Xiaowei Chen

Bio: Xiaowei Chen is an academic researcher from Henan University. The author has contributed to research in topics: Enantioselective synthesis. The author has co-authored 1 publications.

Divergent asymmetric synthesis of azaarene-functionalized cyclic alcohols through stereocontrolled Beckwith-Enholm cyclizations

Abstract: The first enantioselective Beckwith-Enholm cyclization reaction is reported herein. Under cooperative photoredox and chiral hydrogen-bonding catalysis mediated by visible light, cyclization of carbonyls with azaarene-based olefins as a new reaction system offers a general and divergent synthetic pathway to furnish a variety of highly valuable enantioenriched azaarene-functionalized carbocyclic and heterocyclic alcohols, which bear adjacent 1,2- or nonadjacent 1,3-stereocentres on distinct cyclic frameworks, in high yields and enantio- and diastereoselectivities. The good compatibility of various azaarenes and carbonyls as well as the diversity of cyclic structures of the products underscores the generality of the catalysis platform. In addition to the ability to precisely introduce deuterium into molecules in an enantioselective manner, the considerable synthetic value of this method includes the excellent antioxidant stress potential of the products. In particular, molecule 29 was determined to be a promising lead compound for antioxidant stress drug design.

Time-Atom Economical Regio-and Chemoselective Radical Cyclization of Unactivated 1,6-Enynes under Metal- and Oxidant-free Conditions.

Abstract: We developed time-atom economic regio- and chemoselective sulfonyl radical triggered 5-exo-dig cyclization of unactivated 1,6-enynes with sulfonyl halides under metal, additive-free reaction conditions to achieve highly substituted five-membered heterocyclic compounds. This transformation creates three new bonds, such as C-SO2 , C-C, and active C-I/Br bonds. Importantly, one-pot protocols produce desired products directly from sodium sulfinates and have an additional advantage such as minimising chemical waste, saving time, and simplifying practical aspects compared to existing protocols.

Copper(I)-Catalyzed Asymmetric Conjugate Addition of 1,4-Dienes to β-Substituted Alkenyl Azaarenes.

Abstract: Chiral azaarene compounds are extremely important due to their prevalence in pharmaceutical ingredients. Herein, an array of chiral molecules bearing azaaryl groups is synthesized in moderate-to-excellent yields with moderate-to-excellent Z/E ratios, high dr, and excellent enantioselectivity by a copper(I)-catalyzed asymmetric conjugate addition of 1,4-dienes to (E)-β-substituted alkenyl azaarenes. The reaction is carried out under mild proton-transfer conditions, which enjoys very high atom economy. Moreover, the reaction features a broad substrate scope on (E)-α,β-unsaturated azaarenes as various azaarenes are well tolerated, such as benzothiazole, thiazole, N-methyl-benzimidazole, benzoxazole, quinoline, isoquinoline, pyrimidine, pyrazine, and triazine. Interestingly, the reaction with (Z)-α,β-unsaturated azaarenes affords the same products in excellent results but with a reversed absolute configuration. DFT calculations indicate that the C-C bond-forming nucleophilic addition is a Z-/E- and enantio-selectivities-determining step and provides a rationale for the origin of selectivities. At last, the synthetic utilities of the product are showcased by several transformations, including olefin metathesis, [4 + 2] cyclization, [2 + 1] cyclization, and cleavage of the benzothiazole ring.