New interesting molecular topologies by way of modern cross-coupling reactions

Modern transition-metal-catalyzed cross-coupling reactions, especially of the Kumada, Heck, and Suzuki types, have provided facile access to various bridge-annelated (2.2)paracyclophane derivatives including trifoliaphane and its tribenzo analog. The reduc- tion of trifoliaphane with potassium metal in (D 8 )-THF led to hexakis(p-benzyl)benzene anion, which could efficiently be trapped with various electrophiles. Highly efficient multi- fold Suzuki couplings were performed with hexabromobenzene, octabromonaphthalene, and hexabromotriphenylene. The obtained hexa- and octaalkenylarene derivatives disclose inter- esting molecular shapes. Eventually, a newly developed cascade coupling of bromoarenes containing peri-positioned C-H bonds has led to indeno-annelated polycyclic aromatic hydrocarbons including indenocorannulene as well as the tetrakis- and tris(tert-butyl- indeno)pyrene which disclose very interesting spectroscopic properties. In particular, tetrakis(tert-butylindeno)pyrene self-assembles in solution by way of π-stacking, and it can be reduced with potassium metal to a stable dianion, a readily dimerizing trianion radical, and a tetraanion.