Iron‐Catalyzed Positional and Geometrical Isomerization of Alkenes

OBEID, Abdul-halim; Hannedouche, Jérôme

doi:10.1002/adsc.202300052

Cited by 7 publications

(1 citation statement)

References 157 publications

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“…Selective alkene isomerization reactions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and related tandem isomerization/functionalization reactions [19,20] can rapidly generate molecular complexity. Through catalyst control, specific regio-and stereoisomers can be achieved in several reaction contexts.…”

Section: Introductionmentioning

confidence: 99%

A Hydride Migration Mechanism for the Mo‐CatalyzedZ‐2‐Selective Isomerization of Terminal Alkenes

Jenny,

Serviano,

Nova

et al. 2023

ChemCatChem

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The catalytic one‐bond isomerization (transposition) of 1‐alkenes is an emerging approach to Z‐2‐alkenes. Design of more selective catalysts would benefit from a mechanistic understanding of factors controlling Z selectivity. We propose here a reaction pathway for cis‐Mo(CO)4(PCy3)(piperidine) (3), a precatalyst that shows high Z selectivity for transposition of alpha olefins (e.g., 1‐octene to 2‐octene, 18:1 Z:E at 74% conversion). Computational modeling of reaction pathways and isotopic labeling suggests the isomerization takes place via an allyl (1,3‐hydride shift) pathway, where oxidative addition of fac‐(CO)3Mo(PCy3)(η2‐alkene) is followed by hydride migration from one position (cis to allyl C3 carbon) to another (cis to allyl C1 carbon) via several hydride/CO exchanges. Calculated barriers for the hydride migration pathway are lower than explored alternative mechanisms (e.g., change of allyl hapticity, allyl rotation). To our knowledge, this is the first study to propose such a hydride migration in alkene isomerization.

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Section: Introductionmentioning

confidence: 99%

A Hydride Migration Mechanism for the Mo‐CatalyzedZ‐2‐Selective Isomerization of Terminal Alkenes

Jenny,

Serviano,

Nova

et al. 2023

ChemCatChem

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Iron in Organometallic Transformations: A Sustainable Substitute for Noble Metals

Kumar,

Tewari,

Chikkali

2024

ChemCatChem

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Transition metal catalysis plays a pivotal role in chemical synthesis. Noble metals often grab significant attention in organometallic catalysis due to their high reactivity. However, the serious issues associated with these metals such as low abundance, toxicity, geopolitical limitations, and volatile prices are driving the scientific community to discover sustainable alternatives. In this context, iron appears to be the first choice as an alternative metal due to its unique properties, including a range of stable oxidation states, Lewis acidity, high abundance in the earth's crust, and low toxicity. Over the past two decades, substantial progress has been made in iron catalysis. This overview examines the recent developments in iron‐catalyzed industrially relevant transformations such as hydroformylation, olefin isomerization, hydrosilylation, hydrophosphination, carbonylation, Wacker‐type oxidation, and plastic depolymerization. As witnessed throughout this review, the performance of iron can be significantly altered by suitable ligand selection and by tailoring the electronic and steric properties of the iron center. While noble metals remain the industry work‐horse, iron is inching closer and with extensive scientific understanding, it may replace noble metals in the near future.

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Thermally Activated Geometrical Regioselective E→Z Isomerization‐Enabled Cascade Sequences of Conjugated Dienals: Experimental and DFT Studies

Saha

Banerjee

Malo

et al. 2023

Chemistry A European J

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The geometrical regioselective E → Z isomerization of a conjugated alkene under thermal activation poses a challenge due to microscopic reversibility. Herein we report that such reversibility issues can be circumvented by integrating E → Z isomerization with subsequent cyclization cascade. Thus, linearly conjugated dienals in a mixture of toluene‒alcohol (2:1) solvents or only with alcohol at 60‐70 °C can be converted to γ‐alkoxybutenolides in moderate to good yields. The intermediary 2Z,4E‒isomer can be isolated, which includes the first example of isolating the regioselective isomerization product under thermal conditions. Density functional theory (DFT) studies have been employed to shed light on the feasibility of geometrical alkene isomerization and ensuing cascade sequences. It has been observed that the regioselective 2E,4E → 2Z,4E isomerization of dienal is a thermodynamically facile (ΔG < 0) process. The thermodynamic plausibility of the subsequent cascade reaction from the Z‐isomer to the anticipated product in the presence of a polar protic solvent (here MeOH) is also explicated. Out of the two probable pathways, the "hemiacetal pathway" involving a relay proton transfer is kinetically more feasible due to the diminished activation barrier than the conjugate addition pathway.

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Iron‐Catalyzed Positional and Geometrical Isomerization of Alkenes

Cited by 7 publications

References 157 publications

A Hydride Migration Mechanism for the Mo‐CatalyzedZ‐2‐Selective Isomerization of Terminal Alkenes

A Hydride Migration Mechanism for the Mo‐CatalyzedZ‐2‐Selective Isomerization of Terminal Alkenes

Iron in Organometallic Transformations: A Sustainable Substitute for Noble Metals

Thermally Activated Geometrical Regioselective E→Z Isomerization‐Enabled Cascade Sequences of Conjugated Dienals: Experimental and DFT Studies

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