- Organocatalytic syntheses of benzoxazoles and benzothiazoles using aryl iodide and oxone via C-H functionalization and C-O/S bond formation
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An organocatalytic protocol for the syntheses of 2-substituted benzoxazoles and benzothiazoles is described from alkyl-/arylanilides and alkyl-/arylthioanilides using 1-iodo-4-nitrobenzene as catalyst and oxone as an inexpensive and environmentally safe terminal oxidant at room temperature in air via oxidative C-H functionalization and C-O/S bond formation. The procedure is simple and general and provides an effective route for the construction of functionalized 2-alkyl-/arylbenzoxazoles and 2-alkyl-/arylbenzothiazoles with moderate to high yields. The synthetic and mechanistic aspects have been described.
- Alla, Santhosh Kumar,Sadhu, Pradeep,Punniyamurthy, Tharmalingam
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p. 7502 - 7511
(2014/09/16)
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- A metal-free and a solvent-free synthesis of thio-amides and amides: An efficient Friedel-Crafts arylation of isothiocyanates and isocyanates
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A rapid, metal-free and solvent-free (very low loading of solvent in few cases) reaction conditions for synthesizing thioamides and amides using a Bronsted super acid such as triflic acid has been developed. This method shows a broad substrate scope with
- Varun, Begur Vasanthkumar,Sood, Ankush,Prabhu, Kandikere Ramaiah
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p. 60798 - 60807
(2015/02/19)
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- An ionic liquid mediated Friedel-Crafts addition of arenes to isothiocyanates
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A new protocol is developed for the synthesis of N-substituted thioamides, employing arenes and isothiocyanates in 1-butyl-3-methylimidazolium chloroaluminate ionic liquid, [bmim]Cl·2AlCl3, as a homogenous Lewis acid catalyst and solvent. The e
- Naik, Prashant U.,Nara, Susheel J.,Harjani, Jitendra R.,Salunkhe, Manikrao M.
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p. 1057 - 1060
(2007/10/03)
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- Structural Studies on Bioactive Compounds. 23. Synthesis of Polyhydroxylated 2-Phenylbenzothiazoles and a Comparison of Their Cytotoxicities and Pharmacological Properties with Genistein and Quercetin
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A series of polyhydroxylated 2-phenylbenzothiazoles 3 has been prepared by demethylation of the precursor methoxylated 2-phenylbenzothiazoles 9.The key step in the construction of the benzothiazole nucleus involves a Jacobson cyclization of methoxylated thiobenzanilides 8.The target compounds inhibit WiDr human colon tumor cells and MCF-7 human mammary tumor cells in vitro with IC50 values in the low micromolar range, but the activity against MCF-7 cells is not related to estrogen receptor-binding affinity.None of the compounds showed selective cytotoxicity againstAbelson virus-transformed ANN-1 cells encoded with the pp120gag-abl tyrosine kinase compared with the parental 3T3 line.Compounds were only marginally inhibitory to the EGF receptor-associated protein tyrosine kinase from a membrane preparation of A431 cells.The most active compound was 4,6-dihydroxy-2-(4-hydroxyphenyl)benzothiazole (3b) which has the same overall hydroxyl substitution pattern as genistein (1a).The compounds were weakly cytotoxic for an EGF receptor, overexpressing cell line HN5, but when tested for differential toxicity against the EGF receptor tyrosine kinase or the PDGF receptor tyrosine kinase in a standard mitogenesis assay utilizing human fibroplasts, no discrimination was observed.In this assay, the compounds inhibited DNA synthesis when added to cells during S phase.This suggests that inhibition could not be interpreted in terms of tyrosine kinase inactivation but more likely as a relatively broad specificity for the ATP-binding domain of other kinases such as thymidine kinase.
- Stevens, Malcolm F. G.,McCall, Carol J.,Lelieveld, Peter,Alexander, Peter,Richter, Audrey,Davies, Donna E.
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p. 1689 - 1695
(2007/10/02)
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- ANTIMYCOBACTERIAL THIOBENZANILIDES
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A group of 30 thiobenzanilides active against Mycobacterium kansasii have been synthesized and their 1H NMR and UV spectra and RM values (TLC on silica gel impregnated with methylsilicone oil) have been measured.From the correlation between the chemical shifts of the thioamide proton in the 1H NMR spectra and the Hammett constants it can be concluded that the substituents in both aromatic rings uniformly affect the electron density of the thioamide group.The antimycobacterial activity is probably connected with local molecular parameters and can be considered to be approximately additive with respect to both parts of the molecule.
- Waisser, Karel,Houngbedji, Nestor,Machacek, Milos,Sekera, Miroslav,Urban, Josef,Odlerova, Zelmira
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p. 307 - 316
(2007/10/02)
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