SYNTHESIS OF OPTICALLY-ACTIVE ALPHA,BETA-DISUBSTITUTED BETA-AMINO NITRILES AND BETA-AMINO ACIDS STARTING FROM ASPARAGINE

Starting from the enantiomerically pure building block 2 which is read ily available from D-asparagine alpha,beta-disubstituted beta-amino ni triles and beta-amino acids could be synthesized. After deprotonation of the nitrile alpha-position the introduction of substituents was per formed by alkylation of either 2 or the TBDMS-protected derivative 3. Starting from the beta-homoserine equivalent 2 the reaction proceeds v ia a dianionic intermediate resulting in a preferred formation of the threo-configured products 6a,b (ratio of isomers: 7:1). Modification o f the side chain was demonstrated by displacement reactions with LiBH4 or potassium thioacetate.