126214-08-2Relevant academic research and scientific papers
C2-symmetric copper(II) complexes as chiral lewis acids. Catalytic enantioselective carbonyl - Ene reactions with glyoxylate and pyruvate esters
Evans, David A.,Tregay, Steven W.,Burgey, Christopher S.,Paras, Nick A.,Vojkovsky, Tomas
, p. 7936 - 7943 (2007/10/03)
The C2-symmetric complexes [Cu(S,S)-tert-butylbis(oxazolinyl)](SbF6)2 (2a), its bis(aquo) counterpart [Cu(S,S)-tert-butylbis(oxazolinyl)(H2O)2](SbF6)2 (4), and [Cu(S,S)-phenylbis(oxazolinyl)](OTf)2 (1c) have been shown to catalyze the enantioselective ene reaction between glyoxylate esters and various olefins. Monosubstituted, disubstituted, and trisubstituted olefins each react with ethyl glyoxylate in the presence of 0.2 - 10 mol % of catalysts 1, 2, and 4 to afford the ene products in good yield and enantioselectivity. Complex 2a has also been shown to catalyze the addition of 1,1-disubstituted olefins to methyl pyruvate in good yields (76-95%) and excellent enantioselectivies (≥98% ee). The synthetic utility of the glyoxylate - ene reaction was demonstrated by conversion of the resulting α-hydroxy ester into the corresponding methyl ester, free acid, Weinreb amide, and α-azido ester, all with no detectable racemization.
