Accession Number : AD0703457

Title :   HYDROGENOLYSIS OF CYCLIC AND ACYCLIC ORTHOESTERS OF CARBOHYDRATES WITH LITHIUM ALUMINUM HYDRIDE-ALUMINUM TRICHLORIDE,

Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA SASKATOON (SASKATCHEWAN) PRAIRIE REGIONAL LAB

Personal Author(s) : Bhattacharjee,S. S. ; Gorin,P. A. J.

Report Date : 24 JUN 1969

Pagination or Media Count : 12

Abstract : Several cyclic and acyclic carbohydrate orthoesters have been hydrogenolyzed with 1:1 lithium aluminum hydride-aluminum trichloride, and the mechanisms of the reaction have been studied. Generally, cyclic orthoesters are cleaved via cyclic carbonium-ion intermediates that are stereospecifically attacked by the reducing species, giving cyclic acetals in good yield. One example is the cleavage of both diastereoisomers of 1,2-O-(1-methoxyethylidene)-3,4,6-tri-O-methyl-beta-D-mannopyranose to 1,2-O-ethylidene-3,4,6-tri-O-methyl-beta-D-mannopyranose having an exo O-ethylidene proton. Cleavage of carbohydrate acyclic orthoesters with the reagent is less specific. Acyclic methyl orthoesters were formed simultaneously by the action of methyl orthoformate and a trace of acid on 1,2:3,5-di-O-methylene-alpha-D-glucofuranose (I). After removal of the contaminating formic ester of I, the remainder was hydrogenolyzed with the reagent to I and the two methylene acyclic acetals and in the ratios of 5:10:3 (w/w/w). (Author)

Descriptors :   (*CARBOHYDRATES, *REDUCTION(CHEMISTRY)), OXYGEN HETEROCYCLIC COMPOUNDS, ESTERS, CANADA

Subject Categories : Organic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE