Synthesis of functional poly(phenyl isocyanide)s with macromolecular helicity memory and their use as asymmetric organocatalysts

To develop a novel polymer-based asymmetric organocatalyst, a series of helical poly(phenyl isocyanide)s with functional pendant groups were prepared by modifying the side groups of the optically active helical poly(4-carboxyphenyl isocyanide) with a macromolecular helicity memory. Helical polyisocyanides partially modified with achiral amines, such as piperazine, maintained their chiral memory and enantioselectively catalyzed a direct aldol reaction. Although the enantioselectivity was low, the original helical poly(4-carboxyphenyl isocyanide) showed no catalytic activity. These results indicated that the macromolecular helicity of the modified polyisocyanides together with bifunctional amino and carboxy acid pendant residues arranged in a helical array along the polymer backbones plays an important role in the enantioselectivity.