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Versatile Synthons (versatile + synthon)
Selected AbstractsFused quinoline heterocycles VI: Synthesis of 5H -1-thia-3,5,6-triazaaceanthrylenes and 5H -1-thia-3,4,5,6-tetraazaaceanthrylenesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2005Ramadan Ahmed Mekheimer Ethyl 3-amino-4-chlorothieno[3,2-c]quinoline-2-carboxylate (4) is a versatile synthon, prepared by reacting an equimolar amount of 2,4-dichloroquinoline-3-carbonitrile (1) with ethyl mercaptoacetate (2). Ethyl 5-alkyl-5H -1-thia-3,5,6-triazaaceanfhrylene-2-carboxylates 9a-c, novel perianellated tetracyclic heteroaro-matics, were prepared by refluxing 4 with excess of primary amines 7a-c to yield the corresponding amino-thieno[3,2-c]quinolines 8a-c. Subsequent reaction with an excess of triethyl orthoformate (TEO) furnished 9a-c. Reaction of 4 with TEO in Ac2O at reflux, gave the simple acetylated compounds, thieno[3,2- c]-quinolines 12 and 13. Refluxing 4 with benzylamine (7d) gave 10, and subsequent treatment with TEO gave the tetracyclic compound 11. Refluxing 13 with an excess of alkylamines 7a-d gave the fhieno[3,2- c]quino-lines 15. Refluxing the aminothienoquinolines 8b with an excess of triethyl orthoacetate gave thieno[3,2- c]quinoline 17, while heating with Ac2O gave 18 and 19, with small amounts of 16. Reaction of 8a,b with ethyl chloroformate and phenylisothiocyanate generated the new 1-thia-3,5,6-triazaaceanthrylenes 20a,b and 21a,b, respectively. Diazotization of 8a-c afforded the novel tetracyclic ethyl 5-alkyl-5H -1-fhia-3,4,5,6-tetraazaaceanthrylene-2-carboxylates 22a-c in good yields. [source] Stereoselective Conversion of Aucubin into Polyfunctionalized Tetrahydro-1H -cyclopenta[c]furan GlucosidesHELVETICA CHIMICA ACTA, Issue 1 2003Christine Mouriès Mitsunobu reaction of 2,,3,,4,,6,,10-penta- O -pivaloylaucubin (6) with phthalimide, triphenylphosphine, and diethyl azodicarboxylate gave (6R)-6-phthalimido-perpivaloylbartsioside (10) (Scheme,1). Selective oxidation reactions performed with perpivaloylaucubin (12) yielded (1R)- and (1S)-3(, - D -glucopyranosyloxy)-1H -cyclopenta[c]furan-1-carboxaldehydes 13 and 14 respectively (Scheme,2). Similarly, perpivaloyl-6-epiaucubin (9) and 10 afforded the corresponding (1S)-carboxaldehyde 15 and (1R)-carboxaldehyde 16, respectively. The protected cyclopentafuran glycosides obtained in this way are versatile synthons, which may prove useful for further chemical diversification. [source] Chemistry of phosphorus ylides 21 new route for the synthesis of azetidinones.HETEROATOM CHEMISTRY, Issue 6 2005Reaction of phosphonium ylides with benzil-, o -naphthoquinone-, triketonemonoanils Active vinylidenetriphenylphosphoranes are nucleophilic reagents which can be con- sidered as versatile synthons for the synthesis of new heterocycles. The active phosphacumulene ylides, namely N -phenylimino- 2a, 2-oxo- 2b or 2-thioxo-vinylidenetriphenylphosphoranes (2c), react with benzil- (1a,b), o -naphthoquinone- (8), or triketone-monoanils (11), to give the corresponding phenylimino- (3a, d, 9a, 12a), oxo- (3b, e, 9b, 12b), or thioxoazetidinones (3c, f, 9c, 12c), respectively, which constitute an important class of organic compounds with medicinal and biological importance. On the other hand, quinone monoanils 1a, 8, 11 can be converted by reaction with the stabilized alkylidenephosphoranes (5a,d), namely acetylmethylene- 5a, methoxycarbonylmethylene- 5b, ethoxycarbonylmethylene- 5c, and benzoylmethylene-triphenylphosphorane 5d, into the phosphoranylidenes (7a,d, 10a,d, 13a,d). No reaction was observed between iminophosphorane (14) and the monoanil (11). The structures of the new products were assigned according to consistent analytical and spectroscopic data. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:476,483, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20144 [source] Studies on Synthesis and Pharmacological Activities of 1,2,4-Triazolo[3,4- b]1,3,4-thiadiazoles and their Dihydro AnaloguesARCHIV DER PHARMAZIE, Issue 4 2009Vinod Mathew Abstract 4-Amino-5-substituted aryl-3-mercapto-1,2,4-triazoles are versatile synthons for constructing various biologically active heterocycles. Starting from 4-amino-5-substituted aryl-3-mercapto-1,2,4-triazole 3a,c, a series of new 3,5-disubstituted-1,2,4-triazolo-[3,4- b]1,3,4-thiadiazoles and their 5,6-dihydrotriazolothiadiazoles were prepared. The structures of all the newly synthesized compounds have been confirmed by elemental analysis, IR, 1H-NMR, 13C-NMR, and mass spectra. The antimicrobial effects of the synthesized compounds were investigated using the paper disc method. Anti-inflammatory and analgesic activities of the synthesized compounds were assessed by carrageenan-induced rat paw oedema method and by Eddy's hot plate method, respectively. Some of the compounds exhibited promising antimicrobial activities as well as moderate to good anti-inflammatory activity and analgesic activity. [source] | ||||||||||