2-Aminobenzimidazole Organocatalyzed Asymmetric Amination of Cyclic 1,3-Dicarbonyl Compounds

Abstract

The use of a trans-cyclohexanediamine benzimidazole derivative as a hydrogen-bond catalyst for the electrophilic amination of cyclic 1,3-dicarbonyl compounds is herein presented. High yields and enantioselectivities varying from moderate to excellent are generally obtained using mild reaction conditions and as low as 1 mol% of catalyst loading.

Chiral 2-Aminobenzimidazoles in Deep Eutectic Mixtures: Recyclable Organocatalysts for the Enantioselective Michael Addition of 1,3-Dicarbonyl Compounds to β-Nitroalkenes

“…Recently, our research group has demonstrated the usefulness of chiral 2-aminobenzimidazole derivatives 1 and 2 as organocatalysts in the asymmetric Michael addition of malonates, βketoesters, and 1,3-diketones to nitroolefins 24 and maleimides [25][26][27] as well as for the asymmetric α-chlorination 28, 29 and α-amination 30 of these interesting nucleophiles (Scheme 1). Usually, due to the bifunctional Brønsted-base/hydrogen-bonding activation nature of catalysts 1 and 2, very high enantioselectivities have been observed in the studied reactions using volatile organic solvents (VOCs) such as toluene or diethyl ether.…”