Unexpected [4 + 2] Cycloaddition through Chromium Non-Heteroatom-Stabilized Alkynyl Carbene Complexes: Regioselective Access to Substituted 6-Azaindoles

Gómez, Aránzazu; Funes‐Ardoiz, Ignacio; Sampedro, Diego; Santamarı́a, Javier

doi:10.1021/acs.orglett.8b01650

Cited by 13 publications

(3 citation statements)

References 40 publications

(26 reference statements)

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“…With the experimental results in hand, we chose to compare them to nonmetalated and to monometalated analogs as well as to the stronger π-donor metal chromium. It is now beyond controversy that the double-bond character of gold carbene complexes is low. − For this reason, for possible further applications − and for their synthetic connection to late transition metal complexes by transmetalation of the carbenes, we chose chromium(−I) in our study. It forms carbene complexes with stronger π-backbonds and thus broadens the perspective on the electronic structures of [M 2 C(vinyl)] + species beyond what we have experimentally detected before. − …”

Section: Resultsmentioning

confidence: 99%

Sesquicarbene Complexes: Bonding at the Interface Between M–C Single Bonds and M═C Double Bonds

2020

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Allylic dimetalated complexes [M 2 C(vinyl)] + (M = Au(IPr) and Cr(CO) 5 −) incorporate a new coordination mode of carbon. Digold complexes of this type have recently been detected experimentally. The intrinsic bond orbitals, partial charges, and structural parameters of the gold complexes and of chromium analogs were studied computationally and compared to those of the respective monometalated species and hydrocarbons. This showed that such digold complexes have a carbene character at both Au−C bonds comparable to typical carbene complexes of gold. Dichromium complexes with their stronger π-backdonation compete for interaction with carbon's π-orbital; each of the chromium atoms partakes in double bonding that is significant but weaker than that in the carbene analogs. Containing two M−C bonds on the interface between single and double bonds, these bridged complexes can be conceived as "sesquicarbene complexes". The π-system acted in a very adaptive manner and employed additional stabilization of the vinyl system only where needed. Significant carbene character is found simultaneously in both M−C bonds at the same carbon center. The discovery of these complexes with relatively strong double bond character between one carbon and two metal atoms could bring unusual single-carbon-centered organometallic cascade reactions to the horizon.

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Section: Resultsmentioning

confidence: 99%

Sesquicarbene Complexes: Bonding at the Interface Between M–C Single Bonds and M═C Double Bonds

2020

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“…21) that was then treated with trimethylsilyltriflate to generate a reactive alkynyl alkylidene complex 62 . 88…”

Section: Reactivity Umpolung Of Sp2 Hybridized Unsaturated L Ligandsmentioning

confidence: 99%

Reactivity umpolung (reversal) of ligands in transition metal complexes

Morris

2024

Chem. Soc. Rev.

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“…The main characteristics of these low‐valent metal complexes is their electrophilic nature and remarkable instability [47,159,161] . Although the main applications of such complexes in organic synthesis are currently related to alkene and enyne metathesis, great interest exists in exploring a broader scope due to their unique reactivity [162–167] …”

Section: Fischer Carbene Complexes With Metal‐mediated Higher‐order Cycloadditionsmentioning

confidence: 99%

Fischer Carbene Complexes: A Glance at Two Decades of Research on Higher‐Order Cycloaddition Reactions

Feliciano

Vázquez

Benítez‐Puebla

et al. 2021

Chemistry A European J

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The structure of Fischer carbene complexes (FCCs) is electron deficient. If bearing an α,β‐unsaturated system, it can generate a wide variety of compounds by undergoing many different transformations, including higher‐order cycloadditions. The latter are described as pericyclic reactions in which more than six electrons participate. These reactions have been employed in various areas of organic synthesis, resulting in highly selective compounds with a broad range of scaffolds. The first studies on higher‐order cycloadditions involving FCCs frequently yielded competing byproducts. Many groups have attempted to increase selectivity by exploring distinct reaction conditions, reagents and co‐catalysts (e. g., metal‐mediated cycloadditions). The present review is the first to focus exclusively on using higher‐order cycloadditions involving FCCs to synthesize carbocycles and heterocycles. Based on two decades of reports, an analysis is made of the main aspects of the mechanisms proposed for higher‐order cycloadditions and the structural diversity obtained by the substituent effect.

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Unexpected [4 + 2] Cycloaddition through Chromium Non-Heteroatom-Stabilized Alkynyl Carbene Complexes: Regioselective Access to Substituted 6-Azaindoles

Cited by 13 publications

References 40 publications

Sesquicarbene Complexes: Bonding at the Interface Between M–C Single Bonds and M═C Double Bonds

Sesquicarbene Complexes: Bonding at the Interface Between M–C Single Bonds and M═C Double Bonds

Reactivity umpolung (reversal) of ligands in transition metal complexes

Fischer Carbene Complexes: A Glance at Two Decades of Research on Higher‐Order Cycloaddition Reactions

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