Piperidine compounds

Tests against albopictus mosquitoes using either piperidine compound have shown these compounds to be nearly as good as DEET. Subsequent tests... 

In an approach to simple Nuphar quinolizidine alkaloids, the piperidine compound 213 was converted to compound 214 that underwent one-pot detosylation, conjugate reduction, and cyclization to produce the quinolizidin-4-one 215... 

Several diverse classes of potent CCR5 antagonists, Figure 7 have recently been reported [2], Scaffolds reported to support high potency against CCR5 in antiviral cellular assays included the aminocyclohexyl (compound 13) [45], 4,4-disubstituted piperidine (compound 14, GSK163929) [46,47], tetrahydro-2/T-1,3-oxazine (compound 15) [48], pyrrolidine (compound 16) [49], cyclopropyl (compound 17) [50] and 2,3-dihydro-lH-indene (compound 18) [51]. 

Title A-Alkoxv-4,4-Dioxy-Polyalkyl-Piperidine Compounds, Their Corresponding iV-Oxides, and Controlled Radical Polymerization Therewith... 

Eisleb, O. (Winthrop) Piperidine compounds and a process of preparing them, US 2 167 351,1939. 

Ito, F., Kondo, H., Noguchi, H., Ohashi, Y. (Pfizer Inc.) 4-(2-Keto-1-benzimidazolinyl)piperidine compounds as ORL1 -receptor agonists, W09936421 (1999). 

On the basis of this retrosynthetic analysis, design a synthesis of /V-methy 1-4-phenyl piperidine (compound A, where R = CH3, R = C6H5). Present your answer as a series of equations, showing all necessary reagents and isolated intermediates. 

The same synthesis route is also employed for piperidine compounds of the type... 

Piperidine compounds, such as thioridazine, are similar to chlorpromazine, because they are very potent muscarinic antagonists with correspondingly low incidences of movement disorders. 

Moderate asymmetric induction and low yields are observed when the compound 5, prepared from (A, )-hexadienal and (15,25)-pseudoephedrine, undergoes cycloaddition with the nitroso derivative 6. The major cycloadduct 7 is obtained together with minor amounts of diastereomers (d.r. 62 24 11 3) and after chromatography is isolated in 32% yield. Its configuration is first assigned by H NMR, and then by conversion into the known (+ )-(S)-2-methyl-l-(4-toluenesulfonyl)piperidine. Compound 7 is the key intermediate for the total synthesis of an amino allose derivative135. 

Synthesis of a piperidine compound is commonly carried out by reduction of the corresponding pyridine derivative. An excellent discussion has been presented. " Earlier techniques concerned with reduction by the action of sodium and alcohol have been largely replaced by procedures of catalytic hydrogenation. An example is the reduction of pyridine to piperidine in 83% yield over nickel at 170-200°. Reduction of its homologs occurs in the same way. Platinum oxide is poisoned by pyridine... 

The mode of action of hindered piperidine compounds continues to be rather controversial. A recent study of the effect of different N-substituents on the light stabilizing activity of a particular hindered piperidine molecule in polypropylene showed that the nitroxyl radical —O was the most effective... 

Hindered piperidine compounds continue to be investigated in some detail as the most effective stabilisers for a variety of polymers. It has been shown that hindered piperidine molecules are oxidised... 

Another tetrahydroazepine congener (163) displays higher affinity for muscarinic receptors but somewhat lower efficacy than the analogous fused piperidine compounds (161) (197) it was described as a partial agonist. Studies (198) of sulfur analogs and congeners (164-167) of the isoxazolotetrahydropyri-... 

Allen et al. have carried out a wide ranging study in polypropylene on the interaction between various antioxidants and hindered piperidine light stabilisers in both thermal and photochemical oxidation. Generally, phenolic anti-oxidants were found to antagonise the performance of hindered piperidine compound in photochemical oxidation and is associated with the former destroying or preventing the formation of hydroperoxides which are essential for the conversion of the piperidine to a piperidine-N - oxy radical. 

The piperidine compound (163 R, R" = —(CH2)j—) is easily hydrolyzed," and the aniline compound (163 R = Ph R" = H) cannot be prepared by this route. " A number of these compounds have been prepared by the alternative route 160a - 164 - 163." The reaction conditions were modified in more recent studies." Robertson identified 163 (R = 2-pyridyl R" = H) as the unexpected product of the reaction between 2-nitrophenylpropiolic acid and 2-aminopyridine. Further studies are needed to clarify these conflicting, and in some cases tentative, reports. The tautomerism of these compounds (163 R = aryl R" = H) is worthy of further study " (cf. Section II,A,4). Recently, a study of the tautomerism of the carbazide derivatives (165) has been made both tautomers (163, 165) were reportedly identified." ... 

The photostabilisation of polymers still maintains a high level of activity with the mechanistic action and performance of hindered piperidine compounds continuing to attract interest. Some interesting reviews have appeared with one very extensive and highly recommended paper on the mode of action of hindered piperidine light stabilisers while another has dealt with their manufacturing properties. The kinetic reactions and photophysics of light stabilisers have been covered in another review as has the stabilisation of polyacetals. ... 

A hindered amine light stabiliser has been found to enhance the light stability of blends of low and linear low density polyethylene with the latter contributing linearly to the overall stability of the blend. In coatings hindered piperidine light stabilisers are also effective especially when used in conjunction with a benzotriazole absorber while surface protection of styrene copolymers with 2-(2-hydroxy-5-vinylphenyl)benzotriazole requires a small amount of a hindered piperidine stabiliser. Polymeric hindered piperidine compounds on the other hand have been found to inhibit the singlet oxygen attack on poly(butadiene). ... 

Synthesis and Stabilizing Activity of Hindered Amines. As mentioned previously, the hindered piperidine compounds showed excellent light-stabilizing activity in polypropylene. In order to find more efficient compounds, various derivatives of 2,2,6,6-tetramethyl-4-oxopi-peridine (42) were synthesized and tested. In this section we describe some typical examples from the great number of derivatives prepared in our laboratory. 

In addition, we attempted to prepare piperidine compounds bonded with a hindered phenol moiety, since phenolic antioxidants are essential for processing and long-term stabilization. The proposed compounds were expected to have light-stabilizing activity and at the same time thermal stabilizing activity in the polymers. Bifunctional compounds were also synthesized. The corresponding diols were obtained by the reaction of the amines with ethylene oxide (Chart 11). The stabilizing activities of the above compounds are summarized in Table V. 

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