Fluorinated Phenanthrenes as Aryne Precursors: PAH Synthesis Based on Domino Ring Assembly Using 1,1‐Difluoroallenes

Abstract

On treatment with the catalyst InBr 3 , 1,1-difluoroallenes that bear a cyclopentene moiety and an aryl group underwent domino ring assembly in the presence or absence of N-bromosuccinimide or N-iodosuccinimide to afford aryne precursors such as three-ringed ortho-fluoro(halo)phenanthrenes, four-ringed ortho-fluoro(halo)tetraphenes, orthofluoro(halo)chrysenes and fluoro [4]helicenes. Metalation of the aryne precursors followed by elimination of the fluoride resulted in the unprecedented systematic generation of arynes bearing π-extended systems. DielsÀ Alder reactions of these arynes with isobenzofurans afforded the corresponding cycloadducts whose reductive aromatisation in an SnCl 2 /HBr system furnished fully aromatised benzotriphenylenes. In addition, oxidative arylÀ aryl coupling (the Scholl reaction) of these benzotriphenylenes facilitated the synthesis of 'half HBCs' (hexabenzocoronenes).[a] Dr.

An oxanorbornene-fused nanocage consisting of hexaazatrinaphthylene and pyrene units

“…Treatment of 1 with TiCpCl 2 /Zn 26 or Fe 2 (CO) 9 27 led to the recovery of the starting material, while treatment of 1 with LiAlH 4 /TiCl 4 , 28 TiCl 4 /Zn, 29 or NaI/trimethylsilyl iodide (TMSI) 30 resulted in only partial removal of the six bridging oxygen atoms, as indicated by the mass spectra of the crude products. When 1 (C 252 H 234 N 12 O 6 ) in THF was treated with an excess of SnCl 2 in a solution of HBr in acetic acid 31 at room temperature under an atmosphere of N 2 , the HRMS of the crude product (Fig. S14 in the ESI†) showed a major molecular ion peak of m / z = 3439.9520 corresponding to a molecular formula of C 252 H 244 N 12 ( m / z = 3439.9522).…”

Discussion Addendum for: Preparation of 1,1-Difluoroallenes by Difluorovinylidenation of Carbonyl Compounds

“…Secondly, the synthesis of "half HBCs" was facilitated by p-extended aryne generation from 1,1-difluoroallenes (Scheme 2). 6 The structure of half HBCs is a half section of HBCs (hexabenzocoronenes), which are promising as materials for photovoltaic cells. o-Bromoor o-iodofluoroarenes 7 were prepared by the In(III)-catalyzed domino reaction of 1,1-difluoroallenes involving halogenation of the C-In bond with N-bromosuccinimide (NBS) or N-iodosuccinimide (NIS).…”

Fluorine-Activated and -Directed Allene Cycloadditions with Nitrile Oxides and Imine Oxides: Synthesis of Ring-Fluorinated Isoxazole Derivatives

“…In addition to the aforementioned characteristics, the fluorine substituent exhibits an α-carbocation stabilizing effect. − We have reported (i) the In-catalyzed domino cyclization/ring expansion sequence of 1,1-difluoroallenes (eq ) and (ii) the Au-catalyzed regioselective addition of heteroatom nucleophiles to 1,1-difluoroallenes (eq ) by employing this effect. Theoretical computations demonstrated that the In and Au catalysts produced localized difluoroallylic cations from difluoroallenes.…”