Synthesis of methyl 4,6-O-benzylidene-2,3-dideoxy-2-C-formyl-alpha-D-erythro-hex-2-enopyranoside

The synthesis of the title compound was achieved in seven steps and 61% overall yield from methyl alpha-D-glucopyranoside.     

Photoreaction of methyl and phenyl 4,6-O-benzylidene-2,3-dideoxy-2-C-p-tolylsulfonyl-beta-D-erythro-hex-2-enopyranosides in methanol

The title compounds were irradiated with a high-pressure mercury lamp in methanol to give 2-C-hydroxymethyl derivatives having the gluco, altro, and allo configurations as well as an S(N)2' product. Equatorial attack of a hydroxymethyl radical slightly predominated over axial attack. During chromatographic separation on a silica gel column, partial migration of the 4,6-O-benzylidene group in the gluco and altro products occurred to yield the 3',4-O-benzylidene derivatives.     

Kinetically controlled nucleophilic addition-reactions to methyl 4,6-O-benzylidene-2,3-dideoxy-2-nitro-α-d-erythro-hex-2-enopyranoside

Axial attack mainly occurred in the reactions of methyl 4,6-O-benzylidene-2,3-dideoxy-2-nitro-α-d-erythro-hex-2-enopyranoside with sodium borodeuteride, hydrogen peroxide, hydrogen cyanide, and methanol, whereas equatorial attack predominated in the reaction with sodium methoxide and tert-butyl peroxide.     

Synthesis, crystal structure, and high-resolution NMR spectroscopy of methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl-alpha-D-xylo-hexopyranoside

Synthesis of methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl- and -6-O-p-tolylsulfonyl-alpha-D-xylo-hexopyranosides is presented. High-resolution 1H and 13C NMR spectral data for both compounds and their precursors, and the single-crystal X-ray diffraction analysis for methyl 3-azido-2,3-dideoxy-4,6-di-O-p-tolylsulfonyl-alpha-D-xylo-hexopyranoside are reported. The influence of the O-protective group on the chemical shift of adjacent atoms in the 1H and 13C NMR spectra is discussed.     

Synthesis of 2,3:4,6-di-O-isopropylidene-D-allopyranose from D-glucose

2,3:4,6-Di-O-isopropylidene-d-allopyranose can be conveniently prepared from d-glucose via a synthetic sequence, which includes Mitsunobu inversion at O-3, di-O-isopropylidenation of phenyl-1-thio-d-alloside and anomeric deprotection on treatment with NBS/CaCO3.     

X-ray crystallographic and high-resolution NMR spectroscopy characterization of 4,6-di-O-acetyl-2,3-dideoxy-alpha-D-erythro-hex-2-enopyranosyl sulfamide

Single crystal X-ray diffraction and high-resolution ¹H and ¹³C NMR spectral data for 4,6-di-O-acetyl-2,3-dideoxy-α-d-erythro-hex-2-enopyranosyl sulfamide, a selective inhibitor of carbonic anhydrase isozyme IX, are reported. The ⁰H₅ was found to be the preferred form for this glycosyl sulfamide, both in the crystal lattice and in solution.     

O-ethylidene-D-allopyranoses: 1,2-O-,1,2:4,6-, and 2,3:4,6-di-O-ethylidene derivatives

Solutions of 1,2-O-acetoxonium chlorides derived from O-acetylated D-allopyranose derivatives were treated with sodium borohydride to give three pairs of previously unknown 1,2-O-ethylidene-α-D-allopyranose diastereoisomers: 3,4,6-tri-O-acetyl-1,2-O-ethylidene-α-D-allopyranoses; 4,6-di-O-acetyl-3-O-benzyl-1,2-O-ethylidene-α-D-allopyranoses; and 3-O-benzyl-1,2:4,6-di-O-ethylidene-α-D-allopyranoses. Examples of a second class of novel O-ethylidene-D-allopyranoses, the diastereoisomeric methyl 2,3:4,6-di-O-ethylidene-α-D-allopyranosides, were prepared by treating methyl 4,6-O-benzylidene-α-D-alloside with acetaldehyde-sulfuric acid. Assignments of dioxolane ring configurations and pyranose conformations were made by n.m.r. analyses.     

Stereoselective synthesis of methyl 4,6-O-benzylidene-2-C-methoxycarbonylmethyl-alpha-D-ribo-hexopyranosid-3-ulose, and its X-ray crystallographic analysis

Methyl 4,6-O-benzylidene-2-C-methoxycarbonylmethyl-alpha-D-ribo-hexopyranosid-3-ulose has been stereoselectively synthesized in 65% yield by reaction of methyl 4,6-O-benzylidene-alpha-D-arabino-hexopyranosid-2-ulose with diethyl malonate. X-ray crystallographic structure analysis reveals that the chain-branch and the OH group are bonded to C-2 in axial and equatorial positions, respectively. The molecules in the crystal lattice are stacked along a one-dimensional chain, with intermolecular hydrogen bonds between O-8 of one molecule and 2-OH of the next as well as intramolecular hydrogen bonds between O-3 and 2-OH. All phenyl groups are parallel as well as the planes of sugar rings in the molecular columnar stacking.     

Synthesis of the 6-methyl and 3,6- and 4,6-dimethyl ethers of methyl 2-acetamido-2-deoxy-α-D-mannopyranoside

The 6-mono- (6) and 4,6- (16) and 3,6-di-methyl (25) ethers of methyl 2-acetamido-2-deoxy-α-D-mannopyranoside have been synthesized from 6-O-trityl, 4,6-O-benzylidene, and 3-O-methyl derivatives, respectively, by way of O-benzoyl and of O-allyl derivatives. The yields were respectively 37 and 43% for 6, 34 and 50% for 16, and 14 and 25% for 25. These ethers are used as standard compounds for the structure elucidation, by methylation, of polymers containing 2-amino-2-deoxy-D-mannose.     

Inhibition of sweet taste in humans by methyl 4,6-dichloro-4,6-dideoxy-{alpha}-D-galactopyranoside

The glycoside methyl 4,6-dichloro–4,6-dideoxy--D-galactopyranoside,an inhibitor of electrophysiological responses to sweet tastein gerbils, was also found to suppress the perceived intensitiesof various sweeteners in human psychophysical experiments. Incontrast, this compound did not suppress the salty and sourtastes in either species.     

An efficient synthesis of methyl 2,3-anhydro-alpha-D-ribofuranoside

An efficient synthesis of methyl 2,3-anhydro-alpha-D-ribofuranoside is reported. Its preparation is achieved via a four-step sequence from methyl 2,3,5-tri-O-benzoyl-alpha-D-arabinofuranoside in 74% overall yield.