A sunlight-induced click reaction as an efficient route to cyclic aliphatic polyesters

To date, the controlled preparation of cyclic polymers is mainly achieved using click ligation strategies. The light-induced Diels-Alder click coupling has recently been shown to function as an attractive catalyst-free alternative to the copper-catalyzed alkyne-azide cycloaddition. However, the need for a light emitting system limits its applicability. To overcome this drawback, a sunlight-induced Diels-Alder reaction as an efficient route for the preparation of cyclic aliphatic polyesters in high yields and purity based on the same chemistry is demonstrated in the present contribution. The versatility and robustness of the proposed strategy against divergent atmospheric conditions is demonstrated. In light of the simplicity of the strategy presented here, it is suggested that the sunlight-induced Diels-Alder click-cyclization is a world-wide transposable process. A sunlight-induced Diels-Alder reaction is demonstrated for the preparation of cyclic polyesters. Under highly divergent atmospheric conditions, cyclic polyesters of high purity are obtained by taking advantage of the natural UV irradiation from the sun. Both summer and winter conditions show impressive performances, allowing to extrapolate the reported protocol to almost any place on earth.