J. K. N. Jones

Syntheses related to dendroketose

Abstract A stereospecific synthesis of l -dendroketose [4-C-(hydroxymethyl)- l -glycero-pentulose] has been attempted starting from 2,3:4,5-di-O-isopropylidene-aldehydo- d -arabinose (1). A key step in the proposed route is the O-debenzoylation of 1,5-di-O-benzoyl-4-C-(benzoyloxymethyl)-3,4-O-isopropylidene- l -glycero-pentulose (6). However, treatment of 6 with sodium methoxide in methanol at 0° afforded 3,4-O-isopropylidenedendroketose as the dl modification. The racemization process was investigated by deuterium-exchange studies.

Oxidation of a branched-chain alditol by Acetobacter suboxydans: A stereospecific synthesis of l-dendroketose

A synthesis of L-dendroketose (5) has been achieved by microbiological oxidation by Acetobacter suboxydans of the branched-chain alditol 2-C-(hydroxy-methyl)-D-erythro-pentitol (4). Treatment of the oxidation product with acetone, copper(II) sulfate, and sulfuric acid afforded the two di-O-isopropylidene-L-dendro-ketose derivatives 6 and 7. Assignment of configuration at the branching carbon atom (C-4) and at the anomeric center in 6 and 7 was made on the basis of the carbon-13 magnetic resonance spectra of these derivatives.

Reaction of hexopyranoside α-keto toluene-p-sulfonates with triethylamine-methanol☆

Abstract Treatment of methyl 4,6- O -benzylidene-2- O - p -tolylsulfonyl-α- D - ribo -hexopyranosid-3-ulose ( 1 ) with triethylamine-methanol at reflux temperature yields methyl 2,3-anhydro-4,6- O -benzylidene-3-methoxy-α- D -allopyranoside ( 2 ), a derivative ( 3 ) of 3-hydroxy-2-(hydroxymethyl)-4 H -pyran-4-one, and methyl 4,6- O -benzylidene-α- D - ribo -hexopyranosid-3-ulose dimethyl acetal ( 4 ). The reaction of methyl 4,6- O benzylidene-3- O - p -tolylsulfonyl-α- D - arabino -hexopyranosid-2-ulose ( 12 ) with triethylamine-methanol afforded methyl 4,6- O -benzylidene-α- D - ribo -hexopyranosid-2-ulose dimethyl acetal ( 19 ) and methyl 2,3-anhydro-4,6- O -benzylidene-2-methoxy-α- D -allopyranoside ( 20 ); from the reaction of the β- D anomer ( 13 ) of 12 , methyl 4,6- O -benzylidene-β- D - ribo -hexopyranosid-2-ulose dimethyl acetal ( 21 ) was isolated. Syntheses of the α-keto toluene- p -sulfonates 12 and 13 are described. Mechanisms for the formation of the compounds isolated from the reactions with triethylamine-methanol are proposed.

Synthesis of nucleosides by direct replacement of the anomeric hydroxy-group

A novel synthesis of purine nucleosides of aldoses and ketoses has been developed, by a method involving treatment of an appropriately protected sugar derivative having a free anomeric hydroxy-group with 6-chloropurine, diethyl azodicarboxylate, and methyldiphenylphosphine.

Syntheses towards the carbohydrate moiety of lincomycin

A key intermediate in the synthesis of the antibiotic lincomycin, 6-acetamido-6,8-dideoxy-1,2:3,4-di-O-isopropylidene-α-D-erythro-D-galacto-octopyranose (10), has been synthesised from cis-6,7,8-trideoxy-1,2:3,4-di-O-isopropylidene-7-C-nitro-α-D-galacto-oct-6-enose (3). The amino-group at C-6 was introduced by two different procedures.