The (4S,5S)-2-phenyl-4,5-dimethyl-4-formyl-4,5-dihydro-oxazole (4),viathe α, β-unsaturated ester5andre-face addition of nitrogen and sulfur nucleophiles, gave eventually theribo-imidazolino hexose 15 and the methyl α and β-2,3,4-6-tetradeoxy-4-C-methyl-4-trifluoroacetamido-3-thia-L-ribo-hexopyranoside (16). Additionviathe adduct17afforded thearabino-3,4-diamino derivative20and theriboisomer20a, the 3-fluoro-L-riboproduct22, the 2,3-unsaturated L-hexose21and theerythro-2,3,4,6-tetradeoxy compound23. The conformational feature, in solution, of the reported L-hexoses is also discussed on the basis of their1H NMR data.