- Transition Metal-Free Synthesis of Substituted Isothiazoles via Three-Component Annulation of Alkynones, Xanthate and NH4I
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A protocol was described to access diverse isothiazoles with functionalization potential via transition metal-free three-component annulation of alkynones, potassium ethylxanthate (EtOCS2K) and ammonium iodide (NH4I). A sequential regioselective hydroamination/thiocarbonylation/intramolecular cyclization cascade achieved the efficient formation of consecutive C?N, C?S and N?S bonds in a one-pot process. (Figure presented.).
- Li, Jian,Li, Jiaming,Ji, Xiaoliang,Liu, Qiang,Chen, Lu,Huang, Yubing,Li, Yibiao
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p. 1059 - 1068
(2020/12/15)
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- Synthesis of Isoselenazoles and Isothiazoles from Demethoxylative Cycloaddition of Alkynyl Oxime Ethers
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A general method for the synthesis of isoselenazoles and isothiazoles has been developed by the base-promoted demethoxylative cycloaddition of alkynyl oxime ethers using the cheap and inactive Se powder and Na2S as selenium and sulfur sources. This transformation features the direct construction of N-, Se-, and S-containing heterocycles through the formation of N-Se/S and C-Se/S bonds in one-pot reactions with excellent functional group tolerance.
- Zhang, Zhu-Zhu,Chen, Rong,Zhang, Xiao-Hong,Zhang, Xing-Guo
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p. 632 - 642
(2020/12/22)
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- 3,4,5-Triarylisothiazoles via C-C coupling chemistry
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The regiocontrolled preparation of triarylisothiazoles is presented. 3-Halo-5-phenylisothiazole-4-carbonitriles, 1 (hal = Cl) and 18 (hal = I), are converted into the corresponding 4-bromo derivatives 5 (3-hal = Cl) and 24 (3-hal = I) via a Hunsdiecker strategy while the 4-iodo analogues 7 (3-hal = Cl) and 22 (3-hal = I) are prepared via a Hoffmann and Sandmeyer strategy. Regioselective Suzuki, Stille and Negishi reactions occur at C-4 with both the 4-bromo- and 4-iodoisothiazoles 5 and 7, the latter being more reactive than the former. 3-Iodoisothiazoles 22 and 24 fail to give regiocontrolled Suzuki, Stille or Negishi couplings, however, 4-bromo-3-iodo-5-phenylisothiazole 24 gives the regiospecific palladium catalysed Ullmann-type reaction product 3,3′-bi(4-bromo-5-phenylisothiazole) 25. Alkali hydrolysis of 3-chloro-4,5-diphenylisothiazole 8 gives the 3-hydroxy analogue 12 which is converted into 3-bromo-4,5-diphenylisothiazole 13 with POBr3. 3-Bromoisothiazole 13 reacts with phenylzinc chloride to give 3,4,5-triphenylisothiazole 17 but fails to undergo effective Suzuki or Stille couplings. 3,5-Diphenylisothiazole-4-carbonitrile 26 is converted into the 4-bromo- and 4-iodo-3,5-diphenylisothiazoles 30 and 34 both of which are effective for Suzuki and Stille couplings. A series of triarylisothiazoles are prepared in this manner and fully characterised. This journal is The Royal Society of Chemistry.
- Christoforou, Irene C.,Koutentis, Panayiotis A.
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p. 1381 - 1390
(2008/01/03)
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