4567-22-0Relevant articles and documents
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
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.
The Reactions of Amine, Polyamine and Amino Alcohol Corrosion Inhibitors in Water at High Temperatures
Smith, John R. Lindsay,Smart, Alison U.,Twigg, Martyn V.
, p. 939 - 947 (2007/10/02)
A stainless steel reactor has been used to investigate the reactions of mono-, di-, tri- and tetraamines, amino alcohols and amino ethers in degassed aqueous solution at 240-300 deg C.The predominant reactions involved nucleophilic substitutions, where the amino nitrogen acts as the nucleophile, and not solvolyses.With α,ω-diamines, cyclic and bicyclic amines were formed by inter- or intra-molecular processes.Amino alcohols react by displacement of the hydroxy rather than the amino group.The material balance deficit, however, was generally significant, and it issuggested that the missing materials are polyamines arising from polymerisation that competes with cyclisation.The major product from 1,2-diaminoethane and related polyaminoethanes and ethanolamines is diazabicyclooctane.The kinetics of some of the cyclisations were studied.Reactions of α,ω-diamines and 5-aminopentan-1-ol are first order in reactant.Conversion of 1,4-diaminobutane to pyrrolidine occurs with high selectivity at 240 deg C; in contrast the reactions of the less reactive compounds were less selective, probably due to the formation of polymeric materials.The relative reactivity of the substrates is discussed in detail.
