Tetrachloromethane as an editable all-carbon quaternary source

Despite the widespread presence of all-carbon quaternary centers in natural products and bioactive compounds, a concise construction strategy remains very challenging. Herein, we introduce a highly controllable sequential dechlorination strategy of tetrachloromethane by means of relay catalysis with different photocatalysts of eosin Y, 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene and Au₂(µ-dcpm)₂Cl₂. Four C-Cl bonds in CCl₄ can undergo sequential, highly selective cleavage by combination of outer-sphere and inner-sphere crossover single electron transfer mechanism, enabling radical-addition reactions with a wide range of terminal alkenes to construct all-carbon quaternary centers in four steps with 17-38% yields. Furthermore, using 1,1-disubstituted styrene as the substrates, cyclopropanes bearing with challenging vicinal all-carbon quaternary centers are also successfully constructed from CCl₄ in two-pots three steps with moderate yields of 10-50%. This work suggests the possibility of tetrachloromethane as an editable C1 synthon to facilitate the construction of all-carbon quaternary centers.