海洋生物碱2,3-二羟基-10-溴吲哚[3,2-a]咔唑的简易合成

2,3-二羟基-10-溴吲哚[3,2-a]咔唑(1)是一种从海绵体中提取的具有多种潜在生物活性的天然海洋生物碱.本文作者以3,6-二溴吲哚(2)与5,6-二乙酰氧基吲哚(3)为原料,经过酸催化偶联、分子间成环两步关键反应构建吲哚[3,2-a]咔唑母核;所构建的吲哚[3,2-a]咔唑母核在碱性条件下水解脱去酚羟基上的酯基,即得到目标化合物1,总收率为48%.     

Revisiting Indolo[3,2-b]carbazole: Synthesis,Structures, Properties,and Applications

Indolo[3,2-b]carbazole presents a π-skeleton with a remarkable electronic structure and interesting potential applications. It is, however, also associated with ambiguity and controversy. Herein, new derivatives of indolo[3,2-b]carbazole are reported and they have enabled a comprehensive study on the electronic structure of indolo[3,2-b]carbazole and the development of a new n-type organic semiconductor. Experimental and computational studies show that indolo[3,2-b]carbazole has a largely localized p-benzoquinonediimine moiety and significant antiaromaticity. When substituted with (4-silylethynyl)phenyl groups, the indolo[3,2-b]carbazole exhibits one-dimensional π–π stacking and functions as an n-type organic semiconductor in solution-processed field effect transistors.     

Synthesis and properties of methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole

The synthesis and full characterization of new derivatives of indolo[3,2-b]carbazole with differently substituted phenyl groups at nitrogen atoms is reported. Comparative study on their thermal, optical electrochemical, and photoelectrical properties is presented. The synthesized compounds are electrochemically stable. Their highest occupied molecular orbital energy values range from -5.14 to -5.07 eV. The electron photoemission spectra of the films of synthesized materials revealed the ionization potentials of 5.31-5.47 eV. Hole drift mobility of the amorphous film of 5,11-bis(3-methoxyphenyl)-6-pentyl-5,11-dihydroindolo[3,2-b]carbazole exceed 10(-3) cm(2)/V·s at high electric fields, as it was established by xerographic time-of-flight technique. In contrast to diphenylamino substituted derivatives of carbazole, no effect of the position of methoxy groups on the photoelectrical properties was observed for the synthesized methoxyphenyl-substituted derivatives of indolo[3,2-b]carbazole. The indolo[3,2-b]carbazole core has a larger resonance structure that includes 3 phenyl rings, and thus the energy gap of the HOMO and LUMO π orbitals is lower as compared to that of carbazoles. With a larger energy difference between the phenyl substituents and the core moiety, the indolo[3,2-b]carbazole derivatives studied all have a weaker coupling between the phenyl group and a much weaker dependence of the molecular properties on the position of substituents on the phenyl groups as compared to those observed in substituted carbazoles.     

Revisiting Indolo[3,2‐b]carbazole: Synthesis,Structures, Properties,and Applications

Indolo[3,2‐b]carbazole presents a π‐skeleton with a remarkable electronic structure and interesting potential applications. It is, however, also associated with ambiguity and controversy. Herein, new derivatives of indolo[3,2‐b]carbazole are reported and they have enabled a comprehensive study on the electronic structure of indolo[3,2‐b]carbazole and the development of a new n‐type organic semiconductor. Experimental and computational studies show that indolo[3,2‐b]carbazole has a largely localized p‐benzoquinonediimine moiety and significant antiaromaticity. When substituted with (4‐silylethynyl)phenyl groups, the indolo[3,2‐b]carbazole exhibits one‐dimensional π–π stacking and functions as an n‐type organic semiconductor in solution‐processed field effect transistors.     

吲哚并咔唑类衍生物载流子传输性质的理论研究

以密度泛函理论结合跳跃模型, 重点研究了氯原子和烷基链的引入对吲哚并咔唑类衍生物传输性质的影响. 计算结果表明, 与吲哚并[3,2-b]咔唑(1)相比, 氯原子的引入增大了2,8-二氯吲哚并[3,2-b]咔唑(2)和2,8-二氯-5,11-二己基吲哚并[3,2-b]咔唑(3)的最高占据分子轨道(HOMO)的离域程度, 而对最低未被占据分子轨道(LUMO)则无显著贡献, 但明显降低了二者的能级. 上述结果表明, 对于LUMO, 氯原子体现了吸电子效应, 而对于HOMO, 氯原子体现了共轭效应. 烷基链的引入使化合物3的空穴迁移率明显高于化合物1和2, 这主要归因于化合物3具有更加紧密的分子堆积, 尤其在跳跃路径A中, 具有更大的分子间电子耦合和轨道重叠. 同时能带结构的计算结果进一步证明, 氯原子和烷基链的同时引入大大改善了吲哚并咔唑类衍生物的电荷传输性能.     

An efficient synthesis of indolo[3,2-a]carbazoles via the novel acid catalyzed reaction of indoles and diaryl-1,2-diones

A mild and efficient one pot method for the synthesis of indolo[3,2-a]carbazole derivatives by the para-toluenesulfonic acid catalyzed condensation of indole with acyclic 1,2-diones is described. With cyclobutene-1,2-diones the reaction afforded indole substituted carbazole derivatives in good yield.     

Synthesis and alkylation of indolo[3,2-b]carbazoles

Double Fischer cyclisation was used to prepare indolo[3,2-b]carbazole and its 2,8-di-OMe, OH, Br and F-derivatives. N-monosubstituted derivatives of indolo[3,2-b]carbazole (methyl, hydroxymethyl, dimethylaminoethyl) were obtained starting from 5,11-di-Boc-indolo[3,2-b]carbazole.     

Metathesis reactions for the synthesis of ring-fused carbazoles

[reactions: see text] The metathesis reaction is used as a key step for the synthesis of the indolo[2,3-a]carbazole core of rebeccamycin 13 and the sulfur analog of furostifoline 21. Using the same methodology for the attempted synthesis of furostifoline, we unexpectedly formed tert-butyl-2a-methyl-1,2,2a,10c-tetrahydro-6H-cyclobuta[c]furo[3,2-a]carbazole-6-carboxylate 26 from the unstable diene, tert-butyl 2-(2-isopropenyl-3-furyl)-3-vinyl-1H-indole-1-carboxylate 25, presumably via a spontaneous pi8 electrocyclization reaction.     

Facile synthesis of novel indolo[3,2-b]carbazole derivatives and a chromogenic-sensing 5,12-dihydroindolo[3,2-b]carbazole

Novel indolo[3,2-b]carbazole derivatives and a chromogenic-sensing 5,12-dihydroindolo[3,2-b]carbazole have been synthesized starting from tetra-tert-butylated 6,12-diaryl-5,11-dihydroindolo[3,2-b]carbazoles, which were prepared via an efficient tert-butylation of 6,12-diaryl-5,11-dihydroindolo[3,2-b]carbazoles.     

Indolo[3,2-b]carbazole-based thin-film transistors with high mobility and stability

Proper functionalization of indolo[3,2-b]carbazole led to a new class of high-performance organic semiconductors suitable for organic thin-film transistor (OTFT) applications. While 5,11-diaryl-substituted indolo[3,2-b]carbazoles without long alkyl side chains provided amorphous thin films upon vacuum deposition, those with sufficiently long alkyl side chains such as 5,11-bis(4-octylphenyl)indolo[3,2-b]carbazole self-organized readily into highly crystalline layered structures under similar conditions. OTFTs using channel semiconductors of this nature exhibited excellent field-effect properties, with mobility up to 0.12 cm(2) V(-1) s(-1) and current on/off ratio to 10(7). As this class of organic semiconductors has relatively low HOMO levels and large band gaps, they also displayed good environmental stability even with prolonged exposure to amber light, an appealing characteristic for OTFT applications.     

Synthesis of N-protected staurosporinones

We report a method for the synthesis of N-protected staurosporinones, which are useful for the synthesis of indolo[2,3-a]pyrrolo[3,4-c]carbazole alkaloids and related compounds. An interaction of gramine methiodide (2) with 3-(N-benzyl)indolylacetonitrile (3) in the presence of t-BuLi, followed by a CF3COOH-catalyzed intramolecular indole-indole coupling and dehydrogenation with DDQ, produced 5-cyanoindolo[2,3-a]carbazole 6 almost quantitatively. Reduction of its cyano group followed by N-benzylation produced N-benzylaminomethylindolo[2,3-a]carbazole 8b, which was subjected to Pd(OAc)2-catalyzed direct aromatic carbonylation to give N-protected staurosporinone 9b. Treatment with AlCl3 in anisole removed N-benzyl groups to afford staurosporinone quantitatively.     

Oxidative reactions of 6-pentyl indolo[3,2-b]carbazole: formation of novel C-C and C-N coupled dimers

The oxidative coupling reactions of 6-pentyl-5,11-dihydroindolo[3,2-b]carbazole have been studied and as a result, a number of novel dimers of the indolo[3,2-b]carbazole derivative have been prepared, forming C-C coupled compound when treated with FeCl(3) x 6H(2)O or C-N coupled compounds and when oxidized with air or Pd(OAc)(2), respectively.     

Synthesis of novel 2,8-disubstituted indolo[3,2-b]carbazoles

A new synthetic pathway towards 2,8-difunctionalised indolo[3,2-b]carbazoles was investigated. The presented method offers a short and high yielding route towards 2,8-dibromo-5,11-dihexyl-6,12-diphenyl-indolo[3,2-b]carbazole. It is demonstrated that the latter compound is a versatile building block, enabling the synthesis of a number of previously unreported 5,11-dialkyl-6,12-diphenyl-indolo[3,2-b]carbazoles in moderate to good yields, using Suzuki and Sonogashira cross-coupling reaction. Furthermore it is shown that 2,8-dibromo-5,11-dihexyl-6,12-diphenyl-indolo[3,2-b]carbazole can be easily formylated, giving rise to the 2,8-diformyl-5,11-dihexyl-6,12-diphenyl-indolo-[3,2-b]carbazole. The latter compound was successfully subjected to condensation reactions.     

Copper-catalyzed domino intramolecular cyclization: a facile and efficient approach to polycyclic indole derivatives

A mild and efficient Cu(2)O-catalyzed domino intramolecular C-N coupling/C-Y (Y = O, S, N) bond formation was successfully achieved. Thus oxazino[3,2-a]indole, thiazino[3,2-a]indole and indolo[2,1-b]quinazoline derivatives were facilely assembled from readily accessible gem-dibromovinyl systems. The protocol is general and practical, affording a variety of the indole-incorporated products in good to excellent yields even under air atmosphere.     

Structure elucidation of two tryptophan-derived, high affinity Ah receptor ligands

Background: Environmental contaminants, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other structurally related ‘environmental hormones’, exert their harmful biological effects through the Ah receptor signaling pathway. Several naturally occurring substances also bind to this receptor, but its natural role is still obscure. Tryptophan derivatives of the indolo[3,2-b]carbazole type, earlier suggested by us to be endogenous ligands for the receptor, should be a powerful tool in understanding receptor function. We therefore: set out to determine their identity.Results: The two tryptophan-derived Ah receptor ligands have been chemically analyzed and characterized by means of mass spectrometry, ¹H NMR and ¹³C NMR. UV, infra-red and fluorescence spectra were also recorded. All data are in accordance with the two compounds being closely related indolo[3,2-b]carbazole derivatives. Evidence is presented that compound A (MW = 312) is the symmetrical 6,12-diformylindolo[3,2-b]carbazole, and compound B (MW = 284) is the monosubstituted 6-formylindolo[3,2-b]carbazole.Conclusions: The elucidation of the structures of the two high affinity Ah receptor ligands 6,12-diformylindolo[3,2-b]carbazole and 6-formylindolo[3,2-b]carbazole provides the necessary basis for further mechanistic studies of this important group of compounds, and will help in determining the natural role of the Ah receptor.     

Synthesis of ladder-type pi-conjugated heteroacenes via palladium-catalyzed double N-arylation and intramolecular O-arylation

Ladder-type heteroacenes containing pyrrole or furan rings, indolo[3,2-b]carbazoles and dibenzo[d,d']benzo[1,2-b:4,5-b']difurans, were effectively synthesized from the common intermediates, 2,5-bis(o-chloroaryl)hydroquinones. The key reactions are palladium-catalyzed double N-arylation of aniline and intramolecular O-arylation, which enable regioselective ring closure. In addition to the parent indolo[3,2-b]carbazole and dibenzo[d,d']benzo[1,2-b:4,5-b']difuran, their derivatives with an alkyl or cyano group were first synthesized. Photophysical and electrochemical studies showed that the obtained heteroacenes have lower HOMO energy levels and larger band gaps than the corresponding hydrocarbon acene, pentacene. An X-ray analysis of dibenzo[d,d']benzo[1,2-b:4,5-b']difuran revealed that it was packed in herringbone fashion.     

Synthesis, structures, and properties of disubstituted heteroacenes on one side containing both pyrrole and thiophene rings

A new series of ladder-type heteroacenes containing both pyrrole and furan rings, 5,6-disubstituted diindolo[3,2-b:4,5-b']thiophenes (DITs), were effectively synthesized from N-functionalized 3,3'-dibromo-2,2'-biindoles undergoing intramolecular cyclization with bis(phenylsulfonyl) sulfide and organolithium. Single-crystal X-ray results demonstrate that 5,6-dipropyldiindolo[3,2-b:4,5-b']thiophene (4b) forms a herringbone-type of packing motif and 5,6-di(p-tolyl)diindolo[3,2-b:4,5-b']thiophene (4d) forms a parallel packing motif. Both of them have S-S contacts, enhancing the electronic transport between molecules. Their photophysical properties suggest that the skeleton of diindolo[3,2- b:4,5-b']thiophene is more favorable to aggregate in solid than that of indolo[3,2-b]carbazole. The large band gaps and low-lying HOMO energy levels could result in much better stability.     

Synthetic applications of cyanoacetylated bisindoles: synthesis of novel cycloheptadiindoles, indolocarbazoles, and related aza analogues

Cyclization reactions involving cyanoacetylated bisindoles have been studied, providing access to various novel cyclohepta[2,1-b:3,4-b']diindole derivatives as well as some related fused pentacyclic systems. Treatment of 3-cyanoacetyl-2,3'-diindolylmethane with methanesulfonic acid gave 6-(cyanomethyl)indolo[3,2-b]carbazole in a good yield.     

Indolocarbazoles: a new family of anion sensors

Simple preorganised indolo[2,3-a]carbazole derivatives are shown to recognise and sense anionic guest species using fluorescence spectroscopy.     

Synthesis of 2,3′-biindolyls and indolo[3,2-a]carbazoles

Several highly activated 2,3′-biindolyls were prepared from methyl 5,6-dimethoxyindole-2-carboxylate and oxindoles. The 2,3′-biindolyls were further transformed into a hydroxy indolo[3,2-a]carbazole and a bisindole amide.