Asymmetric Synthesis of 2,4,6-Trideoxy-4-(dimethylamino)-3-C-methyl-Llyxohexopyranose (Lemonose)

L-Lemonose, the glycosidic part of (–)-lemonomycin, has been synthesized in ten steps with 18% overall yield from Dthreonine. The key steps are a double, highly diastereoselective Grignard addition to a Weinreb amide and a chemoselective oxidation of a primary alcohol in the presence of a secondary alcohol, a tertiary alcohol and a tertiary amine, leading directly to the lactol.