Designed Construction of One‐Dimensional Positional‐Isomeric Chiral Covalent Organic Frameworks for Asymmetric Aldol Catalysis

Chiral covalent organic frameworks (COFs) represent a versatile platform for heterogeneous asymmetric catalysis. However, constructing positional-isomeric chiral COFs by regulating the position of chiral moieties to enhance their asymmetric catalytic performance remains a significant challenge. In this study, two V-shaped positional-isomeric chiral monomers, namely 4-L-DTP-Boc and 5-L-DTP-Boc, were designed and synthesized using naturally occurring L-proline as the chiral source. Subsequent condensation with 4,4',4'',4'''-(pyrene-1,3,6,8-tetrayl)tetraaniline (BFPPQ) and Boc deprotection afforded two one-dimensional (1D) positional-isomeric chiral COFs (4-L-DTP-BFPPQ and 5-L-DTP-BFPPQ). The resulting chiral COFs were evaluated as heterogeneous catalysts for asymmetric aldol reactions. Remarkably, 4-L-DTP-BFPPQ COF exhibited superior catalytic performance, particularly in terms of enantioselectivity (87%-92%), significantly outperforming 5-L-DTP-BFPPQ COF (62%-78%). The distinct catalytic behaviors of two chiral COFs could be attributed to the synergistic effects of chiral-unit positioning on packing behavior and local chiral microenvironment. These findings establish a correlation between regioisomerism in 1D chiral COFs and their asymmetric catalytic performance, providing a blueprint for the rational design of heterogeneous chiral COF catalysts.