Calcium triflate, Ca(OTf)2/(n-Bu)4NPF6, has been shown as an effective Lewis acid catalyst for the normal electron-demand Diels–Alder reaction. The use of the additive is to enhance the Lewis acidity of Ca(II) ions in order to induce LUMO lowering of dienophiles.

What catalyst is used in Diels-Alder reaction?

Calcium triflate, Ca(OTf)2/(n-Bu)4NPF6, has been shown as an effective Lewis acid catalyst for the normal electron-demand Diels–Alder reaction. The use of the additive is to enhance the Lewis acidity of Ca(II) ions in order to induce LUMO lowering of dienophiles.

What is endo Rule?

Detailed density functional theory calculations definitively rationalize the preference for the endo cycloadduct (also known as endo rule) in text-book thermal Diels-Alder reactions involving maleic anhydride and cyclopentadiene or butadiene.

Is the cycloaddition reaction a concerted or step wise mechanism?

Two stepwise routes through diradical intermediates R3 and R4 are 4–5 kcal/mol higher in energy. We conclude that for the parent hydrocarbons vinylacetylene and acetylene cycloaddition favors a concerted reaction pathway.

Why is xylene used in Diels-Alder reaction?

Xylene (dimethylbenzene) is used as a high-boiling solvent so that the reaction will work fast enough to complete conveniently. In terms of activation, notice that maleic anhydride is a highly reactive dienophile, due to the presence of two electron-withdrawing carbonyl substituents.

What happens when 1/3 butadiene undergoes Diels-Alder with ethylene?

the addition of ethene to 1,3-butadiene to give cyclohexene.

Which is more stable endo or exo?

This is because the transition state of the formation of the endo product is lower in energy due to overlap of secondary orbitals. However, the exo product is more stable and lower in energy and therefore thermodynamically favored.

What is the application of Diels Alder reaction?

Application of Diels-Alder reaction The retro Diels-Alder reaction is used for the industrial production of cyclopentadiene. Cyclopentadiene is a precursor to many norbornenes, which are common monomers. Also, the Diels-Alder reaction is employed in vitamin B6 production.

What is the mechanism of the Diels-Alder reaction?

Mechanism of the Diels-Alder Reaction. Overlap between the highest occupied MO of the diene (HOMO) and the lowest unoccupied MO of the dienophile (LUMO) is thermally allowed in the Diels Alder Reaction, provided the orbitals are of similar energy. The reaction is facilitated by electron-withdrawing groups on the dienophile,…

What can be substituted for dienophiles in Diels Alder?

In addition, either the diene or the dienophile can be substituted with cumulated double bonds, such as substituted allenes. With its broad scope and simplicity of operation, the Diels-Alder is the most powerful synthetic method for unsaturated six-membered rings.

What is aza Diels-Alder reaction?

The aza Diels-Alder reaction involves the use of imines as the dienophile (or diene substituents). The product formed in this reaction is an N-heterocyclic compound. If a nitroso compound is used as the dienophile, the resulting reaction with the diene yields oxazines. 2. Usage of Lewis Acids In this variation, a Lewis acid is used as a catalyst.