Practical asymmetric access to carboxy-differentiated aspartate derivatives via 1,3-dipolar cycloaddition of a nitrone with (R)-4-ethyl-N-vinyloxazolidin-2-one

A new practical approach to enantioenriched carboxy-differentiated aspartate derivatives was achieved in three steps via the 1,3-dipolar cycloaddition of N-benzyl-alpha-carbonyloxyethylnitrone with (R)-4-ethyl-N-vinyloxazolidin-2-one and chemoselective nucleophilic displacement of aspartimide under appropriate conditions (racemization less than 3%). (C) 2008 Elsevier Ltd. All rights reserved.