ChemInform Abstract: Stereoselective Synthesis of 2,4‐Diamino Acids by Asymmetric Hydrogenation.

Abstract

ChemInform Abstract A previously described methodology for the synthesis of optically active neutral amino acids by means of asymmetric hydrogenation of cyclic α,β-dehydro dipeptides of type (III) is now extended to amino acids possessing a functionalized side chain with or without an additional chiral center. Thus, the individual diastereomers of the unusual basic amino acids (IV) and (V) as well as L-ornithine (VII) are obtained by analogous routes using the derivatives (I) of L-and D-alanine as starting materials. The fact that high selectivities are only observed in the hydrogenations leading to (VII) (obtained in "good optical yield") and from (IIIc) to (2S)-(V) indicate that the extent of chiral induction is not only determined by the methyl group of the chiral source (I). -The Rf values (paper chromatography) of the diastereomers (IV) are not identical with that of a metabolic product of Clostridium sticklandii, previously described as 2,4-diaminopentanoic acid.