Construction of Various Bridged Polycyclic Skeletons by Palladium‐Catalyzed Dearomatization

et al. 2021

CCS Chem

Herein, we report a novel palladium (Pd)-catalyzed asymmetric domino Heck/carbocyclization/Suzuki reaction of N-(2-bromoaryl)-2-naphthylacrylamides. The reaction involves a novel and enantioselective dearomative 1,2-insertion of the naphthalene group, thus providing a unique dearomatization strategy of nonactivated naphthalenes. A new phosphoramidite ligand L12, which displayed excellent reactivity and enantioselectivity in the reaction, has been developed. The reaction employs readily available starting materials, and provides straightforward access to a diverse array of spirooxindoles bearing three stereogenic centers in high yields under mild conditions.

Section: Introductionmentioning

confidence: 99%

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

Chen

et al. 2021

CCS Chem

“…Dearomatization is an important reaction for the transformations of readily available planar aromatic compounds into complex 3-dimentional structures such as spirocycles, polycycles and bridged-cycles. [1][2][3][4][5] Recently, transition-metal-catalyzed dearomatization reaction 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 has becoming an emerging concept in organic synthesis. 16 However, due to the inherent stability and high resonance energy of nonactivated arenes, the dearomative transformation of the nonactivated arenes remains an important challenge.…”

Section: Introductionmentioning

confidence: 99%

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

Chen

et al. 2021

CCS Chem.

We report herein a novel Pd-catalyzed asymmetric domino Heck-carbocyclization-Suzuki reaction of N-(2-bromoaryl)-2-naphthylacrylamides. The reaction involves a novel and enantioselective dearomative 1,2insertion of naphthalene group, thus providing an unique dearomatization strategy of nonactivated naphthalenes. A new phosphoramidite ligand L12 which displayed excellent reactivity and enantioselectivity in the reaction has been developed. The reaction employs readily available starting materials, and provides straightforward access to a diverse array of spirooxindoles bearing three stereogenic centers in high yields under mild conditions.

“…11 Tang et al reported a palladiumcatalyzed dearomative cyclization to provide eight types of bridged tetracyclic skeletons bearing various ring sizes and heterocycles, including bicyclic[2.2.1] systems. 12 In addition, Waldmann et al reported [6 + 3] cycloadditions of azomethine ylides with fulvenes, which was combined with a [4 + 2] cycloaddition in one pot to yield bridged bicyclo[2.2.1] skeletons. 13 Despite these advances, there are few efficient methods that can provide diverse scopes of polysubstituted bridged bicyclo[2.2.1] skeletons.…”

mentioning

confidence: 99%

Direct Access to Bridged Polycyclic Skeletons by Merging Oxidative C–H Annulation and Cascade [4 + 2] Cycloaddition

et al. 2021

Org. Lett.

We report a step-economic strategy for the direct synthesis of bridged polycyclic skeletons by merging oxidative C−H annulation and cascade cycloaddition. In the protocol, spiro[cyclopentane-1,3′-indoline]-2,4-dien-2′-ones were first synthesized by oxidative C−H annulation of ethylideneoxindoles with alkynes. Subsequent cascade [4 + 2] cycloaddition with dienophiles gave the bridged bicyclo[2.2.1]quinolin-2(1H)-ones and enabled the one-pot construction of two quaternary carbon centers and three C−C bonds. Mechanistic investigations of the latter suggest a cascade ring-opening, 1,5-sigmatropic rearrangement, and [4 + 2] cycloaddition process.