In organic chemistry, an intramolecular Diels-Alder cycloaddition is a

Diels–Alder reaction In organic chemistry, the Diels–Alder reaction is a chemical reaction between a Conjugated system, conjugated diene and a substituted alkene, commonly termed the Diels–Alder reaction#The dienophile, dienophile, to form a substituted cyclohexe ...

in which the

diene In organic chemistry a diene ( ) (diolefin ( ) or alkadiene) is a covalent compound that contains two double bonds, usually among carbon atoms. They thus contain two alk''ene'' units, with the standard prefix ''di'' of systematic nomenclature ...

and a dienophile are both part of the same molecule. The reaction leads to the formation of the same

cyclohexene Cyclohexene is a hydrocarbon with the formula C6H10. This cycloalkene is a colorless liquid with a sharp smell. It is an intermediate in various industrial processes. Cyclohexene is not very stable upon long term storage with exposure to light a ...

-like structure as usual for a Diels–Alder reaction, but as part of a more complex fused or bridged cyclic ring system. This reaction gives rise to various natural derivatives of

decalin Decalin (decahydronaphthalene, also known as bicyclo .4.0ecane and sometimes decaline), a bicyclic organic compound, is an industrial solvent. A colorless liquid with an aromatic odor, it is used as a solvent for many resins or fuel additives. I ...

Reaction products

Because the two reacting groups are already attached, two basic modes of addition are possible in this reaction. Depending on whether the tether that links to the dienophile is attached to the end or the middle of the diene, fused or bridged polycyclic ring systems can be formed. The tether than attaches the two reacting groups also affects the geometry of the reaction. As a result of its conformational and other structural restrictions, the exo vs endo results are usually not based on the simple (intermolecular) Diels–Alder reaction effects.

Applications

Intramolecular Diels-Alder cycloaddition is extremely useful for the formation of naturally occurring polycyclic rings. The reaction provides ready access to polycyclic compounds with a great deal of

stereoselectivity In chemistry, stereoselectivity is the property of a chemical reaction in which a single reactant forms an unequal mixture of stereoisomers during a non-stereospecific creation of a new stereocenter or during a non-stereospecific transformation ...

. The following are several useful drugs whose complete synthesis has been accomplished using the intramolecular Diels-Alder reaction.

Solanapyrone A

Solanapyrone A is an inhibitor of mammalian

DNA polymerase A DNA polymerase is a member of a family of enzymes that catalyze the synthesis of DNA molecules from nucleoside triphosphates, the molecular precursors of DNA. These enzymes are essential for DNA replication and usually work in groups to create ...

β and λ, repair type DNA polymerase. The compound was isolated from the phytopathogenic fungi ''

Alternaria solani ''Alternaria solani'' is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tube ...

'', the cause of early blight in tomato and potato plants.

Salvinorin A

Isolated from the hallucinogenic sage ''

Salvia divinorum ''Salvia divinorum'' (Latin: "sage of the diviners"; also called ska maría pastora, seer's sage, yerba de la pastora, magic mint or simply salvia) is a plant species with transient psychoactive properties when its leaves are consumed by che ...

'',

Salvinorin A Salvinorin A is the main active psychotropic molecule in ''Salvia divinorum''. Salvinorin A is considered a dissociative hallucinogen. It is structurally distinct from other naturally occurring hallucinogens (such as DMT, psilocybin, and m ...

is a potent and selective κ-opioid agonist. The compound has potential uses in psychotherapuetic treatments and

Alzheimer's Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As ...

treatment.

Himbacine

Himbacine is a potent muscarinic receptor antagonist, Isolated from the bark of ''Galbulimima baccata'', a type of

magnolia ''Magnolia'' is a large genus of about 210 to 340The number of species in the genus ''Magnolia'' depends on the taxonomic view that one takes up. Recent molecular and morphological research shows that former genera ''Talauma'', ''Dugandiodendro ...

tree. The drug is a promising lead in Alzheimer's disease research.

References

{{DEFAULTSORT:Intramolecular Diels-Alder cycloaddition Name reactions Cycloadditions