[2+2] Cycloadditions with an Iron Carbene: A Critical Step in Enyne Metathesis

Hoffbauer, Melissa R.; Iluc, Vlad M.

doi:10.1021/jacs.0c12175

Cited by 34 publications

(43 citation statements)

References 67 publications

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“…In general, iron alkylidene complexes are kinetically unstable.H owever,c helate stabilized iron alkylidene complexes offer aunique opportunity to probe the character and reactivity of iron-carbene linkages similar to those in arange of intermediates of interest. [14,26]…”

Section: Resultsmentioning

confidence: 99%

“…in 57 %isolated yield. Further reaction of K [13]with hydrogen atom sources generates K [14]via aHAT C-H activation reaction.…”

Section: Redox Behaviourmentioning

confidence: 99%

“…Compound K [13]was found to be extremely reactive,and readily underwent hydrogen atom abstraction with anumber of solvents to form the PC alkyl Pf errate K [14]( Scheme 6B). Fore xample,d issolution of K [13]i nd ry THF led to an initially purple solution that quickly (< 1min) turned brown with the formation of K[14]in43% 31 PNMR yield.…”

Section: Forschungsartikelmentioning

confidence: 99%

“…Similarly, K [13]a ctivated C À Hb onds in MeCN,9 ,10-dihydroanthracene (DHA) and NEt 3 .R eaction with MeCN-d 3 generated the isotopologue K[14-d 1 ]c onfirming the solvent as the hydrogen source,w ith deuterium present on the pincer alkyl position, as confirmed by 2 HNMR. Due to this reactivity and its poor solubility in arene solvents,solution characterization of K [13]could not be conducted, although the constitution of K [13]i sv erified through characterization of its hydrogen atom transfer (HAT) product K [14]a nd by in silico studies (see below).…”

Section: Forschungsartikelmentioning

confidence: 99%

“…Although reports of Pt, Pd, Ir, Rh, Os and Ru are known (via double C-H activation of aproligand), [13] access to base metal PC carbene Pp incer complexes remains challenging. [14] Piers reported on Ni PC carbene Pc omplexes (Figure 1, I)g enerated from double electrophilic C-H activation of aproligand with [Ni II Br 2 ]and strong base. [6a,d, 7d] This synthetic approach seems to be specific to group 10 complexes.…”

Section: Introductionmentioning

confidence: 99%

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Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

et al. 2021

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Despite their promising metal–ligand cooperative reactivity, PCcarbeneP pincer ligands are rarely reported for first‐row transition‐metal centres. Using a dehydration methodology, we report access to an Fe0 PCcarbeneP pincer complex (1) that proceeds via an isolated α‐hydroxylalkyl hydrido complex (3). Reversible carbonyl migration to the carbene position in 1 is found to allow coordination chemistry and E−H bond addition (E=H, B, Cl) across the iron–carbene linkage, representing a unique mechanism for metal–ligand cooperativity. The PCcarbeneP pincer ligand is also found to stabilize formal FeII, FeI, and Fe−I oxidation states, as demonstrated with synthesis and characterization of the complexes [11‐X][BArF20] (X=Br, I), 12, and K[13]. Compound K[13] is found to be highly reactive, and abstracts hydrogen from a range of aliphatic C−H sources. Computational analysis by DFT suggests that the formal FeI and Fe−I complexes contain significant carbene radical character. The ability of the PCcarbeneP ligand scaffold to partake in metal–ligand cooperativity and to support a range of iron oxidation states renders it as potentially useful in many catalytic applications.

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Section: Resultsmentioning

confidence: 99%

“…in 57 %isolated yield. Further reaction of K [13]with hydrogen atom sources generates K [14]via aHAT C-H activation reaction.…”

Section: Redox Behaviourmentioning

confidence: 99%

Section: Forschungsartikelmentioning

confidence: 99%

Section: Forschungsartikelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

et al. 2021

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Catalytic Cycloisomerization of Enyne Diesters Derived from Biaryls and Related Substrates

et al. 2023

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Enyne diesters derived from biaryls and related substrates undergo intramolecular [2 + 2]cycloaddition and concomitant cyclo-reversion when treated with 10 mol% In(OTf) 3 in 1,2-dichloroethane. This enyne metathesis type cycloisomerization reaction enables the synthesis of phenanthrene, benzophenanthrene, benzotetraphene and other polycyclic (hetero)aromatic compounds bearing a synthetically useful diethyl β-(hetero)arylidene malonate moiety in a step-and atom-economic manner. In(OTf) 3 -catalyzed two independent intramolecular cycloisomerization on substrates 5 a and 5 b provides direct access to benzotetraphenes 6 a and 6 b containing bis(diethyl β-phenylmethylene malonate) moiety. Tetrasubstituted vinylidene malonate 4 a, substiututed by two different aromatic groups, is stereoselectively converted into Eand Z-isomer of triaryl group containing all carbon tetrasubstituted olefins (8 a, 8 a' and 8 b) via Pd-catalyzed stereoselective decarboxylative arylation reaction.

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Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

et al. 2021

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Despite their promising metal-ligand cooperative reactivity,PC carbene Ppincer ligands are rarely reported for firstrow transition-metal centres.U sing ad ehydration methodology,wereport access to an Fe 0 PC carbene Ppincer complex (1) that proceeds via an isolated a-hydroxylalkyl hydrido complex (3). Reversible carbonyl migration to the carbene position in 1 is found to allow coordination chemistry and EÀHb ond addition (E = H, B, Cl) across the iron-carbene linkage, representing au nique mechanism for metal-ligand cooperativity.T he PC carbene Pp incer ligand is also found to stabilize formal Fe II ,Fe I ,and Fe ÀI oxidation states,asdemonstrated with synthesis and characterization of the complexes [11-X]-[BAr F 20 ]( X = Br,I ), 12,a nd K[13]. Compound K[13]i s found to be highly reactive,a nd abstracts hydrogen from ar ange of aliphatic CÀHs ources.C omputational analysis by DFT suggests that the formal Fe I and Fe ÀI complexes contain significant carbene radical character.T he ability of the PC carbene Pl igand scaffold to partake in metal-ligand cooperativity and to support arange of iron oxidation states renders it as potentially useful in many catalytic applications.

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[2+2] Cycloadditions with an Iron Carbene: A Critical Step in Enyne Metathesis

Cited by 34 publications

References 67 publications

Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

Catalytic Cycloisomerization of Enyne Diesters Derived from Biaryls and Related Substrates

Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

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[2+2] Cycloadditions with an Iron Carbene: A Critical Step in Enyne Metathesis

Cited by 34 publications

References 67 publications

Access to and Reactivity of Fe0, Fe−I, FeI, and FeII PCcarbeneP Pincer Complexes

Access to and Reactivity of Fe0, Fe−I, FeI, and FeII PCcarbeneP Pincer Complexes

Catalytic Cycloisomerization of Enyne Diesters Derived from Biaryls and Related Substrates

Access to and Reactivity of Fe0, Fe−I, FeI, and FeII PCcarbeneP Pincer Complexes

Contact Info

Product

Resources

About

Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes

Access to and Reactivity of Fe⁰, Fe^−I, Fe^I, and Fe^II PC_carbeneP Pincer Complexes