water-compatible proline catalysts (4–6) derived from calixarene bearing a hydrophobic nature have been synthesised. It was found that the compound 4 was a highly efficient organocatalyst for aldol reactions occurred in the water. Under optimised reaction conditions, high yields (up to 82%), good enantioselectivities (ee up to 81%) and high diastereoselectivities (dr up to 91:9) were obtained.
Prolinamides of Aminouracils, Organocatalyst Modifiable by Complementary Modules
作者:Karen M. Ruíz-Pérez、Beatriz Quiroz-García、Marcos Hernández-Rodríguez
DOI:10.1002/ejoc.201800886
日期:2018.11.8
Prolinamide organocatalysts with aminouracils have the features of enhanced NH acidity, an additional hydrogen‐bond donor and the self‐assembly with complementary modules by Watson–Crick pairing. Each module affects the selectivity of the reaction and particularly 2,6‐diaminopyridine is beneficial to the selectivity in the reaction.
successfully used as a cocatalyst for L-proline catalyzed aldolreactions in the presence of water. The anticonfigured products were obtained with good yields (up to 94%), high diastereoselectivities (up to 95:5), and high enantiomeric excesses (up to 93% ee ). The successful results for catalytic efficiency of L-proline in the presence of water reveal the importance of the hydrophobic nature of cholesterol
An efficient asymmetric organocatalyst was developed for the direct aldol reaction between ketones and aldehydes to afford β-hydroxy ketones in high stereoselectivity (anti/syn up to 92:8, ee up to >99%). The key of the success was the use of activated molecular sieves (4 ŠMS), which acted as a water scavenger. The influence of additives such as water or different types of molecular sieves on the reactivity and stereoselectivity of the reaction was also studied.
一种高效的非对称有机催化剂被开发出来,用于酮和醛之间的直接aldol反应,以高立体选择性(anti/syn高达92:8,ee高达>99%)制备β-羟基酮。成功的关键在于使用了活化的分子筛(4 Å MS),其作为水的清除剂。还研究了水分或不同类型分子筛等添加剂对反应活性和立体选择性的影响。
Proline dipeptides containing fluorine moieties as oganocatalysts for the asymmetric aldol reaction
作者:Ardiol Ahmetlli、Nikoleta Spiliopoulou、Angeliki Magi-Oikonomopoulou、Dimitrios-Triantaffylos Gerokonstantis、Panagiota Moutevelis-Minakakis、Christoforos G. Kokotos
DOI:10.1016/j.tet.2018.08.038
日期:2018.10
demonstrated, where aromaticaldehydes afforded products in high yields (up to 100%) with excellent diastereo- (up to 95:5) and enantioselectivities (up to 97%), whereas the aliphaticaldehydes afforded also excellent selectivities, but relatively low yield. A simple addition of fluorine to a dipeptide analogue affords organocatalysts with new interesting properties that can catalyze the aldol reaction