- Metal-Free Stereoselective Synthesis of (E)- And (Z)-N-Monosubstituted β-Aminoacrylates via Condensation Reactions of Carbamates
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N-monosubstituted β-aminoacrylates are building blocks, which have been used in the preparation of amino acids and pharmaceuticals. Two efficient, stereoselective methods of preparation, via acid- or base-promoted condensation reactions of carbamates, are described. The base-promoted reaction is E-selective, while acid catalysis can, through the choice of solvent, selectively form E or Z. The acid-catalyzed E-selective process proceeds through a crystallization obviating the need for chromatographic purification.
- Dion, Amélie,Pollack, Scott R.
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p. 11748 - 11762
(2021/09/07)
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- TiCl4/Et3N-Mediated Condensation of Acetate and Formate Esters: Direct Access to β-Alkoxy- and β-Aryloxyacrylates
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A methodology to build (E)-β-alkoxy- and (E)-β-aryloxyacrylate moieties from acetate and formate esters promoted by the TiCl4/Et3N system is presented. The reaction is compatible with a broad range of structural skeletons and elapses through an unusual condensation pathway. Taking into account the obtained results, we propose a plausible mechanism involving a bimetallic titanium intermediate for this type of transformation.
- álvarez-Calero, José María,Jorge, Zacarías D.,Massanet, Guillermo M.
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p. 6344 - 6347
(2016/12/23)
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- Platinum- and gold-catalyzed hydroalkoxylation and tetramerization of propiolate esters
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PtCl2 was found to efficiently catalyze intermolecular additions of propiolate esters with alcohols. The reaction of propiolate esters and alcohols in the presence of PtCl2 gave (E)-vinyl ethers as the major products at 60 °C, whereas alkyl 3,3-dialkoxypropanoates were predominantly obtained when the reaction temperature was set to 80°C. On the other hand, a novel regioselective tetramerization of propiolate esters catalyzed by AuCl3 under mild conditions afforded 1,2,5,6-tetrasubstituted- cyclooctatetraene (1,2,5,6-COT) in moderate yields.
- Chen, Qian,Zhang, Changyuan,Wen, Chunxiao,Fang, Jin,Du, Zhiyun,Wu, Dongling
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p. 101 - 105
(2014/08/18)
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