Highly stereoselective formation of cis-enediones from α-diazo carbonyl compounds catalysed by [RuCl(η5-C5H5)(PPh3)2]

Abstract

Stereoselective decomposition of the α-diazo carbonyl compounds N₂CHCOR [R = Me, Prⁿ, Prⁱ, (CH₂)₁₀CH₃] catalysed by [RuCl(η⁵-C₅H₅)(PPh₃)₂] (0.1 mol%) in toluene at 65 °C affords quantitatively RCOCHCHCOR carbene dimers, the cis isomers being formed in 95–97% yield; under the same experimental conditions N₂CHCOEt gives diethyl maleate in a purity of greater than 99%, the highest value for a stereoselective carbene–carbene dimer formation reported to date.