Regiospecific insertion of benzylidene ligands into the α-C–H bond of ethers

Fischer, Helmut; Schmid, Johann; Märkl, Robert

doi:10.1039/c39850000572

Cited by 33 publications

(15 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, in contrast to Fischer carbenes, dirhodium carbenes display enhanced electrophilic reactivity, being able to activate nucleophiles as weak as C–H bonds. While this is partly due to the absence of heteroatom stabilization, work by the groups of Nakamura and Berry has identified the importance of σ and π 3c4e bonding interactions in making dirhodium carbenes “superelectrophilic”. , …”

Section: Introductionmentioning

confidence: 99%

Enhanced Electrophilicity of Heterobimetallic Bi–Rh Paddlewheel Carbene Complexes: A Combined Experimental, Spectroscopic, and Computational Study

et al. 2018

View full text Add to dashboard Cite

Dirhodium paddlewheel complexes are indispensable tools in modern organometallic catalysis for the controlled decomposition of diazo-compounds. Tuning the reactivity of the thus-formed transient carbenes remains an active and dynamic field of research. Herein, we present our findings that the distal metal center plays an as yet underappreciated role in modulating this reactivity. Replacement of one rhodium atom in the bimetallic core for bismuth results in the formation of a significantly more electrophilic carbene complex. Bismuth-rhodium catalysts thereby facilitate previously unknown modes of reactivity for α-diazoester compounds, including the cyclopropanation of alkenes as electron deficient as trichloroethylene. While dirhodium paddlewheel complexes remain the catalysts of choice for many carbene-mediated transformations, their bismuth-rhodium analogues exhibit complementary reactivity and show great potential for small molecule and solvent activation chemistry. DFT calculations highlight the importance of metal-metal bonding interactions in controlling carbene electrophilicity. The paucity of these interactions between the 4d orbitals of rhodium and the 6p orbitals of bismuth results in weaker π-back-bonding interactions for bismuth-rhodium carbene complexes compared to dirhodium carbene complexes. This leads to weakening of the rhodium-carbene bond and to a more carbene-centered LUMO, accounting for the observed enhancement in bismuth-rhodium carbene electrophilicity. These findings are supported by a detailed spectroscopic study of the "donor-donor" carbene complexes Rh(esp)C( p-MeOPh) (19) and BiRh(esp)C( p-MeOPh) (20), employing a combination of UV-vis and resonance Raman spectroscopy. The results reveal that carbene chemoselectivity in MRh(L) catalysis can be modulated to a previously unrecognized extent by the distal metalloligand.

show abstract

Section: Introductionmentioning

confidence: 99%

Enhanced Electrophilicity of Heterobimetallic Bi–Rh Paddlewheel Carbene Complexes: A Combined Experimental, Spectroscopic, and Computational Study

et al. 2018

View full text Add to dashboard Cite

show abstract

“…Synthesis of neutral and cationic metal-carbene complexes has been discussed [ 176 ]. Neutral iron-carbene complexes of type 21 are readily available by the method of Fischer [ 137 , 143 ] by treatment of iron pentacarbonyl 19 with lithium or a Grignard reagent, followed by alkylation of acyl complexes on oxygen [ 147 , 177 ] (conversion 19 → 20 → 21). Carbene complexes of type 21 have also been prepared by photochemical exchange of a CO ligand in Fe(CO) 5 with alkylidene [ 178 ].…”

Section: Iron-stabilized Carbenes In Organic Synthesismentioning

confidence: 99%

New chemical and stereochemical applications of organoiron complexes

Fatiadi

1991

J. RES. NATL. INST. STAN.

View full text Add to dashboard Cite

The objective of this review is to provide a current overview of the rapidly developing chemistry of organometallic complexes and particularly organoiron complexes useful in asymmetric and stereoselective reactions. Also covered are stereoselective reactions of α, β-unsaturated acyl ligands bound to the chiral auxiliary [(η5-C5H5) Fe(CO)(PPh3)] and new applications of organoiron complexes in the synthesis of natural products. The mechanistic aspects and stabilizing effects of the Fe(CO)3 group for alkenes or conjugated dienes are discussed. A brief summary of recent work on the special role of iron in biological reactions is also included.

show abstract

“…9 9 4 ( 5 ) C ( 6 )-C ( 7 ) 1.485 (7) 1.512(5) C(7)-C (8) 1 . 3 2 2 ( 7 ) 1.330(7) C(8)-C (9) 1.501 ( 7 ) 1.519(6) C ( 9 ) -C ( l O ) 1.575(6) 1.571 ( 5 ) C(9)-C(ll) 1.534 (7) 1.550(6) C ( l O ) -C ( 1 3 ) 1 . 5 2 4 ( 6 ) 1.508(6) C ( 1 1 )-C( 1 2 ) 1.529 (7) Tab.…”

Section: Lb-endomentioning

confidence: 99%

“…9 2 8 2 ( 8 ) 0 . 3 9 2 6 ( 8 ) 0.3878(10) 0.5604 (13) 0.7389(11) 0.7446 (9 ) 0.5705 (8) 0.5780(1) 0.4533(1) 0.6504 ( 3 ) ( 3 ) 0.024(1) 0.026(1) 0.033( 1 ) 0.051 ( 1 ) 0 . 0 3 2 ( 2 ) 0.052(1) 0.032(2) 0.054( 1 ) 0.033(1) 0.049( 1 ) 0.030(1) 0.047(1) 0 .…”

Section: Pentacarbonyl(3-phenyl-2-thiabicyclo[222]oct-s-en)chrommentioning

confidence: 99%

[4 + 2]‐Cycloadditionen mit Übergangsmetall‐koordinierten Heteroalkenen: Einfluß der Koordination auf die Stereoselektivität der Cycloaddition

et al. 1990

Self Cite

View full text Add to dashboard Cite

4 + 21 Cycloadditions with Transition-Metal-Coordinated Heteroalkenes: The Influence of the Coordination on the Stereoselectivity of the Cycloadditfon Pentacarbonyl(thiobenzaldehyde), -(selenobenzaldehyde), and contrast to the endo selectivity observed in the reactions of 2 -(diphenyl selenoketone) complexes (CO),M[X = C(Ph)R] [R = and 4 with uncomplexed thio-and selenoaldehydes, the ad-H. M = W, X = S (la), Se (lb); M = Cr, X = S (lc), Se (ld); ditions of 2 and 4 to la-d are exo selective. However, the R = Ph: M W, X = Se (1 e)] react with cyclopentadiene (2) reactions of pentamethylcyclopentadiene (6) with 1a.b to form

show abstract

Regiospecific insertion of benzylidene ligands into the α-C–H bond of ethers

Abstract: An orga n isc h -c h e m isc h es Ins tit u t de r Tech n isc h en U n iversita t Munch en, L ic h ten bergs tr. 4

Cited by 33 publications

References 0 publications

Enhanced Electrophilicity of Heterobimetallic Bi–Rh Paddlewheel Carbene Complexes: A Combined Experimental, Spectroscopic, and Computational Study

Enhanced Electrophilicity of Heterobimetallic Bi–Rh Paddlewheel Carbene Complexes: A Combined Experimental, Spectroscopic, and Computational Study

New chemical and stereochemical applications of organoiron complexes

[4 + 2]‐Cycloadditionen mit Übergangsmetall‐koordinierten Heteroalkenen: Einfluß der Koordination auf die Stereoselektivität der Cycloaddition

Contact Info

Product

Resources

About