J.K.N. Jones

Synthesis of deoxy and aminodeoxy sugars by way of chlorodeoxy sugars

Abstract Chlorodeoxy sugars, readily prepared by the reaction of sulfuryl chloride with carbohydrates containing free hydroxyl groups, have been shown to be valuable intermediates in the synthesis of deoxy and aminodeoxy sugars. Hydrogenation of methyl 4,6-dichloro-4,6-dideoxy-α- D -galactopyranoside (1) over Raney nickel in the presence of triethylamine results in a selective dechlorination at the secondary position to give methyl 6-chloro-4,6-dideoxy α- D -xylo-hexopyranoside (2).

The synthesis of D-arcanose☆

Abstract Oxidation of methyl 4,6- O -benzylidene-2-deoxy-α- D - lyxo -hexopyranoside ( 3 ) with ruthenium tetroxide gave the 3-ketone 4 in high yield. Treatment of ketone 4 with methylmagnesium iodide gave predominantly methyl 4,6- O -benzylidene-2-deoxy-3- C -methyl-α- D - xylo -hexopyranoside (5), which was converted into the 3- O -methyl derivative ( 6 ). The reaction of compound 6 with N -bromosuccinimide afforded methyl 4- O -benzoyl-6-bromo-2,6-dideoxy-3- C -methyl-3- O -methyl-α- D - xylo -hexopyranoside (7) in high yield. Compound 7 was converted, by catalytic debenzoylation and reductive debromination, into methyl α- D -arcanoside (9). Acid-catalyzed hydrolysis of glycoside 9 gave D -arcanose ( 10 ). Configurational studies support the 2,6-dideoxy-3- C -methyl-3- O -methyl- xylo -hexose structure for arcanose.

Some structural features of citrus limonia gum (lemon gum)

Abstract Lemon gum contains residues of D -galactose, L -arabinose, L -rhamnose, D -glucuronic acid, and 4- O -methyl- D -glucuronic acid. Graded, acid hydrolysis affords 3- O -β- L -arabinopyranosyl- L -arabinose, 5- O -α- L -arabinopyranosyl- L -arabinose, 4- O -(4- O -methyl-α- D -glucopyranosyluronic acid)- L -arabinose, three acidic trisaccharides [including O -(4- O -methyl-α- D -glucopyranosyluronic acid)-(1→4)- O -α- L -arabinopyranosyl-(1→5)- L -arabinosel, and higher acidic oligosaccharides. The methylated gum yields 2,3,4-tri- O -methyl- L -rhamnose, 2,3,5- and 2,3,4-tri-, and 2,3-, 2,5-, and 3,5-di- O -methyl- L -arabinose, 2,4-di- O -methyl- D -galactose, and 2,3,4-tri- and 2,3-di- O -methyl- D -glucuronic acid, together with small proportions of 2,3,4,6-tetra-, and 2,3,6-, 2,4,6-, and 2,3,4-tri- O -methyl- D -galactose. Partial, acid hydrolysis of the degraded gum, obtained after graded, acid hydrolysis, affords the β-(1→3)- and β-(1→6)-linkid D -galactose disaccharides, 4- O -(4- O -methyl-α- D -glucopyranosyluronic acid)- D -galactose, 6- O -(β- D -glucopyranosyluronic acid)- D -galactose, and 4- O -(α- D -glucopyranosyluronic acid)- D -galactose. Its O -methyl derivative yields 2,3,4-tri- and 2,3-di- O -methyl- L -arabinose, 2,3,4,6-tetra-, 2,3,6- 2,4,6-, and 2,3,4-tri-, 2,6- and 2,4-di-, and 2- O -methyl- D -galactose, and 2,3,4-tri- O -methyl- D -glucuronic acid. The degraded gum was subjected to a Smith-degradation, and lemon gum to two successive Smith-degradations, and the products were examined by linkage and methylation analysis. It is concluded that the molecules of lemon gum are based on galactan frameworks of a branch-on-branch type, to which are attached rhamnose-, arabinose-, and uronic acid-containing side-chains.

Some structural studies on the galactan from the albumen glands of the snail, Strophocheilus oblongus

Abstract The galactan elaborated by the albumen glands of Strophocheilus oblongus is composed mainly, if not entirely, of β-linked D -galactopyranose residues. Acetolysis afforded D -galactose, 3- O -β- D -galactopyranosyl- D -galactose, and higher oligosaccharides. Borohydride reduction of the periodate-oxidized polysaccharide yielded a polyalcohol, which on hydrolysis with acid gave D -galactose and glycerol (Smith-type degradation). Controlled hydrolysis by acid of the polyalcohol (obtained after three Smith-type degradations) yielded a degraded polysaccharide (8%) and glycerol only. The fully methylated galactan after hydrolysis gave 2,3,4,6-tetra- (43 mole%), 2,4,6-tri- (11 mole%), 2,3,4-tri- (2.5 mole%), 2,4-di- (43 mole%), and trace amounts of 2,3,6-tri- (0.5 mole%)- O -methyl- D -galactose derivatives. These results indicate that the galactan of S. oblongus is a highly branched polysaccharide and that it has structural features which differentiate it from galactans of other molluscs that had been studied previously.

Some structural features of the mucilage from the bark of Ulmus fulva (slippery elm mucilage)

Abstract Slippery elm mucilage contains residues of l -rhamnose, d -galactose, 3-O-methyl- d -galactose, and d -galacturonic acid. The methylated polysaccharide yields 3-O- and 4-O-methyl- l -rhamnose, 2,3,4,6-tetra- and 2,3,6-tri-O-methyl- d -galactose, and 2,3,4-tri- and 2,3-di-O-methyl- d -galacturonic acid, in addition to trace amounts of 2,3,4-tri and 3,4-di-O-methyl- l -rhamnose and 2,4,6-tri-O-methyl- d -galactose. Borohydride reduction of the periodate-oxidised polysaccharide yields a polyalcohol, which, on partial hydrolysis with acid, affords O-(3-O-methyl- d -galactopyranosyl)-(1 → 4)-O-(3-O-methyl- d -galactopyranosyl)-(1 → 4)-O-(3-O-methyl- d -galactopyranosyl)-(1 → 4)- l -rhamnose. Mild, acid hydrolysis yields a Smith-degraded polysaccharide. Methylation analyses are reported for the polyalcohol and for the Smith-degraded polysaccharide. It is concluded that the polysaccharide contains chains of 3-O-methyl- d -galactose residues attached to the C-4 positions of certain l -rhamnose residues, and that 3-O-methyl- d -galactose residues occur in some cases as non-reducing end-groups. d -Galactose is attached as single residues or as 4-O-substituted residues to the C-3 positions of some l -rhamnose residues. This evidence indicates that the polysaccharide is more highly branched than was at one time supposed.

Preparation of unsaturated carbohydrates from methyl 4,6-O-benzylidene-3-chloro-3-deoxy-β-d-allopyranoside, and their utility in the synthesis of sugars of biological importance☆

Abstract Methyl 4,6-O-benzylidene-β- d -erythro-hex-3-enopyranoside (2) is readily obtained from methyl 4,6-O-benzylidene-3-chloro-3-deoxy-β- d -allpyranoside (1). Treatment of compound 2 or its 2-O-acetyl derivative (3) with dilute hydrochloric acid in acetone affords the α,β-unsaturated ketone 4 in high yield. Examples of the synthetic utility of compound 4 are provided by its ready conversion into methyl 2,3,6-trideoxy-β- d -threo-hexopyranoside (methyl β- d -rhodinoside, 8) and the d -erythro isomer (methyl β- d -amicetoside, 13).

Isolation of three oligosaccharides from the mucilage from the bark of Ulmus fulva (slippery-elm mucilage). Synthesis of O-(3-O-methyl-β-D-galactopyranosyl)-(1→4)-L-rhamnose

Abstract Borohydride reduction of the periodate-oxidized polysaccharide obtained from slippery-elm mucilage, affords, on partial hydrolysis with hot acid, three oligosaccharides: O -(3- O -methyl-β- D -galactopyranosyl)-(1→4)- O -(3- O -methyl-β- D -galactopyranosyl)-(1→4)- L -rhamnose ( 2 ), O -(3- O -methyl-β- D -galactopyranosyl)-(1→4)- L -rhamnose ( 3 ), and O -(3- O -methyl-β- D -galactopyranosyl)-(1→4)-3- O -methyl- D -galactose ( 4 ). The structure assigned to 3 was corroborated by a synthesis of the disaccharide.

Conversion of 2-hexuloses into 3-heptuloses: synthesis of D-manno-3-heptulose

Abstract A general protocol for the conversion of 2-hexuloses into 3-heptuloses is illustrated by the synthesis of D - manno -3-heptulose ( 9 ) from D -fructose ( 1 ). Oxidation of 2,3:4,5-di- O -isopropylidene-β- D -fructopyranose ( 2 ) with the Pfitzner-Moffatt reagent gave, in high yield, 2,3:4,5-di- O -isopropylidene-β- D - arabino -hexosulo-2,6-pyranose ( 3 ), which was converted into the unsaturated sugar 4 by reaction with methylenetriphenylphosphorane. Addition of iodine trifluoroacetate to 4 , followed by deacylation of the resultant adduct(s) 5 , afforded crystalline 2-deoxy-2-iodo-3,4:5,6-di- O -isopropylidene-β- D - gluco -3-heptulos-3,7-pyranose ( 6 ). Treatment of the iodo-hydrin 6 with sodium hydroxide gave the epoxide 7 , which, by a further treatment with sodium hydroxide, was converted into 3,4:5,6-di- O -isopropylidene-β- D - manno -3-heptulos-3,7-pyranose ( 8 ). Acid-catalyzed hydrolysis of the diol 8 furnished D - manno -3-heptulose ( 9 ).

Reaction of methyl 2,3-O-isopropylidene-6-O-p-tolylsulfonyl-α-d-lyxo-hexofuranosid-5-ulose with triethylamine-methanol

Abstract A synthesis of methyl 2,3- O -isopropylidene-6- O-p -tolylsulfonyl-α- d -lyxo-hexofuranosid-5-ulose (1) is described. Reaction of compound 1 with triethylamine-methanol yielded methyl 2,3- O -isopropylidene-α- d - lyxo -hexofuranosid-5-ulose dimethyl acetal (2) and methyl 6-deoxy-2,3- O -isopropylidene-4-methoxy-α- d - lyxo -hexofuranosid-5-ulose (3) . Mechanisms for the formation of the new products ( 2 and 3 ) are proposed.

Reactions of Unsaturated Carbohydrates in the presence of Iodine

Abstract The addition of the pseudohalogens nitryl iodide (NO2I), iodine nitrate (IONO2), and iodine azide (IN3) to the terminal, unsaturated sugar, methyl 5,6-dideoxy-2,3-di-O-p-tolylsulfonyl-α- l -arabino-hex-5-enofuranoside (1), is described. On treatment with iodine in ether solution, tri-O-acetyl- d -glucal dimerizes to yield the two anomers of 1,3,4,6-tetra-O-acetyl-2-deoxy-2-C-(4,6-di-O-acetyl-2,3-dideoxy-α- d -erythro-hex-2-enopyranosyl)- d -glucopyranose (6).