- Controllable access to multi-substituted imidazoles: Via palladium(II)-catalyzed C-C coupling and C-N condensation cascade reactions
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A novel and efficient protocol for the synthesis of various 2,4-disubstituted, 1,2,4-trisubstituted and 1,2,4,5-tetra-substituted imidazoles via cascade palladium catalyzed C-C coupling followed by intramolecular C-N bond formation was developed. Readily accessible boronic acids and N-substituted-2-aminoacetonitriles were firstly reported as starting materials to construct di-, tri-, and tetra-substituted imidazoles in good to excellent yield.
- Yu, Haihua,Xiao, Li,Yang, Xicheng,Shao, Liming
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supporting information
p. 9745 - 9748
(2017/09/07)
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- Synthetic Uses of Open-Chain Analogues of Reissert Compounds
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Open-chain analogues, 2, of Reissert compounds are readily obtained by reaction of cyanohydrins with primary amines, the resulting aminonitriles, 1, then being acylated.Hydrofluoroborate salts, 3, of 2 are prepared by reaction with fluoroboric acid in glacial acetic acid.The salts, 3, undergo 1,3-dipolar addition reactions with reactive alkynes to give substituted pyrroles and with ethyl acrylate to give a different type of substituted pyrrole, the initial step in this instance being a Diels-Alder reaction.The open-chain Reissert analogues 2 also undergo base-catalyzed reactions, such as alkylation to provide compounds 22, which, in turn, undergo cleavage reactions in ethanolic alkali to give ketones 23.A conjugate addition reaction of the anion 18 to methyl acrylate to give, after some subsequent steps, a substituted pyrrole, 9, has also been demonstrated. α-Anilino ketones 27 result when the anion 18 is caused to react with aldehydes, the initial reaction mixtures being subjected to subsequent alkaline hydrolysis.Finally, N-benzyl Reissert analogues have been found to give desoxybenzoins plus benzonitriles on treatment with sodium hydride in tetrahydrofuran.
- McEwen, William E.,Grossi, Anthony V.,MacDonald, Russell J.,Stamegna, Andrew P.
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p. 1301 - 1308
(2007/10/02)
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