Synthesis of 2,6-Diaminoazulenes by the SNAr Reaction with Cyclic Amines

Abstract

2-Amino-6-bromoazulene derivatives reacted with cyclic amines (pyrrolidine, piperidine and morpholine) under the sealed-tube conditions to afford the corresponding 2,6-diaminoazulenes in excellent yields. Aromatic compounds with multiple-amino functional groups have been of great interest owing to their potential applications in organic electronic devices, such as hole transport materials for organic light-emitting diodes. 1 Therefore, a large number of synthetic procedures for aromatic compounds with multiple-amino groups were found in literatures. 2 In the pioneering works of azulene chemistry by Nozoe et al., 2,6-diaminoazulenes were first synthesized from an aminotropolone derivative, but the procedure requires a multistep reaction for the preparation of the starting tropolone derivatives which are essential to the preparation of 2,6-diaminoazulenes with different amino functions. 3 They have also reported that the most promising intermediate, diethyl 2-amino-6-bromoazulene-1,3-dicarboxylate (1) that could be obtained much easier, does not react with † Dedicated to Professor Isao Kuwajima on the occasion of his 77th birthday

Synthesis of 2-amino- and 2-arylazoazulenes via nucleophilic aromatic substitution of 2-chloroazulenes with amines and arylhydrazines

“…Thus, the reaction was performed at 150 °C in a sealed tube, as these had been shown previously to be successful conditions for the synthesis of 2,6diaminoazulene derivatives. 13 The S N Ar reaction of 2 with morpholine at 150 °C in a sealed tube afforded the desired product 10…”

Synthesis, Properties, and Redox Behavior of Tris(1‐azulenyltetracyanobutadiene) and Tris[1‐azulenylbis(tetracyanobutadiene)] Chromophores Connected to a 1,3,5‐Tri(1‐azulenyl)benzene Core

“…[19] Recently, we have developed various redoxactive chromophores for the creation of stabilized electro-7 chromic materials. [20] As a part of the study, we have reported several TCBD derivatives bearing azulenyl, [10][11][12]14] ferrocenyl, [21] and 2-oxo-2H-cyclohepta[b]-3-furyl [22] substituents, and we have identified some hybrid structures of violene and cyanine with redox activities. [23] Similarly to the TCBD derivatives described previously, these new 1-AzTCBD compounds connected through a 1,3,5-tri(1-azulenyl)benzene core should exhibit a reversible color change under electrochemical reaction conditions, because these compounds showed highly reversible redox waves by CV.…”

“…Recently, we reported the redox potentials of a series of TCBD derivatives. [10][11][12]14] The study revealed that the first reduction potentials of the 1-AzTCBD compounds substituted by π-electron cores decreased as the number of substituted TCBD units increased. With respect to the number of stages for the reduction, Diederich et al reported that the compound with three DAA-substituted TCBD units connected by a 1,3,5-benzenetriyl spacer shows a six-stage reversible reduction wave within a narrow potential range.…”

“…The preparation of tris(1-azulenylacetylene) and tris(1-azulenylethynylarylacetylene) compounds connected to a 1,3,5-tri(1-azulenyl)benzene core (10)(11)(12) for the precursors of new C 3 -symmetrical molecules with multiple 1-AzTCBD units was accomplished by simple one-pot reactions involving repeated Pd-catalyzed alkynylation of the corresponding 1-ethynylazulene derivative 5 with 4 or 7 with methyl 3-[(4-iodophenyl)ethynyl]-7-isopropylazulene-1-carboxylate (8) [14] and methyl 3-[(5-iodo-2-thienyl)ethynyl]-7-isopropylazulene-1-carboxylate (9) [14] under Sonogashira-Hagihara cross-coupling conditions. [15] The cross-coupling reaction of 4 and 5 with [Pd(PPh 3 ) 4 ] as a catalyst and subsequent chromatographic purification of the reaction mixture afforded the desired product 10 in 84 % yield.…”

Direkter Zugang zu Azulenen über eine Gold‐katalysierte Dimerisierung von Diarylalkinen

“…[24] Sowohl das 4-als auch das 6-Fluor-Azulen setzten sich mit Morpholin glatt um und ergaben 3a bzw. Da in unserem Fall alle Positionen des fünfgliedrigen Rings blockiert sind, wird eine selektive Funktionalisierung des siebengliedrigen Rings mçglich.…”