What is the condition for ring opening reaction?

Under aqueous basic conditions the epoxide is opened by the attack of hydroxide nucleophile during an SN2 reaction. The epoxide oxygen forms an alkoxide which is subsequently protonated by water forming the 1,2-diol product.

How do you open an epoxide ring?

Both strong and weak nucleophiles open the epoxide ring by an opposite-side nucleophilic attack. This puts the nucleophile and the alkoxy group of opposite sides and as a result, trans or anti-products are always formed.

What do you mean by acid catalyzed ring opening?

The acid-catalyzed ring-opening reaction of epoxides follows a mechanism with S N2 features (inversion of stereochemistry, no carbocation rearrangements), the mechanism is not strictly a S N2 mechanism.

Can give ring opening polymerization?

Ring-opening metathesis polymerization (ROMP) produces unsaturated polymers from cycloalkenes or bicycloalkenes. It requires organometallic catalysts. The mechanism for ROMP follows similar pathways as olefin metathesis.

How do nucleophiles react with epoxides also known as Oxiranes under basic conditions?

Reactive nucleophiles react with epoxides in an SN2 type of reaction. Reactive nucleophiles are usually anions so the reaction conditions are essentially basic. The leaving group is the oxygen atom of the epoxide in the form of the alkoxide which is converted to the alcohol on an acidic work-up.

What is ring-opening polymerization technique?

In polymer chemistry, ring-opening polymerization (ROP) is a form of chain-growth polymerization, in which the terminus of a polymer chain attacks cyclic monomers to form a longer polymer (see figure). The reactive center can be radical, anionic or cationic.

How does ring-opening occur?

Ring-opening under basic conditions occurs in a regime of strong interaction between the nucleophile (OH –) and the epoxide and the interaction is governed by the steric (Pauli) repulsion. The latter steers the attack preferentially towards the sterically less encumbered C β.

What determines the regioselectivity of epoxide ring-opening reactions?

Quantum chemical activation strain analyses reveal that the regioselectivity of the classical textbook acid- and base-catalyzed epoxide ring-opening reactions are controlled by either strain (acidic regime: weak interactions) or steric interactions (basic regime: strong interactions).

What is regioselectivity and why is it important?

Regioselectivity has now become an important focus for the ring-opening reaction of unsymmetrical epoxides, where obtaining one regioisomer exclusively is extremely difficult to achieve.

What is the epoxide ring-opening protocol used for?

Importantly, this epoxide ring-opening protocol can be used for the introduction of amines in natural products during late-stage transformations.