Of piperidine derivative

Delourme-Houd found that on conversion to quaternary derivatives the capacity of sparteine to intensify and prolong the hypertensive action of adrenaline was increased. Pratesi and Aitieri have investigated the sparteine-like activity of piperidine derivatives of the type, CjHioN. CHj. CHjX where X is NH, NMcj, NEtj, NMePh or a second... 

Diastereoselective synthesis, particularly of piperidine derivatives using chiral and nonracemic A-cyanomethyloxazolidines 99CSR383. 

Dehydrogenation of piperidine derivative 329 with Hg(II)-EDTA reagent afforded a mixture of perhydropyrido[l,2-n]pyrimidin-2-one 330 and pyrido[],2-c][],2,5]oxadiazine 331 (99ZN(B)632). 

Under the circumstance of catalytic hydrogenation of piperidine derivatives 190 in MeOH over Pd/C catalyst afforded an isomeric mixture of perhydropyrido[l,2-c]pyrimidines 174-177 (98TL7021, 00JA5017). The main product was 174 (66%). 

An 1 5 epimeric mixture of piperidine derivatives 191 was cyclized under Mitsunobu condition to afford a mixture of l-iminoperhydropyrido[l,2-c] pyrimidines 153 and 192 (00TL1849). 

Piperidine derivatives. Again, both MM2 and MM3 do a good job in reproducing the experimental axial-equatorial energy differences of piperidine derivatives. All other force fields rather seriously overestimate the stability of axial conformations and consequently underestimate the energy difference. The only exception is UFF, which overestimates the aforementioned energy difference for /V-rncthy I piperidine and 2-methylpiperidine. 

Overall, there is a slight preference for axial quaternization of piperidine derivatives (equation 28). The degradation of amines via these quaternary ammonium salts (Hofmann... 

The reaction of piperidine derivatives with electrophilic and oxidizing agents has been an effective method for functionalizing the positions adjacent to the nitrogen atom. This can be a useful synthetic process and a number of these methods are presented below. 

The electrolytic oxidation of N- methoxycarbonylpiperidines provides an interesting and potentially valuable method for the functionalization of piperidine derivatives (81JA1172). Anodic oxidation of piperidine (101) gave (102) which reacted, presumably through the acyl imine, with enol ethers to form a carbon-carbon bond a to the nitrogen atom (Scheme 9). The regiochemical control in this reaction is illustrated by the exclusive oxidation at the less substituted carbon atom (55JA439). 

The existence of a linear correlation between 15N shifts of piperidine derivatives with predominantly axial N-H bonds and those with predominantly equatorial N-U bonds and the 13C shifts of hydrocarbon analogs showed that, whereas 15N chemical shifts of N-methylpiperidines depend on the configuration of the V-substituent, those of W-H-substituted piperidines... 

The quaternization of simple quinolizidine and related alkaloids has attracted much attention, directed primarily at the stereochemistry of the reaction. Methylation of trans-quinolizidine (545) affords the ra-fused 5-methylquinolizidinium salt (546) its isomer (548) is available only by the cyclization of piperidine derivative (547) (51JA3681). 

The often potent biological properties of piperidine derivatives underlie their vast use in pharmaceuticals, agrochemicals, and natural products. It is for this reason that there exists a myriad of synthetic routes to variously functionalized and substituted piperidine derivatives, which will be highlighted in the subsequent section. In the past year there have been two reviews highlighting two approaches to the synthesis of piperidines. One review focused on the use of aziridines in parallel and solid-phase synthesis of substituted piperidine derivatives as well as other scaffolds <07EJO1717>. The other review covered the synthesis of 3-arylpiperidines by radical 1,4- and 1,2-aryl migration <07T7187>. 

Patent Process for Production of Piperidine Derivatives (Note 1)... 

The anodic oxidation of piperidine derivatives in acetic acid gives a,p-disubstituted products in good yields (equation 49). ... 

A three-component Diels-Alder reaction has been reported. Depending on the chiral auxiliary on the nitrogen end of the l-aza-4-borono-1,3-butadiene, diastereomeric excesses can exceed 95% in moderate yield. The method was applied to solid-phase synthesis of piperidine derivatives with acceptable results <03MI466>. 

Treatment of piperidine derivatives 387 with DBU at 70-80°C for 21 hr afforded a mixture of nitrogen bridge-head compounds 388 and tetrahydro-pyridine derivatives 389 in 21-22 and 50-59% yields, respectively (85H831). 

Preparation of piperidine derivates required the conversion of the auxiliary s amine into an imine function. Subsequent Lewis acid promoted Mannich-Michael reaction with Danishefsky s diene gave aliphatic, resin-bound dehydropiperidi-nones 5. After cleavage, the yields of the obtained enaminones 6 ranged between 13 and 90% (Scheme 12.4). The diastereomeric ratios varied from 78 22 to 99 1. The authors reported that aliphatic substituted enaminones were formed with lower diastereoselectivity than aromatic products. 

Design of piperidine derivatives as selective sigma ligands 01PAC1499. 

Michael acceptors and other activated alkenic double bonds can play the role of electrophilic components in the cyclization of piperidine derivatives to quinolizidines. For example, base-induced )S-elimination of the mesylated alcohol (198) gave the epilupinine precursor (199) (Scheme 35)... 

Chemical degradation with fission of the piperidine ring was once used for establishing the constitution of piperidine derivatives (see below). Three methods were applied. 

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