Oxidation of piperidine

Glutarimide has been prepared from glutaric acid and sulfamide 3 or formamide,4 by distillation of ammonium glutarate,6 by hydrolysis of pentanedinitrile with acetic acid,6 and by oxidation of piperidine with hydrogen peroxide.7... 

A convenient method to affect the oxidation p- to nitrogen in piperidines is based on the anodic oxidation of N-carboalkoxy piperidines (Scheme 35). The electrochemical oxidation of piperidine (152) in the presence of acetic acid and potassium acetate, for example, afforded a mixture of isomeric 2-hydroxy-3-acetoxypiperidines (153) in a combined yield of 93%, following an aqueous workup [61]. Reduction with sodium boro-hydride severed the C-OH bond. Treatment with acid and then base completed a synthesis of pseudoconhydrine (154). 

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). 

It can be seen from the above discussion that the oxidation of piperidines can be a useful and often mild method for the preparation of carbon-substituted piperidines. 

This work concerns mainly the modification of commercial polymers bearing hydroxy fonctions as alcohol, hydroperoxide or carboxylic acid, by reactive gases or liquid volatil compounds capable to penetrate in the polymer matrix. The modifications of membranes properties as gas permeability or surface tension will also be reported. Few examples will also concern the reaction of double bond with 12 and HBr vapor as well as the oxidation of piperidine group by peracetic acid. 

Aryl-A3-iodane oxidation of amines to imines also involves a combination of ligand exchange and successive reductive -elimination. Oxidation of pyrrolidine with iodosylbenzene 18 affords quantitatively an equilibrium mixture of 1-pyrroline and its trimer [72]. When oxidation of piperidine with 18 (2 equiv) was carried out in water, 2-piperidone was produced [73]. In the latter reaction, a sequence of ligand exchange and reductive -elimination was repeated two times [Eq. (38)]. 

Autoreduction of Fe(III) Porphyrins. Oxidation of Piperidine. The autoreduction of TPPFeCl with neat piperidine is rapid, however the reaction rate can be decreased by dilution with CDC13 or DMSO. The NMR spectrum of TPPFeCl in CDC13, on addition of piperidine, shows resonances consistent with the presence of high spin Fe(III) and low spin TPPFen(Pip)2. A low spin TPPFem(Pip)2 species was not observed. It is likely that the latter complex rapidly reduces at room temperature. 

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

Preparation by oxidation of piperidine with 3% hydrogen peroxide. A more satisfactory method is by oxidation of N-ethylpiperidine to the N-oxide followed by Cope elimination. ... 

GABA was formerly known as piperidic acid, because it was synthesized by the oxidation of piperidine at the end of the nineteenth century [1]. 

A related approach to porantherine was reported by the Stevens group about 10 years after publication of the Corey synthesis. The Stevens synthesis emphasized the notion that the stereoelectronic requirement for addition of a nucleophile to an imine (or iminium ion) was development of an anti-periplanar relationship between the nucleophile and the developing lone pair on nitrogen. This notion also leads to the disconnection of 2 —> 3 —> 22, and iminium ion 22 was to be prepared by oxidation of piperidine 23. Thus, the major difference between the Stevens and Corey approaches is the choice of a surrogate for the aldehyde required for generation of iminum ion 3. In the forward direction, the lithium reagent derived from 26 was treated with iminoether 27 to provide 28. Hydroysis of 28 gave enamine 29. 

Diaminoanthraquinone is an important intermediate for vat dyes and disperse dyes, and is prepared by oxidizing leuco-l,4-diaminoanthraquinone with nitrobenzene in the presence of piperidine. An improved process has been reported (45). 

The reactivity of halogens in pyridazine N- oxides towards nucleophilic substitution is in the order 5 > 3 > 6 > 4. This is supported by kinetic studies of the reaction between the corresponding chloropyridazine 1-oxides and piperidine. In general, the chlorine atoms in pyridazine A-oxides undergo replacement with alkoxy, aryloxy, piperidino, hydrazino, azido, hydroxylamino, mercapto, alkylmercapto, methylsulfonyl and other groups. 

Formula (VI) has received support in two ways. The investigations of Winterfeld (with Ronsberg) on the oxidation of dehydrosparteine methoaeetate and of a-didehydrosparteine, indicated thatD was a piperidine ring and this was finally established by Clemo, Morgan and Raper a... 

To return to a more historical development the mercuric acetate oxidation of substituted piperidines (77) should be discussed next. This study established that the normal order of hydrogen removal from the aW-carbon is tertiary —C—H > secondary —C—H > primary —C—H, an observation mentioned earlier in this section. The effect of substitution variations in the piperidine series can be summarized as follow s l-mcthyl-2,6-dialkyl and 1-methyl-2,2,6-trialkyl piperidines, as model systems, are oxidized to the corresponding enamines the 1,2-dialkyl and l-methyl-2,5-dialkyl piperidines are oxidized preferentially at the tertiary a-carbon the 1-methyl-2,3-dialkyl piperidines gave not only the enamines formed by oxidation at the tertiary a-carbon but also hydroxylated enamines as found for 1-methyl-decahydroquinoline (48) (62) l-methyl-2,2,6,6-tctraalkyl piperidines and piperidine are resistant to oxidation by aqueous mercuric acetate and... 

A kinetic study of the mercuric acetate oxidation of l-alkyl-3,5-dimethyl-piperidines (81) and 3-alkyl-3-azabicyclo[3.3.1]nonanes (82) was made to evaluate the effect of the N-alkyl group on the rate of oxidation and to contrast these two ring systems (70). The maximum factor in the piperidine... 

Second-order kinetics are reported for the reactions of halogeno-quinoline iV -oxides with piperidine in several solvents and of halo-geno-nitrothiophenes with piperidine in ethanol. ... 

The A-oxidation of 3-chloropyridazines increases their reactivity toward methoxide and sulfanilamide anions.The reactivity of 4-chloro- or 4-nitro-quinoline and of chloropyridines toward methoxide ion and piperidine is less than that of the corresponding A-oxides (see Tables II and XI, pp. 270 and 338). The activating effect of the A-oxide moiety in 3-halopyridine A-oxides is greater than that of a nitro group, and in fluoroquinoline A-oxides the activation is transmitted to resonance-activated positions in the adjoining rings. 

This compound was boiled with 12 g of dry piperidine in 120 ml of absolute benzene for 12 hours under reflux, a total of 6 g of piperidine hydrochloride being separated out. This was filtered off and the benzene solution was concentrated by evaporation. The residue was taken up in a little chloroform and the solution was applied to a dry aluminum oxide column (according to Brockmann) it was thereafter extracted with chloroform. After concentrating the solution by evaporation, an oil was obtained, which was taken up in absolute diethylether. Introduction of dry HCI gas into the cooled solution gave a precipitate which was dissolved and allowed to crystallize from isopropanol/ether. MP 193° to 199°C. 

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