Conversion of fructose into a building block for the synthesis of carbocyclic mannose mimics

Fructose was converted into C-1 diastereomeric carbocyclic building blocks resembling mannose using ruthenium-catalysed ring-closing metathesis as a key step. The potential use of the compounds in the synthesis of valienamine pseudodisaccharides is demonstrated using Mitsunobu coupling chemistry directly between a carbohydrate sulfonamide and the carbasugar C-1 alcohols.

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Methyl 6-N-[2,3,4,6-tetra-O-benzyl-5a-carba-α-d-lyxo-hex-5(5a)-enopyranosylamino]-2,3,4-tri-O-benzyl-6-deoxy-α-d-mannopyranosideC63H67O9N[α]D22=+27.6 (c 1.0, CHCl3)Source of Chirality: d-Fructose

(3R,4R,5R) 1,3,4,5-Tetra-O-benzyl-2-methylene-hexane-1,3,4,5,6-pentaolC35H38O5[α]D22=-6.5 (c 1.0, CHCl3)Source of Chirality: d-Fructose

1,3,4,5-Tetra-O-benzyl-6-O-benzoyl-d-fructoseC41H40O7[α]D21=-4.2 (c 1.0, CHCl3)Source of Chirality: d-Fructose

2,3,4,6-Tetra-O-benzyl-5a-carba-α-d-lyxo-hex-5(5a)-enopyranoseC35H36O5[α]D23=+10.4 (c 1.0, CHCl3)Source of Chirality: d-Fructose

2,3,4,6-Tetra-O-benzyl-5a-carba-β-d-lyxo-hex-5(5a)-enopyranoseC35H36O5[α]D24=-56.0 (c 1.0, CHCl3)Source of Chirality: d-Fructose