Synthesis of N,N,N′,N′-tetrasubstituted 1,3-bis(4-aminophenyl)azulenes and their application to a hole-injecting material in organic electroluminescent devices

General Suzuki Coupling of Heteroaryl Bromides by Using Tri‐tert‐butylphosphine as a Supporting Ligand

“…The new method proved superior to existing procedures. [18] In one example, coupling of electron-poor p-F 3 CC 6 H 4 B(OH) 2 led to 55 % yield of the product, and the main byproduct was by monoarylation (ca. 30 %).…”

Progress towards synthetic chlorins with graded polarity, conjugatable substituents, and wavelength tunability

“…The same synthesis carried out here at 0.57 mmol reactants gave 119 mg of the chlorin (34%) as shown in Scheme 10. Palladium coupling of ZnC-22 with dimethylamine (10 equiv) with Pd(OAc) 2 (40 mol%), ( tert -Bu) 3 PHBF 4 (40 mol%), and tert -BuONa (3 equiv) in refluxing toluene for 48 h [72] afforded 3-dimethylaminochlorin ZnC-23 in 49% yield. Palladium coupling of ZnC-22 with sodium thiomethoxide under conditions used for aryl thioether formation (20 mol% of Pd 2 (dba) 3 and Xantphos in refluxing xylene) [73] afforded 3-methylthiochlorin ZnC-24 in 95% yield.…”

Synthesis of 1‐Heteroaryl‐ and 1,3‐Bis(heteroaryl)azulenes: Electrophilic Heteroarylation of Azulenes with the Triflates of N‐Containing Heteroarenes

“…[12] More recently, Oda and co-workers reported the efficient Suzuki-Miyaura and Stille cross-coupling reactions of 1-halo-and 1,3-dihaloazulenes. [13] However, the procedures require either an electron-withdrawing group on the azulene ring at the 3-position or an excess amount of arylboronate or stannyl reagent. As a direct heteroarylation of azulenes, we have recently reported the Reissert-Hanzetype reaction of azulenes with N-oxides of heteroarenes in the presence of trifluoromethanesulfonic anhydride (Tf 2 O) to give the corresponding 1-heteroarylazulenes, but in low yields.…”

“…[16] Aromatization of both 20 and 21 was achieved by treatment with KOH in EtOH to afford 22 and 23 in 97 % and 99 % yields, respectively (Scheme 6). The transition-metal-catalyzed synthesis of symmetrically substituted 1,3-diarylazulenes has been reported, [13] but the synthesis of asymmetrically substituted 1,3-diarylazulenes still remains as a problem. Thus, to evaluate this methodology, we also examined the introduction of two different heteroaryl substituents at the 1-and 3-positions of the azulene ring.…”

“…Transition-metal-catalyzed aryl-aryl cross-coupling usually requires both aryl halides and aryl organometallic reagents for the construction of the biaryl compounds. In the azulene chemistry, although many transition-metal-catalyzed aryl-aryl cross-coupling reactions have been developed, [10,11,13] the synthesis of 1-arylazulenes by such methods might be difficult because of the instability of 1-haloazulenes and/or 1-azulenylmetallic reagents. The advantageous feature of our synthetic methodology is that these reactions do not require any transition metal catalyst, aryl halide, or coupling reagent.…”