Rhodium-catalysed decomposition of δ,ε-unsaturated ββ-difluoro-α-diazo esters, the direct formation of bicyclo2.1.0pentane ring systems via intramolecular cyclopropanation

Several δ,ε-unsaturated β,β-difluoro-α-diazo esters, prepared from the corresponding α-keto esters, undergo rhodium-catalysed intramolecular cyclopropanation reaction leading to the unprecedented formation of bicyclo2.1.0pentane ring systems.