Studies on the oxidation of enamines with molecular oxygen. III. Oxidation of some amino styrenes

Abstract

In the oxidation of the amino styrenes 1a–1j only products of the oxidative attack at the C  C double bond and hydrolysis products are obtained. Aprotic dipolar solvents and the addition of molecular sieve 5A promote the oxygen uptake. The addition of hydrochinone to the oxidation system does not influence the rate of oxygen absorption or the yields of the oxidation products.

Silylene and Germylene Intermediates in the Reactions of Silole and Germole Dianions with N,N′‐Di‐tert‐butylethylenediimine

“…Evidently 15 arises via C-oxidation of spirocyclo-enediamine 3 (Scheme 8). Similar oxidation of enamines, enhanced in presence of molecular sieves was described previously by Blau et al [17][18][19] Eur (15) shown with 50 % probability thermal ellipsoids. The germanium-nitrogen bond in 3b (E = Ge) is less stable than a silicon-nitrogen bond and rapidly decomposes in the presence of air to give the cyclo-trigermoletrioxane 16 (Scheme 8), identified by X-ray crystallography and 1 H, and 13 C NMR analysis.…”

Chiral Ionic Liquid/ESI‐MS Methodology as an Efficient Tool for the Study of Transformations of Supported Organocatalysts: Deactivation Pathways of Jørgensen–Hayashi‐Type Catalysts in Asymmetric Michael Reactions

“…Evidently, enamine cation 26 also underwent oxidation and hydrolysis reactions to afford catalytically inactive N ‐formylpyrrolidine 17 (the oxidation of N ‐alkenyl‐ to N ‐formylpyrrolidines by O 2 see ref. 38) in which the amino group was irreversibly blocked by the carbonyl group, and OH‐prolinol 21 , respectively. Cation 21 (relative intensity 140 % after 4 cycles, 24 h each) may serve as a source of OH–catalyst 10 (see Scheme , side catalytic cycle 2), which is also able to catalyze the Michael reaction (see corresponding intermediates 18 , 20 , 21 , 25 , and 28 ; Table 3, column 4; and catalytic cycle in the Supporting information), though less efficiently than O ‐TMS‐catalyst 9 19d.…”

Intramolecular 1,3-dipolar cycloadditions of dihydroimidazolium ylides: synthesis of pyrrolo[1,2,3-de]quinoxalines and imidazo[1,2-a]indoles

“…Indeed, the oxidation of enamine systems by means of molecular oxygen has been reported in the literature. [36][37][38] Presumably, the presence of adventitious molecular oxygen, perhaps originating from undegassed solvents, is the cause of this oxidation process. The reason for different outcomes for the alkyl and aryl bromoketones is unclear but may be due to stabilisation of 17 through conjugation of the double bond with the 3-aryl system.…”