Chiral DHIP- and Pyrrolidine-Based Covalent Organic Frameworks for Asymmetric Catalysis

Covalent organic frameworks (COFs) are a new class of lightweight crystalline organic porous materials that are covalently constructed from organic building blocks. However, it is very difficult to construct the functional COFs. It is particularly very complicated to construct chiral covalent organic frameworks (CCOFs), because asymmetry, porosity, and crystallinity must be contemporaneously taken into account. Here, we prepared two CCOFs, termed TPB2-COF and Tfp2-COF, by directly employing chiral organo-catalysts as building units. Because of the precisely one-dimensional pore channels with periodically appended of chiral organo-catalytic sites as well as the ability to accurately control the environment around chiral organo-catalytic sites, these obtained CCOFs could serve as effective heterogeneous catalysts for an asymmetric Steglich rearrangement and Asymmetric Michael addition, with the stereoselectivity and diastereoselectivity up to 84% enantiomeric excess (ee) value and 86% ee value, 17:1 diastereomeric ratio (dr) value for asymmetric Steglich rearrangement and asymmetric Michael addition, respectively, rivaling or surpassing the homogeneous and amorphous analogues. Our strategy may be used to synthesize a series of functional COFs for a variety of applications.