SO_(2)-Insertion induced enantioselective oxysulfonylation to access β-chiral sulfones with quaternary carbon stereocenters

β-Chiral sulfones are structural motifs widely found in natural products and bioactive molecules, while also serving as important intermediates for the synthesis of valuable chiral scaffolds. In contrast to the rapid growth of sulfur dioxide insertion chemistry over the last decade, enantioselective catalytic variants for accessing β-chiral sulfones, especially those bearing a quaternary carbon stereocenter, remain rare. Herein, we report an enantioselective copper/bisoxazoline catalyzed oxysulfonylation of alkenes to yield isoxazolinyl-containing β-chiral sulfones bearing quaternary carbon stereocenters with moderate to excellent yields and up to 96:4 er. The advantage and irreplaceability of this sulfur dioxide insertion catalytic system have been demonstrated by achieving transformations clearly unavailable with the previously reported sulfonyl chloride system. Additionally,the recoverability of the new-developed bisoxazoline ligand L9 and its reusability without any erosion of the catalytic activity and enantioselectivity further demonstrate the usefulness of the protocol.

Asymmetric synthesis of binaphthyls through photocatalytic crosscoupling and organocatalytic kinetic resolution

By capitalizing on the capability of photoredox catalysis to generate reactive radical intermediate under mild conditions, we established a photocatalytic cross-coupling protocol that could deliver both derivatives from 1-bromo-2-naphthols in combination with 2-naphthols or 2-naphthylamines. This distinct activation mode could overcome structural or electronic limitation associated with conventional coupling pathways. Additionally, a novel kinetic resolution protocol of unprotected BINOLs has been established with azodicarboxylates via chiral phosphoric acid(CPA) catalysis. Selectivity factor of up to 175 could be achieved and delivered to both enantiomers in atropisomerically enriched form after a simple work-up.

Chiral Phosphoric Acid Catalyzed Asymmetric Synthesis of Axially Chiral Compounds

The well-defined conformational properties of axially chiral compounds bring extraordinary values to an assortment of bioactive molecules,advanced materials,organocatalysts as well as chiral ligands in asymmetric transformations.The demonstrated usefulness and untapped potential of axially chiral structural motifs stimulate increasing efforts to develop novel and efficient approaches for their preparation.In this regard,the chiral phosphoric acids broadly used in asymmetric Brønsted acid catalysis have shown high relevance for atroposelective synthesis as well.Our strong interest in reaction chemistry of atropisomers has established a rewarding research programme in our group.The course of studies will be recounted in this account,with discussion focused on the use of chiral phosphoric acids to catalyze construction of several key axially chiral structures such as BINAM,BINOL,NOBIN,arylquinones,SPINOL,arylpyrrole analogues and axially chiral alkenes.

Chiral Phosphoric Acid Creates Promising Opportunities for Enantioselective Photoredox Catalysis

In recent years,visible light driven enantioselective chemical transformations have emerged as new additions to the toolkit of synthetic chemists to accomplish more efficient assembly of chiral molecules.Nonetheless,implementing precise stereocontrol on photoinduced intermolecular radical coupling process remai ns arduous.

Direct Construction of NOBINs via Domino Arylation and Sigmatropic Rearrangement Reactions

of main observation and conclusion Privileged 2-amino-2,-hydroxy-l/l,-binaphthyl(NOBIN)frameworks were constructed through a novel domino arylation of naphthylhydroxylamines with diarylhalonium salts and sigmatropic rearrangement in a transition metal-free fashion.This protocol bears broad substrate generality and proceeds under mild reaction conditions,affording diversified NOBINs in high efficiency with absolute regiocontrol during the rearrangement process.Optically active product was accessible by chiral A/-heterocyclic carbene-catalyzed kinetic resolution in one pot or diastereoselective[3,3]-rearrangement guided by a removable chiral auxiliary.Remarkably,diarylchloronium and diarylbrominium salts have been employed as arylation reagents for the first time in assembling such representative biaryl frameworks.