Edward I. Stout

A facile route to trans cyclic carbonates of sugars

Abstract Five-membered, cyclic carbonates are formed when vicinal trans -hydroxyl groups in D -glucopyranosides are treated with ethyl chloroformate in the presence of triethylamine. With these reagents, methyl 4,6- O -benzylidene-α- D -glucopyranoside 2,3-carbonate ( 2 ), methyl 2,6-di- O -(methylsulfonyl)-α- D -glucopyranoside 3,4-carbonate ( 5 ), and methyl 4- O -(ethoxycarbonyl)-6- O -( p -tolylsulfonyl)-α- D -glucopyranoside 2,3-carbonate ( 8 ) were prepared. In contrast, when pyridine is the base present, only acyclic carbonates are formed.

Reaction of starch with carbohydrate trans-carbonates☆

Abstract Mono- and poly-saccharides possessing certain substituted, vicinal, trans-hydroxyl groups are readily substituted onto starch. Such substitution occurs when a trans-fused, cyclic carbonate derivative of the saccharide is added to starch in the presence of a basic catalyst. Excellent yields of products result on addition of methyl 4,6-O-benzylidene-α- d -glucopyranoside 2,3-carbonate (or 2,3-thionocarbonate), and methyl 2,6-di-O-(methylsulfonyl)-α- d -??? 3,4-carbonate to starch in the presence of triethylamine. ??? of degree of substitution (DS) 0.40 and dextran carbonate of Ds 0.31 ??? with starch under various conditions, in the presence of different catalysts, to give ??? corresponding polysaccharide copolymers.

2,3-thionocarbonate and 2,3-carbonate derivatives of D-glucopyranosides

Abstract A unique sugar derivative, methyl 4,6- O -benzylidene-α- D -glucopyranoside 2,3-thionocarbonate, which contains a trans -fused ring-structure, was prepared in good yield by rearrangement of bis(methyl 4,6- O -benzylidene-2- O -thiocarbonyl-α- D -glucopyranoside) disulfide. The thionocarbonate was converted into the novel methyl 4,6- O -benzylidene-α- D -glucopyranoside 2,3-carbonate in 93% yield by treatment with silver nitrate. By following the same reaction sequence, 2,3-thionocarbonate and 2,3-carbonate groups were introduced into 6- O -tritylamylose. The rearrangement of bis( O -thiocarbonyl) disulfide derivatives provides a new route for the synthesis of carbohydrate thionocarbonates and carbonates previously unavailable.

Ring-opening reactions of trans-carbonates and thionocarbonates

Abstract The reaction of methyl 4,6- O -benzylidene-α-D-glucopyranoside 2,3-carbonate ( 1 ) and the corresponding 2,3-thionocarbonate ( 2 ) with various nucleophines was investigated. Under proper conditions, 1 and 2 reacted with methanol, benzyl alcohol, α-toluenethiol, ammonia, piperidine, and glycine to give the corresponding 2- O -and 3- O -carbonyl and thiocarbonyl adducts, which were obtained in crystalline form. In each reaction product the 2-isomer was preponderant.

Decomposition of dithiobis(thioformates) with p-chlorobenzenethiol

Abstract A simple and fast procedure is described for the decomposition of dithiobis-(thioformates) by reaction with two equivalents of p -chlorobenzenethiol in pyridine for 10 min at 25°. The procedure is effective even with derivatized starch, which is insoluble under the reaction conditions. Use of less than two equivalents of p -chlorobenzenethiol gives the intermediate, mixed disulfide. Other functional groups that react with this reagent are , , , and . However, the functional groups , , , , , , and ROSO 2 C 6 -H 4 Me do not react (R  carbohydrate moiety).