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C-glycoside syntheses: Part I. Dendritic syntheses of hexose and aminohexose C-pyranosides from 2,6-anhydro-5,7-O-benzylidene-1-deoxy-1-nitro-D-guloheptitol (82). Part II. Henry condensation of nitroethane and nitropropane with 4,6-O-benzylidene-D-glucopyranose (81)Wang, Xiaojing 01 January 1993 (has links)
The di-O-acetyl derivative of 4,6-O-benzylidene-1-deoxy-1-nitromethyl-β-D-glucopyranose was reduced by a mixture of elemental iron and nickel in aqueous tetrahydrofuran under CO2, with concurrent O → N acetyl migration to 1-acetamido-4-O-acetyl-2,6-anhydro-5,7-O-benzylidene-1-deoxy-D-glycero-D-guloheptitol. Its 2-O-mesyl derivative was converted by base into the D-manno-2,3-epoxide. The epoxide ring was opened by NH3 to give the 3-amino-β-D-altropyranose derivative, which was subsequently N-benzoylated to 1-acetamido-2,6-anhydro-4-benzoylamino-5,7-O-benzylidene-1,4-dideoxy-D-glycero-D-glucoheptitol. Attempts to prepare 1-acetamido-2,6-anhydro-4-benzoylamino-5,7-O-benzylidene-1,4-dideoxy-3-methanesulfonyl-Dglycero-D-glucoheptitol gave spontaneously the D-allo-oxazoline derivative. However, a 3-O-mesyl derivative could be obtained by mesylation of 1,4-di-acetamido-2,6-anhydro-5,7-0-benzylidene-I,4-dideoxy-D-glycero-D-glucoheptitol. 2,6-Anhydro-5,7-O-benzylidene-1-deoxy-1-nitro-D-glycero-D-guloheptitol was reduced and N-acetylated to the acetamidomethyl derivative. 3,4-Di-O-mesylation of 1-acetamido-2,6-anhydro-5,7-O-benzylidene-1-deoxy-D-glycero-D-guloheptitol gave 1-acetamido-2,6-anhydro-5,7-O-benzylidene-1-deoxy-3,4-dimethanesulfonyl-D-glycero-D-guloheptitol, which reacted with methoxide to give the D-manno-2,3-epoxide, and mostly 2,6-anhydro-5,7-O-benzylidene-1-deoxy-D-glycero-D-gluco-heptitol [1,2,3, : 4',5',6']- 2'-methyl-2'-oxazine, presumably via a D-allo-2,3-epoxide.
The condensation of 4,6-O-benzylidene-D-glucopyranose with nitroethane gave 2,6-anhydro-1,3-O-benzylidene-7,8-dideoxy-7-nitro-D-threo-L-gulooctitol and its diastereomer, which was obtained by an acetylation-deacetylation procedure. 2,6-Anhydro-1,3-O-benzylidene-7,8-dideoxy-7-nitro-L-erythro-L-gulooctitol was reduced by a mixture of elemental Fe°/Ni° in aqueous FHF under CO2 to 7-amino-2,6-anhydro-1,3-O-benzylidene-7,8-dideoxy-L-erythro-L-gulooctitol with retention of the 4,6-O-benzylidene blocking group. Acetylation of 2,6-anhydro-1,3-O-benzylidene-7,8-dideoxy-7-nitro-D-threo-L-gulooctitol produced an open chain compound. Cyclic product was not isolated. The oxime derivative, 4,5-di-O-acetyl-3,7-anhydro-6,8-O-benzylidene-1,2-dideoxy-2-oxime-D-glycero-D-guloheptitol, was separated as a byproduct from the acetylation. The condensation of nitropropane with 4,6-O-benzylidene-B-D-glucopyranose, followed by acetylation of the reaction solution, gave 4,5-di-O-acetyl-2,6-anhydro-1,3-O-benzylidene-7-nitro-7,8,9-trideoxy-D-threo-L-gulononitol and its diastereomer. Deacetylation of 4,5-di-O-acetyl-2,6-anhydro-1,3-O-benzylidene-7-nitro-7,8,9-trideoxy-D-threo-L-gulononitol gave 2,6-anhydro-1,3-O-benzylidene-7-nitro-7,8,9-trideoxy-D-threo-L-gulononitol, which could be reduced to the free amino compound by a mixture of elemental Fe°/Ni° in aqueous THF under CO2.
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