Oxidative Reactions of Azines. 9. Cascade and Stage Oxidation of 1,4-Disubstituted 1,2,3,6-Tetrahydropyridines by Potassium Permanganate

A general scheme was developed for the cascade and stage oxidation of 1,4-disubstituted 1,2,3,6-tetrahydropyridines by potassium permanganate, based on the successive oxidation of the allylic triad of carbon atoms in the piperideine ring. In the case of 4-aryltetrahydropyridines 2-oxotetrahydropyridines are formed initially. 3,4-Dihydroxypiperidin-2-ones and finally 1-aminoalkan-3-ones are then formed. The oxidation of 4-methyl-substituted tetrahydropyridines to the analogous 1-aminoalkanones begins differently - with 3,4-dihydroxylation followed by lactamization of the piperidinediols.     

Quasielastic reactions around the coulomb barrier in 16O+118Sn

Measurement of elastic and quasielastic reaction cross sections were done in ¹⁶O + ¹¹⁸Sn system at two different energies above the barrier. Attempts are being made to understand the results in the framework of coupled reaction channel model.     

Oxidative reactions of azines

Oxidative coupling of 1-alkyl(benzyl)-4-(γ-pyridyl)-1,2,5,6-tetrahydropyridines with acetone in the presence of KMnO₄ follows two pathways and yields both 1-R-2-(acetylmethylene)tetrahydropyridines and 1-R-3,4-dihydroxypiperidin-2-ones. When acetonitrile is used instead of acetone, the reaction under similar conditions occurs as selective ketodihydroxylation of the starting piperideines yielding 1-R-3,4-dihydroxy-4-(γ-pyridyl)piperidin-2-ones. The molecular and crystal structures of one of these products (R=Et) was studied by X-ray diffraction analysis. For part 4, see Ref. 1 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2020–2023, November, 1997.