Diphenylprolinol silyl ether as a catalyst in an enantioselective, catalytic, formal aza [3+3] cycloaddition reaction for the formation of enantioenriched piperidines

(Chemical Presented) Aza-ene reaction: Diphenylprolinol silyl ether was found to be an effective organocatalyst for the formal aza [3+3] cycloaddition reaction of a,b-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.