Development of a strategy for the synthesis of the spherical hydrocarbon p-[42.58]decahedrane

Article abstract of DOI:10.1016/S0040-4020(01)90407-7

A directed synthesis of triketone 20, an immediate precursor to a 'capped' [4]peristylane, has been accomplished in 10 laboratory operations. Starting from the previously described cyclobutanone 11, a fulvene is formed and transformed into 13 by means of a Diels-Alder cycloaddition. The C(s) symmetry of this early intermediate is preserved throughout the remainder of the scheme. Once a cyclopentadiene ring is annealed as in 14, the cyclobutane base is elaborated by [4 + 2]π addition of (Z)-1,2-bis(phenylsulfonyl)ethylene from below-plane, reductive desulfonylation, and [2 + 2] photocyclization. Following cleavage of the oxirane ring with periodic acid, arrival at 20 required debenzylation and oxidation. Unfortunately, the efficiency of this pathway is low (0.05% overall) and requires optimization before subsequent transformations that could produce 2 can be implemented.