6496-48-6Relevant academic research and scientific papers
NOVEL ANNULATION CATALYSTS VIA DIRECT C-H BOND AMINATION
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, (2022/01/24)
Disclosed are compounds, methods, reagents, systems, and kits for the preparation and utilization of monomeric or polymeric metal-based compounds. These metal-based compounds are organometallic catalysts composed of substituted dipyrrin ligands bound to transition metals. C—H bond functionalization catalysis can be performed with the disclosed organometallic catalysts to yield C—N bonds to generate substituted bicyclic, spiro, and fused nitrogen-containing heterocycles, all common motifs in various pharmaceutical and bioactive molecules.
An Iron-Mesoionic Carbene Complex for Catalytic Intramolecular C-H Amination Utilizing Organic Azides
Albrecht, Martin,Keilwerth, Martin,Meyer, Karsten,Pividori, Daniel M.,Stroek, Wowa
supporting information, p. 20157 - 20165 (2021/12/09)
The synthesis of N-heterocycles is of paramount importance for the pharmaceutical industry. They are often synthesized through atom economic and environmentally unfriendly methods, generating significant waste. A less explored, but greener, alternative is
O-benzoylhydroxylamines as alkyl nitrene precursors: Synthesis of saturated N-heterocycles from primary amines
Noda, Hidetoshi,Asada, Yasuko,Shibasaki, Masakatsu
, p. 8769 - 8773 (2020/10/12)
We introduce O-benzoylhydroxylamines as competent alkyl nitrene precursors. The combination of readily available, stable substrates and a proficient rhodium catalyst provides a straightforward means for the construction of various pyrrolidine rings from the corresponding primary amines. Preliminary mechanistic investigation suggests that the structure of the nitrene precursor plays a role in determining the nature of the resulting reactive intermediate.
Direct Manipulation of Metal Imido Geometry: Key Principles to Enhance C-H Amination Efficacy
Baek, Yunjung,Hennessy, Elisabeth T.,Betley, Theodore A.
supporting information, p. 16944 - 16953 (2019/10/19)
We report the catalytic C-H amination mediated by an isolable CoIII imido complex (TrL)Co(NR) supported by a sterically demanding dipyrromethene ligand (TrL = 5-mesityl-1,9-(trityl)dipyrrin). Metalation of (TrL)
Catalytic C-H Amination Mediated by Dipyrrin Cobalt Imidos
Baek, Yunjung,Betley, Theodore A.
supporting information, p. 7797 - 7806 (2019/05/22)
Reduction of (ArL)CoIIBr (ArL = 5-mesityl-1,9-(2,4,6-Ph3C6H2)dipyrrin) with potassium graphite afforded the novel CoI synthon (ArL)CoI. Treatment of (ArL)CoI with a stoichiometric amount of various alkyl azides (N3R) furnished three-coordinate CoIII alkyl imidos (ArL)Co(NR), as confirmed by single-crystal X-ray diffraction (R: CMe2Bu, CMe2(CH2)2CHMe2). The exclusive formation of four-coordinate cobalt tetrazido complexes (ArL)Co(κ2-N4R2) was observed upon addition of excess azide, inhibiting any subsequent C-H amination. However, when a weak C-H bond is appended to the imido moiety, as in the case of (4-azido-4-methylpentyl)benzene, intramolecular C-H amination kinetically outcompetes formation of the corresponding tetrazene species to generate 2,2-dimethyl-5-phenylpyrrolidine in a catalytic fashion without requiring product sequestration. The imido (ArL)Co(NAd) exists in equilibrium in the presence of pyridine with a four-coordinate cobalt imido (ArL)Co(NAd)(py) (Ka = 8.04 M-1), as determined by 1H NMR titration experiments. Kinetic studies revealed that pyridine binding slows down the formation of the tetrazido complex by blocking azide coordination to the CoIII imido. Further, (ArL)Co(NR)(py) displays enhanced C-H amination reactivity compared to that of the pyridine-free complex, enabling higher catalytic turnover numbers under milder conditions. The mechanism of C-H amination was probed via kinetic isotope effect experiments [kH/kD = 10.2(9)] and initial rate analysis with para-substituted azides, suggesting a two-step radical pathway. Lastly, the enhanced reactivity of (ArL)Co(NR)(py) can be correlated to a higher spin-state population, resulting in a decreased crystal field due to a geometry change upon pyridine coordination.
