Piperidine-2-carboxylic acid, reaction

The nitrile may best be saponified with methyl alcoholic potash while heating to 190° to 200°C with application of pressure. After the methyl alcohol has evaporated the salt is introduced into water and by the addition of dilute mineral acid until the alkaline reaction to phenolphthalein has just disappeared, the amphoteric 1-methyl-4-phenyl-piperidine-4-carbOxylic acid is precipitated while hot in the form of a colorless, coarsely crystalline powder. When dried On the water bath the acid still contains 1 mol of crystal water which is lost only at a raised temperature. The acid melts at 299°C. Reaction with ethanol yields the ester melting at 30°C and subsequent reaction with HCI gives the hydrochloride melting at 187° to 188°C. 

It has been found that the tris(tert-butyloxycarbonyl) protected hydantoin of 4-piperidone 2, selectively hydrolyses in alkali to yield the N-tert-butyloxycarbonylated piperidine amino acid 3. The hydrolysis, which is performed in a biphasic mixture of THF and 2.0M KOH at room temperature, cleanly partitions the deprotonated 4-amino-N -(tert-butyloxycarbonyl)piperidine-4-carboxylic acid into the aqueous phase of the reaction with minimal contamination of the hydrolysis product, di-tert-butyl iminodicarboxylate, which partitions into the THF layer. Upon neutralization of the aqueous phase with aqueous hydrochloric acid, the zwitterion of the amino acid is isolated. The Bolin procedure to introduce the 9-fluorenylmethyloxycarbonyl protecting group efficiently produces 4.8 This synthesis is a significant improvement over the previously described method9 where the final protection step was complicated by contamination of the hydrolysis side-product, di-tert-butyl iminodicarboxylate, which is very difficult to separate from 4, even by chromatographic means. 

Alkylation of trifluoro- and trichloroacetamides with a-bromoacetic esters has been utilized for the synthesis of a wide range of a-aminoacetic acids [11-13] (Table 5.13). Hydrolysis of the intermediate a-trihaloacetamidoacetic esters with methanolic potassium hydroxide converts the methyl and ethyl esters directly into the amino carboxylic acids. /-Butyl a-aminoacetates are more stable, but they are hydrolysed under phase-transfer catalytic conditions (see Chapter 9.2). Reaction of the trihaloacetamides with 1,4-dibromobutane and 1,5-dibromopentane and subsequent hydrolysis provides a simple route to pyrrolidine-2-carboxylic acid (75%) and piperidine-2-carboxylic acid (58%) [11, 12],... 

The a is L-lysine, as in the case of piperidine, but the f3 is different. The /3 is a-aminoadipic acid 6-semialdehyde. The q> is L-pipecolic acid, which is synthesized in plants from piperideine-6-carboxylic acid. In the case of many other organisms, the obligatory intermedia (q>) is derived from the /3. The

ring structure. The indolizidine nucleus will be formed only in the synthesis of the x- The deep structmal change occms when

Claisen reaction with acetyl or malonyl CoA (Cra/mCoA) and the ring closme process (by amide or imine) to 1-indolizidinone, which is the x- The second obligatory intermedia ( k ) only has the indolizidine nucleus. 

The fluoro substituents proved to induce changes in the reactivities of the methyl- (X = H) and trifluoromethyl-substituted (X = F) pyrido[3, 2 4,5]furo[3,2- [l,3]oxazin-4(47r)-ones 105 with nucleophiles. When methyl-substituted compounds 105 (X = H) were reacted with piperidine in toluene, Wacetylamino carboxamides 106 were formed by nucleophilic attack at the carbonyl group of the l,3-oxazin-4-one ring (Scheme 16). However, the similar reactions of the trifluoromethyl-substituted analogs 105 (X = F) resulted in formation of amidino carboxylic acids 107 by attack at electron-poor position 2 <1995JFC(74)1>. 

The presence of the propionamide fragment in the stmcture of the anti-inflammatory agent broperamole (125-1) is reminiscent of the heterocycle-based NSAID propionic acids. The activity of this agent may trace back to the acid that would result on hydrolysis of the amide. Tetrazoles are virtually always prepared by reaction of a nitrile with hydrazoic acid or, more commonly, sodium azide in the presence of acid in a reaction very analogous to a 1,3-dipolar cycloaddition. A more recent (and safer) version of the reaction noted later (see losartan, 77-4) uses tributyltin azide. In the case at hand, reaction of the anion of mefa-bromobenzonitrile (125-1) with sodium azide and an acid affords the tetrazole (125-2). Condensation of the anion from that intermediate with ethyl acrylate leads to the product from Michael addition saponiflcation gives the corresponding carboxylic acid (125-3). This is then converted to the acid chloride reaction with piperidine affords broperamole (125-4) [136]. 

Yet another piperidine-based antipsychotic agent replaces the butyrophenone or diarylpropyl function found in earlier compounds by a benzopyrimidine group. The synthesis starts by the conversion of the carboxylic acid in piperidine (22-1) to its acid chloride. Reaction with 1,3-difluorobenzene (22-2) in the presence of aluminum chloride affords the acylated product (22-3). Reaction with hydroxylamine leads to the corresponding oxime (22-4). Treatment of that derivative with a base... 

Synthesis (Janssen, 1959 Dryden and Erickson (Searle), 1978, Kleemann et al., 1999) The reaction of 4-phenyl-piperidine-4-carboxylic acid ethyl ester with 4-bromo-2,2-diphenyl-butyronitrile yields diphenoxylate (Kleemann et al., 1999, p. 250). 

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. 

Treatment of polymer films by reactive gases or reactive volatil compounds allows to easily modify polymers containing alcohols, hydroperoxides, carboxylic acids (or acids halides), double bonds or piperidine groups. New functional groups as organic nitrites, nitrates, iodides, acid halides (Cl, F), amides, esters, peresters and nitroxyl radicals can be generated by a single reaction or by combination of two consecutive treatments. The reactions are very efficient on thin films (ca 50-100 pm) and can be controlled by transmission and reflexion 1R spectroscopy. 

Pinacolone, o-(diphenylphosphino)benzoyl-coordination chemistry, 401 Piperidine, IV-hydroxy-metal complexes, 797 pA a values azole ligands, 77 Plant roots amino acids, 962 carboxylic acids, 962 Plastocyanin copper binding site, 557 copper(II) complexes, 772 copper(II) site in, 770 Platinum, dichlorobis(benzonitrile)-IR spectrum, 264 Platinum, cis-dichlorodianunine-antitumor activity, 34, 979 Platinum, ethylenebis(triphenylphosphine)-reactions with 5,6-dimethyl-2,l,3-benzothiadiazole, 194 Platinum blue formation, 265 Platinum complexes acetylacetone reactions, 380 amides, 491 amidines... 

Formation of quinuclidine-3-carboxylic acid derivatives (68) from these reactions was conclusive proof of saponification of the ethoxy-carbonyl group at position 2 of the diester (61). A similar reaction takes place with diethyl quinuclidine-2,3-dicarboxylate.100 This is in agreement with the known principle of easier saponification of a- than j8-amino acid esters. Some 3-(j8-acyloxyethyl)-2-diethylaminomethyl-quinuclidines (69, 70)123 on distillation at atmospheric pressure cyclize with loss of ester and formation of a new tricyclic system, quinuclidino[2,3-c]piperidine (72). The same reaction takes place by heating the corresponding amino alcohol (71) with phthalic anhydride in the presence of benzenesulfonic acid.123... 

It can be assumed that the small amount of piperidine in the reaction mixture is completely protonated by malonic acid because piperidine is more basic than pyridine. Hence, only the less basic pyridine is available for the formation of the malonic acid enolate D from free malonic acid and for the formation of the malonic acid dianion from the malonic acid mono-carboxylate C. The pKa value of malonic acid with regard to its C,H acidity should be close to the pKa value of malonic acid diethyl ester (p= 13.3). The pKa value of malonic acid monocarboxylate C with regard to its C,H acidity should be larger by at least a factor 10. Hence, the concentration of the malonic acid enolate D in the reaction mixture must be by many orders of magnitude higher than that of any malonic acid dianion. Due to the advantages associated with this enormous concentration D could be the actual nucleophile in Knoevenagel condensations. 

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