Organocatalysis In a Synthetic Receptor with an Inwardly Directed Carboxylic Acid
作者:Siddhartha R. Shenoy、Fernando R. Pinacho Crisóstomo、Tetsuo Iwasawa、Julius Rebek
DOI:10.1021/ja801107r
日期:2008.4.1
A cavitand functionalized with a Kemp's triacid derivative was used to catalyze the epoxide ring-opening cyclizations of 1,5-epoxyalcohols. A deep, cylindrical cavity containing electron-rich aromatic walls and an inwardly directed carboxylic acid displayed the necessary characteristics to bind different 1,5-epoxyalcohols and initiate their cyclization reactions. The reactions inside this synthetic
Ethyl Cyanoformate/Hydrogen Peroxide and Related Combination Systems, Novel Epoxidizing Systems of Olefins
作者:Yukio Masaki、Tsuyoshi Miura、Isao Mukai、Akichika Itoh、Hirohisa Oda
DOI:10.1246/cl.1991.1937
日期:1991.11
A combination system of ethyl cyanoformate and hydrogen peroxide was found to epoxidize olefins in a stereospecific manner at room temperature. Asymmetric epoxidation was observed with menthyl cyanoformate/hydrogen peroxide system.
A reagent combination system, tetracyanoethylene-30% hydrogen peroxide, was found to epoxidize olefins efficiently in acetonitrile at room temperature in a stereospecific manner with retention of the configuration of the double bond.
amplification. Increasing activity with the intrinsic π acidity of benzenes, naphthalenediimides (NDIs) and perylenediimides (PDIs) support that anion-π interactions account for function. Rate enhancements maximize at 270 for anion-πcatalysis on fullerenes and at 5100 M-1 for autocatalysis. The occurrence of anion-π autocatalysis is confirmed with increasing initial rates in the presence of additional product