Sc(OTf)3-catalyzed smooth tandem [3+2] cycloaddition/ring opening of donor–acceptor cyclopropane 1,1-diesters with enol silyl ethers

Catalyzed by Lewis acids, donor–acceptor cyclopropane 1,1-diesters reacted with enol silyl ethers to afford 1,6-dicarbonyl compounds in moderate to excellent yields. This supplied a mild carbon–carbon bond-forming method from the ring opening of cyclopropanes. A smooth tandem [3+2] cycloaddition/ring opening process has been clearly proved by an independent experiment.