Enantioselective Organocatalytic Addition of Oxazolones to 1,1-Bis(phenylsulfonyl)ethylene: A Convenient Asymmetric Synthesis of Quaternary α-Amino Acids
作者:Andrea-Nekane R. Alba、Xavier Companyó、Guillem Valero、Albert Moyano、Ramon Rios
DOI:10.1002/chem.200903025
日期:2010.5.10
A new, easy, and highlyenantioselective method for the synthesis of quaternary α‐alkyl‐α‐aminoacids based on organocatalysis is reported. The addition of oxazolones to 1,1‐bis(phenylsulfonyl)ethylene is efficiently catalyzed by simple chiral bases or thioureas. The reaction affords α,α‐disubstituted α‐aminoacid derivatives with complete C4 regioselectivity and with excellent yields and enantioselectivities
Enantioselective Organocatalytic Addition of Azlactones to Maleimides: A Highly Stereocontrolled Entry to 2,2-Disubstituted-2H-oxazol-5-ones
作者:Andrea-Nekane R. Alba、Guillem Valero、Teresa Calbet、Mercé Font-Bardía、Albert Moyano、Ramon Rios
DOI:10.1002/chem.201000239
日期:2010.8.23
The first highly diastereo‐ and enantioselectiveorganocatalytic synthesis of 2,2‐disubstituted‐2H‐oxazol‐5‐ones is described. The addition of oxazolones to maleimides is promoted by bifunctional thiourea catalysts, which afford the corresponding 2,2‐disubstituted‐2H‐oxazol‐5‐ones with total regio‐ and stereocontrol.