Transition-metal-catalyzed C–H allylation reactions

Allylation reactions are one of the most fundamental and productive C−C bond-forming transformations, as the allyl group can provide a useful handle for further manipulation. Apart from this, their omnipresence in bioactive species makes them invaluable in medicinal science and pharmaceutical industries. Pioneered by Tsuji and Trost, a myriad of synthetic strategies of allylation reactions have evolved significantly over the last few decades. With the emergence of site-selective C–H activation, the perimeter of allylation reactions has extended in different latitudes. C–H activation has averted the over dependency on traditional approaches and has circumvented its major drawbacks. With the present state of knowledge, C–H allylation reactions not only have precluded the need for pre-functionalized substrate and activated allylating reagents but it is also now apparent that they trigger the allylic selectivity of an unsaturated hydrocarbon under proper metal-ligand combination. This review aims to embrace all the aspects of transition-metal-promoted C–H allylation reactions.