4-alkoxycarbonyloxazoles as β-hydroxy-α-amino acid synthons: efficient stereoselective syntheses of 3-amino-2,3,6-trideoxyhexoses and a hydroxy amino acid moiety of Al-77-B
4-alkoxycarbonyloxazoles as β-hydroxy-α-amino acid synthons: efficient stereoselective syntheses of 3-amino-2,3,6-trideoxyhexoses and a hydroxy amino acid moiety of Al-77-B