[reaction: see text] Readily tunable and bifunctional L-prolinamides as novel organocatalysts have been developed, and their catalytic activities were evaluated in the direct asymmetric Aldolreactions of various aromatic aldehydes and cyclohexanone. High isolated yields (up to 94%), enantioselectivities (up to 99% ee), and anti-diastereoselectivities (up to 99:1) were obtained under the optimal conditions
o-Benzenedisulfonimide, a new strong bench-stable Brønsted acid, has been shown to efficiently catalyze the Mukaiyama aldol reaction of aldehydes or dimethyl acetals with silyl enol ethers under mild solvent-free reaction conditions.
Direct asymmetric aldol reactions between aldehydes and ketones catalyzed by l-tryptophan in the presence of water
作者:Zhaoqin Jiang、Hui Yang、Xiao Han、Jie Luo、Ming Wah Wong、Yixin Lu
DOI:10.1039/b921460g
日期:——
Primary amino acids and their derivatives were investigated as catalysts for the direct asymmetric aldol reactionsbetween ketones and aldehydes in the presence of water, and L-tryptophan was shown to be the best catalyst. Solvent effects, substrate scope and the influence of water on the reactions were investigated. Quantum chemical calculations were performed to understand the origin of the observed
Core–shell silica magnetic microspheres supported proline as a recyclable organocatalyst for the asymmetric aldol reaction
作者:Honglei Yang、Shuwen Li、Xiaoyu Wang、Fengwei Zhang、Xing Zhong、Zhengping Dong、Jiantai Ma
DOI:10.1016/j.molcata.2012.07.017
日期:2012.11
enantioselectivity (up to 80%) in the asymmetric aldolreaction between aldehyde acceptors and ketone donors. On the other hand, the synthesized catalyst could be rapidly separated from the reaction mixture through an external magnetic field and reused up to five runs without any obvious loss of activity, indicating its easy-separated property and excellent recyclability.
Highly enantioselective aldol reactions catalyzed by reusable upper rim-functionalized calix[4]arene-based l -proline organocatalyst in aqueous conditions
作者:Zheng-Yi Li、Yuan Chen、Chong-Qian Zheng、Yue Yin、Liang Wang、Xiao-Qiang Sun
DOI:10.1016/j.tet.2016.11.052
日期:2017.1
l-Proline derivatives have been synthesized and employed for the enantioselective aldol reactions between cyclic ketones and aromatic aldehydes in the presence of water. Good to excellent yields (up to 96%), enantioselectivities (up to 99% ee), as well as diastereoselectivities (up to 99:1 dr) were obtained under the optimal reaction conditions. Detailed experiments clearly showed that the hydrophobic