Wang K,
Tang X,
Anjali BA,
Dong J,
Jiang J,
*,
Liu Y,
*,
Cui Y.
*
National University of Singapore, Singapore and Shanghai Jiao Tong University, P. R. of China
Chiral Covalent Organic Cages: Structural Isomerism and Enantioselective Catalysis.
J. Am. Chem. Soc. 2024;
146: 6638-6651
DOI:
10.1021/jacs.3c12555
Key words
chiral covalent organic cages - nickel catalysis - enantioselective Michael addition
Significance
Chiral covalent organic cages (CCOC-1 and 2) were prepared from 5,10-di(3,5-diformylphenyl)-5,10-dihydrophenazine and (1R,2R)-cyclohexanediamine according to equation 1. A CCOC–Ni(OAc)2 complex, generated in situ, promoted the enantioselective Michael addition of 2-acetylazaarenes with E-nitroalkenes in the presence of DIPEA to afford the corresponding Michael adducts in up to 94% yield with 96:4 er (eq 2).
Comment
CCOCs were characterized by means of NMR measurements, FT-IR, MALDI-TOF-MS, SEM, XRD, PXRD, XANES, EXAFS and UV/Vis. In the enantioselective Michael addition of 1-(5-chloro-2-pyridinyl)ethenone with E-β-nitrostyrene, the CCOC-2-Ni(OAc)2 complex was recovered and reused four times without significant loss of its catalytic activity and enantioselectivity (5th run; >78% yield, 93:7 er).
