We report the synthesis of a versatile trifluoromethylsulfonamide calix[6]arenederivative with Brønsted acid features which can influence both molecular recognition and catalytic application. Indeed, in low polarity media, the trifluoromethyl-containing supramolecular wheel is able to respond to the complexation with charged species as a function of its selective ion-pair recognition. In parallel
and facile visible-light-mediated alkylation of indoles and nitroalkenes has been developed. In this protocol, rose bengal acts as a photosensitizer, and environmentally benign water was used as the green and efficient reaction medium. Indoles reacted smoothly with nitroalkenes under the irradiation of visible-light and generated corresponding 3-(2-nitroalkyl)indoles in moderate to good yields (up to
Two air-stable novel Lewisacids of triphenylantimony(V) pentafluorbezenesulfonates (2) and perfluorooctanesulfonates (3) were successfully synthesized and characterized. X-ray studies and thermo-gravimetric analysis found that these complexes showed high anti-hydrolyzability and thermal stability. The high catalytic activity and excellent recyclability of these complexes were achieved in the Michael
Electrostatically Enhanced Phosphoric Acids and Their Applications in Asymmetric Friedel–Crafts Alkylations
作者:Jie Ma、Steven R. Kass
DOI:10.1021/acs.joc.9b01741
日期:2019.9.6
series of electrostatically enhanced phosphoric acid catalysts were synthesized and studied. These compounds possess two positively charged N-octylpyridinium or triarylphosphonium ion centers at the 3,3′-positions of the (R)-BINOL backbone to enhance reactivity and provide needed steric bulk for enantioselective transformations. Catalytic activities for Friedel–Crafts alkylations of indoles with trans-β-nitrostyrenes
Hydrogen-bonding interactions between acidic TSA and methanol boosted the reactivity of the Michael addition of indoles to nitroalkene derivatives. The transformation occurs at a low catalyst loading of 5 mol%, allowing for the synthesis of nitroalkanes with good yields and functionalgroup tolerance.