Robinson annulation

The Robinson annulation is a

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

used in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

for ring formation. It was discovered by Robert Robinson in 1935 as a method to create a six membered ring by forming three new carbon–carbon bonds. The method uses a

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

and a

methyl vinyl ketone Methyl vinyl ketone (MVK, IUPAC name: butenone) is the organic compound with the formula CH3C(O)CH=CH2. It is a reactive compound classified as an Alpha-beta Unsaturated carbonyl compounds, enone, in fact the simplest example thereof. It is a co ...

to form an α,β-unsaturated ketone in a

cyclohexane Cyclohexane is a cycloalkane with the molecular formula . Cyclohexane is non-polar. Cyclohexane is a colorless, flammable liquid with a distinctive detergent-like odor, reminiscent of cleaning products (in which it is sometimes used). Cyclohexan ...

ring by a

Michael addition In organic chemistry, the Michael reaction or Michael addition is a reaction between a Michael donor (an enolate or other nucleophile) and a Michael acceptor (usually an α,β-unsaturated carbonyl) to produce a Michael adduct by creating a carbon ...

followed by an

aldol condensation An aldol condensation is a condensation reaction in organic chemistry in which two carbonyl moieties (of aldehydes or ketones) react to form a β-hydroxyaldehyde or β-hydroxyketone (an aldol reaction), and this is then followed by dehydration to ...

. This procedure is one of the key methods to form fused ring systems. Reaction Scheme for Robinson Annulation

Formation of

cyclohexenone Cyclohexenone is an organic compound which is a versatile intermediate used in the synthesis of a variety of chemical products such as pharmaceuticals and fragrances. It is colorless liquid, but commercial samples are often yellow. Industrially, ...

and derivatives are important in

chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

for their application to the synthesis of many natural products and other interesting organic compounds such as

antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...

and

steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

. Specifically, the synthesis of

cortisone Cortisone is a pregnene (21-carbon) steroid hormone. It is a naturally-occurring corticosteroid metabolite that is also used as a pharmaceutical prodrug; it is not synthesized in the adrenal glands. Cortisol is converted by the action of the enzy ...

is completed through the use of the Robinson annulation. The initial paper on the Robinson annulation was published by William Rapson and Robert Robinson while Rapson studied at Oxford with professor Robinson. Before their work, cyclohexenone syntheses were not derived from the α,β-unsaturated ketone component. Initial approaches coupled the methyl vinyl ketone with a

naphthol Naphthol may refer to: * 1-Naphthol * 2-Naphthol {{Short pages monitor