Sustainable and selective Ni-catalyzed allylation of 2-oxindoles and 2-coumaranones in batch and flow chemistry

2-Oxindoles and 2-coumaranones could be selectively allylated in the presence of low cost catalysts based on nickel, leading selectively to different polysubstituted derivatives. Allyl alcohol was used as an allylating reagent and allowed the synthesis of compounds under neutral conditions with water produced as the sole by-product. Experiments have been performed in batch and in flow chemistry. The latter protocol in flow led to a very efficient and straightforward allylic alkylation of 2-oxindoles in only a few minutes with high chemoselectivities towards either the C,C-bisallylated product or the C,C,N-trisallylated one.