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At least 793 records · Page 44Linked to original sources
PubMed2003

Complexation promoted additions to N-benzoyliminopyridinium ylides. A novel and highly regioselective approach to polysubstituted piperidines.

Unprecedented regioselectivities were observed for the addition of different organometallic nucleophiles to N-benzoyliminopyridinium ylides. Even benzylic and branched aliphatic Grignard reagents, which usually give substantial amounts of 1,4-adducts, showed excellent 1,2-regioselectivities. The electronic nature of the pyridinium ylide is taken into account to explain these results.

Crystallography, X-Ray↗
PubMed2006

sp3 C-H bond arylation directed by amidine protecting group: alpha-arylation of pyrrolidines and piperidines.

A new ruthenium-catalyzed direct sp3 C-H to C-C bond transformation is disclosed. Specifically, a method for the alpha-arylation of cyclic amines, containing either permanent (pyridine, pyrimidine) or removable (amidine) directing groups, is described. This cross-coupling reaction involves heating amine substrates with arylboronate ester at 150 degrees C in a ketone solvent with a catalytic amount of ruthenium carbonyl [Ru3(CO)12]. Arylboronate esters containing either electron-withdrawing or electron-donating substituents could be efficiently coupled. Heteroarene boronates were also effective donors.

Amidines↗
PubMed2002

A piperidine amide extracted from Piper longum L. fruit shows activity against Aedes aegypti mosquito larvae.

Mosquito larvicidal activity of Piper longum fruit-derived materials against the fourth-instar larvae of Aedes aegypti was examined. A crude methanol extract of P. longum fruits was found to be active against the larvae, and the hexane fraction of the methanol extract showed a strong larvicidal activity of 100% mortality. The biologically active component of P. longum fruits was characterized as pipernonaline by spectroscopic analyses. The LC(50) value of pipernonaline was 0.25 mg/L. The toxicity of pipernonaline is comparable to that of pirimiphos-methyl as a mosquito larvicide. In tests with available components derived from P. longum, no activity was observed with piperettine, piperine, or piperlongumine.

Aedes↗
PubMed1995

New antihistamines: substituted piperazine and piperidine derivatives as novel H1-antagonists.

Structural manipulation of polycyclic piperazinyl imide serotonergic agents led to the synthesis of compound 8, 2-[4-[4-[bis(4-fluorophenyl)methyl]-1-piperazinyl]-4, 4a,5,5a,6,6a-hexahydro-4,6-ethenocycloprop[f]isoindole-1,3(2H,3 aH)-dione, which demonstrated good H1-antagonist activity. Substitution of a xanthinyl moiety for the polycyclic imide group led to the identification of novel xanthinyl-substituted piperazinyl and piperidinyl derivatives with potent antihistamine H1-activity without the undesirable antidopaminergic activity of 8. One compound, 24, 7-[3-[4-(diphenylmethoxy)-1-piperidinyl]propyl]- 3,7-dihydro-1,3-dimethyl-1H-pyrine-2,6-dione (WY-49051), is a potent, orally active H1-antagonist with a long duration of action and a favorable central nervous system profile.

Animals↗
PubMed1990

Resolved pyrrolidine, piperidine, and perhydroazepine analogues of the muscarinic agent N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl)acetamide.

A series of conformationally restricted analogues of the partial muscarinic agonist N-methyl-N-(1-methyl-4-pyrrolidino-2-butynyl)acetamide (BM 5; 1) was synthesized. Three of the racemic derivatives were resolved into the enantiomers. The compounds were investigated for muscarinic and antimuscarinic activity in the isolated guinea pig ileum. They were found to be fairly potent muscarinic antagonists or weak partial agonists. The new compounds were either equally or less potent than 1 in inhibiting (-)-[3H]-N-methylscopolamine binding in homogenates of the rat cerebral cortex. Thus, structural modifications to 1 in which the amide moiety and the methyl group in the butynyl chain have been joined to form a six- or seven-membered ring preserve affinity but abolish efficacy. The R enantiomers were found to have 14-79 times higher affinity to ileal muscarinic receptors than the respective antipodes. The enantiomeric affinity ratios were nearly identical in both preparations studied. As suggested by molecular mechanics calculations, the difference in affinity between the five-membered and the six- and seven-membered ring analogues may be rationalized in conformational terms.

Animals↗
PubMed1980

Benzenesulfenamides as antihypertensive agents. Substituted piperidine and 1-arylpiperazine derivatives.

The synthesis and antihypertensive activity of several piperidinebenzenesulfenamides related to the previously reported potent hypotensive agents 1 and a series of 1-arypiperazine-4-benzenesulfenamides 7 are described. A number of the latter compounds exhibit marked antihypertensive properties. The most interesting of these compounds, 7a and 7k, have been evaluated in several other animal models. In addition, benzenesulfinamides 9a and 9b and benzensulfonamides 10a and 10b have been prepared for comparison purposes.

Animals↗
PubMed1976

Oxindole-3-spiropyrrolidines and -piperidines. Synthesis and local anesthetic activity.

The synthesis and local anesthetic properties of five 1-dealkyloxindole-3-spiropyrrolidines and six 1-dealkyloxindole-3-spiropiperidines are described. The compounds studied include members of all five possible positional isomers of the two classes of spirooxindoles; all showed local anesthetic activity by the rat sciatic nerve block method. The coincidence of the least variability in the relative positions of basic nitrogen, amide carbonyl, and aromatic ring (compounds 1 and 6) with lowest normalized toxicity is noteworthy.

Anesthetics, Local↗
PubMed1976

(2-Piperidine)- and (2-pyrrolidine)ethanones and -ethanols as inhibitors of blood platelet aggregation.

(E)-4-[4-(Methylthio)phenyl]-1-(2-piperidinyl)-3-buten-2-one hydrochloride (44, RMI 14 133A) was found to inhibit ADP-induced aggregation of blood platelets. It was selected from a large series of (2-piperidinyl)- and (2-pyrrolidinyl)ethanones synthesized by a modified Schopf reaction from enolate magnesium salts of beta-keto acids and 2,3,4,5-tetrahydropyridine trimer or 3,4-dihydro-2H-pyrrole trimer, respectively. Evaluation of the compounds was carried out in vitro on human blood platelets. Structure-activity relationships are discussed. 44 also inhibited platelet aggregation ex vivo in guinea pigs. Subacute toxicity evaluation in dogs and guinea pigs showed it to have an unfavorable therapeutic ratio. 1-[4'-Chloro(1,1'-biphenyl)-4-yl-a1-2-(2-piperdinyl)ethanone hydrochloride (18, RMI 12436A) was found to lower serum cholesterol levles in rats with concurrent accumulation of (3beta)-cholesta-5,7-dien-3-ol, suggesting inhibition of 7-dehydrocholesterol delta7-reductase.

Adenosine Diphosphate↗