Planar chiral [2.2]paracyclophane-based phosphine–phenols: use in enantioselective [3 + 2] annulations of allenoates and N-tosylimines

Abstract

Planar chiral [2.2]paracyclophane-based phosphine–phenol catalysts, which have a benzene ring spacer inserted between the pseudo-ortho-substituted [2.2]paracyclophanol skeleton and the diarylphosphino group, are highly suitable for enantioselective [3 + 2] annulations of allenoates and N-tosylimines. These catalysts can be tuned by changing the substituent on the benzene rings of the diarylphosphino group. The observed enantioselectivity of 92% is the highest reported to date for phosphine-catalyzed annulations of unsubstituted allenic esters and N-tosylaldimines.