ASYMMETRIC SYNTHESES OF ALL 4 ISOMERS OF 4-AMINO-4-CARBOXYPROLINE - NOVEL CONFORMATIONALLY RESTRICTED GLUTAMIC-ACID ANALOGS

Asymmetric syntheses of all four isomers of 4-amino-4-carboxyprolines, i.e. (2S,4S)-3, (2S,4R)-4, and their corresponding enantiomers, as no vel conformationally restricted analogues of glutamic acid, were perfo rmed from trans-4-hydroxy-L-proline as a homochiral starting material. The key step was the spirohydantoin ring formation by employing the B ucherer-Bergs reaction of 4-oxoproline derivatives. These structures w ere determined by NMR studies.