Lactones are an important class of compounds that are commonly used in the synthesis of polyesters, pharmaceuticals, and can be used to treat specific types of cancers. They can be synthesized by the oxidative cyclizations of diols, which can be accomplished with the help of stoichiometric strong oxidants, though toxic byproducts are often formed during the process. Alternatively, various metal compounds can catalyze this transformation. This project focused on exploring the reactivity of a class of iron catalysts in the oxidative cyclization of both symmetrical and unsymmetrical diols to form lactones. These iron compounds exhibit a similar reactivity as Shvo's diruthenium bridging hydride but are less expensive and are based on an earth-abundant metal. Initially we synthesized and tested several (cyclopentadienone)iron carbonyl catalysts in the lactonization of 1,5-pentanediol using acetone as both the solvent and the terminal oxidant. After the reaction conditions were optimized, the most active catalysts were explored in the lactonization of a series of symmetrical and unsymmetrical diols. Many of the symmetrical diols were transformed into the desired lactones in high yield, and when the appropriate catalyst was selected, high yields of lactones could also be isolated from unsymmetrical diols.

Application of (cyclopentadienone)iron catalysts to the lactonization of diols

2019 Spring National Meeting

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