- An efficient and environmental benign synthesis of 2-benzimidazoles and 2-benzothiazoles using CeCl3-NaI as catalyst
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A one-pot condensation of an aldehyde with 1,2-phenylenediamine or 2-aminothiophenol in dimethyl carbonate at 100°C under O2 in the presence of catalytic amounts of CeCl3-NaI gave an imine intermediate, which cyclised and dehydrogenated to give 2-arylbenzimidazoles or 2-arylbenzothiazoles in good yields.
- Zhu, Xun,Wei, Yunyang
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p. 119 - 121
(2013/04/23)
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- 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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- Chiral phosphoric acid catalyzed transfer hydrogenation: Facile synthetic access to highly optically active trifluoromethylated amines
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Amines to an end: Highly optically active α-CF3- functionalized amines can be obtained using metal-free reaction conditions. The method involves the transfer hydrogenation of CF3-substituted ketimines catalyzed by 1 and reductive ami
- Henseler, Alexander,Kato, Masanori,Mori, Keiji,Akiyama, Takahiko
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supporting information; experimental part
p. 8180 - 8183
(2011/10/09)
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- Two birds with one stone: Redox co-production of 2-arylbenzothiazoles and hydroquinone
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A variety of 2-arylbenzothiazoles are co-produced with hydroquinone in the absence of additional reagents and catalysts under mild conditions. When this inherently waste-free process is employed, none of the reactions require the use of additional redox reagents, and all of them are environmentally friendly with excellent atom economy (≥95%).
- Li, Guiyun,Peng, Yanqing
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experimental part
p. 45 - 48
(2010/08/05)
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- Lewis Acid-prompted Conjugate Reduction of α,β-Unsaturated Carbonyl Compounds by 2-Phenylbenzothiazoline (2-Phenyl-2,3-dihydrobenzothiazole)
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Reduction of various α,β-unsaturated ketones (3a-g) and (4a-d) in methanol by the benzothiazoline (1) in the presence of aluminium chloride gives, in all cases, the corresponding saturated ketones (5a-g) and (6a-d)without any of the unsaturated or saturated alcohol.Reduction of α,β-unsaturated esters (7a,b) similarly gives the saturated esters (9a,b), while reaction of cinnamaldehyde (8) with compound (1) does not occur at all.Among the Lewis acids examined, aluminium chloride gives the best results.Reduction of 2'-azachalcone (21) with 2-phenylbenzothiazoline reveals that, in the reduction product, the deuterium atom is located at the β-position with respect to the carbonyl group.The result obtained from the reduction of the same substrate with compound (1) in methanol shows that no incorporation of a hydrogen atom from the solvent takes place and suggests (indirectly) that the introduced hydrogen atom at the α-position of the product comes from the benzothiazoline (1).The reaction of (Z)-1,2-dibenzoyl-1,2-diphenylethylene (30) with compound (1) in the presence of aluminium chloride stereospecifically yields meso-1,2-dibenzoyl-1,2-diphenylethane (31).This shows that the transfer of two hydrogens from compound (1) to the carbon-carbon double bond of the enone proceeds via cis-addition.Experiments with ethyl phenylpropiolate (28) also support cis-reduction for the present conjugate reduction.These results are interpreted in terms of a mechanism involving synchronous transport of a pair of hydrogens from the benzothiazoline (1); i.e a cyclic addition of the two hydrogens either in exact or nearly exact concurrence.
- Chikashita, Hidenori,Miyazaki, Makoto,Itoh, Kazuyoshi
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p. 699 - 706
(2007/10/02)
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- A RING EXPANSION METHOD FOR THE PREPARATION OF 2,3-DIHYDRO-1,4-BENZOTHIAZINES FROM 2-ARYL-2,3-DIHYDROBENZOTHIAZOLES
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In the presence of KF in dimethylformamide (DMF) 2-aryl-2,3-dihydrobenzothiazoles react with α-haloketones to provide in good yield 2,3-dihydro-2,3-disubstituted-1,4-benzothiazines.
- Mashraqui, Sabir H.,Kellogg, Richard M.
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p. 1457 - 1460
(2007/10/02)
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- Control of acarids using certain benzothiazoles or benzothiazolines
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Compounds having either of the structures SPC1 Have strong acaricidal activity, in which R is a phenyl or naphthyl group, or phenyl with certain designated substitution. Thus, mites may be controlled on such crops as cotton by applying such compounds as 2-(1-naphthyl)benzothiazoline or 2-(5-t-butyl-2-hydroxyphenyl)benzothiazole.
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