Allene chemistry

Organic chemists continually search for transformations to produce compounds in increasingly efficient and expedient ways, and to synthesize new compounds possessing interesting properties. One particularly appealing strategy is to exploit underutilized functional groups. By using this strategy, novel arrays of atoms that were previously unattainable are made possible. There are hurdles to overcome with this approach, that include, but are not limited to, an incomplete understanding of functional group compatibility issues that may arise during their preparation or caused by their presence in subsequent reactions. Even after decades of use, allenes can still be classified as an underutilized functional group. However, great advances in the chemistry of allenes have been made since the 1970s when they were regarded as difficult to prepare and very reactive, and not commonly encountered.

Focusing on a particular functional group at first glance may seem trivial and obvious, but the importance of these types of studies is underscored by the fact that numerous Nobel prizes have been awarded for the study “alkenes in synthesis”. More importantly, transformations involving allenes can provide new scaffolds that lead to an expansion of chemical space where currently nearly half of all existing organic compounds can be described by a mere 143 molecular frameworks. This data supports the notion that we tend towards compounds and functionalities with which we are familiar and understand, but this, nevertheless, creates a limitation to our knowledge of our field.

This Thematic Series represents contributions from leading chemists exploring a wide range of reactions involving allenes as reactants or products. The articles within detail discoveries surrounding the allene group and provide knowledge that chemists need in order to make informed decisions about whether or not to include an allene in a synthetic plan.