Stereoselective synthesis of [2.2]triphenylenophanes<i>via</i>intramolecular double [2 + 2 + 2] cycloadditions

Kawai, Yumiko; Nogami, Juntaro; Nagashima, Yuki; Tanaka, Ken

doi:10.1039/d3sc00571b

Cited by 10 publications

(2 citation statements)

References 99 publications

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“…Transition metal-catalyzed [2+2+2] cycloaddition of three 2π components has attracted much attention, due to its high efficiency and atom economy for the rapid construction of functionalized sixmembered carbo-and heterocycles with high functional group tolerance (1)(2)(3). In particular, transition metal-catalyzed inter-and intramolecular asymmetric [2+2+2] cycloadditions of alkynes have been proven as a powerful tool to synthesize valuable benzenebased skeletons bearing central (4,5), axial (6)(7)(8)(9), planar (10,11), helical chirality (12)(13)(14)(15)(16), and chiral belts (17)(18)(19), which were well established by Tanaka and others (Fig. 1A).…”

Section: Introductionmentioning

confidence: 99%

Ir/Zn-cocatalyzed chemo- and atroposelective [2+2+2] cycloaddition for construction of C─N axially chiral indoles and pyrroles

Yang,

Xie,

et al. 2023

Sci. Adv.

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Here, an Ir/Zn-cocatalyzed atroposelective [2+2+2] cycloaddition of 1,6-diynes and ynamines was developed, forging various functionalized C─N axially chiral indoles and pyrroles in generally good to excellent yields (up to 99%), excellent chemoselectivities, and high enantioselectivities (up to 98% enantiomeric excess) with wide substrate scope. This cocatalyzed strategy not only provided an alternative promising and reliable way for asymmetric alkyne [2+2+2] cyclotrimerization in an easy handle but also settled the issues of previous [Rh(COD) 2 ]BF 4 -catalyzed system on the construction of C─N axial chirality such as complex operations, limited substrate scope, and low efficiency. In addition, control experiments and theoretical calculations disclosed that Zn(OTf) 2 markedly reduced the barrier of migration insertion to significantly increase reaction efficiency, which was distinctly different from previous work on the Lewis acid for improving reaction yield through accelerating oxidative addition and reductive elimination.

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Section: Introductionmentioning

confidence: 99%

Ir/Zn-cocatalyzed chemo- and atroposelective [2+2+2] cycloaddition for construction of C─N axially chiral indoles and pyrroles

Yang,

Xie,

et al. 2023

Sci. Adv.

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“…A representative planar chiral structure is a medium-ring or macrocyclic cyclophane comprising an arene and a bridging chain connected to two points on the arene . While planar chiral macrocyclic paracyclophanes are now accessible by biocatalytic, organocatalytic, transition-metal-catalyzed, and stoichiometric lithiation methods, examples of catalytic, enantioselective synthesis of chiral macrocyclic metacyclophanes remain sparse. − Despite the potential generality of enantioselective macrocyclization reactions where bond formation occurs at the prochiral plane to access planar chiral cyclophanes, there are only two known examples applied to the synthesis of metacyclophanes. Beaudry and co-workers reported the synthesis of enantioenriched planar chiral metacyclophanes related to diarylether heptanoid natural products by enantioselective macrocyclization by Ullman coupling (Scheme A) .…”

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confidence: 99%

Enantioselective Synthesis of Planar Chiral Macrocyclic Metacyclophanes by Pd-Catalyzed C–O Cross-Coupling

Wei

Chen

2023

ACS Catal.

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Despite the presence of planar chiral elements in natural products and in ligands for asymmetric catalysis, catalytic enantioselective methods for installing planar chirality remain underdeveloped relative to methods for installing central and axial chirality. Here, we report an enantioselective Pd-catalyzed C–O bond-forming macrocyclization to access enantioenriched planar chiral macrocyclic metacyclophanes incorporating 2,3,4-trisubstituted pyridines. A variety of bridging chains and substituents can be incorporated in the metacyclophanes under the same reaction conditions (14 examples, 59–85% yields, 79–92% ee) to generate enantioenriched meta-, metaortho-, and metapara- cyclophanes. The syn-/anti-conformational preferences of metacyclophanes were elucidated by the X-ray structures, 1H NMR analyses, and computational studies. We also found that the two enantiomers of the metacyclophane can be obtained using the same enantiomer of the chiral ligand by starting from two regioisomeric linear precursors. This work provides an entry into the design of enantioselective cross-coupling macrocyclizations to access planar chiral structures for applications in medicinal chemistry and catalysis.

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Atroposelective Synthesis of Planar‐Chiral Indoles via Carbene Catalyzed Macrocyclization

Yang,

He,

Wang

et al. 2023

Angewandte Chemie

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Indole‐based planar‐chiral macrocycles are widely found in natural products and bioactive molecules. However, in sharp contrast to the preparation of indole‐based axially chiral structures, the enantioselective catalysis of indole‐based planar‐chiral macrocycles is still a formidable task so far. Here we report an N‐heterocyclic carbene (NHC)‐catalyzed intramolecular atroposelective macrocyclization of 3‐carboxaldehyde indole/pyrroles, featuring with broad substrate scope and good functional group tolerance, and allowing for a rapid access to diverse indole/pyrrole‐based planar‐chiral macrocycles with various tether‐lengths (10–16 members) in good yields and with excellent enantioselectivities. Importantly, the indole‐based macrocyclic structures with both planar and axial chirality were directly and efficiently obtained through this protocol with excellent enantioselectivities and diastereoselectivities. In addition, these synthesized planar‐chiral macrocycles offer many possibilities for chemists to develop new catalysts or ligands, as well as new reactions.

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Stereoselective synthesis of [2.2]triphenylenophanesviaintramolecular double [2 + 2 + 2] cycloadditions

Abstract: Planar chiral [2.2]cyclophanes with two aromatic rings in close proximity have attracted much attention for their applications as chiral materials and catalysts because of their stable chirality and transannular interactions....

Cited by 10 publications

References 99 publications

Ir/Zn-cocatalyzed chemo- and atroposelective [2+2+2] cycloaddition for construction of C─N axially chiral indoles and pyrroles

Ir/Zn-cocatalyzed chemo- and atroposelective [2+2+2] cycloaddition for construction of C─N axially chiral indoles and pyrroles

Enantioselective Synthesis of Planar Chiral Macrocyclic Metacyclophanes by Pd-Catalyzed C–O Cross-Coupling

Atroposelective Synthesis of Planar‐Chiral Indoles via Carbene Catalyzed Macrocyclization

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