- Synthesis, Spectroscopic Characterization, and Crystal Structure Analysis of rac-2-thiohydantoin-methionine
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In this work, we present the synthesis, FT-IR and NMR spectroscopic characterization, and X-ray single-crystal structural study of the heterocyclic compound rac-2-thiohydantoin-methionine, C6H10N2OS2, also known as rac-5-(2-methylthio-ethyl)-2-tioxo-imidazolidin-4-one. This material crystallize in the triclinic system, space group P-1 (N°2), Z = 4, with two independent molecules in the asymmetric unit. In the supramolecular structure, the molecules are linked by N-H...O and N-H...S hydrogen bonds forming infinite bi-dimensional chains along the [100] direction, with graph-set motif R22(8) and C22(9).
- Delgado, Gerzon E.,Hernndez, Manuel O.,Mora, Asilo J.,Bahsas, Ali,Lobaton, Robert,Gonzlez, Teresa
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- Enantioselective Synthesis of 5,5-Disubstituted Hydantoins by Br?nsted Base/H-Bond Catalyst Assisted Michael Reactions of a Design Template
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A new method for the enantioselective synthesis of 5,5-disubstituted (quaternary) hydantoins was developed on the basis of an organocatalytic Michael reaction approach involving the use of 2-benzylthio-3,5-dihydroimidazol-4-ones as key hydantoin surrogates. The method is general with respect to the substitution pattern at the hydantoin N1 (alkyl, aryl, acyl), N3 (aryl), and C5 (linear/branched alkyl, aryl) positions and affords essentially single diastereomeric products with enantioselectivities higher than 95 % ee in most cases. Among the bifunctional Br?nsted base/H-bond catalysts examined, a known squaramide–tertiary amine catalyst and a newly prepared squaramide–tertiary amine catalyst provide the highest selectivity so far with either nitroolefins or vinyl ketones as the acceptor components. Kinetic measurements support a first-order rate dependence on both reaction partners, the donor template and the Michael acceptor, whereas competitive 1H NMR spectroscopy experiments reveal the high ability of the template for catalyst binding.
- Izquierdo, Joseba,Etxabe, Julen,Du?abeitia, Eider,Landa, Aitor,Oiarbide, Mikel,Palomo, Claudio
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p. 7217 - 7227
(2018/05/04)
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