New Strategy of Heterocyclic Design

Free-radical reactions have begun to find increasingly wide application in synthetic chemistry. Because of their high stereoselectivity, some of them are very appealing. At the same time, many such processes have serious limitations since they use iodine-containing systems as substrates. Nevertheless, radical cyclization has become a known technique of both cyclic and heterocyclic system design. 

For most reactions involving radical intermediates, it is required that the radical precursor and the carbon site of radical cyclization be present in the same substrate. Using a radical generated separately, however, seems to be more efficient. In its reaction with a substrate, this radical gives a new radical center, which is responsible for further cyclization. This is the essence of the new strategy of heterocyclic design. 

Based on this approach, the synthesis of fluorine-containing heterocyclic compounds can use one of two possibilities. The first is the introduction of a perfluoroalkyl group together with a radical site into the substrate. The second is the use of a substrate with the above radical and generation of a new radical by addition at an unsaturated group. Some examples of such reactions are given below. 

In one example, accessible perfluoroalkyl iodides were employed as sources of perfluoroalkyl radicals. Irradiation, thermal treatment, or the use of a catalyst lead 

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