Synthesis of 2- and 6-thienylazulenes by palladium-catalyzed direct arylation of 2- and 6-haloazulenes with thiophene derivatives

Abstract

Preparation of 2- and 6-thienylazulene derivatives was established by the palladium-catalyzed direct cross-coupling reaction of 2- and 6-haloazulenes with the corresponding thiophene derivatives in good yield. Several thienylazulene derivatives were also used in the reaction with 2-chloroazulene derivatives in the presence of the palladium-catalyst to afford the thiophene derivatives with two azulene functions in good yield.

Construction of Polycyclic π‐Conjugated Systems Incorporating an Azulene Unit Following the Oxidation of 1,8‐Diphenyl‐9,10‐bis(phenylethynyl)phenanthrene

“…Moreover, recent advances in transition metal‐mediated functionalizations such as borylation, arylation, and silylation have provided methods to develop fascinating azulene‐based materials . Unlike alternant π‐conjugated systems, the non‐alternant structure of azulene contributes to the construction of peculiar π‐conjugated systems . In addition to the electronic perturbations of the alternant π‐conjugated systems, many three‐dimensional nanocarbon structures with curvature have been proposed by embedding pentagons or heptagons in the hexagonal honeycomb lattice .…”

“…[15][16][17][18] Unlike alternant p-conjugated systems, the non-alternant structure of azulenec ontributes to the construction of peculiar p-conjugated systems. [19][20][21][22][23][24][25][26] In addition to the electronic perturbations of the alternant p-conjugated systems, many three-dimensional nanocarbon structuresw ith curvature have been proposed by embedding pentagons or heptagonsi nt he hexagonal honeycomb lattice. [5,[27][28][29][30][31] Thus, the embedding of an azulenec ore into alternant PAHs could change both the molecular geometry and the electronicp roperties of the originalP AHs.…”

Recent Advances in the Functionalization of Azulene Through Pd‐Catalyzed Cross‐Coupling Reactions

“…Shoji et al [115] . reported excellent yields of 2‐thienylazulene derivatives 268 from a palladium‐catalyzed direct cross‐coupling reaction of 2‐chloroazulenes 266 with thiophene derivatives 267 (Scheme 102, Table 9).…”

“…Shoji et al [115] . investigated the cross‐coupling reaction of 266 with the thienylazulenes 269 , and 271 to get thiophene derivatives 270 , and 272 , respectively, having two azulene functionalities.…”

Development of Heterocycle-Substituted and Fused Azulenes in the Last Decade (2010–2020)

“…Direct preparation of 2-thienylazulene derivatives by employing the C–H bond activation reaction has also been reported ( Scheme 29 ) [ 47 ]. The reaction of 2-chloroazulene derivative 89 with 3,4-ethylenedioxythiophene (EDOT) in the presence of Pd(OAc) 2 , PCy 3 ·HBF 4 , pivalic acid (PivOH), and K 2 CO 3 to produce 2-thienylazulene derivative 90 in 81% yield, which reacts further with 89 to afford symmetric 2,5-di(2-azulenyl)thiophene derivative 91 in 88% yield.…”