2-Propynyl 2,3,4,6-tetra-O-acetyl-α-d-mannopyranoside

The 2‐propynyl group in the title compound, C17H22O10, adopts an exoanomeric conformation, with the acetylenic group gauche with respect to position C1. Comparison of 13C NMR chemical shifts from solution and the solid state suggest that the acetylenic group also adopts a conformation anti to C1 in solution. The pyranose ring adopts a 4C1 conformation. Of the three secondary O‐acetyl groups, that on position O4, flanked by two equatorial groups, adopts a syn conformation, in agreement with recent generalizations [González‐Outeiriño, Nasser & Anderson (2005). J. Org. Chem.70, 2486–2493]. The acetyl group on position O3 adopts a gauche conformation, also in agreement with the recent generalizations, but that on position O2 adopts a syn conformation, not in agreement with the recent generalizations.