Four Iodine‐Mediated Electrophilic Cyclizations of Rigid Parallel Triple Bonds Mapped from 1,8‐Dialkynylnaphthalenes

Abstract

Four different types of fused arenes, including fluoranthene, indeno[2,1-a]phenalene, (8H)cyclopenta[a]acenaphthylene, and pyridine[a]acenaphthylene, were efficiently constructed through iodine-mediated electrophilic cyclizations of 1,8-dialkynyl naphthalenes in a single step. Theoretical calculations supported our hypothesis that these reactions had high regioselectivity. Oxidative coupling of the fluoranthene skeleton, followed by aromatization, effectively synthesized perylene derivative 14, which emitted light at 597 nm in dichloromethane with an emission efficiency of 0.81 referred to 5,6,11,12-tetraphenylnaphthacene as a standard.

Intramolecular Domino Electrophilic and Thermal Cyclization of peri‐Ethynylene Naphthalene Oligomers

“…[29] Compound 17 possibly arose from the unstable compound 6 in a sequence of cyclization reactions via the diradical intermediates 17' and 17'' followed by hydrogen migration (Scheme 3). In addition, the homocoupling product of 16, 1,4-bis[8-(2-phenylethynyl)naphthalen-1-yl]buta-1,3-diyne (18), was also separated from the reaction mixture and its structure was determined by X-ray crystallographic analysis ( Figure 3). [30] Similarly, Sonogashira-Hagihara coupling reaction between 11 and 16 did not give the expected product 7, but instead a complicated mixture was obtained.…”

“…Keywords: cyclization · domino reactions · fluoranthenes · hydrocarbons · polycycles naphthalenes. [18] Transition-metal-mediated cycloaromatization of the peri-diyne in 4 with external alkynes was reported by Siegel et al to provide a general route to indenofused PAHs. [19] So far, studies on reactions of peri-ethynylene units have mostly focused on compounds with two parallel triple bonds, but attempts to further elongate the arylene ethynylene oligomeric chain have seldom been reported [20] because of difficulties such as complicated reactions and challenging separation and structural determination of the products.…”

Borylative cyclisation of diynes using BCl3 and borocations

“…Compound 15 can be isolated post pinacol protection in 82% yield and is analogous to the cyclisation product derived from 14 using I 2 as the electrophile. 18 Again the BCl 3 route is complementary to I 2 induced cyclisation as the former installs a C-BPin nucleophilic moiety instead of an electrophilic C-I unit. We attribute the absence of any chlorine incorporated product in the borylative cyclisation of 14 with BCl 3 to a lower barrier to S E Ar due to the vinyl cation intermediate containing a six membered ring (ring A, inset Fig.…”

Synthesis of Benzo[k]fluoranthene Derivatives through Diels–Alder Reaction of 1,3‐Diarylbenzo[c]furans

“…The synthesis of benzo[ k ]fluoranthene was realized through iodine‐mediated cyclization of disubstituted 1,8‐dialkynylnaphthalenes followed by Suzuki coupling and subsequent aromatization with 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ). The dimerization of the resulting benzo[ k ]fluoranthene by DDQ/MeSO 3 H afforded highly conjugated perylene …”