Copper-Catalyzed sp<sup>2</sup> C–H Arylation\nand Alkynylation of Allenes via Hydrogen Atom Abstraction

Development of methods for the sp<sup>2</sup> C–H\ntransformations\nof allenes has received much attention, and it presents a powerful\ntool for the synthesis of complicated allene-containing bioactive\nmolecules. With a copper-catalyzed radical relay, sp<sup>2</sup> allenic\nC–H arylation and alkynylation were established herein, using\nvarious aryl boronic acids and trimethoxysilyl-substituted alkynes\nas carbon nucleophiles and using electrophilic N–F reagents\nas nitrogen-centered radical precursors. These methods featured excellent\nsite selectivity to deliver fully substituted allenes efficiently.\nMoreover, with silyl-substituted allenes as substrates, a subsequent\ndual sp<sup>2</sup> C–H functionalization process was established\nas well, which allowed for the divergent synthesis of multifunctionalized\nallenes, significantly expanding their chemical spaces.