Synthesis of chiral non-proteinogenic 4,5-dihydroxytetrahydropyran derived α-amino acids from d-mannitol

Starting from R-2,3-O-cyclohexylideneglyceraldehyde, which was obtained from d-mannitol, four tetrahydropyran derived chiral, non-proteinogenic α-amino acids have been synthesized. The key step in these syntheses is the ring closing metathesis using the first generation Grubbs’ catalyst.