Ton That Thang

Synthesis of α-azido aldehydes. Stereoselective formal access to the immunosuppressant myriocin

Abstract Stereoselective preparation of an acyclic α-azido aldehyde permitted access in a few steps to a key intermediate in a formal synthesis of myriocin.

Synthesis of benzyl and methyl 3-benzamido-2,3,6-trideoxy-2-fluoro-β-l-galactopyranoside: Protected C-2 fluoro analogues of daunosamine

Abstract The reaction of benzyl 2-benzamido-4,6- O -benzylidene-2-deoxy-3- O -tosyl-α- d -glucopyranoside or benzyl 4,6- O -benzylidene-2,3-benzoylepimino-2,3-dideoxy-α- d -allopyranoside with anhydrous tetrabutylammonium fluoride in hexamethylphosphoric triamide gave ∼40% of benzyl 3-benzamido-4,6- O -benzylidene-2,3-dideoxy-2-fluoro-α- d -altropyranoside ( 6a ). Transformation of 6a into benzyl 3-benzamido-2,3,6-trideoxy-2-fluoro-α- d - arabino -hex-5-enopyranoside ( 13a ) was carried out by well-established methodology. Hydrogenation of the double bond in 13a furnished the title compound in good yield. Methyl 3-benzamido-2,3,6-trideoxy-2-fluoro-β- l -galactopyranoside was also prepared in nine steps from 2-amino-2-deoxy- d -glucose.

The megalomicins. Part 7. A structural revision by carbon-13 nuclear magnetic resonance and X-ray crystallography. Synthesis and conformational analysis of 3-dimethylamino- and 3-azido-D- and -L-hexopyranosides, and the crystal structure of 4″-O-(4-lodobenzoyl)megalomicin A

An X-ray crystallographic study on 4″-O-(4-iodobenzoyl)megalomicin A has led to the revision of the structures of the megalomicins and the XK-41 antibiotics. Crystals are orthorhombic, space group P212121 with a= 12.669(2), b= 19.501 (6), c= 25.741 (9)A, and Z= 4. The structure was solved by the heavy-atom technique, and 1 812 observed reflections led to a final R of 0.095. The novel amino-sugar previously thought to be D-rhodosamine has been shown to have the L-configuration and is therefore renamed L-megosamine. It has also been shown to be glycosidically attached to the tertiary 6-hydroxy group. The 13C n.m.r. and circular dichroism (c.d.) parameters of these macrolides are described. The syntheses of methyl α- and β-D-rhodosaminide, methyl α- and β-D-megosaminide, methyl α- and β-L-megosaminide, methyl α- and β-D-angolosaminide, and methyl 2,3,6-trideoxy-3(dimethylamino)-α-D-xylo-hexopyranoside are described and their conformations and 13C n.m.r. parameters are discussed. Methyl α-D- and -L-amicetoside, methyl α-D- and -L-cineruloside and other model 4-oxopyranosides and pyrans have been synthesized. Their c.d. properties have been determined and they have been shown to exhibit Anti-Octant behaviour.

Synthesis of a derivative of vancosamine, a component of the glycopeptide antibiotic vancomycin

A derivative of the branched-chain sugar 3-amino-2,3,6-trideoxy-3-C-methyl-L-lyxo-hexose (vancosamine) has been synthesised.

A new approach to the stereospecific synthesis of branched-chain sugars

Darzens condensation of two readily available carbohydrate ketones with chloromethyl p-tolyl sulphone gave stereospecifically α,β-epoxy sulphones, in the presence of azide ion the latter afforded branched-chain functionalized azido-sugars.

Chiral synthons for the total synthesis of macrolide antibiotics

All the methyl 2,4-dideoxy-2,4-di-C-methyl-6-O-dimethyl-t-butylsilyl-α-D-hexopyranosides, chiral intermediates in the total synthesis of many biologically important natural products have been prepared.