2-Aminobenzimidazole Organocatalyzed Asymmetric Amination of Cyclic 1,3-Dicarbonyl Compounds
作者:Alejandro Baeza、Paz Trillo、Melania Gómez-Martínez、Diego Alonso
DOI:10.1055/s-0034-1379494
日期:——
The use of a trans-cyclohexanediamine benzimidazole derivative as a hydrogen-bond catalyst for the electrophilic amination of cyclic 1,3-dicarbonylcompounds 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.
C3-Symmetric chiral trisimidazoline: the role of a third imidazoline and its application to the nitro Michael reaction and the α-amination of β-ketoesters
We describe the necessity of the C-3-symmetry and the role of a third imidazoline of trisimidazoline 3, which was recently developed by us as a new entry of organocatalyst. The utility of 3 as a Bronsted base catalyst in the nitro Michael reaction and the alpha-amination of beta-ketoesters was shown, and the re-cyclability of the catalyst was also demonstrated. (C) 2011 Elsevier Ltd. All rights reserved.
Readily Available Chiral Benzimidazoles-Derived Guanidines as Organocatalysts in the Asymmetric α-Amination of 1,3-Dicarbonyl Compounds
α-amination of 1,3-dicarbonylcompounds using di-t-butylazodicarboxylate as aminating agent is herein disclosed. The catalysts are readily synthesized through the reaction of 2-chlorobezimidazole and a chiral amine in moderate-to-good yields. Among all of them, those derived from (R)-1-phenylethan-1-amine (1) and (S)-1-(2-naphthyl)ethan-1-amine (3) turned out to be the most efficient for such asymmetric transformation