Nickel^II-catalyzed asymmetric photoenolization/Mannich reaction of (2-alkylphenyl) ketones

Abstract

A diasteteo- and enantioselective photoenolization/Mannich (PEM) reaction of ortho-alkyl aromatic ketones with benzosulfonimides was established by utilizing a chiral N,Nʹ-dioxide/Ni(OTf)2 complex as the Lewis acid catalyst. It afforded a series...

Enantioselective Radical Addition to Ketones through Lewis Acid-Enabled Photoredox Catalysis

“…In the initial investigation, the addition product C1 from A1 and B1 catalyzed by Sc­(OTf) 3 (10 mol %) was obtained with a 19% yield at room temperature under 10 W LEDs (400 nm) irradiation in MeCN (Table , entry 1). The addition of chiral N , N ′-dioxide ligand − L 3 -RaPr 2 (10 mol %) significantly increased the yield of C1 to 82% with a 73:27 enantiomeric ratio (er) (Table , entry 2). Other Lewis acids were also tested, such as Mg­(OTf) 2 and Y­(OTf) 3 , giving poor yields and enantioselectivities (Table , entries 3–4; see the Supporting Information for details).…”

Accessing unnatural α-amino acids with tetrasubstituted stereogenic centersviacatalytic enantioselective reactions of ketimine-type α-iminoesters/α-iminoamides

“…The first highly enantioselective reaction involving a photoenol was reported by Cao, Feng, and co-workers in 2022 (Scheme 38). 65 This reaction of a 2-alkylaromatic ketone with cyclic sulfonyl ketimines 4 proceeds in the presence of a nickel salt and chiral N , N ′-dioxide ligand 20b under 365 nm LED light, with the corresponding ATAAs 97 obtained in good yields, enantioselectivities, and diastereoselectivities. The authors proposed a transition state for this reaction, in which the Ni( ii )/ N , N ′-dioxide complex activates ketimine 4 in a bidentate-coordination manner.…”

Csp3–H Imination Using Arylazo Sulfone as a N Source: An Approach to Access Imines

“…Imine, being a versatile and widely used synthon, finds application in various reactions such as a Mannich-type reaction, Friedel–Crafts reaction, cycloaddition/cyclization reaction, organometallic addition, Michael addition, and asymmetric synthesis of α-amino acids and their derivatives . The historical background of imine synthesis is extensive and diverse.…”