Heterotricyclodecane. XXVI. 2,6-Dioxatricyclo [3.3.2.03,7]decan, ein neuartiges isomers von 2,6-dioxaadamantan

2,6-Dioxatricyclo [3.3.2.03,7]decane, a Novel Isomer of 2,6-Dioxaadamantane Restriction among the great number of possible diheterotricyclodecanes to such with a carbocyclic 8membered ring (cyclooctane) as basic skeleton, which is crosswise bridged by two heteroatoms, and restriction to 5-, 6- and 7membered heterocyclic rings results in the isomeric diheterotricyclodecanes of the following five different structural types: 2,6-diheteroadamantane (a), 2,7-diheteroisotwistane (b), 2,7-diheterotwistance (c), 2,8-diheterohomotwistbrendane (d), and 2,6-diheterotricyclo [3.3.2.03,7]decane (e; s. Scheme 1). Starting from a suitably C (5)o(2)-functionalized 2,7-dioxaisotwistane, first representatives with the hitherto unknown skeleton of type e were prepared by molecular rearrangement involving neighboring group participation: 2,6-dioxatricyclo [3.3.2.03,7]decane (41) and the derivatives 34–40 thereof (Scheme 7).