C‐Glykoside der N‐Acetylneuraminsäure. Synthese und Untersuchung ihrer Wirkung auf die Vibrio cholerae Sialidase

C‐Glycosides of N ‐Acetylneuraminic Acid The synthesis of the C‐glycosides 8 , 15 , and 9 of N ‐acetylneuraminic acid is described. Hydroxymethylation of the Li‐ester enolate, derived from 5 , yielded the protected C‐glycosides 7 and 10 (46%; 3:1), which were deprotected to yield 8 (54%) and 15 (51%; Scheme 2 ). The mesylate 16 was obtained from 7 (73%) and transformed via the azide 17 (75%) into the acid 18 (66%) and the amino acid 9 ( Scheme 3 ). The configuration at C(2) of 17 was proved by transforming 17 into the bicyclic lactam 19 . Both 8 and 15 are very weak inhibitors of Vibrio cholerae sialidase; 9 appears to stimulate this enzyme.