Oxoammonium salts as oxidizing agents: 2,2,6,6-tetramethyl-1-oxopiperidinium chloride

A study of the scope of the oxidizing ability of the oxoammonium chloride (1) revealed that phenols, enolizable ketones, phosphines, amines and anilines were reactive but that olefins, aromatic ethers, sulfides, and sulfones did not react.     

C-Nitroso compounds—XXXV : Reaction of organometallic compounds with 1-chloro-1-nitroso-2,2,6,6-tetramethylcyclohexane

Reaction of Grignard reagents and organolithium compounds (RM) with the congested 1-chloro-1-nitroso-2,2,6,6-tetramethylcyclohexane 1 leads to the formation of significant amounts of the reduction product 2,2,6,6-tetramethylcyclohexanone oxime 3 (61–90%) together with the corresponding oxime O-R ether 4 (0–11%). Attack on nitrogen is unimportant as shown by very low yields of nitrone. Formation of the products is rationalised with a pathway involving transfer of an electron from RM to 1. This leads—after separation of MCI—to a radical pair consisting of R and the relatively stable iminoxy radical 2 (Schemes 1 and 2). Combination of these radicals explains formation of oxime ether 4 and nitrone 5, while reaction of iminoxy radical 2 with excess of RM can give oxime 3. Reactive radicals R (i.e. Me, Ph, and to a minor extent n-Bu) are furthermore capable of abstracting hydrogen from the solvent (diethyl ether, toluene, or cumene), and the solvent derived radicals can also combine with 2 on oxygen, under formation of oxime ether (26% of 6a). The corresponding benzyl- and cumyl ethers 6b and 6c are only formed in trace amounts because dimerisation of benzyl radicals (7%) and cumyl radicals (22%) is favoured.     

Dual reactivity of 1,2-disubstituted dihydro-N-heteroaromatic systems. 2. Mechanism of the dehydrogenation of N-acyldihydroquinolines and isoquinolines with 2,2,6,6-tetramethyl-1-oxopiperidinium perchlorate

The mechanism of the heterolytic dehydrogenation of various N-acyl derivatives of -substituted 1,2-dihydroquinolines and isoquinolines with 2,2,6,6-tetramethyl-1-oxopiperidinium perchlorate was investigated.See [1] for Communication 1.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 78–84, January, 1981.     

Quantum-chemical investigation of the reaction mechanism of 2-methylimidazole with 1,7-diiodo-2,2,6,6-tetramethyl-2,6-disilaheptane

Quantum-chemical investigation of the mechanism of reaction between 2-methylimidazole and 1,7-diiodo-2,2,6,6-tetramethyl-2,6-disilaheptane by the method B3LYP/6-311G(d,p) provided thermodynamic and kinetic characteristics of the formation channels of the new organosilicon fused and cyclophane structures whose yield depended on the ability of iodomethyl groups to be reduced at the action of HI formed in situ. On adding iodine that initiated the formation of triiodide anions the cyclic structures were stabilized as ionic liquids.     

Radical steps in the reactions of organometallic compounds with 2-methyl-2-nitrosopropane: experimental evaluation of the validity of the nitroxyl method for investigations of homolytic reactions of organometallic compounds

Radical adducts formed in the reactions of organometallic compounds of group II-V elements and of some organochromium and organoiron compounds with 2-methyl-2-nitrosopropane and phenyl(tert-butyl)nitrone were studied by ESR. Nitroso compounds and nitrones can be used as selective spin traps for investigations of homolytic reactions involving organometallic compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 916–920, May, 1994.     

Vinyl ether of 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl and its oligomers

Russian Chemical Bulletin -     

Sonochemical barbier reaction with isocyanates and the synthetic use of the organometallic intermediate

Sonication of aryl halides, t-butyl isocyanate and sodium in THF leads to an organosodium intermediate which is easily and regioselectively ortho-lithiated and reacted with electrophilic reagents.     

Mechanism of free-radical copolymerization of styrene with acrylonitrile and methacrylonitrile mediated by 2,2,6,6-tetramethyl-1-piperidinyloxy

By the examples of chemically similar styrene-acrylonitrile and styrene-methacrylonitrile systems, substantially different mechanisms of TEMPO-mediated copolymerization have been theoretically predicted and experimentally verified. Living copolymer-TEMPO adducts capable of thermal decomposition and polymerization reinitiation via the pseudoliving mechanism predominantly form in the first system. The reaction proceeds under the steady-state regime and is characterized by the living growth of M _n of the copolymer with conversion. In the second system, the probabilities of formation of living and dead macromolecules are equal. Therefore, the living growth of M _n of the copolymer ceases and the reaction passes to the conventional copolymerization regime.