Acetylenic Scaffolding with Subphthalocyanines

Article abstract of DOI:10.1002/ejoc.201501264

A new boron subphthalocyanine (SubPc) derivative with a terminal alkyne substituent on the central boron atom was prepared by substitution of a triflate at the boron atom with but-3-yn-1-ol. This compound was shown to be a versatile building block for metal-catalyzed coupling reactions, such as modified Glaser-Hay, Cadiot-Chodkiewicz, and Sonogashira reactions as well as the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). For example, metal-catalyzed reactions provided access to a SubPc dimer containing a butadiyne bridging unit, two different SubPc-fullerene dyads as well as two cross-conjugated SubPc-tetraethynylethene (TEE) scaffolds. These TEEs containing two silyl-protected alkyne units are potential building blocks for further acetylenic scaffolding. The work shows how the axial position is post-functionalized in steps not involving a substitution reaction at the central boron atom, which is otherwise often used as the terminal step in axial functionalization of SubPcs.