59887-23-9Relevant articles and documents
Redox Property of Enamines
Li, Yao,Wang, Dehong,Zhang, Long,Luo, Sanzhong
, p. 12071 - 12090 (2019/10/11)
Enamines are electron-rich compounds bearing intriguing redox properties. Herein, a series of secondary enamines condensed from primary amine and β-ketocarbonyls were synthesized and their electrochemical oxidation properties were systematically studied by cyclic voltammetry. Furthermore, theoretical calculation of oxidation potentials of enamines, particularly those catalytic intermediates, was also conducted to further broaden the scope investigated. Possible structural factors on oxidation and the nature of the resulted radical cation intermediates were revealed and discussed. Correlation of redox potentials with molecular properties such as highest occupied molecular orbital energies and natural population analysis charge were explored, and there appears no simple linear correlation. On the other hand, a good correlation with Mayr's nucleophilicity parameter N was noted among a range of catalytically relevant enamines. Spin population analysis disclosed that enamine radical cations mainly exhibit the carbon-center free radical feature. Taking experimental and computation data together, a comprehensive picture about the redox property of enamines is presented, which would provide guidance in the development of oxidative enamine catalysis and transformations.
Heterocycle Formation through Aza-Annulation: Stereochemically Controlled Syntheses of (+/-)-5-Epitashiromine and (+/-)-Tashiromine
Paulvannan, K.,Stille, John R.
, p. 1613 - 1620 (2007/10/02)
N-alkenylamines, stabilized through conjugation with an electron-withdrawing group, undergo aza-annulation with acryloyl chloride to provide a convergent route for the construction of six-membered nitrogen heterocycles.In addition to enhancing the C-alkylation process of annulation relative to the competing N-acylation process, the electron withdrawing substituent controlled the regioselectivity of alkene formation in both the intermediate enamine and in the unsaturated lactam product.A variety of functional groups, which include -COMe, -COPh, -CO2R, -CONHPh, -CN, -P(O)(OEt)2, and -SO2Ph, were used to determine the effect of the electron-withdrawing substituents upon both the annulation reaction with acryloyl chloride and the subsequent hydrogenation process.When the enamide annulation product was stabilized through conjugation with ester or amide substituents, catalytic hydrogenation of the aza-annulation product resulted in the formation of vicinal stereocenters with high cis selectivity.The utility of this methodology was demonstrated by application of the condensation/aza-annulation/hydrogenation sequence as the key for construction and stereochemical control of the indolizidine ring system of (+/-)-tashiromine.
