Iron salts catalyse the creation of carbenes for cyclopropanation

A new synthetic strategy uses a simple salt – iron chloride – to catalyse the creation of carbenes from commercial aldehydes. The carbenes quickly react with different alkenes to yield a selection of cyclopropanes ‘with a remarkable structural diversity’, according to Marc Montesinos Magraner, an expert in synthetic chemistry at the University of Valencia, Spain, who wasn’t involved in the study. Such cyclopropanes are ‘really difficult to prepare with existing methods’, but are common in medicines.

This could allow medicinal chemists to design and develop more diverse drug structures, explains lead author David Nagib from Ohio State University in the US. The new route to create carbenes provides ‘rapid access to many different classes of cyclopropanes – with varying substation patterns’, he explains. ‘We expanded on our strategy for harnessing carbenes, [and] add them to many different class of alkenes … to access smaller, more drug-like cyclopropanes.’