Enantioselective α-amination of 1,3-dicarbonyl compounds in batch and flow with immobilized thiourea organocatalysts

Enantioselective α-amination of 1,3-dicarbonyl compounds in batch and flow with immobilized thiourea organocatalysts

*Corresponding authors
aInstitute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans 16, 43007 Tarragona, Spain
bDepartament de Química Orgànica, Universitat de Barcelona, 08080 Barcelona, Spain
Green Chem., 2015, Advance Article

A PS-immobilized thiourea catalyses the enantioselective [small alpha]-amination of dicarbonyl compounds at room temperature. It is not deactivated by azodicarboxylate reagents, allowing multiple recycling in batch as well as use in flow (21 min residence time).
DOI: 10.1039/C5GC00496A

A polymer-supported bifunctional thiourea organocatalyst (PS-TU) has been prepared and successfully used in the enantioselective α-amination of 1,3-dicarbonyl compounds with azodicarboxylates. In contrast to homogeneous thioureas, PS-TU is not irreversibly deactivated by the azodicarboxylate reagents, and simple washing with triethylamine between runs has allowed the reuse (9 cycles) of the PS-TU catalyst. The α-amination mediated by PS-TU has also been adapted to perform the enantioselective amination (93% ee) of ethyl 2-oxocyclopentanecarboxylate in continuous flow (7.5 h operation, 21 min residence time, TON = 37).

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