39806-58-1Relevant articles and documents
Enantioselective Synthesis of 5,5-Disubstituted Hydantoins by Br?nsted Base/H-Bond Catalyst Assisted Michael Reactions of a Design Template
Izquierdo, Joseba,Etxabe, Julen,Du?abeitia, Eider,Landa, Aitor,Oiarbide, Mikel,Palomo, Claudio
supporting information, p. 7217 - 7227 (2018/05/04)
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.
