Allenes are valuable and versatile building blocks in organic chemistry. Numerous elegant transformations based on the catalytic synthesis of allenes have been established. This review mainly focuses on the recent advancements in nickel-catalyzed synthesis of allenes, including the reaction with propargylic derivatives, 1,3-enynes, 1,3-diynes, terminal alkynes, alkenyl halides, and allenyl electrophiles. The mechanistic investigations and synthetic challenges will be discussed.
Allenes are one of the most important functional groups in organic chemistry, featuring unique physical and chemical properties. They are not only the key scaffolds present in natural products, pharmaceutical molecules, and advanced functional materials, but also the valuable and versatile building blocks for the construction of various complex and bioactive molecules in organic synthesis. Accordingly, benefiting from the rapid development of transition metal catalysis, numerous remarkable and efficient approaches for the synthesis of allenes from readily available chemicals have been established in the past decades. In this brief review, we focus on the recent advancements in nickel-catalyzed synthesis of allenes. These transformations are divided into two categories according to the types of reactions and sorted further by starting materials. Moreover, a concise discussion of the limitations and potential areas of improvement in this field is also provided, which would give an inspiration for future study on allene synthesis.Zum Volltext