The complex (p-methoxyphenyl oxazoline)Cr(CO)3 is converted in two steps into a cis-fused [6,8] ring system containing a cycohexadiene ring unit, a cyclooctenone ring and a quaternary carbon at the ring junction. The key steps involve a diastereoselective addition of three C-substituents across an arene double bond, followed by an allylation and ring closing metathesis step. cis-Fused [6,7], [6,6], and [6,5] ring systems are also accessible via this methodology.