Enantioselective Synthesis of 3‐Substituted Cyclobutenes by Catalytic Conjugate Addition/Trapping Strategies

Abstract A copper‐catalyzed tandem process to generate chiral cyclobutene derivatives has been developed. It is based on an enantioselective conjugate addition or reduction of a cyclobutenone and sequential trapping with a chlorophosphate in a one‐pot process. These phosphates are stable under mildly acidic conditions and serve as good electrophiles in Negishi coupling reactions.