Rh/Pd Catalysis with Chiral and Achiral Ligands: Domino Synthesis of Aza‐Dihydrodibenzoxepines

Nitrogen-containing aromatic heterocycles (azaarenes) are of widespread chemical significance, and chiral compounds containing azaarenes feature prominently in pharmaceuticals, agrochemicals, and natural products. ThisPerspective highlights the use of a relatively underdeveloped strategy to prepare chiral azaarene-containing compounds: exploitation of the C=N bond embedded within certain azaarenes to activate adjacent functionality in catalytic asymmetric reactions. Work in this area has resulted in the development of several different types of catalytic enantioselective processes, including reductions, nucleophilic additions, and reductive couplings. It is hoped that this Perspective will encourage more researchers to work in this promising area.

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“…34 A survey of various chiral ligands established that the chiral diene L3 32 provided optimal results.…”

Section: Scheme 7 Enantioselective Rh-catalyzed Arylation Of Alkenylmentioning

confidence: 99%

C═N-Containing Azaarenes as Activating Groups in Enantioselective Catalysis

2013

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“…Furthermore,i mplementation of catalytic transformations poses an even greater challenge,p rimarily because of concerns over catalyst inhibition and turnover efficiency.I ns pite of these challenges,s everal reports of multimetal and multiligand catalytic transformations have appeared recently, [6] most notably the contributions from the Lautens laboratory. [7] We have previously demonstrated an enyne cycloisomerization/Diels-Alder cascade process to assemble the core structure of the echinopines (Scheme 1a). [8] In connection with this study,w ep ondered whether an enyne cycloisomerization product could further participate in other conjugated diene-specific transformations.S pecifically, several transition-metal-mediated, conjugated diene-specific transformations have been reported, [9] and more recently the Yu laboratory demonstrated as erendipitous conjugated diene-assisted CH-activation process in the synthesis of substituted pyrrolidines together with its asymmetric variant (Scheme 1b).…”

mentioning

confidence: 99%

An Asymmetric Pathway to Dendrobine by a Transition‐Metal‐Catalyzed Cascade Process

et al. 2017

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An asymmetric pathway to the caged tetracyclic pyrrolidine alkaloid, dendrobine, is reported. The successful synthetic strategy features a one-pot, sequential palladium-catalyzed enyne cycloisomerization and rhodium-catalyzed diene-assisted pyrrolidine formation by allylic CH activation. The developed transition-metal-catalyzed cascade process permits rapid access to the dendrobine core structure and circumvents the handling of labile intermediates. An intramolecular aldol condensation under carefully defined reaction conditions takes place with a concomitant detosylation, followed by reductive amine methylation, to afford a late-stage intermediate (previously identified by several prior dendrobine syntheses) in only 10 synthetic steps overall.

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“…[5] In doing so,workup and purification are significantly reduced, and the isolation of potentially hazardous and/or labile intermediates is circumvented. [7] We have previously demonstrated an enyne cycloisomerization/Diels-Alder cascade process to assemble the core structure of the echinopines (Scheme 1a). Furthermore,i mplementation of catalytic transformations poses an even greater challenge,p rimarily because of concerns over catalyst inhibition and turnover efficiency.I ns pite of these challenges,s everal reports of multimetal and multiligand catalytic transformations have appeared recently, [6] most notably the contributions from the Lautens laboratory.…”

mentioning

confidence: 88%

An Asymmetric Pathway to Dendrobine by a Transition‐Metal‐Catalyzed Cascade Process

et al. 2017

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An asymmetric pathwayt ot he caged tetracyclic pyrrolidine alkaloid, dendrobine,i sr eported. The successful synthetic strategy features ao ne-pot, sequential palladiumcatalyzede nyne cycloisomerization and rhodium-catalyzed diene-assisted pyrrolidine formation by allylic CH activation. The developed transition-metal-catalyzed cascade process permits rapid access to the dendrobine core structure and circumvents the handling of labile intermediates.A ni ntramolecular aldol condensation under carefully defined reaction conditions takes place with ac oncomitant detosylation, followed by reductive amine methylation, to affordalatestage intermediate (previously identified by several prior dendrobine syntheses) in only 10 synthetic steps overall.

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Rh/Pd Catalysis with Chiral and Achiral Ligands: Domino Synthesis of Aza‐Dihydrodibenzoxepines

Cited by 123 publications

References 45 publications

C═N-Containing Azaarenes as Activating Groups in Enantioselective Catalysis

C═N-Containing Azaarenes as Activating Groups in Enantioselective Catalysis

An Asymmetric Pathway to Dendrobine by a Transition‐Metal‐Catalyzed Cascade Process

An Asymmetric Pathway to Dendrobine by a Transition‐Metal‐Catalyzed Cascade Process

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