Remote stereocontrol in the Nazarov reaction: A new approach to the core of roseophilin

Three different procedures are compared to obtain properly substituted divinyl ketones in which one of the double bonds is embedded in a five-membered heterocyclic structure and therefore suitable to produce cyclopenta-fused pyrrole, derivatives by the acid-catalyzed Nazarov reaction. A convergent procedure base on the umpolung to a vinylstannane gave acceptable yields of the divinyl ketone, which forms a key intermediate in the synthesis of roseophilin.