Asymmetric [5+2] Cycloaddition of Vinylcyclopropanes and π-Systems

Significance

Wender’s group has extended its [5+2] cycloaddition-reaction arsenal. They found that Rh(I)/BINAP is a superior catalyst for the cyclo­addition of vinylcyclopropanes tethered to alkenes for the intramolecular variant. The substrates containing synthetically useful sulfonamide and malono­diester groups gave high yields and excellent enantio­selectivities. Substitution at the cyclopropane group as well as internal substitution on the terminal alkene resulted in high selectivity. Alkyne-substituted substrates showed low ee values, as did a substrate with an internal hydrogen on the terminal alkene when the malonodiester was present in the tether.