Photoinduced 3 + 2 Cycloadditions of Aryl Cyclopropyl Ketones with Alkynes and Alkenes

The five-membered ring skeleton is one of the most pivotal in the area of pharmaceutical and natural products. 3 + 2 cycloadditions of cyclopropyl and unsaturated compounds are a highly efficient and atom-economical way to build a five-member compound. The previous works about the kind of 3 + 2 cycloadditions usually utilized metal or organic small molecule catalysts. However, an ideal 3 + 2 cycloaddition reaction that smoothly happens without any additives and catalysts under mild conditions is underdeveloped. Hence, we report 3 + 2 cycloadditions of aryl cyclopropyl without any additives and catalysts under purple LED. In this method, a broad scope of cyclopropyl, alkyne, and alkene was very compatible, especially drug derivatives ibuprofen and Ioxoprofen, to obtain the corresponding cycloaddition product with a good yield up to 93%.