Enzyme-Catalyzed Carbonyl Olefination by the E. coli Protein YfeX in the Absence of Phosphines

The Wittig‐type carbonyl olefination reaction has no biocatalytic equivalent. To build complex molecular scaffolds, however, C−C bond‐forming reactions are pivotal for biobased economy and synthetic biology. The heme‐containing E. coli protein YfeX was found to catalyze carbonyl olefination by reaction of benzaldehyde with ethyl diazoacetate under aerobic conditions in the absence of a triphenylphosphine oxophile. The reaction was performed in whole cells and showed a product formation of 440 mg L−1 in 1 h. It was, moreover, shown that the reaction could be performed under Wittig‐analogue conditions in the presence of triphenylphosphine or triphenylarsine. Finding Wittig without Phosph‐in: Triphenylphosphine‐free carbonyl olefination can be achieved with the heme‐containing E. coli protein YfeX by using diazo compounds. The reaction can also be performed under Wittig‐analogue conditions with oxophiles. Whole‐cell catalysis with overexpressed YfeX shows a product formation of 440 mg L−1 in 1 h.