Selective reduction and oxidation of 1-aryl-5-aryl-sulfanyl-6-phenylpiperidine-2-ones

Abstract

The work is devoted to investigation of reactions of selective reduction and oxidation of a new type of piperidine systems – trans-5-arylsulfanyl-6-phenylpiperidine-2-ones. It has been found that the use of the reduction system LiAlH4-AlCl3 onto 1,6-diphenyl-5-(4-tolyl)sulfanylpiperidine-2-one provided a selective reduction of the carbonyl group and formation of 3-(4-tolyl)sulfanyl-1,2-diphenylpiperidine isolated as a hydrochloride with the yield of 83%. At the same time, reduction of 1-aryl-5-phenylsulfanyl-6-phenylpiperidine-2-ones by Ni-Raney runs with decomposition of the phenylsulfanyl group and leads to 1-aryl-6-phenylpiperidine-2-ones. Processing the latest by LiAlH4 in the presence of AlCl3 gives 1-aryl-2-phenylpiperidines isolated as hydrochlorides with the yields of 85-88%. It should be noted that hydrogen peroxide in acetone oxidates the arylsulfanyl moiety of 5-arylsulfanyl-6-phenylpiperidine-2-ones to the arylsulfinyl group at room temperature. As a result, a mixture of diastereomeric 5 sulfinilderivatives is formed with almost the same content of each isomer differing by quantity of chemical shifts of protons at the chiral carbons. The selective oxidation of 1,6-diphenyl-5-arylsulfanylpyperidin-2-ones to the corresponding sulfones has been successfully conducted using oxone as an oxidizer in methanol solution. The composition of all compounds synthesized has been proven by elemental analysis and chromatomass-spectra, their structure has been confirmed by IR and 1H NMR (13C) spectroscopy.