Synthesis and resolution of a chiral analogue of 2,2,6,6-tetramethylpiperidine and of its corresponding nitroxide
摘要:
The novel C-2 symmetric chiral amine trans-2,6-dimethyl-2,6-diphenylpiperidine has been synthesized via two successive nitrone nucleophilic addition-oxidation sequences, followed by reduction of the intermediate nitroxide. hue enantiomers have been obtained via resolution with mandelic acid. (C) 1998 Elsevier Science Ltd. All rights reserved.
Nitrones serve as starting materials for the synthesis of many heterocycles. Oxidation of secondary amines using hydrogen peroxide and the catalytic amount of methyltrioxorhenium in ionic liquids is a useful method for the preparation of nitrones. Ultrasonic irradiation and ionic liquids have a positive influence on the reaction. The nitrones required were isolated in good yields. Corresponding hydroxylamines
Molybdenum oxide/bipyridine hybrid material {[MoO3(bipy)][MoO3(H2O)]}n as catalyst for the oxidation of secondary amines to nitrones
作者:Marta Abrantes、Isabel S. Gonçalves、Martyn Pillinger、Carolina Vurchio、Franca M. Cordero、Alberto Brandi
DOI:10.1016/j.tetlet.2011.10.079
日期:2011.12
catalyst for the oxidation of secondaryamines under mild conditions using either urea hydrogen peroxide (UHP) or tert-butylhydroperoxide (TBHP) as the oxidant. Under optimized reaction conditions (2 mol % catalyst, 3–4 equiv TBHP, CH2Cl2 as the solvent, 40 °C), the corresponding nitrones were obtained with different efficiency depending on the nature of the cyclic or acyclic amine used.
The effect of hydrogen bonding between nitrones and urea derivatives in the nucleophilicaddition reaction was examined. Thioureas bearing an electron-withdrawing group on an aromatic ring, behave like Lewis acid to promote the addition of TMSCN and ketene silyl acatals to various nitrones and aldehydes. Presumed interaction between nitrones and thioureas was supported by NMR experiments.
A ‘waterproof’ catalyst for the oxidation of secondary amines to nitrones with alkyl hydroperoxides
作者:Massimiliano Forcato、William A. Nugent、Giulia Licini
DOI:10.1016/s0040-4039(02)02490-5
日期:2003.1
Catalytic oxidation of secondaryamines to nitrones using alkyl hydroperoxides as primary oxidant has been demonstrated for the first time. The titanium alkoxide catalyst is protected from co-product water by the combined use of a tightly binding trialkanolamine ligand and molecular sieves. Nitrones can be obtained in high yield (up to 98%) under homogeneous, anhydrous conditions and even in the absence
Effective Oxidation of Secondary Amines to Nitrones with Alkyl Hydroperoxides Catalysed by (Trialkanolaminato)titanium(IV) Complexes
作者:Massimiliano Forcato、Miriam Mba、William A. Nugent、Giulia Licini
DOI:10.1002/ejoc.200900867
日期:2010.2
The effective catalytic oxidation of secondaryamines to nitrones with alkyl hydroperoxides as the primary oxidants is described. The titanium alkoxide catalysts are protected from the water co-product by the combined use of a tightly binding trialkanolamine ligand and molecular sieves. Nitrones can be obtained in high yields (up to 98 %) under homogeneous, anhydrous conditions and even in the absence