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The modular synthesis of a fluorene-based nanohoop containing six strained alkynes is described herein. We demonstrate its scalability using alkyne metathesis as the macrocyclization method and its reactivity with azides... 

Abstract In this work we report the synthesis, structure, and electronic properties of carbon‐rich compounds dehydrobiphenyleno[12]annulenes (DBP[12]As) comprising antiaromatic four‐membered rings (4MR) and 12‐membered ring (12MR). Ultraviolet–visible absorption spectra and electrochemical behaviors of DBP[12]As confirmed their relatively narrow highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap values and high HOMO energy levels, which were supported by density functional theory simulations. Parent DBP[12]A adopts a slipped herringbone structure in a crystalline state, with the molecules forming 1D stacks via π–π interactions. The experimentally derived bond lengths, bonding analyses using the Wiberg bond indices, and localized orbital locator calculation support a stronger double bond character for the 12MR bonds than the 4MR bonds in the inner six‐membered ring. The chemical shifts of hydrogens in¹H NMR spectra, as well as magnetically induced ring current analyses using quantum chemical calculations, indicate that the 4MRs have stronger antiaromatic character than the 12MR. The present information is useful for a fundamental understanding of carbon‐rich compounds with different antiaromatic units as well as designing novel molecules with unique electronic properties. 

Abstract The activation of chalcogenoglycosides forO‐glycosylation typically involves strong electrophiles requiring low temperature. Herein, we demonstrate that visible‐light irradiation of selenoglycosides in the presence of Umemoto's reagent results in often high‐yieldingO‐glycosylation. We provide evidence that this process is mediated by a novel mode of reactivity, specifically photoinduced electron transfer within a chalcogen‐bonded complex. 

Large scale synthesis of cycloparaphenyleneacetylenes has been challenging due to low macrocyclization yields and harsh aromatization methods that often decompose strained alkynes. Herein, a cis -stilbene-based building block is subjected to alkyne metathesis macrocylization. The following sequence of alkene-selective bromination and dehydrobromination afforded a [8]cycloparaphenyleneacetylene derivative in high yield with good scalability. X-Ray crystal structure and computational analysis revealed a unique same-rim conformation for the eight methyl groups on the nanohoop.