The Synthesis of Isomers of d-Apiofuranosyl l-Phosphate

The α-d-apio-d-furanosyl 1-phosphate and α-d-apio-l-furanosyl 1-phosphate esters of d-apiose have been prepared from a mixture of the β-d-apiose tetraacetates in 20% yield. The β isomers of d-apiose tetraacetate were prepared from a dry syrup of the chromatographically pure sugar in almost quantitative yield. The tetraacetates of the two different ring forms were separated by paper and thin layer chromatography, and they were characterized by gas chromatography and analysis of their nuclear magnetic resonance spectrum. Reaction of the d-apiose tetraacetates with crystalline phosphoric acid resulted in the formation of four isomers of d-apiose monophosphate. The two monophosphate isomers described above and their 1,2-cyclic phosphodiester derivatives were separated by chromatography on Dowex 1-C1 columns. The products were further purified by paper chromatography in several solvent systems. Analytical data indicated the monophosphate esters were pure. The only sugar released on acid or enzymatic hydrolysis of these compounds was indistinguishable from d-apiose on paper chromatography with a wide range of solvent systems. Procedures for evaluating the stereochemical homogeneity of the d-apiose phosphate esters were developed. The configuration and position of the phosphate group was established by periodate oxidation and analysis of nuclear magnetic resonance spectrum. A colorimetric method for the quantitative determination of small amounts of d-apiose and microprocedures for studying the rate of phosphorylation of fully acetylated d-apiose-14C by crystalline phosphoric acid were also developed during the course of this study. The sugar phosphate esters were utilized to identify intermediates involved in the synthesis of the branched chain sugar which is present as a cell wall polysaccharide in Lemna minor and as a flavone glycoside in parsley.