Unifying Dearomatization and Rearomatization via Stereoselective Chlorination/Dechlorination: Resolution of Axially
Naichen Zhang1, Yuyang Chen1, Ganlu Qian2
1Key Laboratory of Synthetic and Natural Functional Molecule of the Ministry of Education, College of Chemistry & Materials Science, Northwest University, Xi'an 710127, China.
Abstract:
We herein report a unified strategy integrating catalytic asymmetric chlorinative dearomatization and stereoselective dechlorinative rearomatization for resolving axially chiral 1-aryl-2-naphthols. By using a Sc(III)/Py-BOX catalytic system, naphthol-based biaryls underwent kinetic resolution through asymmetric chlorinative dearomatization. This process converted the intrinsic C(sp2)-C(sp2) axial chirality of one enantiomer into a conformationally favored C(sp2)-C(sp3) axis by generating a chlorine-containing C(sp3)-stereogenic center. The reaction showed high functional group tolerance and excellent enantioselectivities across a wide range of substrates. Subsequently, a stereospecific rearomatization protocol using triethylamine under blue-light irradiation was developed. This dechlorination method exploited an electron donor-acceptor (EDA) complex mechanism, efficiently converting the stored C(sp2)-C(sp3) axial chirality back to the original C(sp2)-C(sp2) axis, thus enabling full resolution of the biaryl atropisomers. The resolved 1-aryl-2-naphthols can be readily transformed into various catalytically and synthetically valuable molecules, such as axially chiral monophosphine, bisphosphine, aldehyde, and carboxylic acid.
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