Abstract
2,3,4,6-Tetra-O-acetyl-beta-D-mannopyranosyl phosphate, free of the alpha anomer, was coupled with citronellol and dolichol in the presence of triisopropylbenzenesulfonyl chloride to give, after chromatographic purification and deacetylation, the respective polyisoprenyl beta-D-mannopyranosyl phosphates. These compounds were compared with the previously synthesized alpha anomers by means of their chromatographic properties, spectra, optical rotations, and hydrolysis reactions when treated with acid and alkali. To characterize the compounds resulting from these treatments, and to determine the mechanism of the alkaline hydrolysis, beta-D-mannopyranosyl phosphate was converted into beta-D-mannonpyranose 1,2-phosphate, and hence into D-mannose 2-phosphate, obtained as a mixture of alpha and beta anomers, characterized by infrared and nuclear magnetic resonance spectra and elemental analysis. Beta-D-Mannopyranosyl phosphate was readily separated by thin layer chromatography from the corresponding alpha anomer.
Highlights
2,3,4,6-Tetra-O-acetyl+D-mannopyranosyl phosphate, free of the cy anomer, was coupled with citronellol and dolichol in the presence of triisopropylbenzenesulfonyl chloride to give, after chromatographic purification and deacetylation, the respective polyisoprenyl P-D-mannopyranosyl phosphates
To characterize the compounds resulting from these treatments, and to determine the mechanism of the alkaline hydrolysis, P-D-mannopyranosyl phosphate ‘was converted into @-D-mannopyranose 1,2-phosphate, and into D-mannose 2-phosphate, obtained as a mixture of
D-maIInOpyranOSy1 phosphate (II) was the precursor in the synthesis of P-D-mannopyranosyl phosphate (I), P-D-mannopyranose 1,2-phosphate (V), and D-mannose 2-phosphate (VI). These three compounds were required as chromatographic standards for the identification of the products of degradative treatments of the synthetic polyisoprenyl P-D
Summary
B-D-mannopyranosyl phosphate (VIII) and dolichyl P-D-mannopyranosyl phosphate (X), it was necessary to prepare a fully protected derivative of P-D-mannopyranosyl phosphate and to couple this derivative (II) with the appropriate polyprenol. When 2,3,4,6-tetra-o-acetyl-p-D-mannopyranose was prepared from 2,3,4,6-tetra-O-acetyl-cu-D-mannopyranosyl chloride by a modification of the method of Bonner (14) and phosphorylated according to Prihar and Behrman (13), the product was found by TLC to contain some a anomer. Tetra-0-acetyl-cu.D-mannopyranosyl chloride was converted into 2,3,4,6-tetra-o-acetyl-P-D-mannopyranose by a modified treatment with silver carbonate in aqueous diethyl ether, a suitable product could be obtained for phosphorylation purposes. It was directly treated, without recrystallization, with o-phenylene phosphorochloridate and collidine in anhydrous tetrahydrofuran, as described by Prihar and Behrman (13), except that the degree of completion of the phosphorylation was monitored by TLC rather than by paper electrophoresis. These transformations are strong evidence for the presence of a five-membered ring in V (15), which is identified as P-D-mannopyranose l&phosphate
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