| Abstract
| - Formal total syntheses of the naturally occurring deaminated sialic acids KDN (2), a potentialoncofetal antigen, and N-acetylneuraminic acid (Neu5Ac, 1), the most naturally abundant sialicacid, have been accomplished in 46% and 9.3% overall yield, respectively, via a novel ketalization/ring-closing metathesis sequence. The rapid introduction of all oxygen and nitrogen functionalityin a completely stereocontrolled manner exploited a rigid 6,8-dioxabicyclo[3.2.1]oct-2-ene template.The 2,7-anhydro-KDN derivative 40 served as an advanced intermediate in each of the twosyntheses.
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