Tribenzodecacyclene and Hexabenzodecacyclene

Abstract

High-temperature, TiCl₄-catalyzed, triple aldol condensations of aceanthrenone <b>5</b> and acenaphthacenone <b>6</b> gave tribenzodecacyclene <b>3</b> and hexabenzodecacyclene <b>4</b>, respectively, in yields of 16 and 0.8%, respectively. Compound <b>3</b> is a red, crystalline solid that is stable under ordinary conditions; its X-ray structure reveals it to be a strongly pitched, <i>C</i>₃-symmetric, molecular propeller. In contrast, the more highly strained compound <b>4</b> is a blue-black solid whose solutions are unstable to air and light. Its simple NMR spectra, as well as HDFT calculations, indicate that it is a <i>D</i>₃-symmetric molecular propeller