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Novel [2 + 2 + 2 + 1] cycloaddition of enediynes catalyzed by rhodium complexes

Bibia Bennacer1, Masaki Fujiwara, Iwao Ojima

  • 1Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York 11794-3400, USA.

Organic Letters
|September 25, 2004
PubMed

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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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Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
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