General and Selective Olefination of Aldehydes and Ketones Catalyzed by a Cobalt(II) Porphyrin Complex

The Co(II) porphyrin complex Co(TPP) is an efficient and versatile catalyst for selective olefination of carbonyl compounds, including aldehydes and activated and unactivated ketones, with ethyl diazoacetate (EDA) in the presence of triphenylphosphine. The catalytic reactions of aldehydes and activated ketones can be carried out in a one-pot fashion with the use of a stoichiometric amount of diazo reagents, affording olefins in high yields and high E selectivity. In the case of unactivated ketones, a substoichiometric amount of benzoic acid is required to promote the catalytic reactions.