Stereochemical implications toward the total synthesis of aromatic belts

Abstract

AbstractThe synthesis of carbon nanotube (CNT) fragments has long captivated organic chemists, despite the simplistic, symmetric nature of the requisite achiral targets. Such molecules hold the potential to allow for the synthesis of homogeneous CNTs, rendering their properties more suitable for advanced applications in electronics and sensing. The [n]cycloparaphenylene family, comprised of molecules with para-linked phenyl rings in a contiguous macrocycles, represents a major landmark towards achieving absolute control of CNT architecture from the bottom-up. Attempts towards accessing the [n]cyclacene and [n]cyclophenacene families, both of which are comprised of double-stranded macrocyclic belts, have only recently been successful, however. These targets have been plagued by unstable, strained intermediates and stereochemical pitfalls that have largely thwarted accessing these fascinating structures. Herein, we disclose our synthetic strategy toward overcoming several stereochemical challenges en route to [n]cyclophenacenes via highly substituted [n]cycloparaphenylene precursors.