Selected Examples of the Metal-Free Synthesis of Allenes (2017 – 2023)

Abstract

Although metal catalysts are widely used in chemical reactions, there are certain limitations and concerns associated with their use in medicinal chemistry. Many of the metal catalysts used in pharmaceutical production can remain in the final product and be toxic to human health. These impurities might not be easily removed and could negatively impact the quality of the final product. Metal catalysis can also require harsh conditions, such as high temperature and pressure, which can lead to the degradation of sensitive compounds. Furthermore, metal catalysts are from finite resources and their use can have significant environmental impacts. While metal catalysts have their place in organic synthesis, especially in industries outside of pharmaceuticals, the stringent requirements for safety and purity make them less than ideal. This minireview explores some of the latest metal-free methods for the preparation of the highly versatile fictional group, allenes. The methods described within are suitable metal free methods to prepare cumulated dienes which could be used in the production of complex therapeutics.