Showing papers on "Aldose published in 1967"

The mechanisms of hydrolysis of glycosides and their revelance to enzyme-catalysed reactions.

Abstract: Glycoside hydrolysis can be formally represented by (I). where the group O R ( R is alkyl, aryl or a carbohydrate) is displaced from the C1 or C2 atom of an aldose or ketose sugar (or sugar derivative) respectively; the ring system being either five- or six-membered. Like the analogous hydrolysis of acetals, glycoside hydrolysis shows specific catalysis by hydrogen ions and, except where R is an aryl residue, base catalysis is absent. A number of enzymes* catalysing the hydrolysis of particular glycosides have been characterized: all show a high degree of specificity towards the carbohydrate structures present in the substrates. Both the acid-catalysed and the enzyme-catalysed reactions have been much studied, but whereas the former are now reasonably well understood, the mechanisms involved in the latter are still largely unknown.

Use of a Grignard reagent to lengthen a triose carbon chain

Abstract: The addition of vinylmagnesium chloride to 2,3-O-isopropylidene-d-glyceraldehyde (I) gave a mixture of the epimeric pentene derivatives II and V, which were separated by preparative gas–liquid chromatography. Ozonolysis and subsequent deketalization of the individual epimers gave d-threose and d-erythrose, respectively, in yields of ca. 40%. This represents a method of lengthening an aldose carbon chain by one carbon atom.