Iterative synthesis of 1,3,5-polyphenylene dendrons via C-H activation

An iterative synthesis of 1,3,5-polyphenylene dendrons via C-H activation/Suzuki-Miyaura coupling up to a third generation dendron is described. C-H bonds at the focal points of the dendrons are selectively borylated via iridium-catalyzed borylation, eliminating the need for reactive protecting groups. Sequential additions of low catalyst loadings efficiently borylate higher-generation dendrons, whereas higher initial catalyst loadings are less efficient.