One-Pot Enantioselective Construction of Polycyclic Tetrahydroquinoline Scaffolds through Asymmetric Organo/Photoredox Catalysis via Triple-Reaction Sequence

Formal nucleophilic pyrrolylmethylation via palladium-based auto-tandem catalysis: switchable regiodivergent synthesis and remote chirality transfer

Although nucleophilic benzylation-type reaction to introduce various aromatic systems into molecules has been widely explored, the related pyrrolylmethylation version remains to be disclosed. Reported herein is a palladium-catalysed multiple auto-tandem reaction between N-Ts propargylamines, allyl carbonates and aldimines in the presence of an acid, proceeding through sequential allylic amination, cycloisomerisation, vinylogous addition and aromatisation steps. A diversity of formal pyrrolylmethylated amine products were finally furnished efficiently. In addition, switchable regiodivergent 3-pyrrolylmethylation and 4-pyrrolylmethylation were realised by tuning catalytic conditions. Moreover, remote chirality transfer with readily available enantioenriched starting materials was well achieved with an achiral ligand, relying on diastereoselective generation of η2-Pd(0) complexes between Pd(0) and chiral 1,3-diene intermediates in the key vinylogous addition step. A few control experiments were conducted to elucidate the palladium-involved tandem reaction and regiodivergent synthesis.

Enantioselective construction of spiro-tetrahydroquinoline scaffolds through asymmetric catalytic cascade reactions

An efficient and concise strategy has been successfully developed for merging spiro-tetrahydroquinoline with spiro-benzofuranone into a single new skeleton through asymmetric catalytic cascade reactions catalyzed by quinine-derived chiral bifunctional squaramide organocatalysts. In this approach, differently substituted spiro-tetrahydroquinoline derivatives were smoothly obtained with high yields, and excellent diastereoselectivities and enantioselectivities (up to 99% yield, up to >20 : 1 dr, up to >99% ee, 40 examples) under mild reaction conditions.

Palladium-catalyzed radical cascade cyanoalkylsulfonylation/cyclization of 3-arylethynyl-[1,1'-biphenyl]-2-carbonitriles with cyclobutanone oxime esters and DABSO

A palladium-catalyzed radical cascade cyanoalkylsulfonylation/cyclization of 3-arylethynyl-[1,1'-biphenyl]-2-carbonitriles with DABCO·(SO₂)₂ and cyclobutanone oxime esters via cleavage of a C-C single bond and insertion of SO₂ was described. A series of cyanoalkylsulfone-containing cyclopenta[gh]phenanthridines were obtained in moderate-to-good yields, thus featuring mild reaction conditions, a broad substrate scope, and a high functional group tolerance.

Metal-free, visible-light induced enantioselective three-component dicarbofunctionalization and oxytrifluoromethylation of enamines via chiral phosphoric acid catalysis

Using diverse carbon-centered radical precursors and electron-rich (hetero)aromatics and alcohols as nucleophiles, a visible-light driven chiral phosphoric acid (CPA) catalyzed asymmetric intermolecular, three-component radical-initiated dicarbofunctionalization and oxytrifluoromethylation of enamines was developed, which provides a straightforward access to chiral arylmethylamines, aza-hemiacetals and γ-amino acid derivatives with excellent enantioselectivity. As far as we know, this is the first example of constructing a chiral C–O bond using simple alcohols via visible-light photocatalysis. Chiral phosphoric acid played multiple roles in the reaction, including controlling the reaction stereoselectivity and promoting the generation of radical intermediates by activating Togni's reagent. Mechanistic studies also suggested the importance of the N–H bond of the enamine and indole for the reactions.

We have developed a metal-free, visible-light driven chiral phosphoric acid catalyzed asymmetric intermolecular, three-component radical-initiated dicarbofunctionalization and oxytrifluoromethylation of enamines.

Enantioselective Construction of Polycyclic Indazole Skeletons Bearing Five Consecutive Chiral Centers through an Asymmetric Triple-Reaction Sequence

A novel approach for the asymmetric construction of polycyclic indazole skeletons via enamine-imine activation and PCET activation was developed by merging organocatalysis with photocatalysis through an asymmetric triple-reaction sequence. In this process, five C-X bonds and five consecutive chiral centers were efficiently constructed. Differently substituted polycyclic indazole deriatives were successfully constructed with satisfactory results under mild conditions.