Synthesis and transformations of new annulated pyranosides using the Pauson–Khand reaction Original Research Article

The synthesis and transformations of new annulated pyranosides are described. These adducts were prepared by Pauson–Khand reaction on differently functionalized prop-2-ynyl-2,3-dideoxy-α-d-erythro-hex-2-enopyranosides (1–8). Compound 1 with a free hydroxyl group at C-4 afforded significant amounts of the hydrogenolysis product 12 in addition to the normal adduct 13. The C-4 O-protected similar precursors (2–8) gave PK products in yields ranging from 39 to 63%. Pauson–Khand adduct 19 provided intermediate 23 after selective manipulation. The oxidation plus decarbonylation synthetic sequence applied to intermediate 23 gave a poor yield of compound 24 using Wilkinsonʹs catalyst. The t-butyl hydroperoxide promoted decarbonylation of product 23 afforded formate 25 in a typical Baeyer–Villiger rearrangement. The Ferrier-II reaction on intermediate 45, readily available from compound 9, afforded the hydrindane-type derivative 46 in 34% yield using a Ferrier-II type reaction.