Synthesis of 8-[(hydroxy)methyl]-13,13-diethyl-1,4-dioxa-12-azadispiro[4.1.4.3]tetradecane-12-oxyl
M. I. ROGOVOY1, S. A. DOBRYNIN1, YU. I. GLAZACHEV1,2, I. A. KIRILYUK1
1Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
2Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Brach of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: nitroxide, piperidine, heterocyclisation
Abstract
Рiperidine nitroxides have found many applications in various fields of science and technology. The introduction of bulky alkyl substituents in an adjacent position to the N-O fragment imparts useful characteristics to such radicals, increasing their stability in biological samples, enhancing their protective antioxidant properties and making them valuable regulators of radical polymerisation. A sterically hindered nitroxide with a spiro-2-hydroxymethylcyclopentane moiety and two ethyl groups at positions 2 and 6 of the piperidine ring, respectively, was synthesised. For this purpose, the condensation of 2-(2-aminoethyl)-2-methyl-1,3-dioxolane with diethyl ketone under the conditions of acid catalysis was carried out. The resulting spirocyclic piperidine was oxidised to aldonitrone. Spiro-2-hydroxymethylcyclopentane moiety was assembled via the reaction with 4-pentenylmagnesium bromide, followed by oxidation and intramolecular 1,3-dipolar cycloaddition and reductive opening of the isoxazolidine ring. The resulting dispirocyclic piperidine was oxidised to the corresponding nitroxide, 8-[(hydroxy)methyl]-13,13-diethyl-1,4-dioxa-12-azadispiro[4.1.4.3]tetradecane-12-oxyl. The kinetics of reduction of the latter by ascorbic acid has been studied.
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