Photocatalyzed Carbon─Carbon Bond Formation Between Ethylene Glycol and Electron-Deficient Olefins

Ethylene glycol is produced on a very large industrial scale and is used for the preparation of polyesters and antifreeze formulations. Although the diol is mainly manufactured from fossil-based resources, new commercial procedures from carbohydrates are currently being introduced, which eventually will make ethylene glycol an important bio-derived compound in organic chemistry. However, further transformations of the diol for the formation of carbon─carbon bonds have so far received relatively little attention. In the present work, the photocatalyzed coupling between ethylene glycol and electron-deficient olefins is therefore investigated. The results show that an iridium complex can be employed to mediate the reaction with acrylates, acrylamides, acrylonitriles, and vinyl sulfones to generate a range of chain-elongated lactones and diols. Substituents are tolerated in the α position of acrylates while a poor outcome is obtained with substituents in the β position of the electron-deficient olefin. The results illustrate the formation of new carbon─carbon bonds from an abundant alcohol by the use of photocatalytic transformations.