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Alagesan Balasubramani1,2, Rupali Shivachalappa Salgar1, Giribabu Lingamallu3,2

  • 1Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad - 500007, Telangana, India. srihari@iict.res.in.

Organic & Biomolecular Chemistry
|October 1, 2025
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Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
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Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
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