Rh(II)-Catalyzed Denitrogenative Transannulation of <i>N</i>-Sulfonyl-1,2,3-triazolyl Cyclohexadienones for the Synthesis of Benzofurans and Cyclopropa[<i>cd</i>]indole-carbaldehydes

Sontakke, Geetanjali S.; Pal, Kuntal; Volla, Chandra M. R.

doi:10.1021/acs.joc.9b01924

Cited by 28 publications

(6 citation statements)

References 57 publications

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“…On the other hand, recent years have seen the resurgence of vinyl cation intermediates in synthetic chemistry, especially due to their facile generation under metal-free acidic conditions . With our interest in the diverse reactivity of alkynyl cyclohexadienones, , we envisioned that, upon activation by an acid, they could generate a bicyclic vinyl cation intermediate B by interrupting the otherwise ensuing, dienone–phenol rearrangement from A . Therefore, tailoring upon this, herein, we report a metal-free Brønsted acid-catalyzed water mediated rearrangement of alkyne tethered cyclohexadienones to access meta -alkenylated phenols …”

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confidence: 99%

Water Mediated Rearrangement of Alkynyl Cyclohexadienones: Access to meta-Alkenylated Phenols

et al. 2021

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We report an efficient water mediated, Brønsted acid-catalyzed rearrangement of alkynyl cyclohexadienones to access meta-olefinated phenols under metal-free conditions. The reaction displayed excellent substrate scope and yields in water. Synthetic utility of the protocol was highlighted by carrying out gram scale synthesis, further functionalizations, and late stage modification. Mechanistic studies highlighted the key role of water, as the reaction proceeds via a water addition–elimination sequence on to a vinyl cation intermediate.

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confidence: 99%

Water Mediated Rearrangement of Alkynyl Cyclohexadienones: Access to meta-Alkenylated Phenols

et al. 2021

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“…It was also shown that the use of O‐linked triazoles in this transformation led to benzofuran derivatives 51 through an oxy‐Cope rearrangement. In the same year, Volla and co‐workers realized the same reactions under Rh 2 (oct) 4 catalysis in CHCl 3 as solvent at 90 °C …”

Section: Denitrogenative Cyclization Of Triazolesmentioning

confidence: 98%

Synthesis of Heterocycles through Denitrogenative Cyclization of Triazoles and Benzotriazoles

Zhang

2020

Chemistry A European J

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During the past few decades, there has been considerable growth in the development of denitrogenative reactions of triazole skeletons to construct valuable cyclic compounds, particularly heterocycles. Despite the inherent difficulty of the ring‐opening of triazole derivatives, many novel and efficient approaches have arisen in this area mainly with the use of transition metal (such as rhodium, palladium, silver, copper) catalysis, photolysis, or free radical mediated reactions. Generally, these procedures begin with the ring‐opening of 1,2,3‐triazoles or benzotriazoles followed by N2 extrusion and subsequent diverse transformations, which enable the rapid synthesis of various heterocycles in a single step. To avoid overlap with other related reviews, this minireview covers the recent advances in the denitrogenative cyclization of 1,2,3‐triazoles since 2016 and the denitrogenative cyclization of benzotriazoles since 2012.

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“…The groups of Volla and Shi individually reported the synthesis of benzofurans 32.2 and cyclopropa[ cd ]indoles 32.3 through intramolecular cyclopropanation of alkenes from triazole 32.1 containing a tethered cyclohexadienone group in which an O or N atom is present in the linker (Scheme ). Mechanistically, the Rh-bound iminocarbenoid intermediate 32.4 is initially formed from triazole 32.1 and the Rh catalyst.…”

Section: Denitrogenative Transformations Of Triazolesmentioning

confidence: 99%

1,2,3-Triazole and Its Analogues: New Surrogates for Diazo Compounds

2022

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Readily accessible and shelf-stable 1,2,3-triazole and its analogues such as pyridotriazole, triazoloindole, benzotriazole, and thiadiazole exist in equilibrium with their ring-opened isomers, viz., diazo compounds. These ring-opened isomers could be trapped by various metal catalysts (e.g., Rh, Pd, Cu, Co, Ag, etc.) to generate the corresponding metal carbenoids with extrusion of nitrogen. As a consequence, these unique N-heterocycles facilitate access to a realm of N-containing complex structural motifs of biological importance through denitrogenative transformations such as transannulations, insertions, ylide formation, and rearrangements by trapping of the metal carbenoids with a diverse range of coupling partners (e.g., alkenes, alkynes, nitriles, carbo/heterocycles, X–H/C–X bonds, etc.). Hence, suitably substituted triazole derivatives have emerged as efficient surrogates of diazo compounds for the generation of reactive metal carbenoids during the past decades. In this comprehensive review, we aim to discuss in detail the remarkable advancement in their synthesis and synthetic applications.

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Rh(II)-Catalyzed Denitrogenative Transannulation of N-Sulfonyl-1,2,3-triazolyl Cyclohexadienones for the Synthesis of Benzofurans and Cyclopropa[cd]indole-carbaldehydes

Cited by 28 publications

References 57 publications

Water Mediated Rearrangement of Alkynyl Cyclohexadienones: Access to meta-Alkenylated Phenols

Water Mediated Rearrangement of Alkynyl Cyclohexadienones: Access to meta-Alkenylated Phenols

Synthesis of Heterocycles through Denitrogenative Cyclization of Triazoles and Benzotriazoles

1,2,3-Triazole and Its Analogues: New Surrogates for Diazo Compounds

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