Showing papers on "Piperidine published in 1984"

A New Base-Labile Anchoring Group for Polymer-Supported Peptide Synthesis

Abstract: A new base-labile anchoring group, derived from 9-(hydroxymethyl)fluorene-4-carboxylic acid (HO2CFmoH or HOFmCO2H; 7), for polymer-supported peptide synthesis os described. The synthesis of 7 starting from 2,2′-biphenyldicarboxylic acid (1) proceeds in an overall yield of 53%. The group HO2CFmo exhibits properties similar to the well known Fmoc protecting group: It is stable to acidic conditions and cleavable by 15% piperidine in DMF. In combination with acid labile Nα-protecting groups (e.g. Boc, Ddz, Bpoc, Nps etc.), it renders more flexibility to the stepwise synthesis using polymer supports. The versatility of the new anchoring group in solid- and liquid-phase peptide synthesis is demonstrated for the synthesis of a model peptide.

Formation of a reactive iminium derivative by enzymatic and chemical oxidations of 16-O-acetylvindoline.

Abstract: 16-O- Acetylvindoline (1a) was oxidatively transformed into an iminium derivative (2a) by copper oxidases (laccase and human ceruloplasmin), an unknown enzyme system(s) of Streptomyces griseus, and the chemical oxidizing agent 2,3-dichloro-5,6- dicyano -1,4-benzoquinone ( DDQ ). The iminium derivative (2a) was isolated from enzymatic and chemical oxidation mixtures and was identified by spectral and chemical techniques. Reduction of the iminium compound with sodium borodeuteride provided monodeuterated 16-O- acetylvindoline (1b) as the sole product. Mass spectral analysis indicated that the deuterium atom was introduced into position C-3 of the piperidine portion of the alkaloid structure. The location and stereochemistry of the deuterium atom were confirmed by high-field 1H and 2H NMR analyses of the deuterated product to be in the 2H alpha orientation. Hydrolysis of the 16-O-acetyl functional group from the iminium derivative (2a) resulted in the production of a previously identified dimer (5), which forms by intramolecular etherification through the reactive enamine (3). The iminium derivative (2a) reacts with cyanide to provide complex mixtures of products, one of which was identified by mass spectrometry as a cyanide addition product. The results confirm the existence of a reactive iminium intermediate formed by all of the biochemical and chemical systems examined.

Reactions of rhodium trifluoroacetate with various Lewis bases. Formation of 4:1 complexes with pyridine and tert-butyl isocyanide and bond cleavage with phosphorus donors

Abstract: Reactions du trifluoracetate de Rh avec THF, DMSO, DMF, piperidine, pyridine, acetonitrile, PPh 3 . Formation de composes d'addition. Donnees IR et RMN

Use of piperidine-1-sulphenyl chloride as a sulphur-transfer reagent in reactions with diamines: the preparation of sulphur–nitrogen heterocycles

Abstract: The use of piperidine-1-sulphenyl chloride (3) as a sulphur-transfer reagent in reactions with diamines is described. The reaction of (3) with o-phenylenediamine yielded the dihydro-2,1,3-benzothiadiazole (6) and benzothiadiazole (7). Oxidation of (6) with m-chloroperoxybenzoic acid yielded (7). The reactions of (3) with 1,8-diaminonaphthalene and 1,4,5,8-tetra-aminonaphthalene yielded the 1,2,6-thiadiazine derivatives (14) and (16); possible mechanisms are discussed. 1,2-Diamino-N,N′-dimethylethane and (3) yielded the tetrahydrothiadiazole (17), whereas 1,3-diaminopropane and (3) afforded the novel N–S–N chain compound (19). The reactions of morpholine-1-sulphenyl chloride (4) with aromatic diamines gave the same products in low yields.

The stabilities of Meisenheimer complexes. Part 34. Kinetic studies of σ-adduct formation and nucleophilic substitution in the reactions of 2,4,6-trinitrophenetole with aliphatic amines in dimethyl sulphoxide

Abstract: The reaction of 2,4,6-trinitrophenetole with aliphatic amines in dimethyl sulphoxide results in the formation of anionic σ-adducts via zwitterionic intermediates. Rapid attack at the 3-position is followed by attack at the ethoxy-substituted 1-position. The 1-adducts formed by reaction with n-butylamine and benzylamine undergo acid-catalysed expulsion of ethoxide to yield N-substituted picramides; that formed by reaction with piperidine is relatively stable. Rate and equilibrium data for these reactions have been determined and compared with data for reactions of related compounds. Increased steric crowding at the reaction centre caused by a change from primary amines to piperidine results in reductions in the rate of proton transfer from zwitterionic intermediates to amine catalyst and in the rate of leaving-group expulsion.

Polymeric compounds containing piperidine and triazine radicals, process for their preparation, and their use as stabilisers for synthetic polymers

Abstract: Polycondensation compounds containing piperidine and triazine groups, having a mean molecular weight from 1000 to 20,000 and constituted by structural units a and b of the formula ##STR1## are suitable as anti-actinic stabilizers for incorporation in polymeric materials.

Optical rotatory dispersion and absolute configuration. Part 35. Chiroptical properties and conformation of indolizidine

Abstract: 1 H N.m.r. spectroscopy at 360 MHz confirms that indolizidine is trans-fused with the piperidine ring in a chair conformation. The pyrrolidine ring adopts an envelope conformation with the nitrogen atom displaced out of the plane of the four carbon atoms of the ring. An improved synthesis of (+)- and (–)-indolizidine from (–)-and (+)-coniine is described. The o.r.d. and c.d. spectra of indolizidine are compared with those of coniine.

Solvent effects on aromatic nucleophilic substitutions. Part 3. The kinetics of the reaction of 2,4-dinitrochlorobenzene with piperidine in aprotic solvents

Abstract: The kinetics of the reaction between 2,4-dinitrochlorobenzene and piperidine were studied in nitromethane, NN-dimethylformamide, ethyl acetate, dioxane, and 1,1,1-trichloroethane at 15,25, and 40 °C. This reaction was chosen as the simplest example of aromatic nucleophilic substitution. Different correlations of the second-order rate coefficients kA with several solvent parameters were examined for this and earlier work combining 13 aprotic solvents in all with a range of 43 units in the dielectric constants (Iµ) in the series. It was found that the ET(30) parameter is the most useful available measure of the solvent influence in the present reaction if hydrogen-bond donor (HBD) solvents are excluded; the deviation from linearity of these solvents is explained as arising from the highly exposed strong negative charge on Dimroth's betaine which gives a high ET value to HBD solvents. Conversely, the correlation is remarkably successful for the hydrogen-bond acceptor (HBA) solvents since the positive charge in the present reaction is buried similarly to that in the model solute, and the amine hydrogen of the zwitterionic intermediate, ZH, is strongly involved in an intramolecular hydrogen bond. Aliphatic, aromatic, and polychlorinated aliphatic solvents are all well correlated.

Acetoxylation of piperidine derivatives at the 3-position. stereoselective synthesis of pseudoconhydrine and n-methylpseudoconhydrine

Abstract: Anodic oxidation of N-methoxycarbonylpiperidine derivatives in AcOH gave 2,3-diacetoxylated products, which were shown to be useful intermediates for the stereoselective synthesis of 3-hydroxypiperidine derivatives including pseudoconhydrine and N-methylpseudoconhydrine, the Conium alkaloids.

Synthesis of 2,5-bis(piperidinomethyl)piperidine and 1,5-bis(aminomethyl)-3-azabicyclo[3.2.1]octanones

Abstract: Schmidt reaction of mono- and bis-Mannich bases1 and2 c derived from cyclopentanone gave the corresponding basically substituted 2-piperidones3 and4, respectively. Reduction of the latter afforded5. DoubleMannich reaction of2 a–c with primary amines gave 3-azabicyclo[3.2.1]octanone derivatives6 a–e and7. The transamination of2 a was investigated.

Methyl vs. methylene condensation of aromatic aldehydes with 1,1,1-trifluoroacetylacetone

Abstract: From the slow Knoevenagel condensations of 1,1,1-trifluoroacetylacetone (4) with aromatic aldehydes in benzene in the presence of piperidine–AcOH, low yields of three products were isolated: the enol form of the methyl-condensation product ArCHCHCOCHC(OH)CF3(5), the methylene-condensation product ArCHC(COCH3)COCF3(6), and the cleavage product ArCHCHCOCF3(7). The effects of the bulk and the electron donating or withdrawing characteristics of the aldehyde component on the condensation at the CH3vs. the CH2 group were investigated. Compound (5) is the major isolated product in the reaction of 2,4,6-trimethylbenzaldehyde. The low reactivity and the dependence of the Me vs. CH2, selectivity of the diketone (4) on the structure of the aldehyde are ascribed to an initial formation of the enol form of the hydroxy amine CF3C(OH)(NC5H10)CHC(OH)Me (12) formed by the addition of piperidine to (4); (12) is the main product after short reaction times. The acidity of the CH2 group of compound (12) is lower than that of trifluoroacetylacetone (4) and the approach of the aldehyde to the derived anion is more hindered than to the anion derived from Me ionization. The spectral properties of the products are discussed.

Selective synthesis of α-sulphenyl-, α-sulphinyl-, and α-sulphonyl-α,β-unsaturated carbonyl compounds by the knoevenagel reaction

Abstract: Simple treatment of aldehydes with the carbonyl compounds (1)[R2COCH2S(O)nAr; n= 0,1,2] and piperidine stereoselectively produces the condensation products (7), the stereochemistry of which is controlled by the steric requirements of two functional groups COR2 and S(O)nAr in a sulphur-stabilized carbanion intermediate.

A study on the doubleMannich reaction with 1,3-diphenylacetone

Abstract: DoubleMannich reaction of the title compound1 with morpholine acetate in ethanol gave the symmetrical bis-base2, whereas such reaction in acetic acid afforded the vinyl-ketonic base3. Reactions of3 with morpholine, piperidine, thiophenol and dimethyl phosphite were investigated.Mannich reaction of2 with primary amines gave di-basically substituted γ-piperidones6a-b. Compound1 reacts with ethylenediamine and formaldehyde to give the diazatricyclic system7.

Amide derivative and 5-lipoxigenase inhibitor containing said derivative as active component

Abstract: NEW MATERIAL:The compound of formula I (when R 1 is H, R 2 is piperidyl, morpholyl, 4-oxopiperidyl, etc.; when R 1 is methyl, R 2 is morpholyl, 2-hydroxycarbonylanilino, 4-oxopiperidyl, etc.). EXAMPLE: N-Caffeoyl piperidine. USE: Useful as an inhibitor for 5-lipoxigenase activity, i.e. an antiallerigic agent (e.g. remedy for allergic asthma, allertic rhinitis, etc.). It suppresses the production of leucotrienes which are critical factors of allergy. PREPARATION: The compound of formula I can be prepared by reacting the compound of formula II (R 1 is methoxyethoxymethyl or methyl) with an amine such as piperidine, and eliminating the methoxyethoxymethyl group with hydrous acetic acid, trifluoroacetic acid, etc. COPYRIGHT: (C)1985,JPO&Japio

Reaction of 2-cyano-3-(4,5-dibromo-2-furyl)-2-propenenitrile and methyl 2-cyano-3-(4,5-dibromo-2-furyl)-2-propenoate with nucleophiles

Abstract: Reactions avec des nucleophiles RXNa (X=S et R=phenyl, benzimidazolyl-2, benzothiazolyl-2 ou pyrimidinyl-2 ou X=SO 2 et R=phenyl)

Novel piperidine compounds

Abstract: Piperidine compounds of the formula in which R denotes C1-14-alkyl, C1-4-alkoxy-C2-8-alkyl, phenyl-C1-4-alkyl, in which the phenyl ring can carry up to three substituents from the group consisting of hydroxyl and C1-8-alkyl, or denotes phenyl optionally carrying one or two hydroxyl or C1-8-alkyl groups, cyclohexyl, C1-8-alkylcyclohexyl, hydroxy-C5-7-cycloalkyl or furylmethyl and each R1 and R1' independently of one another denotes hydrogen or C1-4-alkyl or both R1 and/R1' together denote a group of the formula -(CH2)3- and substituents known per se are bonded to both valencies drawn in the 4-position of the piperidine ring, their preparation and use as lightscreens.