Rhodium-Catalyzed Asymmetric [2 + 2 + 2] Cycloaddition of α,ω‑Diynes with Unsymmetrical 1,2-Disubstituted Alkenes

It has been established
that a cationic rhodium­(I)/axially chiral
biaryl bisphosphine complex catalyzes the asymmetric [2 + 2 + 2] cycloaddition
of α,ω-diynes with electron-rich and unstrained unsymmetrical
1,2-disubstituted alkenes to give chiral multicyclic compounds with
good yields and ee values. Interestingly, enantioselectivity highly
depends on the structures of α,ω-diynes used presumably
due to the presence of two distinct reaction pathways.