Gallium(III)-Promoted Halocyclizations of 1,6-Diynes

Strom, Kyle R.; Impastato, Anna C.; Moy, Kenneth J.; Landreth, Adrian J.; Snyder, John K.

doi:10.1021/acs.orglett.5b00716

Cited by 13 publications

(8 citation statements)

References 30 publications

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“…23 Under acidic conditions, the iodocyclization products may undergo in situ Friedel-Crafts cyclization. Alternatively, the isolated vinyl iodides may be used as substrates for cross-coupling reactions.…”

Section: Gallium(iii) Iodidementioning

confidence: 99%

Gallium and Indium Compounds in Homogeneous Catalysis

Dagorne

Fliedel

Frémont

2016

Encyclopedia of Inorganic and Bioinorganic Chemistry

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The present contribution highlights the most recent and representative developments on the use of Ga and In species in homogeneous catalysis. Recent studies of various ligand‐supported Ga(III) and In(III) compounds in cyclic esters polymerization catalysis for the production of biodegradable polyester materials are also included. Various organic transformations may now be catalyzed using Ga(III) and In(III) Lewis acids allowing access to a wide range of valuable organic molecules through diverse reaction sequences. The recent use of stable and robust N ‐heterocyclic carbene Ga(III) and In(III) compounds as strong π‐Lewis acid catalysts for various organic reactions is also discussed: such species are certainly promising for the future developments of Ga(III)‐ and In(III)‐mediated reactions. Although Lewis acid‐assisted reactions certainly dominate the field in Ga(III) and In(III) chemistry, discrete low‐valent In(I) species, presently emerging in catalysis, clearly display a distinct reactivity allowing their exploitation both as soft Lewis acids and alkyl‐/allyl‐/arylating agents.

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Section: Gallium(iii) Iodidementioning

confidence: 99%

Gallium and Indium Compounds in Homogeneous Catalysis

Dagorne

Fliedel

Frémont

2016

Encyclopedia of Inorganic and Bioinorganic Chemistry

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“…The catalytic electrophilic activation of alkynes promotes the addition of nucleophiles and allows the formation of new carbon–carbon and carbon–heteroatom bonds in an intermolecular and intramolecular manner. Although this methodology has been associated with the use of carbophilic late precious transition metals such as platinum or gold as catalysts, main group metals such as gallium or indium have been shown as valuable alternatives (Scheme a).…”

Section: Introductionmentioning

confidence: 99%

Indium(III)-Catalyzed Stereoselective Synthesis of Tricyclic Frameworks by Cascade Cycloisomerization Reactions of Aryl 1,5-Enynes

et al. 2021

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The indium(III)-catalyzed cascade cycloisomerization reaction of 1,5-enynes with pendant aryl nucleophiles is reported. The reaction proceeds in cascade under mild reaction conditions, using InI 3 (5 mol %) as a catalyst with a range of 1,5enynes furnished with aryl groups (phenyl and phenol) at alkene (E and Z isomers) and with terminal and internal alkynes. Using 1bromo-1,5-enynes, a one-pot sequential indium-catalyzed cycloisomerization and palladium-catalyzed cross-coupling with triorganoindium reagents were developed. The double cyclization is stereospecific and operates via a biomimetic cascade cation-olefin through 1,5-enyne cyclization (6-endo-dig) and subsequent C−C hydroarylation or C−O phenoxycyclization. Density functional theory (DFT) computational studies on 1,5-enynyl aryl ethers support a two-step mechanism where the first stereoselective 1,5-enyne cyclization produces a nonclassical carbocation intermediate that evolves to the tricyclic reaction product through a S E Ar mechanism. Using this approach, a variety of tricyclic heterocycles such as benzo[b]chromenes, phenanthridines, xanthenes, and spiroheterocyclic compounds are efficiently synthesized with high atom economy.

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“…Over the years, isolated examples of the halo -Nazarov cyclization have been disclosed, although the transformation is often described as an intramolecular Friedel–Crafts arylation . We have recently developed cationic cascades that capitalize upon this halo -Nazarov cyclization to afford complex halocyclopentenes (e.g., Scheme , eq 2), and prior to this recent work, only five studies have focused on the generation and cyclization of halo -pentadienyl cationic intermediates.…”

Section: Introductionmentioning

confidence: 99%

Leveraging the Halo-Nazarov Cyclization for the Chemodivergent Assembly of Functionalized Haloindenes and Indanones

2019

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In this report, we describe a halo-Prins/aryl halo-Nazarov cyclization strategy that employs readily available starting materials, inexpensive reagents, and convenient reaction procedures to generate functionalized haloindenes and indanones. The scope and limitations of the method are outlined, demonstrating that aromatic systems readily react under mild, catalytic conditions when this strategy is implemented. Furthermore, we present both experimental and computational data supporting the notion that cyclizations of 3-halopentadienyl cationic intermediates are more kinetically accessible, as well as more thermodynamically favorable, than cyclizations of the analogous 3-oxypentadienyl cationic systems. The energetic advantage imparted by the halo-Nazarov cyclization design was found to be especially valuable in the cyclizations of arylallyl cationic intermediates, which require disruption of aromaticity.

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Gallium(III)-Promoted Halocyclizations of 1,6-Diynes

Cited by 13 publications

References 30 publications

Gallium and Indium Compounds in Homogeneous Catalysis

Gallium and Indium Compounds in Homogeneous Catalysis

Indium(III)-Catalyzed Stereoselective Synthesis of Tricyclic Frameworks by Cascade Cycloisomerization Reactions of Aryl 1,5-Enynes

Leveraging the Halo-Nazarov Cyclization for the Chemodivergent Assembly of Functionalized Haloindenes and Indanones

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