Palladium‐Catalyzed [2+2+1] Spiroannulation via Alkyne‐Directed Remote C−H Arylation and Subsequent Arene Dearomatization

Abstract

Palladium‐catalyzed alkene‐directed cross‐coupling of aryl iodide with another aryl halide through C−H arylation opens a unique avenue for unsymmetrical biaryl‐derived molecules. However, homo‐coupling of aryl iodides often erodes the overall synthetic efficiency. Reported herein is a highly chemoselective Pd0‐catalyzed alkyne‐directed cross‐coupling of aryl iodides with bromophenols, which was subsequently followed by phenol dearomatization to furnish a very attractive [2+2+1] spiroannulation. Notably, possible homo‐coupling of aryl iodides was not observed at all. Mechanistic studies indicated that a five‐membered aryl/vinyl palladacycle most likely accounts for promoting the key step of biaryl cross‐coupling.

Spirocyclizative Remote Arylcarboxylation of Non-Activated Arenes with CO2 via Visible-Light-Induced Reductive Dearomatization

“…In addition, N-protected aniline linkers with different protecting groups (such as Boc, Ac, Cbz and CO2Ph) were also tolerated (12)(13)(14)(15). Moreover, several substitution patterns on the aniline ring were allowed with the reaction to give desired products in satisfied yields (16)(17)(18)(19)(20)(21). Finally, spiroindolines could be delivered with quinolinyl substrates with the aniline linkers (22 and 23).…”

Spirocyclizative Remote Arylcarboxylation of Nonactivated Arenes with CO 2 via Visible-Light-Induced Reductive Dearomatization

“…In addition, N-protected aniline linkers with different protecting groups (such as Boc, Ac, Cbz and CO 2 Ph) were also tolerated (12)(13)(14)(15). Moreover, several substitution patterns on the aniline ring were allowed with the reaction to give desired products in satisfied yields (16)(17)(18)(19)(20)(21). Finally, spiroindolines could be delivered with quinolinyl substrates with the aniline linkers (22 and 23).…”

Palladium-Catalyzed Asymmetric Domino Heck/Carbocyclization/Suzuki Reaction: A Dearomatization of Nonactivated Naphthalenes

“…Dearomatization is an important reaction for the transformations of readily available planar aromatic compounds into complex three-dimentional (3D) structures such as spirocycles, polycycles, and bridged cycles. [1][2][3][4][5] Recently, transition-metal-catalyzed dearomatization reactions of furans, pyrroles, indoles, pyridines, phenols, anilines, and naphthols have been developed as powerful strategies to construct complex structures, [6][7][8][9][10][11][12][13][14][15] and catalytic asymmetric dearomatization (CADA) is an emerging concept in organic synthesis. 16 However, due to the inherent stability and high resonance energy of nonactivated arenes, the dearomative transformation of nonactivated arenes remains an important challenge.…”