Photochromic Properties of New Benzoindene‐Fused 2H‐Chromenes

The synthesis and the photochromic properties of new photochromic 6,7‐ and 7,8‐benzoindene annellated benzopyrans are described. When compared to parent indeno‐fused 2H‐chromenes (2H‐[1]benzopyrans), compounds 10 and 12 exhibit a significant bathochromic shift of maximum‐absorption wavelength, an increase in the colorability, and similar fading rates.     

Synthesis and Photochromic Behavior of Novel Annelated 2H‐Chromenes Derived from Hydroxy‐9H‐xanthen‐9‐ones

The synthesis of four novel pyrano‐xanthenones derived from hydroxy‐9H‐xanthen‐9‐ones is described, and their photochromic properties in solution are reported. All compounds synthesized exhibit a good colorability, making them good potential dyes. The presence of the chromone system fused in the 7,8‐position seems to lead to more stabilized colored forms.     

Synthesis and Reactivity of Photochromic 2H‐Chromenes Based on 3‐Carboxylated Coumarins

New photochromic 2H‐chromenes (=2H‐1‐benzopyrans) including a 3‐carboxylated coumarin nucleus were synthesized from hydroxycoumarins, and, in one case, the corresponding trimethoxysilylcarboxamide was prepared. The photochromic behavior was studied under flash‐photolysis conditions. The introduction of electron‐withdrawing substituents in this position of the coumarin nucleus led to a global and significant bathochromic shift in the spectra of the open forms and to an interesting intensification in the colorability.     

2‐Diazo‐2H‐indoles

2‐Diazo‐2H‐indoles were prepared by diazotization of the corresponding 1H‐indol‐2‐amines and subsequent neutralization. On the basis of NMR data and ab initio and semiempirical calculations, we suggest that the zwitterionic form A is the most representative structure for 2‐diazo‐2H‐indoles. In fact, spectral data are compatible with a 1H‐indole structure, and the fully optimized molecules gave distances in agreement with those reported for the anion obtained from 1H‐indole. The calculated charges are compatible with a zwitterionic structure in which the negative charge is mainly located at the ring N‐atom at variance with the case of diazopyrroles and 3‐diazo‐3H‐indoles where the negative charge is essentially located on the ipso C‐atom.     

Synthesis and Spectrokinetic Studies of a New Family of Photochromic 2H‐Chromenes (=2H‐1‐Benzopyrans): Dimethyl 6‐Aryl‐2,2‐dimethyl‐2H‐chromene‐7,8‐dicarboxylates

A series of dimethyl 6‐aryl‐2,2‐dimethyl‐2H‐chromene‐7,8‐dicarboxylates were synthesized, and the photochromic properties of this new family of dimethyl‐2H‐chromenes were studied under continuous irradiation. The presence of the methoxycarbonyl groups was shown to stabilize the colored forms. This stabilization depended on the solvent, and in two cases the formation of long‐lived opened forms was observed. Under irradiation with a mercury lamp, this family of 2H‐chromenes showed a strong resistance to photodegradation.     

Synthesis of Some New Spiro,Isolated and Fused Heterocycles Based on 1H‐indole‐2‐One

The reaction of 3‐benzoylcyanomethylidine‐1(H)‐indole‐2‐one ( 1 ) with a variety of active methylene compounds, thioglycolic acid, glycine, hydrazine hydrate and phenyl hydrazine led to the formation of compounds 4a‐d‐10 . 3‐Thiosemicarbazide‐1(H)‐indole‐2‐one 2 on reaction with α‐halocarbonyl compounds gave compounds 11a‐c, 12a‐c . The latter compounds on heating with phosphoryl chloride, cyclization takes place via losing water to give the angular tetracyclic compounds 13a,b and 14a‐c . Cyanoacetic hydrazone derivative 3 readily cyclized upon heating in triethyl orthoformate to give the tricyclic system, oxopyridazino indole 15 . On the other hand, the reaction of 3 with benzylidine malononitrile and benzylidene ethylcyanoactate gave the pyranyl hydrazone derivatives 16a,b .     

Benzo[c,d]indole‐Containing Aza‐BODIPY Dyes: Asymmetrization‐Induced Solid‐State Emission and Aggregation‐Induced Emission Enhancement as New Properties of a Well‐Known Chromophore

A series of symmetric and asymmetric benzo[c,d]indole‐containing aza boron dipyrromethene (aza‐BODIPY) compounds was synthesized by a titanium tetrachloride‐mediated Schiff‐base formation reaction of commercially available benzo[c,d]indole‐2(1H)‐one and heteroaromatic amines. These aza‐BODIPY analogues show different electronic structures from those of regular aza‐BODIPYs, with hypsochromic shifts of the main absorption compared to their BODIPY counterparts. In addition to the intense fluorescence in solution, asymmetric compounds exhibited solid‐state fluorescence due to significant contribution of the vibronic bands to both absorption and fluorescence as well as reduced fluorescence quenching in the aggregates. Finally, aggregation‐induced emission enhancement, which is rare in BODIPY chromophores, was achieved by introducing a nonconjugated moiety into the core structure.     

N‐{4‐Bromo‐2‐[(3‐bromo‐1‐phenylsulfonyl‐1H‐indol‐2‐yl)methyl]‐5‐methoxyphenyl}acetamide

In the title compound, C₂₄H₂₀Br₂N₂O₄S, the indole ring system is planar and the S atom has a distorted tetrahedral configuration. The sulfonyl‐bound phenyl ring is orthogonal to the indole ring system and the conformation of the phenyl­sulfonyl substituent with respect to the indole moiety is influenced by intramolecular C—H⃛O hydrogen bonds involving the two sulfonyl O atoms. The mean plane through the acetyl­amido group makes a dihedral angle of 57.0 (1)° with the phenyl ring of the benzyl moiety. In the crystal, glide‐related mol­ecules are linked together by N—H⃛O hydrogen bonds and C—H⃛π interactions to form molecular chains, which extend through the crystal. Inversion‐related chains are interlinked by C—H⃛π interactions to form molecular layers parallel to the bc plane. These layers are interconnected through π–π interactions involving the five‐ and six‐membered rings of the indole moiety.     

Synthesis,characterization and spectral studies of various newer 4‐benzyloxy‐1H‐indole‐2‐carboxylic acid (arylidene)‐hydrazides

4‐Benzyloxyindole‐2‐carboxylic acid hydrazide reacts with aromatic and heterocyclic aldehydes in alcoholic medium in refluxing conditions to give 4‐benzyloxy‐1H‐indole‐2‐carboxylic acid (arylidene)‐hydrazides, important synthetic intermediates for the synthesis of a newer class of pharmacologically active compounds. We describe here the synthesis of various 4‐benzyloxy‐1H‐indole‐2‐carboxylic acid (arylidene)‐hydrazides by conventional as well as microwave irradiation techniques. The structures of these compounds have been confirmed by spectroscopic techniques (FTIR, NMR and MS). Some of the interesting features of the electron impact mass spectral fragmentation pattern of these compounds are also discussed.     

Transformations of Methyl 2‐[(E)‐2‐(Dimethylamino)‐1‐(methoxycarbonyl)ethenyl]‐1‐methyl‐1H‐indole‐3‐carboxylate

A simple and efficient synthesis of novel 2‐heteroaryl‐substituted 1H‐indole‐2‐carboxylates and γ‐carbolines, compounds 1 – 3 , from methyl 2‐(2‐methoxy‐2‐oxoethyl)‐1‐methyl‐1H‐indole‐3‐carboxylate ( 4 ) by the enaminone methodology is presented.     

An organic photochromic compound: (2S)‐2′‐ethoxy‐1,3,3‐trimethyl‐6′‐(piperidin‐1‐yl)spiro[indoline‐2,3′‐3′H‐naphtho[2,1‐b][1,4]oxazine]

In the course of our synthesis of hybrid photochromic compounds, the unexpected new organic photochromic title compound, C₂₉H₃₃N₃O₂, (I), was obtained. It is a derivative of the parent spirooxazine 1,3,3‐trimethyl‐6′‐(piperidin‐1‐yl)spiro[indoline‐2,3′‐3′H‐naphtho[2,1‐b][1,4]oxazine], (II). The 2′‐ethoxy group gives (I) different photochromic properties from its parent spirooxazine (II).     

Synthesis and fluorescent properties of 2‐(1H‐benzimidazol‐2‐yl)‐phenol derivatives

A high yield one pot synthesis of 2‐(2‐hydroxyaryl)‐1H‐benzirrndazole derivatives by 2‐hydroxy aromatic aldehydes with aromatic 1,2‐diamines in the presence of manganese(III) acetate at room temperature was developed. Nine fluorescencers 2‐(2‐hydroxyaryl)‐1H‐benzirrndazoles with substituent(s) X (X = H, CH₃, CH₃O, Cl) and two fluorescencers 2‐(2‐hydroxyaryl)‐1H‐naphth[2,3‐d]imidazoles with substituent of H or Cl were prepared in 38–87% yield and the ultraviolet absorption and fluorescent spectra of the eleven compounds synthesized were measured in methanol. The fluorescent characteristics of the 2‐(2‐hydroxyaryl)benzimidazole derivatives prepared were investigated on the basis of excited‐state intramolecular proton transfer mechanism, Stokes' shift, quantum yield, and the relationship between fluorescent intensity and the substituents were derived.     

Synthesis and biological activities of new 1H‐1,2,4‐triazole alcohol derivatives containing a ferrocenyl moiety

Fourteen new 1H‐1,2,4‐triazole alcohol derivatives containing a ferrocenyl moiety were synthesized. In addition, six unexpected compounds, the hydroxyls of the title compounds, methylated by methanol, were obtained. The structures of all these new compounds were confirmed using ¹H NMR spectra, ¹³C NMR, MS and elemental analyses. Some compounds were also confirmed with IR spectra. The antifungal and plant growth regulatory activities of the title compounds are discussed. Copyright © 2008 John Wiley & Sons, Ltd.     

(E)‐2‐Methyl‐3‐(2‐methyl‐2‐nitro­vinyl)‐1H‐indole and (E)‐3‐(2‐methyl‐2‐nitro­vinyl)‐2‐phenyl‐1H‐indole

In the title compounds, C₁₂H₁₂N₂O₂, (I), and C₁₇H₁₄N₂O₂, (II), respectively, the indole rings are planar and the vinyl groups lie out of the indole planes, making dihedral angles of 33.48 (5) and 41.31 (8)°, respectively. In (II), the dihedral angle between the phenyl and indole ring planes is 32.06 (6)°. In both mol­ecules, the double bond connecting the methyl­nitro­vinyl group and the indole nucleus adopts an E configuration. Notwithstanding the differences in space group [C2/c for (I) and P2₁2₁2₁ for (II)], the mode of packing of compounds (I) and (II) is determined by similar inter­molecular N—H⋯O hydrogen‐bonding inter­actions, forming chains that run parallel to [101] in (I) and [001] in (II).     

Sensitivity and Resolution Development of Spiropyran‐based Molecular Photoswitches

The phenylazo moiety and its donor‐ and acceptor‐substituted derivatives are studied as effective auxochromes to improve their sensitivity and resolution for distinguishing between the spiro (SP; OFF) and mero (ON) forms in molecular photoswitching applications. Thus, 13 azospiropyran derivatives were synthesized and their spectroscopic and photokinetic behaviors were studied. The quality of photochromic reactions of the synthesized photochromic compounds were compared using a dose–response model. Interestingly, by replacing the nitro group in 6‐nitrospiropyran (ε = 0.42 × 10⁴ M^?1 cm^?1) with a simple phenylazo moiety, the SP form is still colorless and the color intensity of the merocyanine (MC) form is improved desirably by extending the conjugation length ( 1a , ε = 1.35 × 10⁴ M^?1 cm^?1). The presence of a hydrophilic OH group or a CH₃ group at the para position of phenylazo moiety revealed more or less the same photochromic properties as 1a . The OCH₃ group substituted at position 6 of the phenylazo moiety at the para position of the azobenzene moiety effectively increased the photochromic properties with the maximum k‐value for SP to MC switching. Meanwhile, Cl, Br, COOH, and NO₂ groups at the para position of the azobenzene moiety revealed the reduction in photochromic properties compared to 1a .     

Photochromic properties of η6‐2H‐chromene chromium tricarbonyl complexes

In the 2H‐chromene series, complexation of the aromatic ring with chromium tricarbonyl, under thermal conditions, is totally regioselective even when aromatic substituents are introduced on the pyran ring. The complexation stabilizes the open form of these photochromic compounds and reduces the thermal bleaching kinetic constant. Copyright © 1999 John Wiley & Sons, Ltd.     

The Synthesis and Biological Evaluation of N‐Substituted 1H‐Benzimidazol‐2‐yl‐1H‐pyrazole‐3,5‐diamines

The synthesis of 1H‐benzimidazol‐2‐yl‐1H‐pyrazole‐3,5‐diamines has been developed. Synthesized bisheteroaryls contain two privileged medicinal scaffolds, aminopyrazole and benzimidazole, with two diversity positions at N1 of benzimidazole and C3 of pyrazole, respectively. The three‐step synthesis includes the Mitsunobu N‐alkylation of benzimidazole and subsequent one‐pot formation of aminopyrazole involving substitution of methylthio groups with amine and hydrazine followed with final ring closure. Inhibitory activity toward cyclin‐dependent kinase 2/cyclin E and cytotoxicity against two cancer cell lines were evaluated for all novel pyrazoles. Two compounds showed modest cyclin‐dependent kinase inhibition activity and cytotoxicity against cancer cell lines K562 and MCF7.     

A new approach to the synthesis of 2‐aryl‐substituted benzimidazoles,quinazolines, and other related compounds and their antibacterial activity

A new synthesis method of benzimidazoles, dihydroquinazolines, and other related compounds containing a 2,4‐dihydroxyphenyl moiety was elaborated. Their structures were identified from elemental, infrared, ¹H NMR, ¹³C NMR, and mass spectra analyses. The minimal inhibitory concentration values of the compounds toward eight reference bacterial strains were determined by the two‐fold serial microdilution broth method. The compounds exhibited substantial inhibitory effects against the Gram‐positive strains tested contrary to Gram‐negative ones. The compounds of imidazopyridine, N‐methylbenzimidazole, and dihydroquinazoline structures exhibited the largest activity. The magnification of covering a two‐nitrogen atom heterocyclic ring fused to a benzene one decreases the biological effect. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:265–275, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21012     

Sodium 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate dihydrate

The title compound, Na⁺·C₉H₇N₄O₅S⁻·2H₂O, presents a Z configuration around the imine C=N bond and an E configuration around the C(O)NH₂ group, stabilized by two intra­molecular hydrogen bonds. The packing is governed by ionic inter­actions between the Na⁺ cation and the surrounding O atoms. The ionic unit, Na⁺ and 2‐oxo‐3‐semicarbazono‐2,3‐dihydro‐1H‐indole‐5‐sulfonate, forms layers extending in the bc plane. The layers are connected by hydrogen bonds involving the water mol­ecules.     

Synthesis of novel 5H, 11H‐pyrido[2′,3′:2,3]thiopyrano[4,3‐b]‐indoles by fischer‐indole cyclization

The synthesis of the title compounds 5H, 11H‐pyrido[2′,3′:2,3]thiopyrano[4,3‐b]indoles was accomplished by the Fischer indole cyclization of some 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones and 7‐methyl‐2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one phenylhydrazones. The synthesis of the new 2,3‐dihydrothiopyrano[2,3‐b]pyridin‐4(4H)‐one, which was used as one of the starting compounds, is also described.