Ruthenium‐Catalyzed Regioselective Cyclization of Aromatic Ketones with Alkynes: An Efficient Route to Indenols and Benzofulvenes

Chinnagolla, Ravi Kiran; Jeganmohan, Masilamani

doi:10.1002/ejoc.201101364

Cited by 98 publications

(37 citation statements)

References 85 publications

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“…Similar transformations have also been reported by Cheng, 40 Jeganmohan, 41 and Shibata 42 using rhodium, ruthenium, and iridium catalysts respectively. However, if a methyl or methylene group is present at the a-position of the ketone (R 1 ) or the g-position of the alkyne (R 3 ), dehydration takes place affording the fulvene derivatives (18 and 19, respectively).…”

Section: Scheme 16supporting

confidence: 83%

“…Instead of a ketone-directed pathway, the authors proposed an enolate-directed palladation assisted by Cs 2 CO 3 . It was proposed that after the ortho-arylation, a second ketone (or enolate)directed C-H activation occurs to form a seven-membered palladacycle (41). 60 In 2010, Cheng and coworkers reported a ketone-directed ortho-arylation with aryl iodides (Scheme 27).…”

Section: Arylationmentioning

confidence: 99%

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Transition metal-catalyzed ketone-directed or mediated C–H functionalization

et al. 2015

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Transition metal-catalyzed C-H functionalization has evolved into a prominent and indispensable tool in organic synthesis. While nitrogen, phosphorus and sulfur-based functional groups (FGs) are widely employed as effective directing groups (DGs) to control the site-selectivity of C-H activation, the use of common FGs (e.g. ketone, alcohol and amine) as DGs has been continuously pursued. Ketones are an especially attractive choice of DGs and substrates due to their prevalence in various molecules and versatile reactivity as synthetic intermediates. Over the last two decades, transition metal-catalyzed C-H functionalization that is directed or mediated by ketones has experienced vigorous growth. This review summarizes these advancements into three major categories: use of ketone carbonyls as DGs, direct β-functionalization, and α-alkylation/alkenylation with unactivated olefins and alkynes. Each of these subsections is discussed from the perspective of strategic design and reaction discovery.

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Section: Scheme 16supporting

confidence: 83%

Section: Arylationmentioning

confidence: 99%

Transition metal-catalyzed ketone-directed or mediated C–H functionalization

et al. 2015

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“…178 Though diphenyl acetylene was the most commonly used alkyne, unsymmetrical internal alkynes bearing alkyl, silyl, and 1-cyclohexenyl substituents also provided indenols in good yields and with high regioselectivity. A number of acetophenone derivatives and the related 3-acetylindole were effective coupling partners in the transformation.…”

Section: Additions To C=c π-Bonds Followed By Cyclization Upon Pomentioning

confidence: 99%

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

2016

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The transition metal-catalyzed addition of C–H bonds to carbonyls, imines and related polarized π-bonds has emerged as a particularly efficient and powerful approach for the construction of an incredibly diverse array of heteroatom substituted products. Readily available and stable inputs are typically employed, and reactions often proceed with very high functionality group compatibility and without the production of waste byproducts. Additionally, many transition metal-catalyzed C–H bond additions to polarized π-bonds occur within cascade reaction sequences to provide rapid access to a diverse array of different heterocyclic as well as carbocyclic products. This review highlights the diversity of transformations that have been achieved, catalysts that have been used, and types of products that have been prepared through the transition metal catalyzed addition of C–H bonds to carbonyls, imines and related polarized π-bonds.

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“…In particular, the rhodium-catalyzed coupling reactions of (hetero)aromatic substrates with alkynes have offered a unique platform for atom-economical and straightforward annulation [6][7][8][9][10][11][12][13][14] . Recently, the research groups of Cheng and co-workers 8 , Glorius and co-workers 9 and Jeganmohan and co-workers 10 have disclosed the synthesis of indenols through the rhodium-or rutheniumcatalyzed carbonyl-assisted aromatic C-H activation/cyclization of aryl ketones with internal alkynes via a proposed fivemembered metallocyclic intermediate (Fig. 1a).…”

mentioning

confidence: 99%

Unexpected regioselective carbon–hydrogen bond activation/cyclization of indolyl aldehydes or ketones with alkynes to benzo-fused oxindoles

Liu

Song

et al. 2014

Nat Commun

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Rhodium-catalyzed carbon-hydrogen bond activation has attracted great interest in the construction of carbon-carbon and carbon-heteroatom bonds. In recent years, transition metal-mediated oxygen transposition through a 'dehydration-rehydration' process has been considered as a promising strategy towards oxygen-functionalized compounds. Here we describe an unexpected rhodium-catalyzed regioselective carbon-hydrogen bond activation/ cyclization of easily available indolyl aldehydes or ketones with alkynes to afford benzo-fused oxindoles, involving the sequential carbonyl-assisted carbon-hydrogen activation of the indole ring at the 4-position, [4 þ 2] cyclization, aromatization via dehydration, nucleophilic addition of water to iminium and oxidation. Isotopic labelling experiments disclose the occurrence of apparent oxygen transposition via dehydration-rehydration from the indolyl-3-carbonyl group to the 2-position of pyrrole to forge a new carbonyl bond. The tandem reaction has been used as the key step for the concise synthesis of priolines, a type of alkaloid isolated from the roots of Salvia prionitis.

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Ruthenium‐Catalyzed Regioselective Cyclization of Aromatic Ketones with Alkynes: An Efficient Route to Indenols and Benzofulvenes

Cited by 98 publications

References 85 publications

Transition metal-catalyzed ketone-directed or mediated C–H functionalization

Transition metal-catalyzed ketone-directed or mediated C–H functionalization

Transition-Metal-Catalyzed C–H Bond Addition to Carbonyls, Imines, and Related Polarized π Bonds

Unexpected regioselective carbon–hydrogen bond activation/cyclization of indolyl aldehydes or ketones with alkynes to benzo-fused oxindoles

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