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Asymmetric Mannich Reaction of Malonates with Aldimines Using Yb III ‐Pybox Complexes Supported on Self‐Assembled Organic–Inorganic Hybrid Silica with an Imidazolium Framework
Author(s) -
Karimi Babak,
Jafari Ehsan,
Enders Dieter
Publication year - 2014
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201402713
Subject(s) - chemistry , aldimine , catalysis , enantioselective synthesis , mannich reaction , malonate , mesoporous material , organocatalysis , organic chemistry , ionic liquid , mesoporous silica , polymer chemistry
Yb(OTf) 3 / i Pr‐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.