The Acetylcholinesterase Surface. VII. Interference with the Surface Binding as Reflected by Enzymatic Response to Turicine, Betonicine and Related Heterocycles<sup>1</sup>
作者:S. L. Friess、A. A. Patchett、B. Witkop
DOI:10.1021/ja01559a062
日期:1957.1
The Enantioselective Michael Addition of Thiols to Cycloalkenones by Using (2<i>S</i>, 4<i>S</i>)-2-Anilinomethyl-1-ethyl-4-hydroxypyrrolidine as Chiral Catalyst
Catalytic asymmetric addition of thiols to 2-cycloalkenone was studied by using the chiral amino alcohols, derived from L-hydroxyproline or (S)-proline, as base catalysts. Detailed investigation was carried out on the effects of the structure of the catalyst, the reaction medium, the temperature, and the concentration on the enantioselectivity. Good optical yields (47–88%) were achieved by the reaction
Enantioselective Organocatalytic Biginelli Reaction: Dependence of the Catalyst on Sterics, Hydrogen Bonding, and Reinforced Chirality
作者:Satyajit Saha、Jarugu Narasimha Moorthy
DOI:10.1021/jo101717m
日期:2011.1.21
From a systematic investigation involving the synthesis of a series of catalysts and screening studies, the organocatalyst 16, which is sterically hindered, contains a strong hydrogen-bonding site, and is endowed with reinforced chirality, is shown to promote the Biginelli cyclocondensation of aromatic as well as aliphatic aldehydes with ethyl acetoacetate and urea in a remarkably high enantioselectivity (ee ca. 94-99%).