Synthetic Studies on Sialoglycoconjugates. 3: Synthesis of 5-Acetamido-3,5-Dideoxy-l-Arabino-2-Heptulosonic Acid Derivatives and Analogs

Abstract

5-Acetamido-3,5-dideoxy-L-arabino-2-heptulosonic acid derivatives and analogs (shorter carbon-chain analogs of N-acetylneuraminic acid) were synthesized. Periodate oxidation followed by sodium borohydride reduction and O-acetylation of methyl [2-(trimethylsilyl)ethyl 5-acetamido-3, 5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosid)onate (3), prepared by condensation of the 2-β-chloro derivative of pentaacetylneuraminic acid methyl ester (1) with trimethylsilylethanol and subsequent O-deacetylation, gave methyl (trimethylsilylethyl 5-acetamido-4,7-di-O-acetyl-3,5-dideoxy-β-L-arabino-2-heptulopyranosid)onate (4). Starting from compound 4, the 7-bromo, 2-α-chloro, and 2-β-thio analogs were synthesized.