Exceptionally Simple Enantioselective Syntheses of Chiral Hexa- and Tetracyclic Polyprenoids of Sedimentary Origin

Coupling between a sulfone and an acylsilane fragment (see below) constitutes the first step in the exceptionally short total syntheses of two chiral hexacyclic hydrocarbons isolated from Eocene Messel shale (Germany). Like the first step, subsequent steps also employ a powerful synthetic tactic: polycyclization of a specially constructed chiral, multiply unsaturated oxirane. TBS=tBuMe2Si.