THE SYNTHESIS OF D-EVALOSE

D-Evalose (1: 6-deoxy-3-C-methyl-D-mannose) was synthesized from methyl 3, 3′-anhydro-4, 6-O-benzylidene-3-C-hydroxymethyl-2-O-methyl-α-D-mannopyranoside (3) through five-step derivations, and the structure was confirmed by the conversion into D-nogaloside (8: methyl 6-deoxy-3-C-methyl-2,3,4-tri-O-methyl-α-D-mannopyranoside)

A FACILE SYNTHESIS OF METHYL 4,6-DIDEOXY-3-c-METHYL-4-METHYLAMINO-α-L-MANNOPYRANOSlDE (SIBIROSAMINIDE)

The title branched-chain sugar obtained by methanolysis of sibiromycin was easily synthesized from L-rhamnose through eight-step conversions

Branched-chain Sugars. XII. The Stereoselectivities in the Reaction of Methyl 4,6-O-Benzylidene-α- and -β-D-hexopyranosid-3-uloses with Diazomethane

The stereoselectivities in the diazomethane reaction of methyl 4,6-O-benzylidene-2-O-methyl-α-D-ribo-hexopyranosid-3-ulose (2), its 2-epimer (3), β-anomer of 2 and the corresponding 2-O-Benzoyl derivative were examined, in comparison with those in the Grignard reaction and sodium borohydride reduction. The complemental stereoselectivity of diazomethane reaction in the case of 2 and 3 indicated that the electrostatic attractive effect in the transition state between diazomethyl cation and the axial methoxyl oxygen at the α-position to carbonyl function in 3 is much stronger than that at β-position which is predominat in the case of 2. In cases of β-anomers having no axial oxygen, stereoselectivies were preferentially controlled by the usual steric factors

SYNTHESIS OF METHYL β-D-VIRENOSIDE

Methyl 6-deoxy-3-C-methyl-β-D-gulopyranoside (1: methyl β-D-virenoside) has been synthesized from galactose. The introduction of methyl branching at C-3 position was achieved by the Grignard reaction

Branched-chain Sugars. IX. Reaction of 3,6-Anhydro-1,2-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose with Nitromethane or Hydrogen Cyanide

3,6-Anhydro-1,2-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose (2) was converted into 5,6-di-O-acetyl-1, 2-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose (5) by the protection of the carbonyl function with hydroxylamine, followed by acetylation and removal of the protecting group with chromium(II) acetate. Nitromethane condensation of 2 and 5 at room temperature gave the corresponding 3-nitromethyl derivatives having D-gluco- and D-allo-configuration, respectively. The difference in the stereoselectivity was explained by the easiness of isomerization of the initial product to thermodynamically stable epimer, because the reaction temperature was essential to control the selectivity in the same reaction of 1,2 : 5,6-di-O-isopropylidene-α-D-ribo-hexofuranos-3-ulose. Reaction of 2 with hydrogen cyanide in dry pyridine followed by acetylation gave the corresponding 3,5,6-tri-O-acetyl-3-cyano derivative of D-allo-type, whereas, the reaction in water gave instantly 3-(hydroxycarbonimidoyl)-1,2-O-isopropylidene-α-D-allofuranose 3′,5-lactone, by the participation of the C5-hydroxyl group

Synthesis of Methyl-branched 2,3,4,5-Tetrahydroxycyclohexanone Derivatives via 6-Deoxyhex-5-enopyranosides

Seven novel methyl-branched 2,3,4,5-tetrahydroxycyclohexanone derivatives were prepared in good yields by Ferrier reaction via corresponding key intermediates: 6-deoxyhex-5-enopyranosides

SYNTHESIS OF EVERNITROSE AND ITS ENANTIOMER

Evernitrose (1: 2,3,6-trideoxy-3-C,4-0-dimethyl-3-nitro-Larabino-hexopyranose) and its enantiomer (17) were synthesized frommethyl 2,6-dideoxy-4-o-methyl-a-L-erythro-hexopyranosid-3-ulose and methyl 4,6-o-benzylidene-2-deoxy-a-D-erythro-hexopyranosid-3-ulose, respectively. In both cases, the unique nitro group attached to thetertiary branching carbon was introduced by oxidation of the corresponding amino derivatives prepared by Bourgeois\u27s method

Synthesis of the Functionalized Cyclohexanecarbaldehyde Derivative. A Potential Key Compound for Total Synthesis of Optically Active Tetrodotoxin

Oxidation of 1L-(1,2,3′,4,5/3,6)-3-hydroxymethyl-2,4,5-tri-O-methoxymethyl-3,3′-O-methylene-6-nitro-2,3,4,5-tetrahydroxycyclohexanecarbaldehyde dimethyl acetal with potassium t-butoxide and m-chloroperbenzoic acid has given corresponding carbonyl derivative in 65% yield. The carbonyl compound has been successfully converted into the desired key compound for tetrodotoxin synthesis in excellent yield via the spiro α-chloro-epoxide derivative

Branched-chain Sugars. XXXV. The Synthesis of L-Rubranitrose (2,3,6-trideoxy-3-C-methyl-4-O-methyl-3-nitro-L-xylo-hexopyranose)

The title compound was stereoselectively synthesized from methyl 2,6-dideoxy-4-O-methyl-β-L-thero-hexopyranosid-3-ulose (11) through the successive conversions; cyanomesylation, reductive spiro aziridine formation, reductive ring-opening to the methyl-branched amino sugar, oxidation to the corresponding nitro sugar

Convenient Synthesis of Hex-5-enopyranosides

Hex-5-enopyranosides were prepared in an one-pot procedure from 6-bromo-6-deoxy- or 6-O-tosylhexopyranoside by the successive treatment with iodide anion and 1,8-diazabicyclo-[5.4.0]undec-7-ene in DMSO