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PubMed2003

Facile transformation of 2-azetidinones to 2-piperidones: application to the synthesis of the indolizidine skeleton and (8S,8aS)-perhydro-8-indolizinol.

The highly functionalized bicyclic lactam 7 was prepared from diolefinic-2-piperidone 18 by the use of ruthenium-catalyzed RCM, and in turn, 18 was derived via a two-carbon addition process from readily accessible 4-olefinic-2-azetidinone 13. Bicyclic lactams 7 and 20 could serve as potentially valuable intermediates for the chiral synthesis of various hydroxylated indolizidine alkaloids as exemplified by the synthesis of (8S,8aS)-perhydro-8-indolizinol 19.

Journal Article↗
PubMed1999

Synthesis of Aryl-Substituted Piperidines by Superacid Activation of Piperidones.

Diarylpiperidines (8-12) may be prepared in good to excellent yields (80-99%) by the reaction of piperidones (3d-h) with benzene and the Bronsted superacid, trifluoromethanesulfonic acid (CF(3)SO(3)H, TfOH). Tropinone (6) and quinuclidone (7) also react in good yields with benzene in TfOH to give the condensation products (13 and 14). Ketal and acetal derivatives also give condensation products (8 and 24) upon reaction with C(6)H(6) in TfOH. The conversion of 3g to 11 is sensitive to both acid quantity and acid strength; a mechanism is proposed for the conversion that invokes dicationic intermediates.

Journal Article↗
PubMed2000

Lewis acid-directed cyclocondensation of piperidone enol ethers with 2-methoxy-4-(N-phenylsulfonyl)-1,4-benzoquinoneimine: a new regioselective synthesis of oxygenated carbolines

Lewis acid-directed cyclocondensations of piperidone enol ethers with 2-methoxy-4-(N-phenylsulfonyl)-1,4-benzoquinoneimine are reported. Benzofurans are obtained with BF3.OEt2 as a promoter, whereas use of excess amounts of TiCl4:Ti(OiPr)4 leads to tetrahydrocarbolines. The latter reactions provide expedient routes to oxygen-substituted tetrahydrocarbolines and carbolines. As applications of this new methodology, the preparations of 1-[3-(dimethylamino)propyl]amino-7-methoxy- and 1-[3-(dimethylamino)propyl]amino-7,8-dimethoxy-5H-pyrido[4,3-b]indoles are described.

Journal Article↗
PubMed2005

Enantioselective synthesis of 2-aryl-4-piperidones via rhodium/phosphoramidite-catalyzed conjugate addition of arylboroxines.

[reaction: see text] The highly enantioselective synthesis of 2-aryl-4-piperidones by rhodium/phosphoramidite-catalyzed conjugate addition of arylboroxines to 2,3-dihydro-4-pyridones is described. Both enantiomers of a variety of products with sterically and electronically different R substituents were obtained in high isolated yield and with excellent enantioselectivity up to 99%.

Journal Article↗
PubMed1984

The effect of 3-methyl substitution on the carcinogenicity of nitroso-4-piperidone.

The carcinogenic activity of the 3-methyl derivative of nitroso-4-piperidone was compared with that of the compound without the methyl group, by chronic administration to rats at equimolar doses in drinking water. Nitrosopiperidone induced both liver and esophageal tumors, whereas the 3-methyl derivative induced only tumors of the esophagus in a much shorter time.

Animals↗
PubMed2004

3,5-Bis(4-methoxybenzylidene)-1-methyl-4-piperidone and 3,5-bis(4-methoxybenzylidene)-1-methyl-4-oxopiperidinium chloride: potential biophotonic materials.

In the title compound 3,5-bis(4-methoxybenzylidene)-1-methyl-4-piperidone, C(22)H(23)NO(3), (I), the central heterocyclic ring adopts a flattened boat conformation, while in the related salt 3,5-bis(4-methoxybenzylidene)-1-methyl-4-oxopiperidinium chloride, C(22)H(24)NO(3)(+).Cl(-), (II), the ring exhibits a 'sofa' conformation in which the N atom deviates from the planar fragment. The pendant benzene rings are twisted from the heterocyclic ring planes in both molecules in the same direction, the range of dihedral angles between the ring planes being 24.5 (2)-32.7 (2) degrees . The dominant packing motif in (I) involves centrosymmetric dimers bound by weak intermolecular C-H...O hydrogen bonds. In (II), cations and anions are linked by strong N-H...Cl hydrogen bonds, while weak C-H...O and C-H...Cl hydrogen bonds link the cations and anions into a three-dimensional framework.

Journal Article↗
PubMed2006

Piperidones with activity against Plasmodium falciparum.

The increasing resistance of the malaria parasites has enforced new strategies of finding new drug targets. We have isolated two genes involved in spermidine metabolism, encoding deoxyhypusine synthase (DHS) and eukaryotic initiation factor 5A (eIF-5A) in the malaria parasites. eIF-5A is activated by the formation of the unusual amino acid hypusine. This process occurs in two steps. DHS transfers an aminobutyl moiety from the triamine spermidine to a specific lysine residue in the eIF-5A precursor protein to form deoxyhypusine. In a second step, deoxyhypusine hydroxylase (DHH), completes hypusine biosynthesis. We used DHH inhibitors, being effective in mammalian cells, to study an antiplasmodicidal effect in Plasmodium falciparum. Experiments with the antifungal drug ciclopiroxolamine, an alpha-hydroxypyridone, and the plant amino acid L: -mimosine, a 4-pyridone, resulted in an antiplasmodial effect in vitro. Using mimosine as a lead structure, alkyl 4-oxo-piperidine 3-carboxylates were found to have the most efficient antiplasmodial effects in vitro and in vivo.

Animals↗
PubMed1989

Structure of (3S)-3-tert-butyloxycarbonylamino-2-piperidone.

C10H18N2O3, Mr = 214.27, monoclinic, P2(1), a = 15.515 (2), b = 6.730 (1), c = 12.541 (2) A, beta = 113.6 (2) degrees, V = 1200.0 A3, Z = 4, Dx = 1.186 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.54 cm-1, F(000) = 464, T = 295 K. The final R value for 1611 observed (3139 unique) reflections is 0.055. In both the independent molecules A and B of the asymmetric unit of the title compound, the conformation of the urethane moiety is trans. The lactam group of molecule A is non-planar, the C(9)-N(2)-C(10)-C(6) torsion angle being 12.4 (14) degrees. One main difference between molecules A and B is in the value of the phi[C(5)-N(1)-C(6)-C(10)] torsion angle [52.3 (11) degrees for molecule A while -86.5 (10) degrees for molecule B] as a consequence of a rotation of the ring relative to the tert-butyloxycarbonylamino substituent. A second major difference is the delta-lactam ring conformation which is approximate half-chair for molecule A while boat for molecule B.

Chemical Phenomena↗