Asymmetric Mannich Reaction of Malonates with Aldimines Using YbIII-Pybox Complexes Supported on Self-Assembled Organic-Inorganic Hybrid Silica with an Imidazolium Framework

Yb(OTf)(3)/iPr-pybox (3b) immobilized on a self-assembled organic-inorganic hybrid silica with ionic liquid phase (SAILP) (Catalyst A) behaves as an efficient and recyclable catalyst in the enantioselective Mannich reaction of malonate esters with N-Boc aldimines to afford the corresponding products in good yields and enantioselectivities. In particular, it has been shown that the use of catalyst A resulted in much superior enantioselectivities in comparison with either 1: 2 Yb(OTf)(3)/3b on a periodic mesoporous organosilica with 10 percent imidazolium framework (catalyst C) or a catalyst comprising 1: 1 Yb(OTf)(3)/3b on SAILP under the same reaction conditions. Catalyst A could be recycled and reused at least four times with only a slight decrease in either catalytic activity or enantioselectivity.