Water‐assisted, Highly‐selective and Rapid Synthesis of Cyclopropane Derivatives by a [2+1] Annulation Reaction

Abstract The [2+1] annulation reaction of α‐keto sulfur ylides and β, γ‐unsaturated‐α‐ketoesters was studied in detail. A series of 1,2,3‐trisubstituted cyclopropane derivatives were acquired in moderate to good yields with excellent diastereoselectivities through this rapid and effective reaction in only 10 minutes. The reaction condition is simple and mild without any alkali, catalyst or additive. The corresponding experiments revealed that single cyclopropane product could be obtained in the assistance of water in this reaction.