Enantioselective Synthesis of 1,2-Benzothiazine 1-Imines via RuII /Chiral Carboxylic Acid-Catalyzed C-H Alkylation/Cyclization.

Sulfondiimines are diaza-analogues of sulfones with a chiral sulfur center. Compared to sulfones and sulfoximines, their synthesis and transformations have so far been studied to a lesser extent. Here, we report the enantioselective synthesis of 1,2-benzothiazine 1-imines, i.e., cyclic sulfondiimine derivatives from sulfondiimines and sulfoxonium ylides via C-H alkylation/cyclization reactions. The combination of [Ru(p-cymene)Cl2 ]2 and a newly developed chiral spiro carboxylic acid is key to achieving high enantioselectivity.

Synthesis of Polysubstituted Enamides by Hydrogen Atom Transfer Alkene Isomerization Using Dual Cobalt/Photoredox Catalysis.

M-HAT isomerization is a highly reliable method to access thermodynamically stable alkenes with high functional group tolerance. However, synthesis of heteroatom-substituted alkenes by M-HAT isomerization reaction is still underdeveloped. Herein, we report an enamide synthesis using M-HAT via a combination of cobalt and photoredox catalysis. This method tolerates a variety of functional groups including haloarenes, heteroarenes, free hydroxy groups, non-protected indoles, and drug derivatives. Furthermore, this method can isomerize styrene derivatives in good yield and E/Z selectivity.

C-H γ,γ,γ-Trifluoroalkylation of Quinolines via Visible-Light-Induced Sequential Radical Additions.

The photocatalyst-free C-H γ,γ,γ-trifluoroalkylation of quinolines under visible light irradiation is reported. By the combination of readily available alkenes and Umemoto's reagent II, a variety of γ,γ,γ-trifluoroalkyl groups were installed into quinolines via chemoselective sequential radical processes. This transformation provides rapid access to a variety of quinoline derivatives with scarcely explored fluoroalkyl groups, affording a novel library of N-heteroaromatic compounds and versatile building blocks for applications in medicinal chemistry.