Sulfonated chiral covalent organic frameworks-mediated asymmetric Michael addition of acetone to β-nitroolefins

Organo-catalysts for the Michael addition reaction of nitrostyrene with acetone are essential to improve the efficiency and enantioselectivity, and their recycling also faces great challenges. Herein, a sulfonated chiral covalent organic framework (SDA-CCOF) was successfully constructed by post modification of the pre-prepared sulfonated COF with chiral 1, 2-diaminocyclohexane via N-sulfonylation. The catalytic performance was evaluated by the asymmetric Michael addition reaction of beta-nitrostyrene with acetone. Under the optimized conditions, 81% conversion of beta-nitrostyrene and 90% enantioselectivity were achieved. The generality of the catalyst was examined for diverse substrates with 84-96% enantioselectivity. Moreover, a possible catalytic mechanism of the Michael reaction by SDA-CCOF was speculated based on the characterization results and previous reports. This novel catalyst may provide inspirations for the development of CCOF and the loading of organo-catalysts. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a sulfonated chiral covalent organic framework (SDA-CCOF) was successfully synthesized and used as a catalyst for the asymmetric Michael addition reaction of acetone with nitrostyrene. The catalyst exhibited good catalytic performance with a high enantioselectivity of 90%. It also demonstrated high enantioselectivity for diverse substrates.