Decarboxylative cyclizations and cycloadditions of palladium-polarized aza-ortho-xylylenes

Wang, Chao; Pahadi, Nirmal K.; Tunge, Jon A.

doi:10.1016/j.tet.2009.04.071

Cited by 74 publications

(48 citation statements)

References 24 publications

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“…2b). Notably, trapping of these intermediates with electrophilic components for cycloaddition was hitherto unknown and remains a challenging goal in this field of Pd-catalysed DC reactions because, as Tunge concluded, ''ypalladium-polarized aza-ortho-xylylenes (D) (note: intermediate I here) prefer to react with electron deficient olefinsy'' 30 . More significantly, via this approach, an important indoline core that is ubiquitous in many biologically active natural and synthetic chemicals could be conveniently constructed in a highly enantioselective and diastereoselective manner [31][32][33] .…”

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confidence: 99%

Asymmetric trapping of zwitterionic intermediates by sulphur ylides in a palladium-catalysed decarboxylation-cycloaddition sequence

Tan

et al. 2014

Nat Commun

157

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Through nearly 50 years of development, sulphur ylides have been established as versatile and powerful reagents for the construction of carbocycles and heterocycles. Despite advances, two important and yet elusive bottlenecks continue to inhibit the advancement of this chemistry: a limited number of reagents with polar groups to react with sulphur ylides, and the wide utilization of chiral auxiliaries or substrates to achieve asymmetric cycloaddition processes in the majority of known reports. Herein, we apply an asymmetric palladium catalysis strategy to the chemistry of sulphur ylides to address these two fundamental problems. We thus achieve an unprecedented decarboxylation-cycloaddition sequence of cyclic allylic esters with sulphur ylides through the enantioselective trapping of Pd-stabilized zwitterionic intermediates by the ylides. As a result, a series of biologically and synthetically important 3-vinyl indolines are rapidly assembled with a high reaction efficiency and stereoselectivity.

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confidence: 99%

Asymmetric trapping of zwitterionic intermediates by sulphur ylides in a palladium-catalysed decarboxylation-cycloaddition sequence

Tan

et al. 2014

Nat Commun

157

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“…In 2009, the Tunge group investigated the palladium‐catalyzed decarboxylative allylic amination reaction of vinyl benzoxazinanones 38 a (Scheme ) . When aliphatic amines were used, branched products 40 were obtained in 82–98 % yield, whereas, when N ‐tosyl aniline ( 42 ) was used, only linear product 43 was obtained in 65 % yield.…”

Section: Hydrogen‐bonding Interactionsmentioning

confidence: 99%

“…Then, in 2001, Trost and Jiang reported the first palladium-catalyzed asymmetrica llylic alkylation of b-ketoesters 21 with isoprene monoepoxide (20). [14] A range of b-ketoesters were amenable to this transformation, thereby affording branched productst hat contained chiral quaternary all-carbon stereocenters (22)i nm oderate-to-good yields with excellent enantioselectivities (Scheme 6). Notably,i n 2003, this reaction was used for the asymmetrics ynthesis of the cyclopentyl core of viridenomycin, which hasi mportant biological activities.…”

Section: Oxygen Anions As the Hydrogen-bond Donormentioning

confidence: 99%

“…[21] In 2009, the Tunge group investigated the palladium-catalyzed decarboxylative allylic amination reactiono fv inyl benzoxazinanones 38 a (Scheme 10). [22] When aliphatic amines were used, branched products 40 were obtained in 82-98 % yield, whereas, when N-tosyl aniline (42)w as used, only linear product 43 was obtained in 65 %y ield. Twop ossible reaction modes were proposed to explain these results:1 )for aliphatic amines,ahydrogen-bonding interaction was suggested to direct the attack of the amine to the adjacent position; and 2) for N-tosyl aniline (42), owing to its comparably highera cidity,t he deprotonatedn itrogen nucleophile could attack the sterically favored terminal positiont oa fford the linear product.…”

Section: Nitrogen Anions As the Hydrogen-bond Donormentioning

confidence: 99%

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Non‐Bonding Interactions Enable the Selective Formation of Branched Products in Palladium‐Catalyzed Allylic Substitution Reactions

Wang

Xiao

2018

Chemistry An Asian Journal

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Palladium-catalyzed allylic substitution reactions have become established as an important tool for the construction of carbon-carbon and carbon-heteroatom bonds in modern organic synthesis. However, controlling the regioselectivity of this type of transformation to afford chiral branched products, in addition to controlling the enantioselectivity, is a significant challenge. Excitingly, controlling nonbonding interactions between the substituents on the π-allyl-palladium intermediate and the nucleophile or palladium catalyst has been shown to be effective in achieving this goal. This Focus Review highlights representative advances in this field, according to the mode of non-bonding interaction, including hydrogen-bonding, electrostatic, and coordination interactions.

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“…[10] These intermediates underwent av ariety of [4+ +n]c ycloaddition (n = 1-4) reactions. [10] These intermediates underwent av ariety of [4+ +n]c ycloaddition (n = 1-4) reactions.…”

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confidence: 99%

Visible‐Light‐Driven Aza‐ortho‐quinone Methide Generation for the Synthesis of Indoles in a Multicomponent Reaction

et al. 2017

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A visible-light-driven radical-mediated strategy for the in situ generation of aza-ortho-quinone methides from 2-vinyl-substituted anilines and alkyl radical precursors is described. This process enables an efficient multicomponent reaction of 2-vinylanilines, halides, and sulfur ylides, and has a wide substrate scope and good functional group tolerance. Treatment of the cycloaddition products with a base leads to densely functionalized indoles in a single-flask operation.

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Decarboxylative cyclizations and cycloadditions of palladium-polarized aza-ortho-xylylenes

Cited by 74 publications

References 24 publications

Asymmetric trapping of zwitterionic intermediates by sulphur ylides in a palladium-catalysed decarboxylation-cycloaddition sequence

Asymmetric trapping of zwitterionic intermediates by sulphur ylides in a palladium-catalysed decarboxylation-cycloaddition sequence

Non‐Bonding Interactions Enable the Selective Formation of Branched Products in Palladium‐Catalyzed Allylic Substitution Reactions

Visible‐Light‐Driven Aza‐ortho‐quinone Methide Generation for the Synthesis of Indoles in a Multicomponent Reaction

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