- Structure and thermal reactivity of some 2-substituted 1,3-oxathiolane S-oxides
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Isomerization of 2-benzylidene-1,3-dioxolane to 3-phenylbutyrolactone occurs readily under flash vacuum pyrolysis (FVP) conditions. 2-Diphenylmethyl-1,3-oxathiolane and 2-benzyl-1,3-oxathiolane have been prepared and the latter compound has been oxidized to the corresponding sulfoxide, whose structure and conformation are examined by 1H NMR, and to the sulfone whose X-ray structure is determined. 2-Benzylidene-1,3-oxathiolane is also prepared and the behavior of the three S-oxidized oxathiolane derivatives upon FVP is examined. While extrusion of SOn to give ethene and a carbonyl compound predominates in all three cases, the sulfoxide gives also bis(2-hydroxyethyl) disulfide, most likely formed via thiirane S-oxide and 1,2-oxathietane.
- Aitken, R. Alan,Henderson, Sarah,Slawin, Alexandra M. Z.
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p. 422 - 434
(2018/03/26)
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- Non-imidazole histamine H3 ligands. Part VI. Synthesis and preliminary pharmacological investigation of thiazole-type histamine H3-receptor antagonists with lacking a nitrogen nucleus in the side chain
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Background: Antagonists to the H3 receptor are considered to be potential drugs for the treatment of Alzheimer's disease, attention deficit-hyperactive disorder, memory and learning deficits, and epilepsy. The initial development of potent H3 receptor antagonists focused on extensive modification of the natural ligand histamine. However, it has appeared that imidazole-containing ligands are associated with inhibition of cytochrome P450 enzymes, caused by imidazole nitrogen complexation to heme iron in the active site of the enzyme. For these reasons, the development of potent non-imidazole H3 receptor antagonists was eagerly awaited. Objective: Previously, we reported the synthesis and pharmacological in vitro characterization of series of potent histamine H3-receptor non-imidazole antagonists belonging to the class of substituted 2-thiazol-4-n-propylpiperazines. A lead compound 1 of this family was a derivative carrying the ethylaminomethylpropyl chain. Methods: With the aim of increasing lipophilicity, that will help the ligands to cross the blood-brain barrier, we synthesized a series of new 2-thiazol-4-n-propylpiperazines where the ethylaminomethylpropyl moiety was replaced by a p-substituted-, an unsubstituted benzene ring, and ω-phenylalkyl substituent at positions 4 and 5 of thiazole ring, respectively. All compounds were tested for H3 antagonistic effects in vitro using the electrically contracting guinea pig jejunum. Results: The most active compounds of presented series 3d, 3e, and 3j showed lower affinity than the lead compound 1 and additionally, derivatives 3d and 3j possessed weak, competitive H1-antagonistic activity. This is in contrast to the lead compound 1 that has no affinity at H1 receptor. Conclusion: We can conclude that a side chain in the 2-thiazol-4-n-propylpiperazine scaffold should contain a basic center and should be present at a favorable position 5 of thiazole ring.
- Guryn, Roman,Staszewski, Marek,Kopczacki, Piotr,Walczyński, Krzysztof
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- ANTAGONISTS OF THE VANILLOID RECEPTOR SUBTYPE 1 (VR1) AND USES THEREOF
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The present invention is directed to compounds of formula (I) (I) wherein variables W, X, Y, D, A, n, R1, R2 and R9 are as defined in the description.
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Page/Page column 50
(2008/06/13)
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- Practical regioselective method for (E)-enol ehter
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A new practical and highly regioselective synthetic method for (E)-enol ether is reported. (E)-enol ethers (E:Z = 93:7-99:1) were prepared from the corresponding enol acetates (E:Z?3:1) in two steps by bromination and anti- elimination of α-bromodialkylac
- Park, Hyeung-Geun,Kim, Dong-Hwa,You, Misuk,Park, Mi-Kyoung,Jew, Sang-Sup
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p. 4579 - 4582
(2007/10/03)
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- BROMINATION OF DIMETHYLACETALS WITH Br2-CHLOROTRIMETHYLSILANE-NaBr
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α-Bromodimethylacetals are obtained in excellent yields by treating dimethylacetals with Br2-NaBr-chlorotrimethylsilane in CH3OH/CH3CN (2:1). The method is suitable for large scale preparation.
- Bellesia, Franco,Boni, Monica,Ghelfi, Franco,Pagnoni, Ugo Maria
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p. 629 - 632
(2007/10/02)
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- Ketene Chemistry 2. A General Procedure for the Synthesis of 2-Alkoxycyclopropanecarboxylic Esters and Acids Starting from Aldehydes and Ketene
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Alkyl 3-alkoxy-4-bromocarboxylates are prepared by the Lewis acid-catalyzed reaction of α-bromoaldehyde acetals with ketene.Base-catalyzed cyclization of these intermediates affords 2-alkoxycyclopropanecarboxylic esters.
- Rasmussen, Preben Boedstrup,Boewadt, Soeren
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p. 114 - 117
(2007/10/02)
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- SELENIUM CATALYZED CONVERSION OF VINYL HALIDES INTO α-ALKOXY ACETALS
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The reaction of vinyl halides with phenylselenenyl chloride in alcohols affords α-alkoxy acetals and diphenyl diselenide which can be oxidized to PhSe cations by nitrate or persulfate anions.The reaction can be carried out with catalytic amounts of PhSeCl or PhSeSePh.The reaction proceeds through the formation of the methoxyselenenylation product which then suffers solvolysis.Under controlled conditions, the 1-phenyl-1-methoxy-2-bromo-2-phenylselenenyl ethane was isolated from the reaction of β-bromostyrene and PhSeCl in methanol.Several deselenenylation reactions of this α-halogenoselenide are reported.
- Tiecco, Marcello,Testaferri, Lorenzo,Tingoli, Marco,Chianelli, Donatella,Bartoli, Donatella
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p. 2273 - 2282
(2007/10/02)
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