91Ó°ÊÓ

The Diels Alder reaction comprises a concerted mechanism where the bond making and breaking happens in a single step. These reactions are identical to a nucleophile-electrophile reaction.

The different stereochemical features of the Diels-Alder reactions include s-cis conformation of the Diene, syn stereochemistry and the endo rule.A secondary overlap among the p orbitals of the electron-withdrawing group and the central carbon atoms of the diene happens in a Diels-Alder reaction.

(a)

The treatment of 2-methoxycyclopenta-1,3-diene with methyl propionate forms a new carbon-carbon bond in the resulting product. The reaction can be given as:

Diels-Alder reaction of compound a

(b)

The treatment of 1-methoxycyclohexa-1,3-diene with cyclohex-2-enone creates the product. The reaction can be given as:

Diels-Alder reaction of compound b

(c)

The treatment of 2-methoxybuta-1,3-diene with acylaldehyde creates the product. The reaction can be given as:

Diels-Alder reaction of compound c

(d)

The treatment of (E)-2-methylpenta-1,3-diene with acrylonitrile generates the product. The reaction can be given as:

Diels-Alder reaction of compound d