Search

We developed a regiodivergent syntheses of 4- and 5-bromo-substituted 1,2,3-triazoles in copper-catalyzed azide–alkyne cycloadditions (CuAACs) by taking advantage of bromo(phosphoryl)ethyne 1 as a ...

Photoluminescent diamino-substituted dinaphthopentalenes were synthesized successfully by the treatment of in situ prepared dinaphthocyclooctadiyne with lithium amide. This reaction involves a series of transformations including the nucleophilic addition of the lithium amide to a triple bond of the cyclooctadiyne moiety, transannulation, protonation of the resulting pentalene anion, and the nucleophilic substitution of the pentalene core with the lithium amide. In this procedure, a novel double amination step plays a key role. When the diamino-substituted dinaphthopentalenes were irradiated with UV light in toluene, fluorescence was observed at around 580 nm (ΦF < 0.03).

A series of dibenzocyclooctatetraenes 6 bearing phenylethynyl and phenylsulfonyl groups were synthesized from bromo-substituted formylbenzyl sulfone 4 via cyclic dimerization of 4 and Sonogashira coupling of the resulting dibromocyclooctatetraene 3 with terminal acetylenes. The diamino derivative 6b exhibited dual emission with emission maxima at 436 and 547 nm. Furthermore, in the fluorescence of 6b, solvatofluorochromism was observed in response to solvent polarity, whereas in the solid states, mechanofluorochromism was observed.

Diiodo- and bromo, iodo-substituted dibenzopentalenes were obtained by treatment of 5,6,11,12-tetradehydrodibenzo[a,e]cyclooctene with I(2) and IBr, respectively. These dihalo-substituted pentalenes reacted with terminal ethynes in Sonogashira coupling and with arylboronic acid in Suzuki-Miyaura coupling to give a series of phenylethynyl- and/or aryl-substituted pentalenes. Suzuki-Miyaura coupling of the halopentalenes with in situ prepared pentaleneboronic esters provided bis-, tri-, and tetra(dibenzopentalene)s. It was found that these dibenzopentalene oligomers underwent facile electrochemical reduction and exhibited a bathochromic shift in UV-vis absorption spectra because of their expanded π-systems.

[reaction: see text] Syntheses of 2-aryl and 2,3-substituted indoles were realized by modified double elimination protocol. Under basic conditions, vinyl sulfones derived from the reaction of 2-aminobenzyl sulfone with benzaldehydes underwent cyclization and alkylation followed by elimination of sulfinic acid to afford 2,3-substituted indoles.