(.eta.5-C5H5)(CO)2FeCH2S+(CH3)2 BF4-: a methylene transfer reagent for the direct cyclopropanation of alkenes

O'Connor, Edward J.; Brandt, Steven; Helquist, Paul

doi:10.1021/ja00246a036

Cited by 59 publications

(14 citation statements)

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“…Monitoring the reaction of complex 8 with ethylene by 19 F NMR showed complete consumption of the carbene after 12 h at room temperature. Although several new resonances were observed, none could be assigned to the expected cyclopropanation product [52]. X-ray quality crystals obtained from the reaction solution revealed a new divalent product, Mn(Phen) 2 (OTf) 2 , 9 (Figure 2).…”

Section: Methodsmentioning

confidence: 99%

Synthesis and Reactivity of Mn–CF3 Complexes

et al. 2019

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The synthesis, characterization and reactivity of several bi- and tridentate, N-ligated manganese carbonyl trifluoromethyl complexes are presented. These complexes exhibit elongated Mn–CCF3 bonds (versus Mn(CF3)(CO)5), suggesting a lability that could be utilized for the transfer or insertion of the CF3 functional group into organic substrates. Unlike their Mn–X congeners (X = Cl, Br), these Mn–CF3 complexes exhibit a preference for hard donor ancillary ligands, thus enabling the synthesis of 4 N-ligated Mn–CF3 complexes including a mixed-donor tridentate complex using an NNS Schiff base ([2-(methylthio)-N-(1-(pyridin-2-yl)ethylidene)aniline]). Although we have not yet identified efficient CF3 transfer reactions, fluoride abstraction from the Mn–CF3 complexes using trimethylsilyl triflate affords the first stable Mn fluorocarbenes as evidenced by 19F NMR spectroscopy.

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Section: Methodsmentioning

confidence: 99%

Synthesis and Reactivity of Mn–CF3 Complexes

et al. 2019

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“…In connection with our investigation of thallium(I)-promoted substitution of chloride in chloromethyl alkyl complexes by neutral nucleophiles we generated several new [CpFe(CO) 2 CH 2 SR 2 ] + salts including [CpFe(CO) 2 CH 2 SPh 2 ]BF 4 . Not unexpectedly, the diphenylsulfonium salt proved to be considerably more reactive for cyclopropanation of olefins than either the dimethyl- or methylphenylsulfonium salts studied by Helquist …”

Section: Introductionmentioning

confidence: 94%

“…A variety of molecular complexes have been utilized as reagents for conversion of alkenes to cyclopropanes. One class of reagents developed by Helquist for this purpose are salts of the cations {Fe(η 5 -C 5 H 5 )(CO) 2 [CH(R 1 )SR 2 R 3 ]} + . The salt [FeCp(CO) 2 CH 2 S(CH 3 ) 2 ]BF 4 has been most extensively studied .…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of Cyclopropanation of Cyclooctene by [Fe(η⁵-C₅H₅)(CO)₂CH₂SPh₂]BF₄

and

Barefield

1998

Organometallics

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The kinetics of reaction of [Fe(η 5 -C 5 H 5 )(CO) 2 CH 2 SPh 2 ]BF 4 with cyclooctene in CH 2 Cl 2 solution have been studied under pseudo-first-order conditions at room temperature. The variation of k obs is nonlinear in both cyclooctene and added Ph 2 S. The results are interpreted in terms of a two-step reaction in which the cation [Fe(η 5 -C 5 H 5 )(CO) 2 CH 2 SPh 2 ] + undergoes reversible, dissociative loss of Ph 2 S followed by competitive capture of the methyleneiron complex by cyclooctene to produce bicyclo[6.1.0]nonane. The methyleneiron intermediate is 4-5 times more reactive toward diphenylsulfide than cyclooctene. In the absence of added Ph 2 S, millimolar solutions of the iron complex react with cyclooctene at room temperature with a half-life of about 36 min to give >85% yields of bicyclo[6.1.0]nonane after 3 h, and it is thus more reactive than the dimethyl-and methylphenylsulfonium salt analogues.

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“…Readily accessible iron complex (η 5 −C 5 H 5 ) (CO) 2 FeCH 2 S + Me 2 • BF 4 − 35 undergoes direct reaction with a range of alkenes to give cyclopropanes (equation 67) 106,107 . The salt is sensitive to steric effects and the reaction proceeds most reliable for mono-and disubstituted alkenes with high stereospecificity.…”

Section: Methylenementioning

confidence: 99%