Isomerization of 4-arylamino-1,2-naphthoquinones to 2-arylamino-1,4-naphthoquinones

4-Arylamino-1,2-naphthoquinones isomerize into 2-arylamino-1,4-naphthoquinones upon refluxing in acetic acid. The isomerization follows two routes via intermediate 2-hydroxy-1,4-naphthoquinone and 2-arylamino-1,4-naphthoquinone 4-N-arylimines.     

Reaction of 2-chloro-3-(4-N,N-dimethylaminoanilino)-1,4-naphthoquinone with cyclic amines (piperidine,morpholine, and pyrrolidine)

It was shown that the reaction of 2-chloro-3-(4-N,N-dimethylaminoanilino)-1,4-naphthoquinone with piperidine in the absence of a solvent gives not only a product of replacement of the chlorine atom by a piperidino group, 3-(4-N,N-dimethylaminoanilino)-2-piperidino-1,4-naphthoquinone, but also 2-(4-N,N-dimethylaminoanilino)-1,4-naphthoquinone and 2-(4-N,N-dimethylaminoanilino-2-piperidino)-1,4-naphthoquinone. The latter compounds are the only reaction products formed in dimethyl sulfoxide. The reaction with morpholine occurs in a similar way, whereas that with pyrrolidine gives only a product of replacement of the chlorine atom by hydrogen.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2451–2454, December, 1995.     

Stereospecific synthesis of conjugated (1E,3E)- and (1Z,3Z)-1,4-di(n-N,N-dimethylaminophenyl)-1,3-butadienes from 2-chloro-1-(n-N,N-dimethylaminophenyl)ethenes: fluorescence properties

The conjugated 1,4-di(n-N,N-dimethylaminophenyl)-1,3-butadienes (n=o-, m-, p-) were efficiently synthesised by homocoupling of the appropriate 2-chloro-1-(n-N,N-dimethylaminophenyl)ethene (n=o-, m-, p-) with stoichiometric amounts of zerovalent nickel complexes. The 1,3-butadienes were obtained as a mixture of stereoisomers, with independence of the starting E or Z chlorovinyl isomer. Moreover, the stereospecific (Z,Z) stereoisomer was obtained by partial hydrogenation of the corresponding 1,3-butadiyne, while the stereospecific (E,E) stereoisomer was obtained by exposure to the sunlight radiation of the (Z,Z) or the (Z,E) compound in ethanol.     

Novel porphyrin-quinazoline conjugates via the Diels-Alder reaction

Novel derivatives of meso-tetraphenylporphyrin with appended quinazoline moieties were synthesized, via the Diels-Alder reaction, between a 4-(porphyrinyl)pyrimidine ortho-quinodimethane and 1,4-benzoquinone, 1,4-naphthoquinone and N-(p-nitrophenyl)maleimide. The structure of one bis adduct was established by X-ray crystallography and mass spectrometry. We have unequivocally confirmed that the 2:1 adducts obtained from the reaction of pyrimidine-fused 3-sulfolenes with N-arylmaleimides have an open-chain structure and not a cyclooctapyrimidine structure, as previously published.     

Oxidative arylamination of 1,7-dihydroxynaphthalene

1,7-Dihydroxynaphthalene reacts with aniline orp-toluidine in the presence of oxidants to give the correspondingN-aryl-7-hydroxy-1,4-naphthoquinone 4-imines, 2-arylamino- and 2,8-diarylamino-N-aryl-7-hydroxy-1,4-naphthoquinone 4-imines, and benzo[a]oxophenoxazinimine derivatives. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 347–350, February, 1999.     

Stereospecific preparation of symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes from 1-bromo-1-fluoroalkenes

A straightforward method to prepare symmetrical (1Z, 3Z)- and (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes is described. High E/Z ratio 1-bromo-1-fluoroalkenes, prepared by isomerization from the E/Z ≈ 1:1 isomeric mixtures, reacted with Bu₃SnSnBu₃ and Pd(PPh₃)₄ to afford (1Z, 3Z)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes in good yield. (Z)-1-Bromo-1-fluoroalkenes, which were prepared by kinetic reduction from 1-bromo-1-fluoroalkenes (E/Z ≈ 1:1), can undergo similar reaction with Bu₃SnSnBu₃ and Pd(PPh₃)₄/CuI to prepare (1E, 3E)-2,3-difluoro-1,4-disubstituted-buta-1,3-dienes.     

Synthesis of some NH- and NH,S- substituted 1,4-quinones

A series of NH-substituted-1,4-quinones, possessing one, two, three or not chlorine, were synthesized by the reaction between different quinones (p-chloranil (1), p-toluquinone (2), or 2,3-dichloro-1,4-naphthoquinone (3)) and (-)-cis-myrtanylamine (5) via nucleophilic reactions. Moreover, 2-bromo-1,4-naphthoquinone (4) was reacted with 2-(methylthio)ethylamine (11) to produce amino-substituted naphthoquinones (12 and 13), bearing with bromine and not bromine. In addition, 2-bromo-1,4-naphthoquinone (4) was reacted with 4′-aminodibenzo-18-crown-6 (14) and 4′-aminobenzo-18-crown-6 (16) to yield crown-containing 1,4-naphthoquinones (15 and 17), respectively. New compounds were characterized, providing ¹H NMR, ¹³C NMR, FTIR, MS-ESI, UV/Vis and elemental analysis.     

Efficient synthesis of N,N′-dialkyl-N″-dialkylaminocarbothioyl thioureas from cyclic secondary amines, CS2, and N,N′-dialkyl carbodiimides in water

A mild, convenient, and practical one-pot procedure for direct synthesis of N,N′-dialkyl-N″-dialkylaminocarbothioyl thioureas is described via three-component reaction of cyclic secondary amines, CS₂, and N,N′-dialkyl carbodiimides in water at room temperature.     

A study of tautomerism in N,N-dialkyl-4(5)-bromoalkanecarboxamides

N,N-Dialkyl-4-bromobutanamides exist in solution in tautomeric equilibrium with N,N-dialkyl-N-(tetrahydrofuran-2-ylidene)ammonium bromides, while related 4,5-dibromopentanamides show no similar interconversions with the corresponding iminium salts. A similar difference is observed when comparing the chemical behavior of their homologs, viz., N, N-dialkyl-5-bromopentanamide and N, N-dialkyl-5,6-dibromohexanamide     

Quantum chemical study of mechanisms of organic reactions: V. Addition of ethane-1,2-dithiol to 4-hydroxy-4-methylpent-2-ynenitrile

The mechanism of nucleophilic addition of ethane-1,2-dithiol to 4-hydroxy-4-methylpent-2-ynenitrile has been studied at the DFT B3LYP/6-311++G(d,p) level of theory. The base-catalyzed reaction involves nucleophilic attack by deprotonated ethane-1,2-dithiol on the ß-carbon atom of the nitrile with formation of intermediate Z-vinylic carbanion which undergoes intramolecular cyclization with closure of 1,3-dithiolane ring. Further transformation of 2-[2-(2-hydroxypropan-2-yl)-1,3-dithiolan-2-yl]acetonitrile to 6,6-dimethyl-7-oxo-1,4-dithiaspiro[4.4]nonan-8-imine has also been studied.     

Novel capto-dative (Z,E)-2-(alkylthio)alk-2-en-4-ynals: synthesis and heterocyclization

An efficient synthesis of new (Z,E)-2-(alkylthio)alk-2-en-4-ynals by aldol condensation reaction of ynals with (alkylthio)-acetaldehydes using NaOH/DMF system has been developed.The reaction of these products with N,N-diphenylethylene-diamine and p-tosylmethyl isocyanide proceeds at the carbonyl group to form the corresponding imidazolidine and oxazole derivatives.     

Photolysis of p-benzoquinone in N2 matrices at 12K: a novel decomposition pathway

Photolysis of _p-benzoquinone in N₂ matrices at 12K has been found to give acetylene and CO; 1,4-naphthoquinone and 9,10-anthraquinone, however, are inert under similar conditions.     

Reactions of 5-oxo-1-phenylpyrrolidine-3-carbohydrazides with 1,4-naphthoquinone derivatives and the properties of the obtained products

N′-(4-Oxo-1,4-dihydronaphthalen-1-ylidene)-1-phenyl-5-oxopyrrolidine-3-carbohydrazides and N′-(3-methyl-4-oxo-1,4-dihydronaphthalen-1-ylidene)-1-phenyl-5-oxopyrrolidine-3-carbohydrazides were synthesized by reactions of 5-oxo-1-phenylpyrrolidine-3-carbohydrazides with 1,4-naphthoquinone or 2-methyl-1,4-naphthoquinone. The alkylated analogues of the above products were obtained using ethyl iodide. The interaction of 5-oxo-1-phenylpyrrolidine-3-carbohydrazides with 2,3-dichloro-1,4-naphthoquinone was followed by formation of N′-(3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)-1-phenyl-5-oxopyrrolidine-3-carbohydrazides. All these compounds were characterized using ¹H, ¹³C NMR, IR and mass spectra. Some of the new compounds were tested for the antimicrobial and antifungal activity.     

π-Extended conjugate phenylacetylenes. Synthesis of 4-[(E) and (Z)-2-(4-ethenylphenyl)ethenyl]pyridine. Dimerization, quaternation and formation of charge-transfer complexes

The conjugate (E)- and (Z)-(4′-pyridylethenyl)-4-phenylethyne (E-4 and Z-4) has been satisfactorily prepared by two different routes: (a) by dehydrohalogenation of 4′-pyridylethenyl-4-phenyl-β-chloroethene; (b) by the Wittig reaction between p-(iodobenzyl)(triphenyl)phosphine ylide and 4-pyridinecarboxaldehyde, E/Z isomer separation, and cross-coupling with 2-methyl-but-3-yn-2-ol followed the propanone elimination. The Glaser oxidative dimerization of (Z)-4 yields (Z,Z)-1,4-di[(4′-pyridylethenyl)-4-phenyl]-buta-1,3-diyne in good yield, (Z,Z)-5. (E,E)-5 was obtained by phase transfer oxidative dimerisation of (E)-4 in presence of their N-methyl salt (E)-10. Mono- and di-N-methylated salts of conjugate (E,E)-5 and (Z,Z)-5, were obtained by quaternation with iodomethane. The (Z,Z)-5 di-N-methylated salt forms charge-transfer complexes with TCNE, TCNQ and TMPD.     

Single crystal X-ray structure of 2,6-di-tert-butyl-4-(3-(4-chlorophenyl)-4-methyl-4,5-dihydroisoxazol-5-yl)phenol 1,4-dioxane hemisolvate

The title compound (2,6-di-tert-butyl-4-(3-(4-chlorophenyl)-4-methyl-4,5-dihydroisoxazol-5-yl)phenol is synthesized and studied by the single crystal X-ray diffraction method. The structure of the product was confirmed by IR, ¹H and ¹³C NMR spectroscopy. The crystal structure of 1,4-dioxane hemisolvate of the product is solved in the monoclinic space group P2₁/c with a = 17.713(6) Å, b = 9.529(3) Å, c = 13.972(4) Å, β = 94.09(4)°, V = 2352.3(13) ų, Z = 4, T = 120(2) K.     

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%).     

Synthesis of pyrrolo[3,2-b]benzofurans and pyrrolo[3,2-b]naphthofurans via addition of a silyloxypyrrole to activated quinones

The uncatalyzed reaction of N-(tert-butoxycarbonyl)-2-tert-butyldimethylsilyloxypyrrole 3 with 1,4-quinones bearing an electron withdrawing group at C-2 has been studied. Use of 1,4-quinones 4, 5 bearing an ester group at C-2 provided an efficient synthesis of the respective pyrrolidinobenzofuran adduct 9 or pyrrolidinonaphthofuran adduct 10 whereas use of 1,4-quinones 6, 7 and 8 bearing an acetyl group at C-2 afforded silyloxypyrroles 11, 12 and 13 resulting from direct electrophilic substitution of the silyloxypyrrole by the electrophilic quinone. Addition of Eu(fod)₃ to the reaction of 2-acetyl-1,4-naphthoquinone 7 and 3-acetyl-5-methoxy-1,4-naphthoquinone 8 with N-(tert-butoxycarbonyl)-2-tert-butyldimethylsilyloxypyrrole 3 provided a method for obtaining the pyrrolidinonaphthofuran adducts 14 and 15 together with silyloxypyrroles 12 and 13. Oxidative rearrangement of pyrrolidinonaphthofuran adduct 15 to pyrrolidino pyranonaphthoquinone 16 using ceric ammonium nitrate in acetonitrile provided a novel approach for the synthesis of an aza-analogue of the pyranonaphthoquinone antibiotic kalafungin.     

1,4-Diazobicyclo[2.2.2]octane-catalyzed coupling of aldehydes and activated double bonds. Part 3. A short ans practical synthesis of mikanecic acid (4-vinyl-1-cyclohexene-1,4-dicarboxylic acid)

The title dicarboxylic acid 1d has been prepared in 24% overall yield via, 1,4-diazabicyclo[2.2.2]octane (DABCO)-catalyzed coupling of ethanal and tert-butyl propenoate ( 3 ) to 4 , S_N2′-reaction to tert-butyl (Z)-2-romomethyl-2-butenoate ( 5a ), dehydrobrominatin to tert-butyl 2-methylidene-3-butenoate ( 2c ), dimerizatoin to di-tert-butyl 4-vinyl-1-cyclohexene-1,4-dicarboxylate ( 1c ) and acidic ester cleavage. Acidic cleavage of easily obtainable 5a affords (Z)-2-bromomethyl-2-butenoic acid ( 5a ) in 68% yield with respect to ethanal.     

Synthesis and structures of two hydrazone compounds derived from 4-methylbenzohydrazide

Two hydrazone compounds N′-(2,4-dichlorobenzylidene)-4-methylbenzohydrazide monohydrate (1) and 2-chloro-5-nitro-N′-(4-methylbenzylidene)benzohydrazide (2) derived from 4-methylbenzohydrazide with different benzaldehydes are synthesized and characterized by physicochemical methods and single crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic space group P2₁2₁2₁ with unit cell parameters a = 4.714(2) Å, b = 13.093(3) Å, c = 24.754(3) Å, V = 1527.9(8) ų, Z = 4, R ₁ = 0.0812, and wR ₂ = 0.1623. Compound 2 crystallizes in the monoclinic space group Cc with unit cell parameters a = 11.564(2) Å, b = 13.271(2) Å, c = 9.462(2) Å, β = 96.860(2)°, V = 1441.7(4) ų, Z = 4, R ₁ = 0.0461, and wR ₂ = 0.0896. The crystals of the compounds are stabilized by intermolecular hydrogen bonds as well as π…π stacking interactions.     

Titanometrische Untersuchung der 11-Methylbenzo(a)phenoxazon-(9)- und Dibenzophenoxazon-(5)-Derivate

Zusammenfassung Eine potentiometrische Methode der titanometrischen Bestimmung von 11-Methylbenzo(a)phenoxazon-(9), Dibenzo(a,j)phenoxazon-(5), Dibenzo(a,h)phenoxazon-(5) und ihrer Derivate mit 0,01-n TiCl₃ unter Stickstoffatmosphäre in 1-n Salzsäure wurde ausgearbeitet. Mit Hilfe der Methode der Gemische wurden die formalen Redoxpotentiale von 11-Methylbenzo(a)phenoxazon-(9) und einigen seiner Derivate in 50%igem Äthanol vermessen. Diese Verbindungen haben sich als geeignete visuelle Indikatoren für die titanometrische Bestimmung von Fe³⁺, Au³⁺, Cr₂O₇ ^2–, VO₃ ^–, [Fe(CN)₆]^3–, insbesondere für die genaue Bestimmung von 1-Nitroso-2-naphthol, p-Nitrosodimethylanilin, p-Nitrosodiäthylanilin, 2,3-Dichlor-1, 4-naphthochinon, 1,2-Naphthochinon-4-natriumsulfonat und 1,4-Naphthochinon erwiesen.

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Titanometric Investigation of 11-methylbenzo(a)phenoxazone-(9)- and dibenzophenoxazone-(5)-derivatives

Summary A potentiometric method has been developed for the titanometric determination of 11-methylbenzo(a)phenoxazone-(9), dibenzo(a,j)phenoxazone-(5), dibenzo(a,h)phenoxazone-(5) and their derivatives in 1N hydrochloric acid with 0.01N TiCl₃ under an atmosphere of nitrogen. The formal redox potentials were determined (in 50% ethanol) of 11-methylbenzo(a)phenoxazone-(9) and several of its derivatives. These compounds have been found suitable visual indicators for the titanometric determination of Fe³⁺, Au³⁺, Cr₂O₀ ^2–, VO₃ ^–, [Fe(CN)₆]^3– and especially for the precise determination of 1-nitroso-2-naphthol,p-nitrosodimethylaniline,p-nitrosodiethylaniline, 2,3-dichloro-1,4-naphthoquinone, 1,2-naphthoquinone-4-sodium sulfonic acid, and 1,4-naphthoquinone.