Strategies for the Synthesis of Alkylated Coumarins Using Various Alkyl Radical Precursors

Coumarins are known for their biological significance. Various coumarin derivatives are found in nature and they show intriguing biological activities. Several methods are reported in the literature for the construction of coumarins. Recently, an interesting feature of the motif has been realized that it can trap free radical species, especially alkyl radicals, thus it acts as a radical scavenger. Various alkylated coumarin derivatives have been constructed using coumarin as a sink for these radical species. In this review, recent developments in regioselective functionalization of coumarin derivatives using various precursors for the generation of alkyl radicals through distinct approaches have been compiled and critically reported to give a perspective about the development of new coumarin derivatives and their future scope.