A NEW ALPHA-AMINO-ACID GAMMA-ANION EQUIVALENT - DIRECT SYNTHESIS OF ENANTIOMERICALLY PURE PROTECTED AMINO-ACIDS

Treatment of the glutamic acid derived iodide 7 with Rieke copper at -78-degrees-C generates the functionalised alkyl copper reagent 6b, an alpha-amino acid gamma-anion equivalent, which reacts directly with acid chlorides and allylic chlorides at -30-degrees-C to give the products of substitution 10-12. In two cases, the enantiomeric purity of the products was established by comparison of optical rotation data with literature values, indicating that the coupling process occurs without racemisation.