1978 Volume 51 Issue 12 Pages 3595-3598
The Grignard reaction of 3-O-benzyl-6-deoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranos-5-ulose (5) with ethylmagnesium bromide yielded 3-O-benzyl-6-deoxy-5-C-ethyl-1,2-O-isopropylidene-α-D-glucofuranose (6) as a major product in 91% stereoselectivity. Hydrolysis of 6 followed by successive periodate oxidation and lithium aluminium hydride reduction gave 2-O-benzyl-5-deoxy-4-C-ethyl-D-arabinitol. Selective benzoylation of 9 followed by successive 3,4-O-isopropylidenation, debenzoylation, hydrogenolysis, and two-stage oxidation with periodate-hypoiodite afforded (4R,5S)-(+)-5-ethyl-2,2,5-trimethyl-1,3-dioxolane-4-carboxylic acid (15) in 24.6% overall yield from 5. Hydrolysis of 15 gave (2R,3S)-(−)-2,3-dihydroxy-3-methylpentanoic acid. The acetonide 15 is usefull as a synthon for pyridomycin synthesis.
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