- Cyanide as a powerful catalyst for facile synthesis of benzofused heteroaromatic compounds via aerobic oxidation
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Highly efficient synthesis of benzofused heteroaromatic compounds via aerobic oxidation catalyzed by cyanide anion has been developed. The Schiff bases derived from 2-aminophenol and aldehydes provided the corresponding benzoxazoles in high yields in the presence of a catalytic amount of cyanide in an open flask under ambient conditions without the use of any external metal co-oxidants and bases. Furthermore, we have developed a catalytic sequential one-step protocol for the synthesis of benzoxazoles by adding a catalytic amount of NaCN to Schiff bases generated in situ from 2-aminophenol and aldehydes without the isolation of imine intermediates. This one-pot protocol was further extended to the synthesis of benzothiazoles from 2-aminothiophenol and aldehydes. A variety of aldehydes could be applied to this sequential one-pot protocol and the desired benzofused azole products were obtained in high yields.
- Cho, Yeon-Ho,Lee, Chun-Young,Cheon, Cheol-Hong
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p. 6565 - 6573
(2013/07/26)
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- Rare-earth metal chlorides as efficient catalysts for the simple and green synthesis of 1,2-disubstituted benzimidazoles and 2-substituted benzothiazoles under ultrasound irradiation
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Under solvent-free and ultrasonic irradiation conditions, efficient methods for the synthesis of 1,2-disubstitued benzimidazoles and 2-substitued benzothiazoles by employing rare-earth metal chlorides as catalysts are described. The methods have the advan
- Zhang, Li-Jun.,Xia, Jing,Zhou, Yong-Qing,Wang, Hua,Wang, Shao-Wu.
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experimental part
p. 328 - 336
(2011/11/12)
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- Reductive tert-butylation of anils by tert-butylmercury halides
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tert-Butyl radicals add to the carbon atom of benzylideneanilines to form anilino radicals, which are protonated in the presence of PTSA or NH4+ in Me2SO. Reduction of the resulting aniline radical cations occurs readily by the ate complex, t-BuHgI2. In the absence of a proton donor, f-BuHgI will also transfer a hydrogen atom to the anilino radical to give the reductive alkylation product. Protonation can promote a free radical chain process involving electron transfer by substrate activation and/or by increasing the electron affinity of the intermediate radicals. Since the adduct radicals formed from benzylideneanilines are more easily protonated than the parent Schiff bases, PTSA but not NH4+ demonstrates substrate activation, although both proton donors promote the free radical reaction.
- Russell, Glen A.,Wang, Lijuan,Rajaratnam, Ragine
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p. 8988 - 8991
(2007/10/03)
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