A stereocontrolled synthesis of a new class of 3,4,5,6-tetrahydropyrimidine-based chiral amino acids

The stereocontrolled synthesis of seven 2-substituted-4-carboxy-3,4,5,6-tet rahydropyrimidines bearing either one chiral center at C-4 or two chiral ce nters at C-4 and C-8 was performed by condensation of (S)- or (R)-2, 4-diam inobutyric acid (Daba) with iminoethers derived from glycine. (S)- and (R s erine, (S)- and (R)-tyrosine. Under the conditions reported, epimerization was always completely prevented at the C-4 center, whereas at the C-8 cente r, it was completely avoided in the case of tyrosine derivatives and consid erably diminished for the serine derivatives. (C) 1999 Elsevier Science Ltd . All rights reserved.