Total Synthesis of (-)-Cylindrocyclophane F: A Yardstick for Probing New Catalytic C-C Bond-Forming Methodologies.

A short and efficient total synthesis of the C2 -symmetric (-)-cylindrocyclophane F is presented, using a cross olefin metathesis dimerization strategy for construction of the [7,7]-paracyclophane macrocycle. The synthesis of the dimerization building block includes a Pd-catalyzed sp3 -sp2 Negishi cross coupling of a sterically hindered Zn-reagent with an aromatic triflate, an enantiospecific Zn-catalyzed sp3 -sp3 cross coupling of an α-hydroxy ester triflate with a Grignard reagent and the application of an enantioselective Rh-catalyzed C-allylation of an electron rich arene.