The Synthesis of Carbon-13 Enriched Monosaccharides Derived from Glucose and Mannose

Abstract

A modified Kiliani-Fischer reaction is used to prepare multigram quantities of [1-¹³C]-enriched glucose and mannose which are converted chemically or enzymatically into other labeled monosaccharides. The simplest conversion is the synthesis of labeled fructose from labeled glucose using commercially available immobilized glucose isomerase. The equilibrium for this reaction provides a 1:l mixture of glucose and fructose which can be separated by chromatography. The equilibrium can be shifted toward fructose by treating the reaction with germanate ion. [1-¹³C]Mannose can be converted into more useful sugars using a modification of the Lobry de Bruyn-Alberda van Ekenstein transformation. In this reaction, D-[1-¹³C]mannose is treated with an aqueous solution of dilute alkali and phenylboronate to form a mixture of labeled fructose, mannose and glucose. Fructose can be converted to a mixture of methyl fructofuranosides by using trifluoroacetic acid in methanol. [2-¹³C]Dihydroxyacetone can be prepared from methyl D-[2-¹³C]fructose by treatment with periodate followed by reduction with borohydride and acid hydrolysis.