Generation and Reactivity of a One‐Electron‐Oxidized Manganese(V) Imido Complex with a Tetraamido Macrocyclic Ligand

Shi, Hua‐Tian; Xie, Junwei; Lam, William W. Y.; Man, Wai‐Lun; Mak, Chi-Keung; Yiu, Shek‐Man; Lee, Hung Kay; Lau, Tai‐Chu

doi:10.1002/chem.201902405

Cited by 20 publications

(16 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Related iron‐ [22] and manganese‐TAML [23] complexes were found to be active in stoichiometric nitrene transfer to thioanisole derivatives, but catalytic activity has not been reported to date. Thus, inspired by the catalytic activity of PPh 4 [Co III (TAML red )] under aerobic conditions in the aziridination of alkenes, we decided to explore its catalytic activity for sulfimidation reactions.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Chemoselective Sulfimidation with an Electrophilic [Co^III(TAML)]⁻‐Nitrene Radical Complex**

Leest

Vlugt

Bruin

2020

Chemistry A European J

View full text Add to dashboard Cite

The cobaltspecies PPh 4 [Co III (TAML red)] is ac ompetent and stable catalystf or the sulfimidationo f(aryl)(alkyl)substituteds ulfides with iminoiodinanes, reaching turnover numbers up to 900 and turnover frequencies of 640 min À1 under mild and aerobic conditions. The sulfimidationp roceeds in ah ighly chemoselective manner,e ven in the presence of alkenes or weak CÀHb onds, as supported by interand intramolecular competition experiments. Functionalization of the sulfide substituent with various electron-donating and electron-withdrawing arenes and several alkyl, benzyl and vinyl fragments is tolerated, with up to quantitative product yields. Sulfimidation of phenyla llyl sulfide led to [2,3]-sigmatropic rearrangement of the initially formed sulfimide species to afford the corresponding N-allyl-S-phenylthiohydroxylamines as attractive products. Mechanistic studies suggestt hat the actual nitrenet ransfer to the sulfide proceeds via (previously characterized) electrophilicn itrene radicali ntermediatest hat afford the sulfimide productsv ia electronically asynchronous transition states, in which SET from the sulfide to the nitrener adicalc omplexp recedes NÀSbond formation in as ingle concerted process.

show abstract

Section: Introductionmentioning

confidence: 99%

Catalytic Chemoselective Sulfimidation with an Electrophilic [Co^III(TAML)]⁻‐Nitrene Radical Complex**

Leest

Vlugt

Bruin

2020

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“… [9] Use of a tetraanionic tetraamido macrocyclic ligand (TAML) enabled the isolation of Mn V imido complex 3 (Figure 2 c). [10] Further oxidation to the corresponding Mn VI complex was necessary to engender nitrene transfer chemistry. In the context of porphyrin‐supported nitrenoids, acylation of Mn V nitrido complex 4 with trifluoroacetic anhydride affords Mn V nitrenoid 5 , which was characterized by 1 H NMR and UV‐vis spectroscopies and displays olefin aziridination activity (Figure 2 d).…”

Section: Introductionmentioning

confidence: 99%

Nitrene Photochemistry of Manganese N‐Haloamides**

et al. 2021

View full text Add to dashboard Cite

Manganese complexes supported by macrocyclic tetrapyrrole ligands represent an important platform for nitrene transfer catalysis and have been applied to both C−H amination and olefin aziridination catalysis. The reactivity of the transient high‐valent Mn nitrenoids that mediate these processes renders characterization of these species challenging. Here we report the synthesis and nitrene transfer photochemistry of a family of MnIII N‐haloamide complexes. The S=2 N‐haloamide complexes are characterized by 1H NMR, UV‐vis, IR, high‐frequency and ‐field EPR (HFEPR) spectroscopies, and single‐crystal X‐ray diffraction. Photolysis of these complexes results in the formal transfer of a nitrene equivalent to both C−H bonds, such as the α‐C−H bonds of tetrahydrofuran, and olefinic substrates, such as styrene, to afford aminated and aziridinated products, respectively. Low‐temperature spectroscopy and analysis of kinetic isotope effects for C−H amination indicate halogen‐dependent photoreactivity: Photolysis of N‐chloroamides proceeds via initial cleavage of the Mn−N bond to generate MnII and amidyl radical intermediates; in contrast, photolysis of N‐iodoamides proceeds via N−I cleavage to generate a MnIV nitrenoid (i.e., {MnNR}7 species). These results establish N‐haloamide ligands as viable precursors in the photosynthesis of metal nitrenes and highlight the power of ligand design to provide access to reactive intermediates in group‐transfer catalysis.

show abstract

“…[9] Use of a tetraanionic tetraamido macrocyclic ligand (TAML) enabled the isolation of Mn(V) imido complex 3 (Figure 2c). [10] Further oxidation to the corresponding Mn(VI) complex was necessary to engender nitrene transfer chemistry. In the context of porphyrin-supported nitrenoids, acylation of Mn(V) nitrido complex 4 with trifluoroacetic anhydride affords Mn(V) nitrenoid 5, which was characterized by 1 H NMR and UV-vis spectroscopies and displays olefin aziridination activity (Figure 2d).…”

Section: Introductionmentioning

confidence: 99%

Nitrene Photochemistry of Manganese N-Haloamides

Trieste

Hicks

Das

et al. 2021

Preprint

View full text Add to dashboard Cite

Manganese complexes supported by macrocyclic tetrapyrrole ligands represent an important platform for nitrene transfer catalysis and have been applied to both C-H amination and olefin aziridination catalysis. The reactivity of the transient high-valent Mn nitrenoids that mediate these processes renders characterization of these species challenging. Here we report the synthesis and nitrene transfer photochemistry of a family of Mn(III) N-haloamide complexes. The S = 2 Nhaloamide complexes are characterized by 1 H NMR, UV-vis, IR, high-frequency and -field EPR (HFEPR) spectroscopies, and single-crystal X-ray diffraction. Photolysis of these complexes results in the formal transfer of a nitrene equivalent to both C-H bonds, such as the a-C-H bonds of tetrahydrofuran, and olefinic substrates, such as styrene, to afford aminated and aziridinated products, respectively. Low-temperature spectroscopy and analysis of kinetic isotope effects for C-H amination indicate halogen-dependent photoreactivity: Photolysis of N-chloroamides proceeds via initial cleavage of the Mn-N bond to generate Mn(II) and amidyl radical intermediates; in contrast, photolysis of N-iodoamides proceeds via N-I cleavage to generate a Mn(IV) nitrenoid (i.e., {MnNR} 7 species). These results establish N-haloamide ligands as viable precursors in the photosynthesis of metal nitrenes and highlight the power of ligand design to provide access to reactive intermediates in group-transfer catalysis.

show abstract

Generation and Reactivity of a One‐Electron‐Oxidized Manganese(V) Imido Complex with a Tetraamido Macrocyclic Ligand

Cited by 20 publications

References 39 publications

Catalytic Chemoselective Sulfimidation with an Electrophilic [Co^III(TAML)]⁻‐Nitrene Radical Complex**

Catalytic Chemoselective Sulfimidation with an Electrophilic [Co^III(TAML)]⁻‐Nitrene Radical Complex**

Nitrene Photochemistry of Manganese N‐Haloamides**

Nitrene Photochemistry of Manganese N-Haloamides

Contact Info

Product

Resources

About

Generation and Reactivity of a One‐Electron‐Oxidized Manganese(V) Imido Complex with a Tetraamido Macrocyclic Ligand

Cited by 20 publications

References 39 publications

Catalytic Chemoselective Sulfimidation with an Electrophilic [CoIII(TAML)]−‐Nitrene Radical Complex**

Catalytic Chemoselective Sulfimidation with an Electrophilic [CoIII(TAML)]−‐Nitrene Radical Complex**

Nitrene Photochemistry of Manganese N‐Haloamides**

Nitrene Photochemistry of Manganese N-Haloamides

Contact Info

Product

Resources

About

Catalytic Chemoselective Sulfimidation with an Electrophilic [Co^III(TAML)]⁻‐Nitrene Radical Complex**

Catalytic Chemoselective Sulfimidation with an Electrophilic [Co^III(TAML)]⁻‐Nitrene Radical Complex**