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4,5-Dialkyl-1,2-bis(5-tropolonylethynyl)benzenes 5a and 5b were synthesized, and dioctyl derivative 5a was converted into the corresponding trinuclear palladium(II) macrocycle 1a by reacting it wit...

Tropolone-terminated oligomeric fluorophores (Tp2OP, Tp2OPV, and Tp2OPE) were prepared by palladium-catalyzed coupling reactions. A phenylene-type Tp2OP showed an emission maximum in the blue fluor...

Crystal structure of 2-Carboxy-1,3-dibenzo[a,c]tropolone (4) is characterized by intramolecular hydrogen bonds with d(O···O) of 2.400(5) A, which is one of the shortest distances reported for 3-hydroxyenones. An averaged structure of 4 suggested by solid state 13C (CP/MAS) NMR may be attributed to a genuine symmetry rather than a dynamically averaged one. Namely, the tautomer may have a symmetric structure resulting from the extremely short O···O distance.

The laser fluorescence excitation spectrum of jet-cooled tropolone-3-d has been measured to investigate the effect of an unsymmetrical substitution of a deuterium on proton tunneling and the equilibrium geometry.

The structures of abnormal reaction products (1:1 and 1:2) between 5-nitrosotropolone and arylamine are elucidated. The reaction of 5-nitrosotropolone with arylamine (e.g., aniline and p-toluidine) affords initially a bicyclic addition product, having 8-azabicyclo[3.2.1]octane system which could be formed by the attack of the amine on 4- and 1-positions of the tropolone ring. The adduct contains two isomers having syn and anti configuration with respect to the hydroxyimino group. These adducts easily isomerized under alkaline conditions to form lactams having the 6-azabicyclo[3.2.1]octane system, which may have been resulted from skeletal rearrangement of a seven-membered ring to a six-membered one. The former adducts, the 8-azabicyclo[3.2.1]octane system, further react with another mole of arylamine to give 1:2 products containing a lactam moiety via similar skeletal rearrangement.

A potent cytotoxic compound, miltipolone, isolated from the fresh root of Salvia miltiorrhiza has been determined to have a novel tropolonoid norditerpene structure.

The steric compression-assisted proton dissociation in 3,7-disubstituted tropolones generates a new resonance hybrid of the tropolone, which contains the tropylium ion moiety and proton. This resonance hybrid model explains the observed unusual chemical properties of 3,7-disubstituted tropolones.

Treatments of 3-isopropenyltropolone with quarternary ammonium tribromides in tetrahydrofuran afforded 3-methyl-8H-cyclohepta[b]furan-8-one. The reactions in methanol–dichloromethane gave 7-bromo-3-methyl-8H-cyclohepta[b]furan-8-one. Bromination of 3-acetyltropolone with the tribromides in tetrahydrofuran produced 3-(bromoacetyl)tropolone, while the reaction in the methanolic solvent gave 7-bromo- and 5,7-dibromo-substituted 3-acetyltropolones. The brominations of 4′-hydroxyacetophenone were also carried out.

To a solution of tropolone (1) in ethanol was added a solution of Mo2O42+ in 2 M HCl. The mixture was stirred at 25 °C for 15 min yielding the title new complex, [Mo2O4(trop)2] (2), with two molecu...

New troponoid liquid crystals with an electron-withdrawing cyano group at the C-5 position of tropolone and 2-aminotropone rings were prepared. Tropolone derivatives had nematic phases with lower thermal stabilities and smectic A phases with higher thermal stabilities than the corresponding benzenoids while thermal stabilities of the aminotropone derivatives were better than those of the benzenoids. The X-ray diffraction studies indicated that the ratios of the layer spacing measured in the smectic A phase and the calculated molecular length are 1.3 for a tropolone derivative and 1.45 for an aminotropone derivative. They formed interdigitated bilayers.

Twin-type troponoid liquid crystals show a monotropic smectic C phase while the corresponding benzenoids are non-mesogenic. The corresponding troponoid monomers, show a monotropic smectic A phase, could form a head-to-tail alignment. In the twins, molecules have to shift to form a head-to-tail alignment since the dipole moment of the two tropolone parts directs oppositely.

2-Aminotroponimine (1) is conveniently synthesized in high yield and is isolated in pure form, starting from 2-aminotropone via 2-methoxytroponiminium fluorosulfonate. N,N′-Dimethyl derivative of 1 is prepared similarly.

Troponoids were shown to form 2:1-complexes with β-cyclodextrin and 1:1-complexes with α-cyclodextrin. The photoisomerization of complexed tropolone and 2-methoxytropone gave optically active 1-hydroxy- and 1-methoxybicyclo[3.2.0]hepta-3,6-dien-2-ones in improved yields. The pyrolysis of the (+)-1-methoxybicyclo[3.2.0]hepta-3,6-dien-2-one gave the (+)-3-methoxybicyclo[3.2.0]hepta-3,6-dien-2-one, ruling out the two-fold supra-antara-1,3-sigmatropy.

Condensation of p-tropoquinones and 5-hydroxytropolones, preferably by acid, yielded dicycloheptafurandione derivatives, which have the same carbon framework with utahin, a naturally-occurring dimeric tropolone. Partial oxidation of 5-hydroxytropolones and partial reduction of p-tropoquinones respectively yielded the condensates. This should exemplify the “phenol oxidation” in troponoids.

Cycloocta[d]tropolone (4) was synthesized by hydrolysis of an adduct of 1H-cyclopentacyclooctene and dichloroketene. The tropolone was found to exist as a mixture of valence bond isomers (4a) and (4b).

The reaction of tropone with aniline, p-toluidine, p-anisidine, and p-chloroaniline in the presence of copper(II) acetate gave 2-arylaminotropones and 2-arylamino-N-aryltroponeimines. However, when o-toluidine and o-anisidine were used, only the corresponding 2-arylaminotropones were obtained. The reaction of tropolone with methylamine, ethylamine, and isopropylamine afforded 3-aminotropolone derivatives, while the reaction with dimethylamine, pyrrolidine, and morpholine gave 3- and 5-aminotropolone derivatives, the latter being minor products.

Biphenylene-2,3-quinone reacts with diazomethane in the presence of boron trifluoride etherate to give 7-hydroxy-6H-benzo[3,4]cyclobuta[1,2]cyclohepten-6-one (5) and its boron difluoride chelate. The latter is convertible quantitatively into the former. Compound 5 has a reduced troponoid character due to fusion of the benzocyclobutadiene ring. Tautomerism of the tropolone ring in 5 seems to be imposed exclusively to one of the tautomers. Protonation of 5 gives a tropylium ion whose positive charge is partially localized. Bromination, nitration, and azo-coupling of 5 give only 7-substituted products. The reaction of 5 with maleic anhydride gives the Diels-Alder adduct in good yield.

2-Arylmethoxytropones, i.e., 2-benzyloxytropone, 2-(p-tolylmethoxy)tropone, 2-(4-bromophenylmethoxy)tropone, 2-(4-chlorophenylmethoxy)tropone, 2-(4-methoxyphenylmethoxy)tropone, and 2-(1-naphthylmethoxy)tropone, rearranged upon heating to the 3-and 5-arylmethyltropolones via the radical intermediates. Similarly, 5-bromo-2-(p-tolylmethoxy)tropone gave 5-bromo-3-(p-tolylmethyl)tropolone.

1,2-Dimethoxybiphenylene reacted with dichlorocarbene to give three chloro(methoxy)-6H-benzo[3,4]cyclobuta[1,2]cyclohepten-6-one derivatives, two chloro(methoxy)fluorenones and two dimethoxyfluorenones. The reaction with dibromocarbene gave similar products. The formation of these products serves as unequivocal chemical evidence for bond fixation of 1,2-dimethoxybiphenylene. The chloro(methoxy)-6H-benzo[3,4]cyclobuta-[1,2]cyclohepten-6-one was led to 9-chloro-5-hydroxy-6H-benzo[3,4]cyclobuta[1,2]cyclohepten-6-one, the first tropolone analogue of biphenylene. This compound was shown to exist in only one of the two possible tautomers in contrast with general monocyclic tropolones.

The tropolone analoques of p- and o-benzosemiquinone (p- and o-troposemiquinone) were generated from cyclohepta-3,6-diene-1,2,5-trione and cyclohepta-4,6-diene-1,2,3-trione, respectively, and characterized by e.s.r. spectroscopy.

3-(2-Methyl-1,3-dioxolan-2-yl)tropolone, prepared from 3-acetyltropolone, was methylated with diazomethane to afford 2-methoxy-3-(2-methyl-1,3-dioxolan-2-yl)tropone (3a) and 2-methoxy-7-(2-methyl-1,3-dioxolan-2-yl)tropone (3b). The methyl ether 3a reacted with hydrazine to afford 2-hydrazono-3-(2-methyl-1,3-dioxolan-2-yl)-3,5-cycloheptadien-1-one and 3-methyl-1,8-dihydrocycloheptapyrazol-8-one. The reaction with methylhydrazine afforded 3-(2-methyl-1,3-dioxolan-2-yl)-2-methylhydrazono-3,5-cycloheptadien-1-one and 1,3-and 2,3-dimethyl-dihydrocycloheptapyrazol-8-ones. Another methyl ether 3b reacted with hydrazine to afford 2-hydrazino-7-(2-methyl-1,3-dioxolan-2-yl)tropone, while the reaction with methylhydrazine gave 2-(2-methyl-1,3-dioxolan-2-yl)-7-(2-methylhydrazino)tropone, 2-(2-methyl-1,3-dioxolan-2-yl)-7-(1-methylhydrazino)tropone, and 1,3-dimethyl-8-methylhydrazono-1,8-dihydrocycloheptapyrazole. On the other hand, the methyl ether 3a reacted with guanidine, acetamidine, and benzamidine to give 4-(2-m...

A methylene-linked bisquinone, 3-(3,6-dioxo-1,4-cyclohexadienyl)methyl-p-tropoquinone, was prepared from 2,5-bis(arylmethoxy)tropone by consecutive reaction, a homolytic rearrangement, subsequent debenzylation, and a DDQ–dehydrogenation. According to cyclic voltammetry, this four-electron redox system was operative, in sharp contrast to the case of the benzenoid bisquinones, via four successive one-electron transfer processes. Two other tropolone derivatives carrying p-benzoquinone segment were also prepared by a similar procedure. The first reduction potentials of these benzoquinones showed a slight enhancement by intramolecular hydrogen bonding.

Unlike the benzenoid equivalent, p-methoxyphenol, the cerium(IV) ammonium nitrate (CAN)-oxidation of 5-hydroxy-2-methoxytropone gave C–C coupling products. On the other hand, either by thallium(III) nitrate (TTN) or CAN at 50 °C, 5-hydroxytropolone, a free tropolone, gave 3-methoxy-p-tropoquinone together with p-tropoquinone and 8-oxabicyclo[3.2.1]octenone derivatives, but no dimeric product.

The treatment of 4-[1-acetamido-3-(3,4,5-trimethoxyphenyl)propyl]tropolone with ethereal diazomethane gave the 6- and 4-substituted title compounds in 51 and 38% yields, respectively. The 270-MHz 1H-NMR spectral analysis performed on these compounds, colchicine, and two methyl ethers of hinokitiol permits unequivocal assignment of the position of the C-substituent on these 2-methoxytropone rings. Attempts were made to effect the direct B-ring closure of these intermediates and 4-[1-acetamido-3-(3,4,5-trimethoxyphenyl)propyl]-5-aminotropolone using various oxidizing reagents.

2-Hydroxy-3H-cyclohept[a]azulen-3-one (azuleno[2,1-d]tropolone) (2) was synthesized, starting from 1,2-diformylazulene (3). Methylation of 2 yielded two kinds of methyl ethers (4 and 6), differing from benzotropolones. In trifluoroacetic or dil. sulfuric acid, 2, 4 and 6 exist in cyclohept[a]azulenylium ions (2a, 4a and 6a).

The reaction of tropolone and phosphorus oxychloride gave 2-chlorotropone. Similarly, 5-cyano-, 5-nitro, and 5-chlorotropolones afforded the corresponding 2-chlorotropone derivatives in moderate yields. 3-Cyanotropolone gave 2-chloro-7-cyanotropone, while 3-phenyltropolone afforded only 2-chloro-3-phenylbenzaldehyde. When 3-bromotropolone and 5-bromotropolone were treated similarly, 2, 7-dichloro- and 2, 5-dichlorotropones were obtained respectively, with a facile halogen exchange. The further treatment of 2, 5-dichlorotropone with phosphorus oxychloride afforded 2, 5-dichloro- and 3,4-dichlorobenzaldehydes. The reaction of 5-p-tolylazo-, 5-phenylazo-, and 5-p-nitrophenylazotropolones with phosphorus oxychloride gave the corresponding 5-arylazo-2-chlorotropones, which, on further treatment with an excess of the reagent, gave 2-aryl-4, 5-dichloroindazoles.

The reactions of 5-azidotropolone (I), its methyl ether (II), and tosylate (XIII) with active methylene compounds were investigated. Several tropolones and azulenes which possess the 1,2,3-triazole ring as a substituent were obtained. The order of reactivities in these reactions were found to be: tropolone tosyl groups>azido groups>tropolone methyl ether groups. The direction of the addition of the azido groups to active methylene compounds was also clarified.

The bromination of 4-acetyltropolone was examined, and two kinds of monobromo compounds, 4-acetyl-3-bromo- and 4-acetyl-7-bromotropolones, two kinds of dibromo compounds, 4-acetyl-3,7-dibromo- and 7-bromo-4-(ω-bromoacetyl)tropolones, a tribromo compound, 4-acetyl-3,5,7-tribromotropolone, and a tetrabromo compound, 3,5,7-tribromo-4-(ω-bromoacetyl)tropolone, were obtained. The third isomer of the monobromo compounds, 4-acetyl-5-bromotropolone, was synthesized from 4-acetyltropolone through 4-acetyl-5-aminotropolone. Moreover, an isomeric dibromo compound, 4-acetyl-5,7-dibromotropolone, was obtained by the debromination of the tribromo compound.

Several 5-azidotropolones were synthesized by the reaction of sodium azide with tropolone diazonium salts which has been prepared from the corresponding 5-aminotropolones. Most of the 5-azidotropolones thus obtained were stable except for the 4-alkyl derivatives. Their electrophilic substitution reactions took place at their 3- and 7-positions, and also their hydroxyl groups behaved like those of other tropolones. 5-Azidotropolone methyl ether did not react with aromatic amines, but it did with aliphatic amines and guanidine to give 2-aminotropone derivatives and 1,3-diazaazulene derivative. The thermolysis of 5-azidotropolone and its methyl ether afforded 5-aminotropolone and its methyl ether respectively; however, 5-azido-4-phenyltropolone gave indolo[3,2-d]tropolone.

既報に引きつづき,5-シアノトロポロン-鉄(III)キレート(1:1)について検討した。温度を25.0°±0.1℃,イオン強度を2.00としたとき,5-シアノトロポロンの酸解離定数としては1.9×10-4を,1:1鉄(III)キレートの安定度定数としては3.7×107を得た。これらの値は前に報告したトロポロン-5置換体について得られたlogk1対pKαの直線にのる。

The dipole moments of Ortho-substituted tropones were measured in benzene solution at room temperature. The values obtained are as follows : 2-bromotropone, 4.94 D ; 2,7-dibromotropone, 5.27 D; 2-mercaptotropone, 4.36 D; 2-aminotropone, 3.78 D; 2-methylmercaptotropone, 4.64 D. These values together with those of tropolone and methoxytropone were compared with the calculated moments and the following conclusions were derived. The moments of the bromotropones are lower than those calculated by simple vector addition owing to ortho effect. In tropolone, mercaptotropone and aminotropone, the substituent groups take such configurations that these groups are conjugated with the cycloheptatriene ring in the highest degree and that an intramolecular hydrogen bond is formed between the carbonyl oxygen and the hydrogen atom of each of the substituent groups. In methoxytropone and methyl mercaptotropone, on the other hand, the conjugation is weak and each of the substituent groups lies in a plane nearly perpendicula...

Polarized absorption spectra of cupric complexes with tropolone, hinokitiol, acetylacetone and salicylaldehyde have been determined in the visible and ultra-violet by Tsuchida-Kobayashi’s microscopic method. The above compounds all exhibit two bands at about 40 to 55×1013/sec. (band A) and at about 70×1013/sec. or shorter wave-length (specific band). The following rules on the dichroism which are common for the above complexes, have been induced : For the band A, the absorption parallel to the complex plane is highly hyperchromic to the absorption normal to the complex-plane. For the specific band, the absorption parallel to the π-electron system is found considerably bathochromic to the absorption normal to the plane. With different ligand ions, the wave-length of the band A of the cupric complexes have been compared, and the following hypsochro mic order has been derived: acetylacetone> salicylaldehyde> tropolone>, hinokitiol. The same order has been found for the wave-length shift of the specific band ...

The reaction of tropone and potassium hydroxide in the presence of potassium ferricyanide gave tropolone, salicylaldehyde, and p-hydroxybenzaldehyde, while in the presence of the copper ammine complex it afforded 2-aminotropone and salicylonitrile. Similarly, when tropone was reacted with aqueous ammonia, methylamine, or dimethylamine, 2-aminotropone and its N-methyl derivatives were formed. The reaction of 2-phenyltropone with ammonia and methylamine, and the reaction of 2-α-naphthyltropone and 4-bromo-2-phenyltropone with methylamine in the presence of copper salt, also afforded 2-aminotropone derivatives and/or salicylaldehyde derivatives.

4-スチリルト繋ポロンから誘導されるメチルエーテル,クロルトロポンおよびトシラートの各2種の異性体について,シアン酢酸エチルとの縮合反応を行なった。2-メトキシ-4-スチリルトロポン(IIb)からは,2-アミノ-5-スチリルアズレン-1.3-ジカルボン酸ジエチル(VII)が得られ,これから脱アミノおよび脱炭酸により5-スチリルアズレン(X)に導くことができた。2-クロル-および2-トシルオキシ-4-スチリルトロボン(IIIbおよびIVb)からは,異常置換をともなっての縮合により,6-スチリル型アズレン誘導体(XII)が得られ,このものからは,6-スチリルアズレン(XIV)が合成された。一方6-スチリル型トロポン誘導体(IIa,IIIaおよびIVa)は上記の4-スチリル型(II,IIIbおよびIVb)にくらべて,反応しがたく,長時間反応させてもアズレン誘導体は得がたく,原料を回収したり,あるいは転位生成物と思われる化合物が生成される。

The reaction of tropolone with several bi- and tervalent metal ions has been studied spectrophotometrically. Their stability constants (k1) have been found to be 7.40, 3.82, 3.06, 2.45, 7.46, 4.60, and 6.25 for Be(II), Mg(II), Ca(II), Sr(II), Y(III), Cd(II), and La(III) respectively, at 25±0.1°C and at an ionic strength of 0.10. A plot of logk1 against e2⁄r gave a straight line for all the non-polarizable metal ions except Be(II) and Mg(II). The logk1 values for all the polarizable metal ions are large. The correlation of logk1 with the second or the third ionization potentials for bi- and tervalent metal ions gave a fairly straight line.

Reaction of tropolone and p-benzoquinone was carried out in methanol containing acetic acid and the structure of products so obtained was determined. Tropolone gave 5-(4′-hydroxyphenoxy)tropolone and 3-(p-benzoquinonyl)-tropolone, 3-bromotropolone gave 3-bromo-7-(p-benzoquinonyl) tropolone, and 3, 7-dibromotropolene gave 3,7-dibromo 5-4′-hydroxy-phenoxy)tropolone by this reaction. Benzofurotropones were derived from benzoquinonyltropolones. In order to prove the structure of the product by admixture, benzocoumarin derivative was prepared by the reaction of the diazonium salt of anthranilate and p-benzoquinone.

The ultraviolet absorption spectra of tropone (I) and tropolone (II) were measured with sulfuric acid solutions of various acidities. The accurate pKa values, as determined by the proposed method, were −1.02 and −0.86 for I and II respectively. The Raman spectra of II were measured with sulfuric acid solutions of various acid concentrations. The bands in the 6 and 15 μ regions change sharply when the solvent acidity changes from 5 to 25%, corresponding well to the ultraviolet absorption change. The infrared absorption spectra of II were measured with the concentrated deuterosulfuric acid solution in the 6 μ region. The vibrationals mode of the protonated tropolone were discussed.

The current-voltage curves of tropolone were recorded at the dropping mercury electrode in buffer solutions of various pH’s containing no borate. One reduction wave was observed in the pH region of 2.2 to 4.0, two waves with nearly equal heights, in the pH region of 5 to 6 and one wave, in the solution of pH higher than 8. All waves except the second in the intermediate pH region were found to shift to negative potentials with the increase of pH of the solution by approximately 70 mV./pH. The number of electrons involved in the reduction was determined by the controlled potential coulometric method. One-electron reduction was confirmed for the first wave at lower pH’s, two-electron reduction for the two-step waves at the intermediate pH region and two-electron reduction for the wave at higher pH’s. The current-voltage curves which were recorded with the solution preliminarily subjected to the controlled potential electrolysis gave two new waves; one is anodic and the other, cathodic. The former decreased ...

Infrared absorption spectra of tropone, 2-chlorotropone, and tropolone in the region of 1700∼1500 cm−1 were measured in various states and in various solvents, and the variation of two strong Bands I and II in the region of 1700∼1530 cm−1 was investigated. The data are shown in tables and figures. These two bands are explained as the participation of both of the C=O and C=C stretching vibrations in a tropone skeleton. The variation of the spectrum of tropolone with the measuring condition is much smaller than that of tropone. This is because the carbonyl group in tropolone is fixed by the intramolecular hydrogen bond.

The electrophilic substitution reactions of 2-aminotropone (I), 2-methylaminotropone (II), and 2-dimethylaminotropone (III) were investigated. The structure of the products was proved by hydrolysis to lead to known tropolone derivatives. By the nitrosation of II, N-nitroso-2-methylaminotropone was obtained in a good yield; this compound is a new type of active troponoid compound. The substitution reactions of III gave tropolone derivatives, accompanied by the hydrolysis of the dimethylamino group. The mechanism of the hydrolysis is then discussed.

The molecular orbital treatment was carried out on tropolone. The π -electron distribution, interatomic distances, free valence indices and dipole moment were derived. It was found that the dipole moment is very high (second approximation value of π -electron moment = 4.4 D) owing to resonance and lies along a line from the center of the ring to the middle point between two O-atoms with its positive end at the ring and that the resonance energy amounts to about 1.5 times that of benzene in general agreement with experimental results. It was shown that the substitution by electrophilic atoms and groups are most liable to occur at C-atoms 7, 3 and 5.

Thorium formed a 1 : 1 chelate with tropolone-5sulfonic acid in a strong acidic solution and a 1:2 chelate in a solution of pH about 3.0. The stability constants of these chelates were determined spectrophotometrically and found to be 9.0 x 107 and 1.4 x 106 respectively at 25 deg C and ionic strengih of 2.00. For the determination of a small amount of thorium, the 1:2 chelate was used with good results. Beer's law held and the molar extinction coefficient of the 1: 2 chelate was 20,000 at 385 m mu .

The nucleophilic substitution reactions of 2-aminotropone (I), 2-methylaminotropone (II), 2-dimethylaminotropone (III), and 2-troponyl trimethylammonium iodide (IV), and their alkyl derivatives were investigated. It was found that the properties of I and II are similar to those of tropolones. On the other hand, those of III are analogous to those of tropolone methyl ethers, while those of IV are, rather, comparable to those of 2-halotropones or tropolone tosylates.