69169-28-4Relevant academic research and scientific papers
Switchable Stereoselectivity in Bromoaminocyclization of Olefins: Using Br?nsted Acids of Anionic Chiral Cobalt(III) Complexes
Jiang, Hua-Jie,Liu, Kun,Yu, Jie,Zhang, Ling,Gong, Liu-Zhu
, p. 11931 - 11935 (2017/09/20)
Br?nsted acids of anionic chiral CoIII complexes act as bifunctional phase-transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric chiral CoIII-templated Br?nsted ac
A new method for intramolecular chloroamination of unfunctionalized olefins
Liu, Gong-Qing,Li, Wei,Li, Yue-Ming
, p. 395 - 402 (2013/05/08)
A new method for the intramolecular chloroamination of unfunctionalized olefins is reported. The reactions were carried out at room temperature for 3 h using hydrated copper(II) chloride as both promoter and chlorine source, and the corresponding vincinal haloamines were obtained in good isolated yields.
Intramolecular hydroamination of aminoalkenes by calcium and magnesium complexes: A synthetic and mechanistic study
Crimmin, Mark R.,Arrowsmith, Merle,Barrett, Anthony G. M.,Casely, Ian J.,Hill, Michael S.,Procopiou, Panayiotis A.
, p. 9670 - 9685 (2011/03/20)
The β-diketiminate-stabilized calcium amide complex [{ArNC(Me)CHC(Me)NAr}Ca{N(SiMe3)2}-(THF)] (Ar = 2,6-diisopropylphenyl) and magnesium methyl complex [{ArNC(Me)CHC(Me)NAr}Mg(Me) (THF)] are reported as efficient precatalysts for hydroamination/cyclization of aminoalkenes. The reactions proceeded under mild conditions, allowing the synthesis of five-, six-, and seven-membered heterocyclic compounds. Qualitative assessment of these reactions revealed that the ease of catalytic turnover increases (i) for smaller ring sizes (5 > 6 > 7), (ii) substrates that benefit from favorable Thorpe-Ingold effects, and (iii) substrates that do not possess additional substitution on the alkene entity. Prochiral substrates may undergo diastereoselective hydroamination/cyclization depending upon the position of the existing stereocenter. Furthermore, a number of minor byproducts of these reactions, arising from competitive alkene isomerization reactions, were identified. A series of stoichiometric reactions between the precatalysts and primary amines provided an important model for catalyst initiation and suggested that these reactions are facile at room temperature, with the reaction of the calcium precatalyst with benzylamine proceeding with ΔG°(298 K) = -2.7 kcal mol-1. Both external amine/amide exchange and coordinated amine/amide exchange were observed in model complexes, and the data suggest that these processes occur via low-activation-energy pathways. As a result of the formation of potentially reactive byproducts such as hexamethyldisilazane, calcium-catalyst initiation is reversible, whereas for the magnesium precatalyst, this process is nonreversible. Further stoichiometric reactions of the two precatalysts with 1-amino-2,2-diphenyl-4-pentene demonstrated that the alkene insertion step proceeds via a highly reactive transient alkylmetal intermediate that readily reacts with N-H σ bonds under catalytically relevant conditions. The results of deuterium-labeling studies are consistent with the formation of a single transient alkyl complex for both the magnesium and calcium precatalysts. Kinetic analysis of the nonreversible magnesium system revealed that the reaction rate depends directly upon catalyst concentration and inversely upon substrate concentration, suggesting that substrate-inhibited alkene insertion is rate-determining.
