Diphenylprolinol Silyl Ether as a Catalyst in an Enantioselective, Catalytic, Formal Aza [3+3] Cycloaddition Reaction for the Formation of Enantioenriched Piperidines

Aza‐ene reaction: Diphenylprolinol silyl ether was found to be an effective organocatalyst for the formal aza [3+3] cycloaddition reaction of α,β‐unsaturated aldehydes and enecarbamates (see scheme). The reaction proceeds through an asymmetric catalytic ene reaction, isomerization, hydrolysis, and cyclization to afford piperidine derivatives in good yields and excellent enantioselectivities.