Asymmetric Phosphoric Acid-catalyzed Aza-Friedel-Crafts Reaction of Furan with Cyclic N-Sulfimines

摘要

The asymmetric catalytic Friedel-Crafts reaction is a powerful, straightforward, and convenient method for fabricating carbon-carbon bonds between electron-rich aromatic compounds and electron-deficient alkenes, yielding chiral centers at the a- or P-position of various aromatic derivatives.1 Among the electron-rich aromatic compounds amenable to the Friedel-Crafts reaction, indole and its derivatives are popular substrates because of the widespread interest in their skeletons as ubiquitous constituents in biologically active natural products and pharmaceutical agents.2 A number of efficient and useful asymmetric catalytic systems have been developed for the reaction of indoles with electron-deficient alkenes, such as α, β-unsaturated carbonyls, nitroalkenes, imines, enamines, and alkylidene malonates.3