Bifunctional primary amine-squaramide catalyzed enantioselective intramolecular Michael addition of keto-enones: A convenient process to the stereocontrolled construction of trans-dihydrobenzofuran skeletons

摘要

A highly diasterero- and enantioselective intramolecular Michael addition of keto-enones has been realized. By using the (R,R)-1,2-diphenylethane-1,2- diamine-based bifunctional primary amine-squaramide catalyst, the reaction proceeded smoothly to generate the corresponding trans-2,3-disubstituted dihydrobenzofuran derivatives in excellent yields with good to excellent diastereo- and enantioselectivities (up to 97:3 dr, up to >99 % ee).