Stoichiometric reactions of nonconjugated dienes with zirconocene derivatives. Further delineation of the scope of bicyclization and observation of novel multipositional alkene regioisomerization

A quarter of a century of explorations in organozirconium chemistry

“…Presumably, anti-disposition of two five-membered rings, each of which is cis-fused onto the zirconacyclopentane ring must be thermodynamically most favorable. 110 A similar preference for cis fusion has also been observed in the construction of the dendrobine skeleton. 83 A recent study has revealed that the Cp 2 Zr-promoted bicyclization of trienes with an internal (Z)-alkene moiety gives predominantly the cis-fused products under the thermodynamically controlled condition.…”

E -Olefins through intramolecular radical relocation

“…Our protocol is efficient toward substrates with electron-withdrawing functional groups such as ketone or ester (14,15), the pharmaceutically relevant trifluoromethyl, and potentially coordinating amine groups (16,17). Functional groups that are frequently reactive in typical precious-metal catalysis-e.g., nitrile (20), bromide (13), or boronic ester (23)-were also tolerated (Fig.…”

5.34 Early Transition Metal Mediated Reductive Coupling Reactions

“…65 As illustrated in Scheme 25A, simple unsaturated hydrocarbon substrates containing substituted alkenes rapidly isomerize to conjugated dienes rather than undergoing cyclization. Interestingly, it has been demonstrated that substitution in the tether between the two alkenes can result in regaining the ability to accomplish cyclization.…”