Formal [4 + 4]-, [4 + 3]-, and [4 + 2]-cycloaddition reactions of donor–acceptor cyclobutenes, cyclopropenes and siloxyalkynes induced by Brønsted acid catalysis

An Ag/Au-catalyzed divergent cascade reaction of alkyne embedded diazoketones with indoles has been described. Preliminary mechanistic studies indicate that the reaction goes through a [4 + 2]-cycloaddition of an in situ formed isobenzopyrylium intermediate with indole, followed by a sequential retro-Michael addition/carbene NÀ H insertion process to give the benzo[i]phenanthridines products with gold catalysis; whereas a dearomatization/rearomatization sequence occurs favourably when the reaction is catalyzed by a silver catalyst, delivering benzo [b]carbazoles in generally high to excellent yields. Notably, this is a rare example of using indole as the dienophile for cycloaddition with the isobenzopyrylium species, providing a concise and practical approach for the selective construction of N-doped polycyclic aromatic hydrocarbons (PAHs) with structural diversity and broad functional-group compatibility.

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Yb(OTf)₃-Catalyzed Formal (4 + 3) Cycloaddition Reactions of 3-Benzylideneindoline-2-thiones with Donor–Acceptor Cyclopropanes

Jiang,

Ma,

Wang

et al. 2023

J. Org. Chem.

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A Yb(OTf)3-catalyzed formal (4 + 3) cycloaddition reaction of donor–acceptor cyclopropanes with 3-benzylideneindoline-2-thiones as sulfur-containing 4π components has been successfully achieved. A series of functionalized 5,10-dihydro-2H-thiepino[2,3-b]indole derivatives were synthesized with good yields and moderate to good diastereoselectivity. The reaction described herein represented the inaugural (4 + 3) cycloaddition of 3-benzylideneindoline-2-thiones.

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Formal [4 + 4]-, [4 + 3]-, and [4 + 2]-cycloaddition reactions of donor–acceptor cyclobutenes, cyclopropenes and siloxyalkynes induced by Brønsted acid catalysis

Cited by 8 publications

References 83 publications

Enantioselective Synthesis of Cyclopropenes

Enantioselective Synthesis of Cyclopropenes

Divergent Construction of N‐Doped Polycyclic Aromatic Hydrocarbons with Indole as the Nitrogen Source Building Block

Yb(OTf)₃-Catalyzed Formal (4 + 3) Cycloaddition Reactions of 3-Benzylideneindoline-2-thiones with Donor–Acceptor Cyclopropanes

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Formal [4 + 4]-, [4 + 3]-, and [4 + 2]-cycloaddition reactions of donor–acceptor cyclobutenes, cyclopropenes and siloxyalkynes induced by Brønsted acid catalysis

Cited by 8 publications

References 83 publications

Enantioselective Synthesis of Cyclopropenes

Enantioselective Synthesis of Cyclopropenes

Divergent Construction of N‐Doped Polycyclic Aromatic Hydrocarbons with Indole as the Nitrogen Source Building Block

Yb(OTf)3-Catalyzed Formal (4 + 3) Cycloaddition Reactions of 3-Benzylideneindoline-2-thiones with Donor–Acceptor Cyclopropanes

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Yb(OTf)₃-Catalyzed Formal (4 + 3) Cycloaddition Reactions of 3-Benzylideneindoline-2-thiones with Donor–Acceptor Cyclopropanes