Reactions of 4-Methoxy-3-quinolinyl and 1,4-Dihydro-4-oxo-3-quino-linyl Sulfides Aiming at the Synthesis of 4-Chloro-3-Quinolinyl Sulfides

The preparation of 1,4-dihydro-4-oxo-3′-alkylthio-3,4′-diquinolinyl sulfides 3 or 1,4-dihydro-4-oxo-3-(alkylthio)quinolines 4 by acid catalysed hydrolysis of 4-methoxy-3′-alkylthio-3,4′-diquinolinyl sulfides 1 or 4-methoxy-3-(alkylthio)-quinolines 2 is described. The reactions of 4-methoxy-3′-alkylthio-3,4′-diquinolinyl sulfides 1 or 1,4-dihydro-4-oxo-3′-alkylthio-3,4′-diquinolinyl sulfides 3 with phosphoryl chloride in DMF afforded 4-chloro-3′-alkylthio-3,4′-diquinolinyl sulfides 5 . Treatment of the title compounds 1 or 3 with boiling phosphoryl chloride systems:leads to 4-chloro-3-(alkylthio)quinolines 6 and thioquinanthrene but those of alkoxy- or oxo-quinolines 2 or 4 lead to 4-chloro-3-(alkylthio)quinolines 6 . The reactions of N-methyl-4(1H)-quinolinones 3n and 4n with phosphoryl chloride directed to 4-chloro-3-(alkylthio)quinolines 6 were studied as well.     

3′-Methylsulfinyl-3,4′-diquinolinyl sulfides

Reactions of 4-methoxy- or 1,4-dihydro-4-oxo-3′-methylthio-3,4′-diquinolinyl sulfides 1 and 7 with a nitrating mixture ran as the 3′-methylthio group 5-mono-oxidation followed by C₆- and C₈-nitration and led to the mixture composed of products 3, 4, 5 and 6 (in the case of substrate 1 ) or compounds 5 and 6 (for substrate 7 ). In the reaction with hydrochloric acid 4-methoxy-3′-methylsulfinyl-3,4′-diquinolinyl sulfides 3 and 4 could be hydrolysed to 3′-methylsulfinyl-4(1H)-quinolinones 5 or 6 respectively, the methylsulfinyl group remaining unaffected.     

Chemical constituents from Piper marginatum Jacq. (Piperaceae)—antifungal activities and kinetic resolution of (RS)-marginatumol by Candida antarctica lipase (Novozym 435)

The leaves of Piper marginatum contain the antifungal compounds 3,4-methylenedioxypropiophenone 1, 2-methoxy-4,5-methylenedioxypropiophenone 2, 1-(3,4-methylenedioxyphenyl)propan-1-ol 3 (marginatumol), 5,4′-dihydroxy-7-methoxyflavanone 4 and 5,7-dihydroxy-4′-methoxyflavanone 5. The absolute configuration of natural marginatumol was determined as (+)-(R)-3 (ee 48%) by comparison of its optical properties with the chiral forms obtained by kinetic resolution of racemic 3 using Candida antarctica lipase (Novozym 435).     

Anomalous behavior in the two-step reduction of quinones in acetonitrile

The electrochemical reduction of eight quinones, 9,10-anthraquinone (1), duroquinone (2), 2,6-di-tert-butyl-1,4-benzoquinone (3), 2,6-dimethoxy-1,4-benzoquinone (4), 9,10-phenanthrenequinone (5), tetrachloro-1,2-benzoquinone (6), tetrabromo-1,2-benzoquinone (7) and 3,5-di-tert-butyl-1,2-benzoquinone (8), have been studied in acetonitrile. In every case it was found that cyclic voltammograms differed in significant ways from those expected for simple stepwise reduction of the quinone to its radical anion and dianion. The various types of deviations for the eight quinones have been cataloged and some speculation is offered concerning their origins.     

Iron pentacarbonyl assisted photochemical route to 2,5- and 2,6-divinyl-substituted 1,4-benzoquinones from 1-ene-3-ynes

Photochemical reaction between the enynes, (Z)-1-methoxybut-1-ene-3-yne, 1 or isopropenyl acetylene, 2 with CO in presence of Fe(CO)₅ yields the 2,6- and 2,5-divinyl-substituted 1,4-benzoquinones: 2,6-bis{(Z)-2-methoxyvinyl}-1,4-benzoquinone (3, 42%), 2,5-bis{(Z)-2-methoxyvinyl}-1,4-benzoquinone (4, 31.5%), [{η²,η²:2,6-di(prop-1-en-2-yl)-1,4-benzoquinone}tricarbonyliron] (5, 45%), and {η²,η²:2,5-di(prop-1-en-2-yl)-1,4-benzoquinone}tricarbonyliron] (6, 65%).     

Oxidative free radical reactions between 2-amino-1,4-benzoquinones and carbonyl compounds

The manganese(III) initiated oxidative free radical reactions of 2-amino-1,4-benzoquinone are described. The free radical reaction of 5,6-dimethyl-2-methylamino-1,4-benzoquinone (1) provides a novel method for the synthesis of indole-4,7-dione and indole-2,4,7-trione. High chemoselectivity was observed in different solvents. The regioselectivity of this reaction was also studied with 5-methyl-2-methylamino-1,4-benzoquinone (19). In most cases, indole-4,7-diones 20 and 21 were produced in high regioselectivity.     

Transformations of S-substituted 5,7-dimethyl-4а,5а-diphenyl-3-thioxoperhydroimidazo[4,5-e]-1,2,4-triazin-2-ones under treatment of 1,2-benzoquinones and photochemical properties of reaction products

For the first time 5,7-di-tert-butyl-1,3-dimethyl-3a,9a-diphenyl-3,3a-dihydro-1H-benzo[5,6][1,4]dioxino[2,3-d]imidazol-2(9aH)-one 13 and complex 9 of 4,6-di-tert-butyl-3-nitrobenzene-1,2-diol with 1,3-dimethyl-4,5-diphenyl-1H-imidazol-2(3H)-one 10a were prepared by the reactions of 3-alkylthio-5,7-dimethyl-4a,7a-diphenyl-4a,5,7,7a-tetrahydro-1H-imidazo[4,5-e]-1,2,4-triazin-6(4H)-ones with 3,5-di-tert-butyl-1,2-benzoquinone 1 and 4,6-di-tert-butyl-3-nitro-1,2-benzoquinone 2, respectively. Photochemical transformations of compounds 9 and 10a as well as products of its photooxygenation involving singlet oxygen under UV irradiation: urea 16, isomeric 1,3-dimethyl-4,5-diphenylimidazolidin-2-ones 17 and 17′, and compound 18 were studied by the spectral-kinetic method. Data on the absorption and fluorescence properties of synthesized compounds and their photoproducts were obtained.     

Preparation and use of MeO-PEG-supported chiral diphosphine ligands: soluble polymer-supported catalysts for asymmetric hydrogenation

Two new chiral MeO-PEG-supported (R)-BINAP and (3R,4R)-Pyrphos ligands were synthesized and employed in the Ru(II)- and Rh(I)-catalyzed asymmetric hydrogenation of 2-(6′-methoxy-2′-naphthyl)propenoic acid 5 and prochiral enamides 10. The results showed that these new soluble polymeric catalysts exhibited high catalytic activity and enantioselectivity. Enantiomeric excesses (e.e.s) in the ranges 90–96% and 86–96% were achieved in the hydrogenation of 5 and 10, respectively. Furthermore, these catalysts could be recovered easily and the recycled catalysts were shown to maintain their efficiency in subsequent reactions.     

A study of the reactions of α-aminoacros with a model aminochrome

Chemical and spectroscopic evidence leads to the conclusion that all common α-aminoacids, with the exception of proline and hydroxyproline, undergo oxidative deamination by the action of the model aminochrome, 4-methyl-5-(1′-pyrrolidyl)-1,2-benzoquinone(2), to give the same intensely greenish-blue phenoxazine dye 3. This new colour-forming reaction may form the basis for a new method for the detection, specifically, of α-aminoacids. Unlike ninhydrin, 2 is not capable to bring about the oxidative deamination of β-amino-acids and amines. As expected, the SH-containing aminoacid cysteine reacts differently with 2, giving a yellow condensation product, identified as 3-carboxy-5-hydroxy-8-methyl-7-(1′-pyrrolidyl)-2H-1,4-ben (7).     

A novel oxidative free radical reaction between 2-amino-1,4-benzoquinones and benzoylacetonitriles

The manganese(III) initiated oxidative free radical reaction between 2-amino-1,4-benzoquinones and benzoylacetonitriles is described. This free radical reaction provides a novel method for the synthesis of spirodione 3 and spirolactone 4. With 5,6-dimethyl-2-methylamino-1,4-benzoquinone, spirodione 3 was obtained exclusively. On the contrary, with 5-methyl-2-methylamino-1,4-benzoquinone, spirolactone 4 was produced in high chemo- and regioselectivity. By heating with sodium acetate, spirodione 3 can be converted to 4 effectively.     

Synthesis of a New Naturally Occurring 3-Phenyl-4H-1-Benzopyran-4-One

7-Hydroxy-8-methoxy-3-(3,4-methylenedioxyphenyl)-4H-1-benzopyran-4-one (1), a new isoflavone reported to occur in the aerial parts and roots of Tephrosia maxima has been synthesized by the oxidative rearrangement of 2′-hydroxy-3′-methoxy-4′-benzyloxy-3,4-methylenedioxychalcone (4) with thallium (III) nitrate (TTN) in trimethyl orthoformate (TMOF), followed by acid catalysed cyclization and debenzylation. It has also been synthesized by another method from 2,3,4-trihydroxy-3,4′-methylenedioxydeoxybenzoin; the hitherto unknown biisoflavone, 7,7′-dimethoxy-3′,4″,3″,4″-dimethylenedioxy-8,8′-biisoflavonyl ether was also formed during this method.     

Flavanoid epoxides—XIII : Acid and base catalysed reactions of 2′-tosyloxychalcone epoxides. Mechanism of the algar-flynn-oyamada reaction

2′-Tosyloxychalcone epoxide (6a) on reaction with alkali gave flavonol (4a) while similar treatment of 6′-methoxy-2′-tosyloxychalcone epoxide (6b), both at room temperature and at the boiling point of the reaction medium, afforded 5-methoxyaurone (5b). The latter result indicates that an epoxide is not an intermediate in the production of flavanols from 2′-hydroxy-6′-methoxychalcone epoxides on treatment with alkaline hydrogen peroxide (AFO Reaction) at the higher temperature. Epoxide 6a on treatment with boron trifluoride etherate gave a mixture of flavanonol and flavonol while epoxide 6b gave formyldesoxybenzoin (9) under similar conditions.     

A Facile One-Step Synthesis of New Types of 8-Thiazolyl and 8-Thiadiazinyl Coumarins

N-[4-(7-Methoxy-4-methyl-2-oxo-2H-chromen-8-yl)-thiazol-2-yl]-guanidine ( 2 ) has been prepared by the condensation of 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin ( 1 ) with guanylthiourea. 4-Methyl-7-methoxy-8-[2-(N′-(1-phenyl-ethylideneisopropylidene)-hydrazino]-thiazol-4-yl]chromen-2-ones ( 3 , 4 , and 5 ) have been prepared by reaction of 4-methyl-7-methoxy-8-(2-bromoacetyl) coumarin ( 1 ) and thiosemicarbazide in presence of acetophenone or acetone without any solvent. The formation of these compounds was further confirmed by the condensation of acetophenone/acetone thiosemicarbazones with 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin ( 1 ) in anhydrous ethanol in a two-step process. Similarly 8-[2-[N′-(benzylidene)hydrazine]-thiazol-4-yl]-7-methoxy-4-methyl-chromen-2-ones ( 6 , 7 , and 8 ) have been prepared by the condensation of 4-methyl-7-methoxy-8-(2-bromoacetyl)chromen-2-one with thiosemicarbazide and various aromatic aldehydes in a single step without any solvent. The formation of these compounds was further confirmed by the condensation of appropriately substituted benzaldehyde thiosemicarbazones with 4-methyl-7-methoxy-8-(2-bromoacetyl)coumarin in anhydrous ethanol. 4-Methyl-7-methoxy-8-(2-bromoacetyl) chromen-2-one (1) upon condensation with 3,5-dimercapto-4-amino-s-triazole in anhydrous ethanol resulted in the formation of 8-(3-mercapto-3H-[1,2,4]triazolo[3,4-b]thiadiazin-6-yl)-7-methoxy-4-methyl chromen-2-one (9). This compound ( 9 ) on reaction with various alkyl and phenacyl halides in anhydrous ethanol gave corresponding 4-methyl-7-methoxy-8-[3-(2-oxo-substituted sulphanyl)-7H-[1,2,4]triazolo[3,4-b]thiadiazin-6-yl]chromen-2-ones ( 10 to 18 ). The structures of newly prepared compounds have been confirmed from analytical and spectral data.     

First stereoselective synthesis of serinol-derived malyngamides and their 1′-epi-isomers

A stereoselective synthesis of 1a {N-[(1R)-2-hydroxy-1-methoxy-methyl ethyl]-(4E,7S)-7-methoxy-4-eicosenamide} has been accomplished in 10 steps from 1-tetradecanol for the first time in 28% overall yield. The key steps involved the coupling reaction of a chiral alkyne with a protected bromide in the presence of t-BuLi, as well as the amidation reaction of (4E,7S)-7-methoxyeicos-4-enoic acid with (R)-methoxyamino alcohol. Acetylation of 1a finished the preparation of 1b {N-[(1S)-2-acetyloxy-1-methoxy-methyl ethyl]-(4E,7S)-7-methoxy-4-eicosenamide}. Their 1′-epi-isomers have also been synthesized with a similar strategy.     

Microwave-mediated Claisen rearrangement followed by phenol oxidation: a simple route to naturally occurring 1,4-benzoquinones. The first syntheses of verapliquinones A and B and panicein A

The naturally occurring 1,4-benzoquinones 2-methoxy-6-propyl-1,4-benzoquinone (1), 2-methoxy-6-pentyl-1,4-benzoquinone (primin 2), 2-methoxy-6-pentadecyl-1,4-benzoquinone (3), 2-methoxy-6-heptadecyl-1,4-benzoquinone (dihydroirisquinone, pallasone B; 4) were synthesized by a simple protocol involving microwave accelerated Claisen rearrangement of allyl ethers 10, followed by hydrogenation of the side chain alkene, and oxidation to the quinone. The Claisen-based methodology was extended to the first synthesis of the marine benzoquinones verapliquinones A and B (5 and 6), and panicein A (7). Isoarnebifuranone (9) was also synthesized by a similar strategy.     

One pot,three-component synthesis of novel 3,4-dihydrophthalazin-2(1H)-yl-4-phenyl-4H-pyrans

Green and efficient one pot, three-component synthesis of novel 2-amino-6-(1,4-dioxo-3,4-dihydrophthalazin)-2(1H)-yl-4-phenyl-4H-pyran-3,5-dicarbonitriles 6 has been developed by condensing 3-(1,4-dioxo-3,4-dihydrophthalazin-(1H)-yl)-3-oxopropanenitrile 3, benzaldehydes 4 and active methylene compounds 5 using l-proline as catalyst in EtOH at RT.     

Synthesis of polycyclic pyridazinediones as chemiluminescent compounds

Reactions of 1,3-disubstituted 5-aminopyrazole-4-carbonitrile derivatives 3a-o with dimethyl acetylenedicarboxylate in the presence of potassium carbonate in dimethyl sulfoxide gave the corresponding dimethyl 1,3-disubstituted pyrazolo[3,4-b]pyridine-5,6-dicarboxylates 4a-o which were allowed to react with excess hydrazine hydrate under ethanol refluxing conditions followed by heating at 250-300° to give 1,3-disubstituted 4-amino-1H-pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyridazine-5,8(6H,7H)-diones 7a-s in good yields. Similarly, 1,3-disubstituted 4-hydroxy-1H-pyrazolo[4′3′:5,6]pyrido[2,3-d]pyridazine-5,8(6H,7H)-diones 10a-c were obtained from alkyl 1,3-disubstituted 5-aminopyrazole-4-carboxylates 8a-c . These tricyclic pyridazine derivatives were alternatively synthesized from 4-hydroxypyrrolo[3,4-e]pyrazolo[3,4-b]pyridine-5,7-diones 13a-c prepared by reactions of 5-aminopyrazoles (8e-g) with methyl 1-methyl-4-methylthio-2,5-dioxo-1H-pyrrole-3-carboxylate (11a) followed by the Gould/Jacobs reaction. 1-Methyl-4-methylthio-2,5-dioxo-1H-pyrrole-3-carbonitrile smoothly reacted with 2-aminobenzimidazoles to give the corresponding 5-amino-3-methyl-1H-pyrrolo[3′4′:4,5]pyrimido[1,2-a]benzimidazole-1,3(2H)-diones 16a-e , which were readily converted to the desired 12-aminopyridazino[4′,5′:4,5]pyrimido-[1,2-a]benzimidazole-1,4(2H,3H)-diones 17a-e in good yields. Other pyridazinopyrimidine derivatives were also obtained by the reaction of the corresponding 2-aminoheterocycles with the maleimide in good yields. Substituted anilines reacted 11b in refluxing methanol to give the corresponding methyl 4-phenylamino-1-methyl-2,5-dioxo-1H-pyrrole-3-carboxylates 25a-e which were converted in good yields to 2-methylpyrrolo[3,4-b]quinoline derivatives 26a-e by heating in diphenyl ether. Reaction of 26a-c with hydrazine hydrate gave 10-hydroxypyridazino[4,5-b]quinoline-1,4(2H,3H)-diones 27a-e in good yields. The desired 10-aminopyridazino[4,5-b]pyridazine-1,4(2H,3H)-diones 30a-e were obtained in good yields by the chlorination of 4a-e with phosphorus oxychloride followed by aminolysis with 28% ammonium hydroxide. Some pyridazino[4,5-a][2.2.3]cyclazine-1,4(2H,3H)-diones 37a,b as luminescent compounds were synthesized via several steps from indolizine derivatives. The key intermediates, dimethyl 6-dimethylamino[2.2.3]cyclazine-1,2-dicarboxylates 34, 36 , were synthesized by the [8 + 2] cycloaddition reaction of the corresponding 7-dimethylaminoindolizines 33, 35 with dimethyl acetylenedicarboxylate in the presence of Pd-C in refluxing toluene. Some were found to be more efficient than luminol in light production. 4-Amino-3-methylsufonyl-1-phenyl-1H-pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyridazine-5,8(6H,7H)-dione (7r) , 10-hydroxypyridazino[4,5-b]-quinoline-1,4(2H,3H)-diones 27a-e , and 10-aminopyridazino[4,5-b]quinoline-1,4(2H,3H)-diones 30a-e showed the greatest chemiluminescence intensity in the presence of hydrogen peroxide peroxidase in a solution of phosphate buffer at pH 8.0.     

Synthesis of linear and cyclic compounds containing the 3,4-bis(furazan-3-yl)furoxan fragment

Some chemical transformations of 3,4-bis(4-aminofurazan-3-yl)furoxan (1) and 3,4-bis-(4-nitrofurazan-3-yl)furoxan (2) were considered. Compounds 1 and 2 are valuable synthons for the preparation of linear and cyclic compounds containing the 3,4-bis(furazan-3-yl)furoxan fragment. The reaction of compound 2 with a series of N- and O-nucleophiles afforded novel heterocyclic systems: 7-R-7H-difurazano[3,4-b:3′,4′-f]furoxano[3″,4″-d]azepine and difurazano[3,4-b:3′,4′-f]furoxano[3″,4″-d]oxepin.     

Carbazoledioxazines having long alkyl groups 1. Synthesis of carbazoledioxazines with linear type structure

Carbazoledioxazines with linear type structure (5,15-dialkyl-8,18-dichloro-5,15-dihydrodiindolo[3,2-b:-3′,2′-m]triphenodioxazine) were selectively synthesized by demethanolation ring closure of 2,5-bis(2-methoxy-9-alkyl-3-carbazolylamino)-3,6-dichloro-1,4-benzoquinone in a high boiling solvent. The structure has been confirmed by ¹H-nmr and X-ray crystallography.     

Indenone chemistry—III: Use of the 2-carboethoxymethyl-6-methoxyindenone in the synthesis of the gibbane skeleton

The 2-carboethoxymethyl-6-methoxyindenone 5 has been synthesized in good yield. The endo head-to-tail dimer 6 and the exo head-to-tail dimer 7 can be synthesized stereoselectively from the indenone 5. Diels Alder addition of 5 to 1,3-butadiene affords the 7-methoxy-9aα-carboethoxymethyl-9a, 1,4aα, 4-tetrahydrofluorenone 8. The corresponding acid 9 can be cyclised to the 2 - methoxy - 4bαH - gibba - A,5 - tetraene - 8,10 - dione 10.