Synthese und Kristallstruktur des Dichlor‐Adduktes von 2, 3‐Dihydro‐1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐yliden [1]

Synthesis and Crystal Structure of the Dichlorine Adduct of 2, 3‐Dihydro‐1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐ylidene [1] 2, 3‐Dihydro‐1, 3‐diispropyl‐4, 5‐dimethylimidazol‐2‐ylidene ( 1 , Im) reacts with hexachloroethane to give the charge‐transfer adduct Im‐Cl‐Cl ( 2 ) in almost quantitative yield. The crystal structure of 2 reveals the presence of a near linear C‐Cl‐Cl fragment [Cl‐Cl 3.159(3)Å, C‐Cl‐Cl 166.1(1)°] which is discussed as weak chlorine interaction causing hypervalency at the central chlorine atom.     

PPh3‐catalyzed knoevenagel condensation: A facile synthesis of 5‐(1H‐indol‐3‐yl)Meth‐ ylene)‐2, 2‐Dimethyl‐1, 3‐Dioxane‐4, 6‐dione,and their N‐alkyl derivatives by using peg‐600 as the reaction medium

Triphenylphosphine (TPP) has been utilized as a novel and efficient catalyst for the Knoevenagel condensation of indole‐3‐carboxaldehydes 1(a–e) , 1‐methyl‐1H‐indole‐3‐carboxaldehydes 4(a–e) , and 1‐ethyl‐1H‐indole‐3‐carboxaldehydes 6(a–e) with the active methylene compound, that is, meldrum's acid ( 2 ), to afford substituted derivatives 5‐((1H‐indol‐3‐yl) methylene)‐2,2‐dimethyl‐1,3‐dioxane‐4,6‐dione 3(a–e) , 2,2‐dimethyl‐5‐((1‐methyl‐1H‐indol‐3‐yl)methylene)‐1,3‐dioxane‐4,6‐dione 5(a–e) , and 2,2‐dimethyl‐5‐((1‐ethyl‐1H‐indol‐3‐yl)methylene)‐1,3‐dioxane‐4,6‐dione 7(a–e) , respectively, in ethanol medium at RT just within 1 h in excellent yields. The products 3(a–e) were reacted independently with alkylating agents, that is, DMS and DES in the presence of PEG‐600 as an efficient and green solvent, to afford the corresponding N‐substituted methyl and ethyl derivatives 5(a–e) and 7(a–e) , respectively. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 23:41–48, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20750     

A structural study of (1RS,2SR,3RS,4SR,5RS)‐2,4‐dibenzoyl‐1,3,5‐triphenylcyclohexan‐1‐ol chloroform hemisolvate and (1RS,2SR,3RS,4SR,5RS)‐2,4‐dibenzoyl‐1‐phenyl‐3,5‐bis(2‐methoxyphenyl)cyclohexan‐1‐ol

(1RS,2SR,3RS,4SR,5RS)‐2,4‐Dibenzoyl‐1,3,5‐triphenylcyclohexan‐1‐ol or (4‐hydroxy‐2,4,6‐triphenylcyclohexane‐1,3‐diyl)bis(phenylmethanone), C₃₈H₃₂O₃, (1), is formed as a by‐product in the NaOH‐catalyzed synthesis of 1,3,5‐triphenylpentane‐1,5‐dione from acetophenone and benzaldehyde. Single crystals of the chloroform hemisolvate, C₃₈H₃₂O₃·0.5CHCl₃, were grown from chloroform. The structure has triclinic (P) symmetry. One diastereomer [as a pair of (1RS,2SR,3RS,4SR,5RS)‐enantiomers] of (1) has been found in the crystal structure and confirmed by NMR studies. The dichoromethane hemisolvate has been reported previously [Zhang et al. (2007). Acta Cryst. E 63 , o4652]. (1RS,2SR,3RS,4SR,5RS)‐2,4‐Dibenzoyl‐3,5‐bis(2‐methoxyphenyl)‐1‐phenylcyclohexan‐1‐ol or [4‐hydroxy‐2,6‐bis(2‐methoxyphenyl)‐4‐phenylcyclohexane‐1,3‐diyl]bis(phenylmethanone), C₄₀H₃₆O₅, (2), is also formed as a by‐product, under the same conditions, from acetophenone and 2‐methoxybenzaldehyde. Crystals of (2) have been grown from chloroform. The structure has orthorhombic (Pca2₁) symmetry. A diastereomer of (2) possesses the same configuration as (1). In both structures, the cyclohexane ring adopts a chair conformation with all bulky groups (benzoyl, phenyl and 2‐methoxyphenyl) in equatorial positions. The molecules of (1) and (2) both display one intramolecular O—H...O hydrogen bond.     

Ligand‐free,copper‐catalyzed,one‐pot,three‐component synthesis of novel 1,2,3‐triazole‐linked indoles in magnetized water

Magnetized water (MW) is used as a green and new solvent‐promoting medium for the one‐pot, three‐component synthesis of novel 1,2,3‐triazole‐linked indoles catalyzed by copper iodide. A broad range of 2‐aryl‐1‐(prop‐2‐ynyl)‐1H‐indole‐3‐carbaldehydes were reacted with alkyl halides and sodium azide via copper‐catalyzed azide–alkyne cycloaddition reactions in MW in the absence of any ligand. This method offers the advantages of short reaction times, green procedure, low cost, simple work‐up, quantitative reaction yields, and no need for any organic solvent.     

A New Class of Organosuperbases,N‐Alkyl‐ and N‐Aryl‐1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐ylidene Amines: Synthesis,Structure, pKBH+ Measurements,and Properties

A series of stable organosuperbases, N‐alkyl‐ and N‐aryl‐1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐ylidene amines, were efficiently synthesized from N,N′‐dialkylthioureas and 3‐hydroxy‐2‐butanone and their basicities were measured in acetonitrile. The derivatives with tert‐alkyl groups on the imino nitrogen were found to be more basic than the tBu P₁ (pyrr) phosphazene base in acetonitrile. The origin of the high basicity of these compounds is discussed. In acetonitrile and in the gas phase, the basicity of the alkylimino derivatives depends on the size of the substituent at the imino group, which influences the degree of aromatization of the imidazole ring, as measured by ¹³C NMR chemical shifts or by the calculated ΔNICS(1) aromaticity parameters, as well as on solvation effects. If a wider range of imino‐substituents, including electron‐acceptor substituents, is treated in the analysis then the influence of aromatization is less predominant and the gas‐phase basicity becomes more dependent on the field‐inductive effect, polarizability, and resonance effects of the substituent.     

Functionalization of Quinazolin‐4‐ones Part 3: Synthesis,Structures Elucidation,DNA‐PK,PI3K,and Cytotoxicity of Novel 8‐Aryl‐2‐morpholino‐quinazolin‐4‐ones

A series of novel 8‐aryl‐2‐morpholino quinazolines ( 11a – n , 12a – d , 14a – f , and 15 ) were synthesized from the precursor 2‐thioxo quinazolin‐4‐ones 8 . The 8‐aryl‐2‐morpholino quinazolines compounds were assayed for DNA‐PK and PI3K. All compounds showed low DNA‐PK % inhibition activity at 10 μM compound concertation, and the most active was 8‐(dibenzo[b,d]thiophen‐4‐yl) 12d with 38% inhibition. Similar pattern of PI3K α, β, γ, and δ isoforms inhibition activity at 10 μM were observed. The most active isoform was PI3K δ of 41% inhibition for 8‐(dibenzo[b,d]furan‐4‐yl) compound 11 . Most compounds were less active than expected in spite of the strong structural resemblance to known inhibitors ( NU7441 , 3 , 4 , and 6 ). Loss of activity could be attributed to the tautomerization to the aromatic enol (4‐OH), which could specify that the important functional group for the activity is the 4‐carbonyl (C=O) group. Alternatively, the aromatization of the pyrimidine heterocyclic ring could alter the conformation, and thus binding site, of the 2‐morpholine ring, which could reduce the compound‐receptor hydrogen bonding to the morpholine 4‐oxygen. Selected compounds displayed appreciable cytotoxicity with 6‐chloro‐8‐(dibenzo[b,d]thiophen‐4‐yl)‐2‐morpholinoquinazolin‐4(1H)‐one 11j exhibiting the greatest activity with an IC₅₀ of 9.95 μM. Therefore, the mechanism of the cytotoxicity of compound 11j were not through DNA‐PK or PI3K inhibition activity.     

Synthesis,characterization, and crosslinking of methacrylate‐telechelic PDMAAm‐b‐PDMS‐b‐PDMAAm copolymers

The synthesis and molecular characterization of a new amphiphilic conetwork (APCN) designed for silicone hydrogel use is described. The synthesis strategy, outlined in Scheme 1 , calls for the preparation, by the RAFT technique, of a new methacrylate‐telechelic amphiphilic pentablock, MA‐PHEA‐b‐PDMAAM‐b‐PDMS‐b‐PDMAAm‐b‐PHEA‐MA, and its crosslinking to the target APCN. The sketch shows the architecture of the APCN (dotted lines, PDMAAm; solid lines, PDMS; clusters, MA‐based crosslinking sites; see Fig. 3 ). All six synthesis steps proceed smoothly and efficiently, and the products are optically clear, colorless membranes exhibiting properties appropriate for ophthalmic use. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4284–4290, 2007     

Trimerization of 4‐Amino‐3,5‐dinitropyrazole: Formation,Preparation, and Characterization of 4‐Diazo‐3,5‐bis(4‐amino‐3,5‐dinitropyrazol‐1‐yl) pyrazole (LLM‐226)

4‐Amino‐3,5‐dinitropyrazole (LLM‐116, 1 ) undergoes trimerization to 4‐diazo‐3,5‐bis(4‐amino‐3,5‐dinitropyrazol‐1‐yl) pyrazole (LLM‐226) upon heating. A mechanism is proposed and discussed. LLM‐226 is a new diazo‐based energetic material, thermally stable, and insensitive to impact, friction, and spark. The material may be prepared by heating 1 and 4‐diazo‐3,5‐dinitropyrazole ( 2 ) in a mixture of toluene and butyl acetate at 110°C or heating 1 alone in dichlorobenzene at 160°C. The characterization of LLM‐226 including X‐ray crystallographic analysis and small‐scale safety properties will be discussed.     

Synthesis,Characterization, and Herbicidal Activities of New 1,3,4‐Oxadiazoles, 1,3,4‐Thiadiazoles,and 1,2,4‐Triazoles Derivatives Bearing (R)‐5‐Chloro‐3‐fluoro‐2‐phenoxypyridine

Synthesis of some novel 1,2,4‐triazoles, 1,3,4‐oxadiazoles and 1,3,4‐thiadiazoles bearing a (R) 5‐(1‐(4‐(5‐chloro‐3‐fluoropyridin‐2‐yloxy)phenoxy)ethyl) unit, as a moiety of commercial herbicide, using their thiosemicarbazides in an alkaline, iodine and acidic media is reported, respectively. The structure of the synthesized compounds was characterized by IR, ¹H, ¹³C NMR spectroscopic data, and elemental analyses. The herbicidal activities of synthesized compounds were evaluated against Echinochloa cruss‐galli, Avena fatua, and Sorgum halepense weeds. Compounds 7 and 12a showed potential herbicidal activity against gramineous weeds. Our results may provide some guidance for synthesis development of some novel oxa or thiadiazole and triazole‐based herbicidal lead structures.     

Structure and Photochemical Properties of r‐1, c‐2, t‐3, t‐4‐l, 3‐Bis [2‐ (5‐R‐benzoxazolyl) ] −2,4‐di (4‐R' ‐phenyl) cyclobutane

r‐1, c‐2, t‐3, t‐4‐1,3‐Bis[2‐(5‐R‐benzoxazolyl)]‐2,4‐di(4‐R'‐phenyl)cyclobutane (IIa: R=R' = H; IIb: R=Me, R'= H; IIc: R = Me, R' = OMe) was synthesized with high stereo‐selectivity by the photodimerization of trans‐l‐[2‐(5‐R‐benzoxazolyl)]‐2‐(4‐R'‐phenyl) ethene (Ia: R=R' = H; Ib: R = Me, R' = H; Ic: R = Me, R' = OMe) in sulfuric acid. The structures of IIa–IIc were identified by elemental analysis, IR, UV, ¹H NMR, ¹³C NMR and MS. The molecular and crystal structure of IIc has been determined by X‐ray diffraction method. The crystal of IIc (C₃₄H₃₀N₂O₄. 0.5C₂OH) is monoclinic, space group P2₁/n with cell dimensions of a = 1.5416(3), b =0.5625(1), c = 1.7875(4) nm, β = 91.56 (3)°, V= 1.550(1) nm³, Z = 2. The structure shows that the molecule of IIc is centrosymmetric, which indicates that the dimerization process is a head‐to‐tail fashion. The selectivity of the photodimerization of Ia–Ic has been enhanced by using acidic solvent and the reaction speed would be decreased when electron donating group was introduced in the 4‐position of the phenyl group. That the photodimerization is not affected by the presence of oxygen as well as its high stereo‐selectivity demonstrated that the reaction proceeded through an excited singlet state. It was also found that under irradiation of short wavelength UV, these dimers underwent photolysis completely to reproduce its trans‐monomers, and then the new formed species changed into their cis‐isomers through trans‐cis isomerization.     

Safe,Low‐Cost,Fast‐Kinetics and Low‐Strain Inorganic‐Open‐Framework Anode for Potassium‐Ion Batteries

A key challenge for potassium‐ion batteries is to explore low‐cost electrode materials that allow fast and reversible insertion of large‐ionic‐size K⁺. Here, we report an inorganic‐open‐framework anode (KTiOPO₄), which achieves a reversible capacity of up to 102 mAh g^?1 (307 mAh cm^?3), flat voltage plateaus at a safe average potential of 0.82 V (vs. K/K⁺), a long lifespan of over 200 cycles, and K⁺‐transport kinetics ≈10 times faster than those of Na‐superionic conductors. Combined experimental analysis and first‐principles calculations reveal a charge storage mechanism involving biphasic and solid solution reactions and a cell volume change (9.5 %) even smaller than that for Li⁺‐insertion into graphite (≈10 %). KTiOPO₄ exhibits quasi‐3D lattice expansion on K⁺ intercalation, enabling the disintegration of small lattice strain and thus high structural stability. The inorganic open‐frameworks may open a new avenue for exploring low‐cost, stable and fast‐kinetic battery chemistry.     

Safe,Low‐Cost,Fast‐Kinetics and Low‐Strain Inorganic‐Open‐Framework Anode for Potassium‐Ion Batteries

A key challenge for potassium‐ion batteries is to explore low‐cost electrode materials that allow fast and reversible insertion of large‐ionic‐size K⁺. Here, we report an inorganic‐open‐framework anode (KTiOPO₄), which achieves a reversible capacity of up to 102 mAh g^?1 (307 mAh cm^?3), flat voltage plateaus at a safe average potential of 0.82 V (vs. K/K⁺), a long lifespan of over 200 cycles, and K⁺‐transport kinetics ≈10 times faster than those of Na‐superionic conductors. Combined experimental analysis and first‐principles calculations reveal a charge storage mechanism involving biphasic and solid solution reactions and a cell volume change (9.5 %) even smaller than that for Li⁺‐insertion into graphite (≈10 %). KTiOPO₄ exhibits quasi‐3D lattice expansion on K⁺ intercalation, enabling the disintegration of small lattice strain and thus high structural stability. The inorganic open‐frameworks may open a new avenue for exploring low‐cost, stable and fast‐kinetic battery chemistry.     

Synthesis,structure, and antibacterial evaluation of new N‐substituted‐3‐amino‐ 5‐oxo‐4‐phenyl‐2,5‐dihydro‐1H‐pyrazole‐1‐carbothioamides

Novel N‐substituted‐3‐amino‐5‐oxo‐4‐phenyl‐2,5‐dihydro‐1H‐pyrazole‐1‐carbothioamide derivatives were synthesized by means of two methods. First is the cyclization reaction of 1‐(cyanophenyl)acetyl‐4‐substituted thiosemicarbazide, and the second one is reaction of cyanophenyl acetic acid hydrazide with isothiocyanate. Structures of new compounds were confirmed by elemental analysis, ¹H NMR, and X‐ray diffraction analysis. Biological evaluation showed that some of them possess promising antibacterial activities. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:215–221, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20598     

Water‐Soluble Flavonol (=3‐Hydroxy‐2‐phenyl‐4H‐1‐benzopyran‐4‐one) Derivatives: Chemical Synthesis,Colouring, and Antioxidant Properties

Water‐soluble derivatives of rutin, a very common glycoside of quercetin (=3,3′,4′,5,7‐pentahydroxyflavone=2‐(3,4‐dihydroxyphenyl)‐3,5,7‐trihydroxy‐4H‐1‐benzopyran‐4‐one) and a potent plant antioxidant from the flavonol family, were synthesized by simple chemical procedures aimed at introducing carboxy or sulfo groups at the sugar moiety (Scheme 1). Such derivatives form stable molecular complexes with malvin, a polyphenolic pigment from the anthocyanin family, and thereby prove to be very effective in the enhancement (hyperchromism) and variation (bathochromism) of natural colours. The H₂O‐solubilizing carboxylate and sulfate groups are shown to deeply modify the enthalpy‐entropy balance of the pigment‐flavonol complexation (copigmentation). A molecular interpretation of the complexation‐induced bathochromic shift in the pigment VIS band is proposed. Finally, the H₂O‐soluble rutin derivatives are shown to retain the high antioxidant ability of rutin as evidenced by their efficient trapping of the coloured radical DPPH (=2,2‐diphenyl‐1‐(2,4,6‐trinitrophenyl)hydrazyl).     

Three‐component,negative‐type,alkaline‐developable,thermally stable,and photosensitive polymer based on poly(2,6‐dihydroxy‐1,5‐naphthalene), a crosslinker,and a photoacid generator

A negative working and chemically amplified photosensitive polymer has been developed, which is based on poly(2,6‐dihydroxy‐1,5‐naphthalene) (PDHN), the crosslinker 4,4′‐methylenebis[2,6‐bis(hydroxymethyl)]phenol, and the photoacid generator (5‐propylsulfonyloxyimino‐5H‐thiophen‐2‐ylidene)‐(2‐methylphenyl)acetonitrile. PDHN, with a number‐average molecular weight of 25,000, was prepared by the oxidative coupling polymerization of 2,6‐dihydroxynaphthalene with di‐μ‐hydroxo‐bis[(N,N,N′,N′‐tetramethylethylenediamine)copper(II)] chloride in 2‐methoxyethanol at room temperature. The resulting PDHN showed a 5% weight loss temperature of 440 °C in nitrogen and a low dielectric constant of 2.82. The resist showed a sensitivity of 8.3 mJ cm^?2 and a contrast of 11 when it was exposed to 436‐nm light, followed by postexposure baking at 100 °C for 5 min and development with a 2.38 wt % aqueous tetramethylammonium hydroxide solution at 25 °C. A fine negative image featuring 10‐μm line‐and‐space patterns was obtained on a film 3 μm thick exposed to 10 mJ cm^?2 of ultraviolet light at 436 nm in the contact‐printed mode. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2235–2240, 2004     

Synthesis,Characterization, and Energetic Properties of 6‐Amino‐tetrazolo[1,5‐b]‐1,2,4,5‐tetrazine‐7‐N‐oxide: A Nitrogen‐Rich Material with High Density

The synthesis and energetic properties of a novel N‐oxide high‐nitrogen compound, 6‐amino‐tetrazolo[1,5‐b]‐1,2,4,5‐tetrazine‐7‐N‐oxide, are described. Resulting from the N‐oxide and fused rings system, this molecule exhibits high density, excellent detonation properties, and acceptable impact and friction sensitivities, which suggests potential applications as an energetic material. Compared to known high‐nitrogen compounds, such as 3,6‐diazido‐1,2,4,5‐tetrazine (DiAT), 2,4,6‐tri(azido)‐1,3,5‐triazine (TAT), and 4,4′,6,6′‐tetra(azido)azo‐1,3,5‐triazine (TAAT), a marked performance and stability increase is seen. This supports the superior qualities of this new compound and the advantage of design strategy.     

Synthesis of Polyfunctionalized 1,4‐Dihydropyridine‐Fused‐1,3‐Diazaheterocycles: One‐Pot Reaction of 1,1‐Bis(methylthio)‐2‐nitroethylene, 1,n‐Diamine,Arylaldehyde, and Malononitrile

An efficient, one‐pot synthetic protocol for polyfunctionalized 1,4‐dihydropyridine‐fused‐1,3‐diazaheterocycles, a class of biologically active compounds, starting from 1,1‐bis(methylthio)‐2‐nitroethylene, 1,n‐diamine, arylaldehyde, and malononitrile is described. The reactions are completed within 12–15 h under refluxing conditions and in the presence of 10 mol % of piperidine as a basic catalyst to produce the title compounds in 60–75% yields.     

Simple,Efficient, and Catalyst‐Free Synthesis of (2‐Amino‐4H‐1‐benzopyran‐4‐yl)phosphonates in Polyethylene Glycol

Several (2‐amino‐4H‐1‐benzopyran‐4‐yl)phosphonates were efficiently synthesized by employing a multicomponent protocol involving a salicylaldehyde, malononitrile or ethyl cyanoacetate, and a trialkyl phosphite in polyethylene glycol. The latter could be recovered and re‐used. No additional solvent or catalyst was required. To the best of our knowledge, this is the first report of the one‐pot preparation of (2‐amino‐4H‐1‐benzopyran‐4‐yl)phosphonic acid dimethyl esters.     

The First Solvent‐Free,Microwave‐Accelerated,Three‐Component Synthesis of Thiazolidin‐4‐ones via One‐Pot Tandem Staudinger/aza‐Wittig Reaction

An efficient and rapid, solvent‐free, microwave‐accelerated, one‐pot, three‐component protocol for thiazolidin‐4‐ones synthesis from organic azides has been reported for the first time via Staudinger/aza‐Wittig reaction. The microwave‐accelerated, solvent‐free approach overcomes the limitations associated with the prevailing solution phase methodologies. In particular, its novelty is that it eradicates the vital limitation, that is, accumulation of water (byproduct) that is known to affect the yield and rate of the reaction. Thus, a library of thiazolidin‐4‐ones has been synthesized in short time in excellent yields (92–96%).     

Rose Bengal‐Sensitized Photooxidation of the Dipeptides l‐Tryptophyl‐l‐Phenylalanine,l‐Tryptophyl‐l‐Tyrosine and l‐Tryptophyl‐l‐Tryptophan: Kinetics,Mechanism and Photoproducts¶

The Rose Bengal‐sensitized photooxidations of the dipeptides l ‐tryptophyl‐l ‐phenylalanine (Trp‐Phe), l ‐tryptophyl‐l ‐tyrosine (Trp‐Tyr) and l ‐tryptophyl‐l ‐tryptophan (Trp‐Trp) have been studied in pH 7 water solution using static photolysis and time‐resolved methods. Kinetic results indicate that the tryptophan (Trp) moiety interacts with singlet molecular oxygen (O₂(¹Δ_g)) both through chemical reaction and through physical quenching, and that the photooxidations can be compared with those of equimolecular mixtures of the corresponding free amino acids, with minimum, if any, influence of the peptide bond on the chemical reaction. This is not a common behavior in other di‐ and polypeptides of photooxidizable amino acids. The ratio between chemical (k_r) and overall (k_t) rate constants for the interaction O₂(¹Δ_g)‐dipeptide indicates that Trp‐Phe and Trp‐Trp are good candidates to suffer photodynamic action, with k_rlk_t values of 0.72 and 0.60, respectively (0.65 for free Trp). In the case of Trp‐Tyr, a lower k_rlk_t value (0.18) has been found, likely as a result of the high component of physical deactivation of O₂(¹Δ_g) by the tyrosine moiety. The analysis of the photooxidation products shows that the main target for O₂(¹Δ_g) attack is the Trp group and suggests a much lower accumulation of kynurenine‐type products, as compared with free Trp. This is possibly because of the occurrence of another accepted alternative pathway of oxidation that gives rise to 3a‐oxidized hydrogenated pyrrolo[2,3‐b]indoles.