Torsional strain inversed chemoselectivity in a Pd-catalyzed atroposelective carbonylation reaction of dibenzothiophenium

Zhang, Qiu‐Chi; Xue, Xiaoping; Hong, Biqiong; Gu, Zhenhua

doi:10.1039/d2sc00341d

Cited by 32 publications

(16 citation statements)

References 73 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…52−54 However, sulfonium 23 with two substituents next to the axis would undergo the ring-opening coupling to form the key biaryl palladium intermediate Int9 in the Pd-catalyzed aminocarboxylation reaction (Scheme 11B). 55 With the assistance of BoPhoz, the enantiocontrol of these axially chiral thioethers could reach moderate to excellent levels. 5-Phenyl-5H-dibenzo[b,d]thiophen-5-ium (23b), whose dibenzo[b,d]thiophenium part displays planar characters, 56 showed poor reactivity in this ring-opening reaction.…”

Section: Asymmetric Ring-opening Ofmentioning

confidence: 99%

“…Dibenzo[ b , d ]thiophene and thianthrene derived sulfonium salts are usually used as electrophilic agents. The corresponding S -aryl sulfoniums can be used in Pd-catalyzed cross-coupling reactions, where the exo aryl ring usually acts as the transferred group (Scheme A). − However, sulfonium 23 with two substituents next to the axis would undergo the ring-opening coupling to form the key biaryl palladium intermediate Int9 in the Pd-catalyzed aminocarboxylation reaction (Scheme B) . With the assistance of BoPhoz, the enantiocontrol of these axially chiral thioethers could reach moderate to excellent levels.…”

Section: Asymmetric Ring-opening Of Dibenzothiopheniums and Silanesmentioning

confidence: 99%

See 1 more Smart Citation

Transition Metal-Catalyzed Biaryl Atropisomer Synthesis via a Torsional Strain Promoted Ring-Opening Reaction

2022

Self Cite

View full text Add to dashboard Cite

Conspectus Arising from the restricted rotation of a single bond caused by steric or electronic effects, atropisomerism is one of the few fundamental categories for molecules to manifest their three-dimensional characters into which axially chiral biaryl compounds fall. Despite the widespread occurrence of axially chiral skeletons in natural products, bioactive molecules, and chiral ligands/organocatalysts, catalytic asymmetric methods for the synthesis of these structures still lag behind demand. Major challenges for the preparation of these chiral biaryls include accessing highly sterically hindered variants while controlling the stereoselectivity. A couple of useful strategies have emerged for the direct asymmetric synthesis of these molecules in the last two decades. Recently, we have engaged in catalytic asymmetric synthesis of biaryl atropisomers via transition metal catalysis, including asymmetric ring-openings of dibenzo cyclic compounds. During these studies, we serendipitously discovered that the two substituents adjacent to the axis cause these dibenzo cyclic molecules to be distorted to minimize steric repulsion. The distorted compounds display higher reactivity in the ring-opening reactions than the non-distorted molecules. In other words, torsional strain can promote a ring-opening reaction. On the basis of this concept, we have successfully realized the catalytic asymmetric ring-opening reaction of cyclic diaryliodoniums, dibenzo silanes, and 9H-fluoren-9-ols, which delivered several differently substituted ortho tetra-substituted biaryl atropisomers in high enantioselectivity. The torsional strain not only activates the substrates toward ring-opening under mild conditions but also changes the chemoselectivity of bond-breaking events. In the palladium-catalyzed carboxylation of S-aryl dibenzothiophenium, the torsional strain inversed the bond selectivity from exocyclic C–S bond cleavage to the ring-opening reaction. In this Account, we summarize our studies on copper-, rhodium-, or palladium-catalyzed asymmetric ring-opening reactions of dibenzo cyclic compounds as a useful collection of methods for the straightforward preparation of ortho tetra-substituted biaryl atropisomers with high enantiopurity on the basis of the above-mentioned torsional strain-promoted ring-opening coupling strategy. In the last part, the torsional strain energies are also discussed with the aid of density functional theory (DFT) calculations.

show abstract

Section: Asymmetric Ring-opening Ofmentioning

confidence: 99%

Section: Asymmetric Ring-opening Of Dibenzothiopheniums and Silanesmentioning

confidence: 99%

Transition Metal-Catalyzed Biaryl Atropisomer Synthesis via a Torsional Strain Promoted Ring-Opening Reaction

2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…15b In comparison with thioethers, the sulfonium salts should have higher reactivity, however, the enantioselective ring- opening of cyclic diarylsulfonium salts is unexplored until very recently. 16 Gu's group reported their Pd-catalyzed asymmetric ring-opening/carbonylation reaction of cyclic sulfonium salts for the synthesis of axially chiral biaryl thioethers using L6 as the chiral ligand. In the presence of 1 atm CO as the carbonylation reagent and substituted aromatic/aliphatic amines as nucleophiles, a structurally diverse set of thioether-containing axially chiral biaryls were obtained in good yields and chiral control under mild conditions.…”

Section: C-s Bond Cleavagementioning

confidence: 99%

Catalytically atroposelective ring-opening of configurationally labile compounds to access axially chiral biaryls

et al. 2022

View full text Add to dashboard Cite

show abstract

“…On one hand, the distinct torsional strain effect not only provides an opportunity to modulate the reactivity of the bridged biaryls by simply altering the two ortho substituents but also inverses the chemoselectivity in particular cases. [12] However, on the other hand, it narrows down the substrate scope significantly and makes the access to tri-orthosubstituted biaryls under the same catalytic system infeasible. Not surprisingly, the implementation of mechanistically different processes that could get rid of the above torsional strain-dependent reactivity issue is extremely desirable.…”

Section: Introductionmentioning

confidence: 99%

“…In general, substrates with only one or without ortho substituent barely having torsional strain display much lower reactivity or even inert under the optimal conditions. On one hand, the distinct torsional strain effect not only provides an opportunity to modulate the reactivity of the bridged biaryls by simply altering the two ortho substituents but also inverses the chemoselectivity in particular cases [12] . However, on the other hand, it narrows down the substrate scope significantly and makes the access to tri ‐ ortho ‐substituted biaryls under the same catalytic system infeasible.…”

Section: Introductionmentioning

confidence: 99%

Torsional Strain‐Independent Catalytic Enantioselective Synthesis of Biaryl Atropisomers

et al. 2022

View full text Add to dashboard Cite

Catalytic asymmetric dynamic kinetic resolution of configurationally labile bridged biaryls is emerging as a powerful strategy for atropisomer synthesis. However, the reported examples suffer from an inherent challenge as the reactivity is highly dependent on the torsional strain of the biaryl substrates, which significantly narrows down the scope and hampers the application. Herein, we report our discovery and development of a torsional strain‐independent reaction between biaryl thionolactones and activated isocyanides. By employing auto‐tandem silver catalysis, a universal synthesis of both tri‐ and tetra‐ortho‐substituted thiazole‐containing biaryls was realized in high yields with high enantioselectivities. In addition, these products could be facilely converted to a novel type of bridged biaryls bearing an eight‐membered lactone. Mechanistic studies were carried out to elucidate the cause of this unusual torsional strain‐independent reactivity.

show abstract

Torsional strain inversed chemoselectivity in a Pd-catalyzed atroposelective carbonylation reaction of dibenzothiophenium

Abstract: A palladium-catalyzed enantioselective ring-opening/carbonylation of cyclic diarylsulfonium salts is reported. In comparison to thioethers, the sulfonium salts displayed high reactivity and enabled the reaction being performed at mild conditions (room...

Cited by 32 publications

References 73 publications

Transition Metal-Catalyzed Biaryl Atropisomer Synthesis via a Torsional Strain Promoted Ring-Opening Reaction

Transition Metal-Catalyzed Biaryl Atropisomer Synthesis via a Torsional Strain Promoted Ring-Opening Reaction

Catalytically atroposelective ring-opening of configurationally labile compounds to access axially chiral biaryls

Torsional Strain‐Independent Catalytic Enantioselective Synthesis of Biaryl Atropisomers

Contact Info

Product

Resources

About