Robinson annulation

What is Robinson annulation?

Robinson annulation is a chemical reaction used to synthesize cyclic compounds by combining a conjugated enone and a ketone to form a cyclohexenone product. The reaction was developed by Robert Robinson in the 1930s and is named after him. It is an important method for the synthesis of cyclic compounds, which are widely used as flavors, fragrances, and intermediates in the production of pharmaceuticals and other materials..

The reaction mechanism of Robinson annulation involves the formation of an intermediate enolate, which is formed by the deprotonation of the conjugated enone. The intermediate enolate then reacts with the ketone to form the cyclohexenone product..

One of the main advantages of Robinson annulation is its compatibility with a wide range of functional groups, including alkyl, aryl, and vinyl groups. This makes it a useful method for synthesizing a wide range of cyclic compounds and other compounds..

Robinson annulation is typically performed under mild reaction conditions, which makes it suitable for synthesizing sensitive and labile compounds. However, it can be prone to side reactions, such as the formation of unwanted byproducts, which can reduce the yield and selectivity of the reaction..

There are several variations of Robinson annulation that have been developed to improve its efficiency and scope, including the use of different catalysts and the use of modified reaction conditions. For example, the use of a lithium or magnesium base as a catalyst has been shown to improve the yield and selectivity of Robinson annulation..


Robinson annulation is a powerful tool for synthesizing cyclic compounds and has numerous applications in the chemical and pharmaceutical industries. It is an important method in organic chemistry and continues to be an area of active research and development..