A New Member of the BN-Phenanthrene Family: Understanding the Role of the B-N Bond Position.
1. Departamento de Quimica Organica y Quimica Inorganica, Instituto de Investigacion Quimica "Andres M. del Rio" (IQAR) , Universidad de Alcala , 28805 Alcala de Henares , Spain. 2. Departamento de Quimica, Centro de Investigacion en Sintesis Quimica (CISQ) , Universidad de La Rioja , Madre de Dios 53 , 26006 Logrono , Spain.
3,4-Dihydro-4-aza-3-boraphenanthrene, which shows the highest fluorescence quantum yield of all nonsubstituted BN-phenanthrenes reported to date (varphiF = 0.61), has been synthesized in only three steps (76% overall yield) from easily accessible 1-bromo-2-vinylnaphthalene, along with several substituted derivatives. The reactivity of these previously unknown BN-aromatic compounds toward organolithium compounds and bromine has been studied. This latter reaction affords bromo-substituted compounds that are suitable for further functionalization via Suzuki and Sonogashira couplings, with complete regioselectivity. The optical properties and excited state deactivation mechanisms of selected compounds were studied using computational methods.