反应的最高对映体过量值（ee）可达88%。