Chiral Squaramide‐Catalyzed Michael/­Alkylation Cascade Reaction for the Asymmetric Synthesis of Nitro‐Spirocyclopropanes

Abstract

AbstractA new diastereoselective and enantioselective cyclopropanation reaction has been developed by employing a Michael/alkylation cascade reaction between (E)‐3‐arylenechroman‐4‐one or (E)‐2‐arylideneindan‐1‐one derivatives and a bromonitroalkane with a chiral squaramide catalyst. This reaction constitutes a facile asymmetric synthesis for nitro‐spirocyclopropanes that have three adjacent stereogenic centers, including one quaternary center, in moderate to good yields (up to 90 %) with excellent enantio‐ [up to >99 % ee (enantiomeric excess)] and diastereoselectivities [up to >99:1 dr (diastereomeric ratio)].