Condensation of 1,2,5-trimethyl-4-piperidone with p-diethynlbenzene

A mixture of stereoisomeric diacetylenic piperidols was obtained by the reaction of 1,2,5-trimethyl-4-piperidone with p-diethynylbenzene in liquid ammonia in the presence of sodium amide. Each of the two pure alcohol and glycol geometrical isomers were isolated by chromatography with columns filled with aluminum oxide. Assumptions relative to the three-dimensional structure of the synthesized compounds are expressed on the basis of the principles of conformational analysis, the chromatographic data, and a study of the IR and NMR spectra. Saturated piperidols were obtained by catalytic hydrogenation on a Raney nickel catalyst.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1646–1651, December, 1970.The authors thank O. V. Agasikin for this assistance in interpreting the IR and NMR spectra.     

Ein acidimetrisches Bestimmungsverfahren alkylsubstituierter 1-Methyl-4-piperidone

Ohne Zusammenfassung     

ESR investigation of kinetic basicity of N-methyl-4-piperidone

Kinetic and thermodynamic parameters of the reversible reaction of proton transfer between 3,6-di-tert-butyl-2-hydroxyphenoxyl and N-methyl-4-piperidone have been investigated by means of ESB. It has been found that proton transfer from the semiquinone radical to the piperidone leads to enolization of the keto-base; and the ESR spectrum of the system undergoes a broadening of the HFS lines, which is characteristic for intermolecular proton exchange. The existence of a keto-enol equilibrium in the piperidone is also responsible for a negative value of the activation energy of the forward reaction of proton transfer.Karaganda University. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 2, pp. 178–184, March–April, 1991, Original article submitted May 23, 1986.     

Nucleophilic addition to 1,2,2,6,6-pentamethyl-3,5-dimethylene-4-piperidone

Like branched primary amines, unbranched mercaptans react with 1,2,2,6,6-pentamethyl-3,5-dimethylene-4-piperidone to give products of ring opening. On the basis of the data obtained, a reaction scheme that includes the intermediate formation of 3,7-diazabicyclo[3.3.1]nonan-9-one seems less likely as compared with a scheme involving elimination from the monocyclic piperidine system. It is also shown that steric interaction of the vicinal substituents is one of the important factors that promote elimination.Translated from Khimiya Geterotsiklichekikh Soedinenii, No. 6, pp. 804–809, June, 1987.     

Studies on the stereochemistry of 1,2,6-trimethyl-4-piperidone

In the effort to create new derivatives of analgesically active spiropiperidines intermediate 1,2,6-trimethyl-4-piperidone was synthesized. The substitution of the skeleton gives rise to configurational as well as conformational isomerism. Despite the symmetry of 1,2,6-trimethyl-4-piperidone two different sets of signals were present in the ¹H and ¹³C NMR spectra. They were supposed to arise from a cis/trans mixture of 1,2,6-trimethyl-4-piperidone. In contrast to this explanation only two signals of the methyl groups and hydrogens at carbon atoms 2 and 6 were observed in the ¹H and ¹³C NMR spectra, normally expecting one for the cis- and two for the trans-isomer. To solve this discrepancy, the kind of isomeric mixture of 1,2,6-trimethyl-4-piperidone leading to the ¹H and ¹³C NMR spectra was examined. Energy differences between chair conformations of both the cis- and the trans-isomer of 1,2,6-trimethyl-4-piperidone and the potential energy surface of the equilibration process of the trans-isomer of 1,2,6-trimethyl-4-piperidone between its chair conformers were determined by quantum chemical calculations. The barrier height of the equilibration process was measured by high and low temperature NMR measurements to confirm the theoretical outcome. The results of all investigations agree nicely and proved a cis-/trans-mixture of 1,2,6-trimethyl-4-piperidone being present at room temperature.     

Reaction of 2-vinylpyridine with 2.5-dimethyl-4-piperidone

2-Vinylpyridine adds to 2,5-dimethyl-4-piperidone in the 1 position in the presence of acetic acid and in the 5 position in the presence of sodium metal.     

Synthesis and properties of 1,2,2,6,6-pentamethyl-3,5-dimethylene-4-piperidone

1,2,2,6,6-Pentamethyl-3,5-dimethylene-4-piperidone was synthesized, whereas analogous compounds in the 4-piperidone series could not be isolated. An unusual reaction of the compound obtained with primary aliphatic amines, consisting of successive addition of the amine at the C=C bonds, with a possible formation of an intermediate bicyclic adduct and further elimination of methylamine, was detected.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 937–942, July, 1984.     

Selenium heterocycles XIV. 2,6-diaryltetrahydroselenopyran-4-ones

In our previous communications, we have reported that selenium heterocycles could be easily obtained either by using selenium dioxide (3) or by selenium (4). In continuation of our studies on the synthesis and chemistry of selenium heterocycles, it was of interest to use aluminum selenide as the precursor of selenium in the preparation of selenium heterocycles.     

Addition of tris(trimethylsilyl) phosphite to N-substituted 4-piperidone

Russian Journal of General Chemistry - Convenient methods for the synthesis of functionalized phosphonic acids containing piperidine moieties via the reaction of tris(trimethylsilyl) phosphite with...     

Novel route to spiropiperidines using N-methyl-4-piperidone,malononitrile and electrophiles

A new pathway to spiropiperidine rings via sequential one pot reaction of N-methyl-4-piperidone, malononitrile, and electrophiles or Michael acceptor in the presence of triethyl amine in ethanol under reflux condition is reported.     

Photolysis of 2,6-diphenyl-4h-pyran-4-thione and 2,6-diphenyl-4h-thiopyran-4-thione

Photolysis of 2,6-diphenyl-4H-pyran-4-thione and 2,6-diphenyl-4H-thiopyran-4-thione resulted in desulfurization and furnished 2,2′,6,6′-tetraphenyl-4,4′-di(pyranylidene) and 2,2′,6,6′-tetraphenyl-4,4′-di(thiopyranylidene) as the products. The mechanism was studied by quantum yield measurements. In dioxane, the quantum yield of di(pyranylidene) formation was concentration-dependent, while in benzene, it was independent of the concentration. The photoreaction proceeds via the triplet state of 2,6-diphenyl-4H-pyran-4-thione and 2,6-diphenyl-4H-thiopyran-4-thione and the H atom abstraction from solvents appears to be a key step in the formation ofdi(pyranylidene).