Synthesis of 2-alkyl-chroman-4-ones via cascade alkylation-dechlorination of 3-chlorochromones.

An efficient and mild synthetic approach for 2-alkyl-substituted chroman-4-ones via zinc-mediated cascade decarboxylative ß-alkylation and dechlorination of 3-chlorochromones was developed. This transformation employed commercially available starting materials and was performed under mild conditions without heat, visible light, peroxide or heavy metals. Moreover, various alkyl NHPI esters with functional groups and differently substituted 3-chlorochromones were tolerated, affording the targeted products with moderate to excellent yields. This protocol could be utilized to construct a diverse library of 2-substituted chroman-4-one derivatives, which could be useful in the discovery of lead compounds for drug discovery in the future.