Catalytic control of reactions of dipoles and carbenes; 1 an easy and efficient synthesis of cycloheptatrienes from aromatic compounds by an extension of Buchner's reaction

Rhodium salts from strong carboxylic acids [particularly rhodium(II) trifluoroacetate] are novel and highly efficient catalysts for the preparation of substituted cycloheptatriene carboxylates from aromatic hydrocarbons and diazo-esters, and in contrast with the classical Buchner procedures these rhodium catalysts lead specifically to the 1-isomer (3), avoiding its subsequent prototropic conversion into conjugated isomers.