Showing papers on "Piperidine published in 1980"

Simultaneous Catalytic Hydrodenitrogenation of Pyridine and Hydrodesulfurization of Thiophene

Abstract: The study of the simultaneous catalytic hydrogenation of pyridine and hydrosulfurization of thiophene, model compounds representing sulfur and nitrogen content in oil shale and coal-derived liquid fuels was extended to higher, industrially relevant pressures, up to 7 MPa The reactions were carried out in a continuous plug-flow microreactor at 200 to 400C and thiophene and pyridine partial pressures of 124 kPa each, over a commercial 31% by wt NiO/15% MoO/sub 3//Al/sub 2/O/sub 3/ catalyst Thiophene hydrodesulfurization was inhibited by pyridine under all the conditions studied In the absence of thiophene, pyridine reached a thermodynamic equilibrium with piperidine above 350C at all pressures studied (11 4 to 7 MPa), but this equilibrium was not reached in the presence of thiophene because of the inhibition of pyridine hydrogenation and enhancement of piperidine hydrogenolysis The combined conversion of pyridine plus piperidine, ie, the over-all rate of hydrodenitrification, was enhanced by thiophene at > 300C and > 355 MPa

Synthesis of 2-Azabicyclo[3.3.1]nonanes

Abstract: This review highlights advances in the synthesis of morphan compoundsfrom 1980 to the present day. 1 Introduction 2 Synthetic Approaches from Carbocyclic Compounds 2.1 Aminocyclization Processes Forming the C(1)-NBond 2.1.1 From Amino Alkenes 2.1.2 From Amino Ketones 2.1.3 By Amine Alkylation 2.1.4 By Amino Conjugate Addition upon Enones 2.2 Aminocyclization Processes Forming the N-C(3)Bond 2.3 Cyclization Processes Forming the C(3)-C(4) Bond 2.4 Cyclization Processes Forming the C(4)-C(5) Bond 2.4.1 Aldol Reactions 2.4.2 Piperidine Ring Closure by a Heck Reaction 2.4.3 Alkenylation of Enolates 2.4.4 Radical Cyclizations 2.4.5 Miscellaneous Approaches 3 Synthetic Approaches from Piperidine Derivatives 3.1 Cyclization upon Iminium Ions Forming the C(1)-C(8) Bond 3.2 Cyclization Processes Forming the C(5)-C(6) Bond 3.3 Cyclization Processes Forming the C(6)-C(7) Bond 4 Cascade Processes 5 Rearrangements 6 Synthesis of 5-Phenylmorphans 7 Conclusions

1,3,5-Triazines containing at least one piperidine radical

Abstract: Novel oligomer or polymer polyamine-1,3,5-triazines containing at least one polyalkylpiperidine radical, for example that of the formula ##STR1## processes for their production, their use for stabilizing organic material, and the organic material protected therewith against oxidative and light-induced degradation.

Novel 3-(1-piperidinylalkyl)-4H-pyrido[1,2-a]pyrimidin-4-one derivatives

Abstract: Novel 3-(1-piperidinylalkyl)-4H-pyrido[1,2-a]pyrimidin-4-one derivatives, wherein the piperidine ring is substituted with an aroyl radical or a functional derivative thereof, said compounds being potent serotonin-antagonists.

Synthesis of nitrosourea derivatives of pyridine and piperidine as potential anticancer agents

Abstract: Nitrosourea derivatives 18-22 which utilize either a piperidine or pyridine ring as a carrier group were synthesized and evaluated for anticancer activity. N'-(1-Benzyl-4-piperidinyl)-N-(2-chloroethyl)-N-nitosourea hydrogen maleate (19) exhibited good activity against intracranial L1210 leukemia as well as the mouse ependymoblastoma brain tumor system. Compound 19 exhibited comparable activity in the Lewis lung carcinoma system to N,N'-bis(2-chloroethyl)-N-nitrosourea. Replacement of the N-benzyl group in both the 3-piperidinyl- and 4-piperidinylnitrosoureas resulted in less active compounds in all tumor systems tested. The 3-pyridylnitrosourea 22 was inactive in the L-1210 leukemia system.

Novel piperidine derivatives

Abstract: Novel compounds represented by the following general formula: (FORMULA) wherein Ar represents naphthyl, phenyl, or substituted phenyl, Q represents -C-, -CH2, or-CH- (FORMULA) (wherein R1 represents hydrogen, alkyl, alkanoyl or alkoxycarbonyl, R represents hydrogen or alkyl Z represents substituted benzimidazolinyl, and the broken line in the piperidine ring indicates that 3- and 4-positions of the piperidine ring are saturated or indicates a double bond therebetween Said compounds and the medically acceptable acid addition salts thereof show a hypotensive action, thus being useful as medicines

Novel piperidine derivatives and pharmaceutical compositions containing them

Abstract: Novel compounds represented by the following general formula: wherein Ar represents naphthyl, phenyl, or substituted phenyl, Q represents represents hydrogen, alkyl, alkanoyl or alkoxycarbonyl, R represents hydrogen or alkyl. Z represents substituted benzimidazolinyl, and the broken line in the piperidine ring indicates that 3- and 4-positions of the piperidine ring are sat u - rated or indicates a double bond therebetween. Said compounds and the medically acceptable acid addition salts thereof show a hypotensive action, thus being useful as medicines.

Photofragmentation of Dibenzyl Ketone in the Presence of Tetramethylpiperidine Derivatives. Studies on light stabilizer mechanisms [1]

Abstract: The interaction of selected tetramethylpiperidine derivatives with radicals arising from the Norrish-type I cleavage of dibenzyl ketone under oxygen was studied. Product analyses and kinetic studies showed that the investigated sterically hindered piperidine derivatives have a pronounced effect on both the nature and distribution of the products of photolysis of dibenzyl ketone in the presence of oxygen. Observations indicated that the phenylperacetoxyl radical is formed as an intermediate during irradiation and that it interacts with the additives used. Possible mechanisms of the reactions studied are discussed. The observation that oxidation of an isolated double bond by the radicals formed in dibenzyl ketone photolysis under oxygen is strongly inhibited in the presence of the studied sterically hindered amines is discussed in the light of the results presented. The findings are considered in relation to the problem of polymer stabilization.

Influence of sensitisers on the photostabilising action of a hindered piperidine compound in polypropylene

Abstract: The influence of prior thermally generated hydroperoxides and added anthraquinone have been examined on the photostabilising action of a hindered piperidine compound, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, in polypropylene film using ESR spectroscopy and flash photolysis techniques. The hindered piperidine compound was found to effectively inhibit both the hydroperoxide and carbonyl group sensitised photooxidation of the polymer. Using ESR spectroscopy evidence is presented to show that the hindered piperidine compound reacts stoichiometrically with the hydroperoxide groups generated by thermal oxidation to give a stable nitroxyl radical. On flash photolysis of anthraquinone in hexane transient formation due to the semi-quinone radical and subsequent formation of the hydroquinone were found to be effectively inhibited by a stable N-oxyl radical compound but not the amine. It is concluded that the nitroxyl radical is the effective stabilising species and operates by a radical scavenging mechanism to form the hydroxylamine.

Structures and Syntheses of Two Phenolic Amides from Piper nigrum L

Abstract: Two phenolic amides were isolated from the fruits of white pepper (Piper nigrum L.) and identified to be N-trans-feruloyl tyramine (2a) and N-5-(4-hydroxyphenyl)-2E, 4E-pentadienoyl piperidine (6a) on the basis of chemical and specrtal evidence. Both compounds were synthesized.

Piperidine derivatives and pharmaceutical compositions containing same

Abstract: A new piperidine derivative represented by the formula: ##STR1## wherein X is oxygen, sulfur, carbonyl, hydroxymethylene or methylene; R is straight-chain alkylene having 1-4 carbon atoms with or without lower alkyl substituent(s); m and n are 0 or 1, and are different from each other (i.e., both m and n are not 0 or 1); and (D) m' , R 1 and (R 2 )n' are usually used as substituents, has a hypotensive activity.

Studies on Pyrimidine Derivatives. XVIII. Reaction of Active Methyl Groups on Pyrimidine N-Oxides

Abstract: Knoevenagel-type condensation and the Mannich reaction were investigated with various pyridine N-oxides having an active methyl group For example, 6-methyl-4-phenylpyrimidine 1-oxide (Va) readily reacted with benzaldehyde in an aqueous ethanolic solution of potassium hydroxide, while 4-methyl-6-phenylpyrimidine (IVa) failed to react with benzaldehyde under the same conditions When Va was treated with piperidine hydrochloride and paraformaldehyde, bis piperidinomethylation occurred at the 6-methyl group The product was transformed into 4-phenyl-6-(2-piperidinoethyl) pyrimidine 1-oxide (XXIIa) by treatment with 5% sulfuric acid at 90°

Nucleophilic addition to activated olefins. 3. Reactions of piperidine and morpholine with benzylidenemalononitrile in 50% dimethyl sulfoxide-50% water. Intrinsic barriers in nucleophilic additions

Abstract: Die Titelreaktion mit Piperidin (IIa) fuhrt uber ein zwitterionisches Addukt und dessen Deprotonierung uber das Intermediarprodukt (III) zu den Produkten (IV) und (V), die auch in Abwesenheit von Aminen, aber dann erheblich langsamer entstehen.

Piperidine derivatives as stabilizers for synthetic polymers

Abstract: The invention relates to novel piperidine compounds that act as light, heat and oxidation stabilizers for synthetic polymers, especially hydrocarbon polymers. The compounds are Piperidinolcarbamate the formula: wherein R In particular, A represents a monovalent to tetravalent, each bonded via nitrogen atoms to the rest Carboxypiperidinreste.