10.1002/adsc.201000355
The research focuses on the development of a highly efficient, large-scale asymmetric direct intermolecular aldol reaction using l-prolinamide as a recoverable catalyst. The purpose of this study was to create a simple, bifunctional, recoverable, and reusable organocatalyst that promotes aldol reactions with a high level of enantioselectivity. The catalyst was effective with a wide range of aromatic and heteroaromatic aldehydes with cyclic and acyclic ketones, yielding anti-aldol products with up to 99:1 anti/syn ratio and 98% ee. The catalyst could be easily recovered and reused with only a slight decrease in enantioselectivity over five cycles. The study concluded that l-prolinamide 1b is a robust and effective catalyst for highly enantioselective aldol reactions, and its application can be scaled up while maintaining the same level of enantioselectivity, offering significant potential for industrial applications. Key chemicals used in the process include l-prolinamide derivatives as catalysts, 3-methylbenzoic acid as a cocatalyst, and various aldehydes and ketones as substrates.
10.1016/j.tetasy.2011.05.008
The study focuses on the development of a simple, inexpensive, and efficient method for asymmetric direct aldol reactions using L-prolinamide as a recyclable organocatalyst. The main objective was to obtain highly enantiomerically enriched anti-aldol products, which are valuable in industrial applications. A series of prolinamides (compounds 1-10) were synthesized and tested for their catalytic activity in the asymmetric aldol reaction between benzaldehyde and cyclohexanone. The study found that prolinamide 6, in particular, showed high catalytic efficiency with only 5 mol % catalyst loading and 4 equivalents of ketone, yielding aldol products with high diastereoselectivity (up to anti/syn 99:1) and enantioselectivity (up to 99%), and significantly enhanced reaction yield (up to 99%). The catalyst could be easily recovered and reused without a significant decrease in enantioselectivity, making it a promising candidate for large-scale industrial applications. The chemicals used in the study included various prolinamides, benzaldehyde, cyclohexanone, and acetic acid, serving as catalysts, reactants, and a cocatalyst, respectively, to facilitate the aldol reaction and improve its efficiency and selectivity.
10.1021/jacs.0c09075
The study presents the rational design and synthesis of novel chiral 2-substituted DMAP-N-oxides, derived from L-prolinamides, for use as acyl transfer catalysts in the dynamic kinetic resolution (DKR) of azlactones. The purpose of these catalysts is to enhance the catalytic activity and utilization of the C2 position of the pyridine ring while avoiding steric hindrance. The researchers used simple methanol (MeOH) as a nucleophile to produce various L-amino acid derivatives with high yields (up to 98%) and enantioselectivities (up to 96% ee). The study also involved the use of benzoic acid to reduce the activation energy by participating in the construction of a hydrogen-bond bridge, which improved the reaction rate. Experiments and DFT calculations revealed that the oxygen atom in the 2-substituted DMAP-N-oxide acted as the nucleophilic site, and the N?H bond functioned as the H-bond donor, with high enantioselectivity governed by steric factors. This work paves the way for the development of chiral 2-substituted DMAP-N-oxides as efficient acyl transfer catalysts.