KCN/CuCN-mediated complete cyanation of hexabromotriphenylene

Complete cyanation of highly brominated aromatics is often hindered by the challenge of converting multiple carbon-bromine (C-Br) bonds within a single molecular framework. 2,3,6,7,10,11-Hexabromotriphenylene (HBTP) exemplifies this challenge, as its conversion to triphenylene-2,3,6,7,10,11-hexacarbonitrile (HCNTP) requires the replacement of all six C-Br bonds with cyano groups. Herein, we report an efficient cyanation of HBTP using potassium cyanide (KCN) and copper(i) cyanide (CuCN) in dimethyl sulfoxide (DMSO). The combination of KCN and CuCN effectively promoted the complete cyanation of HBTP, whereas either cyanide reagent alone led to limited or negligible formation of HCNTP. Among the examined conditions, a KCN/CuCN molar ratio of 1 : 2 gave HCNTP in a 66.4% isolated yield after recrystallization. This result is consistent with the suppression of DMSO coordination to Cu(i) by free CN^- ions supplied by KCN, which maintains the active copper species required for the complete six-fold cyanation of HBTP. This approach offers a practical synthetic route to cyano-functionalized triphenylene derivatives from heavily brominated precursors, providing a promising π-acceptor building block for conductive MOFs and n-type organic materials.