New method for forming carbon-carbon bonds: fast, efficient and in mild conditions

Sunday 9 June 2013 will see a publication in Nature Chemistry describing a breakthrough in the most essential chemical reaction for preparing molecules: the formation of carbon-carbon bonds. The article was written by the research group of the Groningen chemist Prof. Ben Feringa.

The key to this discovery is palladium catalysis. This new method enables organolithium compounds to be used very efficiently in mild conditions, thereby allowing carbon fragments to bind directly with each other. The chemical method has created new possibilities for manufacturing medicines and advanced materials.

Innovation

The essence of chemical synthesis (building molecules in both the laboratory and industry) is the ability to form carbon-carbon bonds (C-C bond). Although countless ways of effecting this chemical bond already exist, there is a constant demand for new and innovative techniques for durable synthesis offering high selectivity, less waste, fewer chemical steps and mild reaction conditions.

Over the past decades, most of the methods developed for forming C-C bonds have featured catalytic coupling reactions. These reactions (known as cross-coupling reactions) caused a revolution in the preparation of dyes, medicines and materials used in OLEDs, organic electronics and LCD screens.

Organometallic compounds such as organoboron, organozinc or organotin compounds are the most common compounds used in these coupling methods. In many cases, the organometallic compounds are made from the corresponding organolithium compounds. Up until now, it had proved impossible to use organolithium directly in these coupling reactions, mainly because organolithium compounds are highly reactive and lack selectivity in the process.

Tamed

Researchers from Groningen have now managed to ‘tame’ the organolithium compounds so that they can be directly used to form C-C bonds. The fundamental discovery provides a high-speed step for transferring the organic part of the organolithium compound to the palladium catalyst being used. As a result, coupling reactions, which currently require high temperatures and lengthy reaction times, can now be effected swiftly and in mild conditions.

An added advantage is that organolithium compounds are one of the cheapest organometallic compounds available. The production of chemical waste will be drastically reduced and other toxic tin compounds will become unnecessary. The researchers think that these new synthesis methods will soon be used to prepare a wide range of new molecular materials.

More information

Prof. Ben L. Feringa

Reference: Direct catalytic cross-coupling of organolithium compounds, Massimo Giannerini, Martín Fañanás-Mastral, Ben L. Feringa. Nature Chemistry, 9 June 2013.

DOI: 10.1038/NCHEM.1678