A diastereoselective C–C bond formation at C-5 of d-gulose. A convenient approach to (5S)-5-C-alkyl-β-l-lyxo-hexofuranoses

A flexible approach to the stereoselective synthesis of (5S)-5-C-methyl- and (5S)-5-C-ethyl-β-l-lyxo-hexofuranoses 15a, 22 starting from 1,2:5,6-di-O-isopropylidene-α-d-gulofuranose 3 as the source of chirality is described. The corresponding C-5 alkyl groups were introduced via a Wittig olefination followed by Pd/C-mediated hydrogenation of the conformationally restricted alkenes in a highly diastereoselective manner.

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5-Deoxy-1,2-O-isopropylidene-5-C-methylene-β-l-lyxo-hexofuranoseC10H16O5[α]D20=+40.1 (c 0.58, CHCl3)Source of chirality: d-guloseAbsolute configuration: (1R,2R,3R,4S)

5-Deoxy-1,2:3,6-di-O-isopropylidene-5-C-methylene-β-l-lyxo-hexofuranoseC13H20O5[α]D20=-84.0 (c 0.64, CHCl3)Source of chirality: d-guloseAbsolute configuration: (1R,2R,3R,4S)

(5S)-5-Deoxy-1,2:3,6-di-O-isopropylidene-5-C-methyl-β-l-lyxo-hexofuranoseC13H22O5[α]D20=+2.1 (c 0.40, CHCl3)Source of chirality: d-guloseAbsolute configuration: (1R,2R,3R,4S,5S)

(5S)-5-Deoxy-5-C-ethyl-1,2:3,6-di-O-isopropylidene-β-l-lyxo-hexofuranoseC14H24O5[α]D20=-35.0 (c 0.20, CHCl3)Source of chirality: d-guloseAbsolute configuration: (1R,2R,3R,4S,5S)

(5R)-5-Deoxy-1,2-O-isopropylidene-5-C-methyl-β-l-lyxo-hexofuranoseC10H18O5[α]D20=-2.0 (c 0.20, CHCl3)Source of chirality: d-guloseAbsolute configuration: (1R,2R,3R,4S,5R)

(5S)-5-Deoxy-1,2-O-isopropylidene-5-C-methyl-β-l-lyxo-hexofuranoseC10H18O5[α]D20=+4.5 (c 0.20, CHCl3)Source of chirality: d-guloseAbsolute configuration: (1R,2R,3R,4S,5S)

(5S)-5-Deoxy-5-C-ethyl-1,2-O-isopropylidene-β-l-lyxo-hexofuranoseC11H20O5[α]D20=+33.7 (c 0.25, CHCl3)Source of chirality: d-guloseAbsolute configuration: (1R,2R,3R,4S,5S)