Synthesis, Characterization, and Functionalization of 1‐Boraphenalenes

Abstract

1-Boraphenalenes have been synthesized by reaction of BBr₃ with 1-(aryl-ethynyl)naphthalenes, 1-ethynylnaphthalene, and 1-(pent-1-yn-1-yl)naphthalene and they can be selectively functionalized at boron or carbon to form bench-stable products. All of these 1-boraphenalenes have LUMOs localized on the planar C₁₂ B core that are closely comparable in character to isoelectronic phenalenyl cations. In contrast to the comparable LUMOs, the aromatic stabilization of the C₅ B ring in 1-boraphenalenes is dramatically lower than the C₆ rings in phenalenyl cations. This is due to the occupied orbitals of π symmetry being less delocalised in the 1-boraphenalenes.