Cleavage of Unstrained C−C Bonds in Acenes by Boron and Light: Transformation of Naphthalene into Benzoborepin

Abstract

Naphthalene and acenaphthene with peri 2-pya nd BMes 2 (py = pyridyl, Mes = mesityl) substituents have been found to undergo facile phototransformation, cleavage of a CÀCb ond of naphthalene,a nd formation of 2-py-bound benzoborepins as the major products.Mechanistic pathways of this photoreaction have been established by examination of both excited and ground states by using CASSCF and CASPT2 methods in DFT and time-dependent DFT calculations.T he mesityl to py-naphthyl charge-transfer transition and the mesityl migration from the boron atom to the naphthyl moiety drive this unprecedented CÀCb ond cleavage and boron-insertion reaction. Scheme 1. Photoreactivity of peri naphthalenes (top), examples examined in this work (middle),a nd synthetic procedure (bottom).

Tetrahydrodibenzophenanthridine-Based Boron-Bridged Polycyclic Aromatic Hydrocarbons: Synthesis, Structural Diversity, and Optical Properties

“…The B−N and B−C bond distances fall in the range 1.646(3)−1.669(2) and 1.583(3)− 1.626(3) Å, respectively (Table 1), which are consistent with the values reported in the literature for B←N coordinated boron complexes. 9,11,16 The molecular structures of all the compounds showed that the boron atom coordinates to the pyridyl nitrogen atom to form a five-membered ring (Figure 1). The Ar group attached to pyridyl becomes coplanar due to B←N coordination.…”

Isomerization and rearrangement of boriranes: from chemical rarities to functional materials

“…Aside from the direct use of base-stabilized boriranes in materials science, these high energy species can also be used as reactive intermediates in the facile preparation of functional materials such as singly annulated borepins [56] and chiral N,B,X-heterocycles (X = S or O) [57]. Borepins are charge neutral, boron-containing analogues of the tropylium cation, where the boron atom is typically protected by bulky substituents [58].…”

Bis-borylated arylisoquinoline-derived dyes with a central aromatic core: towards efficient fluorescent singlet-oxygen photosensitizers

“…34 Structure A is prepared by a modular synthetic approach and shows helical chirality. The Wang group introduced structure B, showing interesting photochemical reactivity, 35 similar to earlier systems that were based on ( ppy)BMes 2 ( ppy = 2-phenylpyridine). 28 Substituting the pyridyl unit with an isoquinolyl enabled our group to design arylisoquinolinederived fluorophores with naphthyl (structures C with varying electron-donating substituents R) or anthryl (structure D).…”