Selective Palladium‐Catalyzed ipso Arylation of α,α‐Disubstituted Benzo[b]thien‐2‐ylmethanols with Aryl Bromides Using PCy<sub>3</sub> as Ligand.

Bíró, Anna-Mária; Kotschy, András

doi:10.1002/chin.200724098

Cited by 4 publications

(4 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus the aryl ring that tends to break the C–C bond will approach the Pd atom to construct axial chirality. Third, the reaction prefers to break the C–C bond attached to the thiophene ring, which has been confirmed in previous studies. ,, …”

supporting

confidence: 78%

Atroposelective Kinetic Resolution of 8H-Indeno[1,2-c]thiophen-8-ols via Pd-Catalyzed C–C Bond Cleavage Reaction

Yang

et al. 2022

Org. Lett.

View full text Add to dashboard Cite

The present work demonstrates a palladium-catalyzed kinetic resolution/ring-opening reaction of 8H-indeno[1,2c]thiophen-8-ols. The reaction proceeds in a highly regioselective manner, and both optically active thiophene-phenyl atropisomers and stereogenic 8H-indeno[1,2-c]thiophen-8-ols were obtained with high enantiomeric excesses. The synthetic applications of the obtained thiophenyl atropisomers were briefly investigated.

show abstract

supporting

confidence: 78%

Atroposelective Kinetic Resolution of 8H-Indeno[1,2-c]thiophen-8-ols via Pd-Catalyzed C–C Bond Cleavage Reaction

Yang

et al. 2022

Org. Lett.

View full text Add to dashboard Cite

show abstract

“…As displayed in TS1 and TS2 , axial chirality will be built during the process of the aryl ring approaching the Pd atom. Since the carbon–carbon bond connected to the thiophene ring is more favored to be cleaved than the one connected to the phenyl ring, − the process through intermediate Int16 is significantly faster than that through intermediate Int15 . Thus, the kinetic resolution of (±)- 30a can be realized.…”

Section: Asymmetric Ring-opening Through C–c Bond Cleavagementioning

confidence: 99%

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

2022

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

“…To prevent such regioselectivity issues, an alternative approach to direct arylation for the formation of aryl–aryl bonds is the cleavage of aryl–carbon bonds. Bilodeau and Forgione reported a palladium-catalyzed cross-coupling of heteroaryl carboxylic acids and aryl halides that was believed to proceed through the β-carbon elimination of CO 2 (Scheme :1). − Likewise, Miura et al reported that α,α-disubstituted arylmethanols in the presence of palladium could undergo β-carbon elimination to yield a ketone and an aryl-palladium species that could then be coupled with various aryl halides (Scheme :2). − These types of aryl cross-couplings have since been dubbed ipso -arylations and have subsequently been used in a handful of other notable examples. − Both methods have been used as an alternative to traditional organometallic cross-coupling methods in the synthesis of conjugated polymers. , …”

Section: Introductionmentioning

confidence: 99%

Transition-Metal-Free ipso-Arylative Condensation

et al. 2020

View full text Add to dashboard Cite

The development of economical synthetic methods remains an important step toward the widespread use of conjugated polymers. Most well-established methods require either prefunctionalization with organometallic reagents or the use of expensive transition-metal catalysts. We have shown that 2-hydroxyalkyl- and 2-hydroxyaryl-substituted thiazole N-oxides can proceed through an ipso-arylative condensation that yields bithiazole-containing conjugated small molecules and polymers. The use of 2-hydroxyaryl substituents enables access to a wide scope of thiazole N-oxide substrates and presents an economical route to the synthesis of bithiazole-based conjugated polymers with varying physical and electronic properties.

show abstract

Selective Palladium‐Catalyzed ipso Arylation of α,α‐Disubstituted Benzo[b]thien‐2‐ylmethanols with Aryl Bromides Using PCy₃ as Ligand.

Cited by 4 publications

References 1 publication

Atroposelective Kinetic Resolution of 8H-Indeno[1,2-c]thiophen-8-ols via Pd-Catalyzed C–C Bond Cleavage Reaction

Atroposelective Kinetic Resolution of 8H-Indeno[1,2-c]thiophen-8-ols via Pd-Catalyzed C–C Bond Cleavage Reaction

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

Transition-Metal-Free ipso-Arylative Condensation

Contact Info

Product

Resources

About

Selective Palladium‐Catalyzed ipso Arylation of α,α‐Disubstituted Benzo[b]thien‐2‐ylmethanols with Aryl Bromides Using PCy3 as Ligand.

Cited by 4 publications

References 1 publication

Atroposelective Kinetic Resolution of 8H-Indeno[1,2-c]thiophen-8-ols via Pd-Catalyzed C–C Bond Cleavage Reaction

Atroposelective Kinetic Resolution of 8H-Indeno[1,2-c]thiophen-8-ols via Pd-Catalyzed C–C Bond Cleavage Reaction

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

Transition-Metal-Free ipso-Arylative Condensation

Contact Info

Product

Resources

About

Selective Palladium‐Catalyzed ipso Arylation of α,α‐Disubstituted Benzo[b]thien‐2‐ylmethanols with Aryl Bromides Using PCy₃ as Ligand.