Task‐Specific Design of a Porous Aromatic Framework as an Ultrastable Platform for Enantioselective Organocatalysis.

A hydroxyl‐tagged porous aromatic framework <bold>PAF‐NBU2‐OH</bold> was task‐specifically designed and successfully synthesized targeted toward immobilizing chiral catalysts. Using proline‐type compound as model chiral organocatalyst, <bold>PAF‐NBU2‐OH</bold> was used as a platform to covalently link proline‐type group. The obtained PAF‐immobilized organocatalyst <bold>PAF‐NBU2‐OPro</bold> featured high chemical stability in different solvents even under very harsh conditions. <bold>PAF‐NBU2‐OPro</bold> showed excellent catalytic activity, diastereoselectivity and enantioselectivity with complete and easy recyclability when catalyzing the aldol reaction between <italic>p</italic>‐nitrobenzaldehyde and cyclohexanone, which could undergo at least 30 cycles without any activity, diastereoselectivity or enantioselectivity loss for catalyzing the current reaction. [ABSTRACT FROM AUTHOR]