A Chiral [2+3] Covalent Organic Cage Based on 1,1’‐Bi‐2‐naphthol (BINOL) Units

Abstract A [2+3] chiral covalent organic cage is produced through a dynamic covalent chemistry approach by mixing two readily available building units, viz. an enantiopure 3,3’‐diformyl 2,2’‐BINOL compound ( A ) with a triamino spacer ( B ). The two enantiomeric ( R , R , R ) and ( S , S , S ) forms of the cage C are formed nearly quantitatively thanks to the reversibility of the imine linkage. The X‐ray diffraction analysis of cage ( S , S , S )‐ C highlights that the six OH functions of the BINOL fragments are positioned inside the cage cavity. Upon reduction of the imine bonds of cage C , the amine cage D is obtained. The ability of the cage D to host the 1‐phenylethylammonium cation ( E H + ) as a guest is evaluated through UV, CD and DOSY NMR studies. A higher binding constant for ( R )‐ E H + cation (Ka=1.7 10 6 ±10 % M −1 ) related to ( S )‐ E H + (Ka=0.9 10 6 ±10 % M −1 ) is determined in the presence of the ( R , R , R )‐ D cage. This enantiopreference is in close agreement with molecular dynamics simulation.