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

Abstract

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 reduction of trifoliaphane with potassium metal in [D8]-THF led to hexakis[p-benzyl]benzene anion, which could efficiently be trapped with various electrophiles. Highly efficient multifold Suzuki couplings were performed with hexabromobenzene, octabromonaphthalene, and hexabromotriphenylene. The obtained hexa- and octaalkenylarene derivatives disclose interesting 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-butylindeno)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.