New Bis‐o‐Benzoquinoid Ligands with Ethylene Bridge and Their Metal Complexes

The treatment of di‐o‐quinone 4,4′‐(ethane‐1,2‐diyl)‐bis(3,6‐di‐tert‐butyl‐o‐benzoquinone) (Q–CH₂–CH₂–Q, 1 ) leads to its rearrangement to form di‐p‐quinomethide 4,4′‐(ethane‐1,2‐diylidene)bis(2‐hydroxy‐3,6‐di‐tert‐butyl‐cyclohexa‐2,5‐dienone) ( 2 ). The subsequent oxidation of 2 by an alkaline solution of K₃[Fe(CN)₆] yielded the new di‐o‐quinone 4,4′‐(ethene‐1,2‐diyl)bis(3,6‐di‐tert‐butyl‐o‐benzoquinone) (Q–CH=CH–Q, 3 ), which contains an ethylene bridge. The formation of mono‐ and poly‐reduced derivatives of 2 and 3 with potassium, thallium was studied by EPR technique. The dinuclear thallium derivative of 3 , Tl(SQ–CH=CH–SQ)Tl, was found to exist in the diamagnetic quinomethide form. The most stable derivatives of 2 and 3 are triphenyltin(IV) bis‐p‐quinomethide‐phenolate ( 4 ) and triphenylantimony(V) bis‐catecholate ( 5 ), which have been synthesized and isolated. The molecular structures of 2 , 3 , and 5 were characterized by single‐crystal X‐ray diffraction.     

1,1′‐[(Ethane‐1,2‐diyldioxy)di‐o‐phenylene]bis(indoline‐2,3‐dione) (L) and a novel [Ag2L2]2+ metallocycle based on coordination‐driven Ag—O and Ag—π bonds

1,1′‐[(Ethane‐1,2‐diyldioxy)di‐o‐phenylene]bis(indoline‐2,3‐dione), C₃₂H₂₄N₂O₆, L or (I), adopts a trans conformation with the two terminal indoline‐2,3‐dione groups located on opposite sides of the central ether bridge, as required by a centre of inversion located at the mid‐point of the ethane C—C bond. However, in the discrete binuclear Ag^I metallocycle complex salt bis{μ‐1,1′‐[(ethane‐1,2‐diyldioxy)di‐o‐phenylene]bis(indoline‐2,3‐dione)}disilver(I) bis(hexafluoridoantimonate), [Ag₂(C₃₂H₂₄N₂O₆)₂][SbF₆]₂, (II), synthesized by combination of L with AgSbF₆, L adopts a gauche conformation to bind Ag^Ivia the two indolinedione O atoms and two C atoms from the phenoxy ring. One dione O atom from the opposite side of the ether bridge completes the irregular coordination environment of each Ag^I atom. The complex is on a centre of inversion located between the Ag^I atoms. In the solid state, these binuclear [Ag₂L₂]²⁺ metallocycles stack together via intermolecular π–π interactions to generate a one‐dimensional chain motif, with the [SbF₆]⁻ counter‐ions, which are disordered, located between the chains.     

On the Redox Reaction of 1,2-Bis(diphenylphosphino) Alkanes Toward o-, and p-Quinones

Abstract

The reaction of 1,2-bis(diphenylphosphino)ethane with substituted o-benzo-quinones afforded new bis(6-hydroxycyclohexa-2,4-dienone) derivatives. Treatment of the same reagent with o-naphthoquinone, phenanthrenequinone, and acenaphthenequinone gave the respective bis(diphenylphosphoryl)ethylidenes or diacenaphthylenone derivatives. On the other hand, p-quinones react with 1,2-bis(diphenylphosphino)methane to yield the corresponding 4-hydroxycyclohexa-2,5-dien-1-ones. Possible reaction mechanisms are considered and the structural assignments are based on compatible analytical and spectroscopic data.     

Triclinic and monoclinic polymorphs of meso‐(E,E)‐1,1′‐[1,2‐bis(4‐chlorophenyl)ethane‐1,2‐diyl]bis(phenyldiazene): the high‐yield synthesis of an unexpected product,concomitant polymorphism and configurational disorder

Pyrazolidine‐3,5‐diones and their derivatives exhibit a wide range of biological activities. Seeking to explore the effect of combining a hydrocarbyl ring substituent, as present in sulfinpyrazone (used to treat gout), with a chlorinated aryl ring, as present in muzolimine (a diuretic), we explored the reaction between 1‐phenylpyrazolidine‐3,5‐dione and 4‐chlorobenzaldehyde under mildly basic conditions in the expectation of producing the simple condensation product 4‐(4‐chlorobenzylidene)‐1‐phenylpyrazolidine‐3,5‐dione. However, the reaction product proved to be meso‐(E,E)‐1,1′‐[1,2‐bis(4‐chlorophenyl)ethane‐1,2‐diyl]bis(phenyldiazene), C₂₆H₂₀Cl₂N₄, and a tentative mechanism is proposed. Crystallization from ethanol produces two concomitant polymorphs, i.e. a triclinic form, (I), in the space group P, and a monoclinic form, (II), in the space group C2/c. In both polymorphs, the molecules lie across centres of inversion, but in (II), the molecules are subject to whole‐molecule disorder equivalent to configurational disorder with occupancies of 0.6021 (19) and 0.3979 (19). There are no hydrogen bonds in the crystal structure of polymorph (I), but the molecules of polymorph (II) are linked by C—H...π(arene) hydrogen bonds into complex chains, which are further linked into sheets by C—H...N interactions.     

Synthesis of Indeno[1,2‐d]pyrimidin‐5‐Ones and Their Fluorescence in Solid State

New fluorescent compounds, 2‐substituted indeno[1,2‐d]pyrimidin‐5‐ones ( 3a , 3b , 3c , 3d ) were synthesized in good yield by the reaction of 2‐[bis(methylsulfanyl)methylene]indan‐1,3‐dione ( 1 ) with the respective amidine derivatives [guanidine carbonate ( 2a ), acetamidine hydrochloride ( 2b ), S‐methylisothiourea sulfate ( 2c ), and S‐benzylisothiourea sulfate ( 2d )]. 4‐Substituted amino‐2‐aminoindeno[1,2‐d]pyrimidin‐5‐ones ( 7b , 7c , 7d ) were synthesized by a one‐pot reaction of 1 , 2a and the respective amine compounds ( 4b , 4c , 4d ) in pyridine. These fused pyrimidine derivatives showed fluorescence in the solid state.     

Synthesis of 4‐(2‐hydroxyphenyl)‐1‐phenyl‐1,2,4‐triazolidine‐3,5‐dione derivatives through cyclic transformations of 3‐(2‐phenylcarbazoyl)‐2(3H)‐benzoxazolone derivatives

Four 3‐(3‐benzylidene‐2‐phenylcarbazoyl)‐2(3H)‐benzoxazolone derivatives 3 have been synthesized from benzoxazolone derivatives 1 and benzaldehyde N‐chloroformylphenylhydrazone 2. By acid hydrolysis, these compounds yielded 3‐(2‐phenylcarbazoyl)‐2(3H)benzoxazolone derivatives 4 which were not isolated and were transformed via an intramolecular reaction into 4‐(2‐hydroxyphenyl)‐1‐phenyl‐1,2,4‐triazolidine‐3,5‐dione derivatives 5 in a good yield. Attempts to cyclize these compounds by intramolecular elimination of water into tricyclic compounds 6 with various dehydrating agents were unsuccessful.     

Efficient synthesis and spectral determination of 11‐[(o‐ m‐ and p‐substituted)‐phenyl]‐8‐chloro‐3,3‐dimethyl‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐ones

A new synthesis to obtain eleven novel derivatives of 11‐[(o‐ m‐ and p‐substituted)‐phenyl]‐8‐chloro‐3,3‐dimethyl‐2,3,4,5,10,11‐hexahydro‐1H‐dibenzo[b,e][1,4]diazepin‐1‐ones with possible pharmacological activity in the central nervous system in two efficient steps has been developed. The final products were obtained by condensation and cyclization between 3‐[4‐chloro‐1,2‐phenylenediamine]‐5,5‐dimethyl‐2‐cyclohexenone with (o‐ m‐ and p‐substituted)benzaldehyde. The structure of all products was corroborated by ir, ¹H‐nmr, ¹³C‐nmr and high resolution in ms.     

Synthesis and Structures of the Novel Biferrocenamine‐Based Receptor and its Voltammetric Responses to Transition Metal Ions

Reactions of formylferrocene and 1,2‐di‐(o‐aminophenoxy)ethane yield the novel bis(ferrocenyl) receptor (FcL). This compound has been characterized by IR, ¹H NMR and elemental analysis. In addition, the electrochemical behavior of FcL was investigated in detail in 0.1 M tetra‐n‐butylammonium perchlorate (TBAP) + CH₃CN by cyclic voltammetry (CV) and chronoamperometry. Its co‐ordination properties with metal ions in acetonitrile were also studied. The FcL shows a two‐wave behavior for H⁺, Cu²⁺, Zn²⁺ and Ni²⁺, but was unresponsive to Mg²⁺ and Ca²⁺. The maximum oxidation peak shift of about 250 mV was found for FcL in the presence of Cu²⁺, Zn²⁺ or Ni²⁺.     

Synthesis and Anti‐influenza Virus Activity of Novel bis(4H‐chromene‐3‐carbonitrile) Derivatives

An efficient and convenient method for the synthesis of bis(4H‐chromene‐3‐carbonitrile) derivatives by one‐pot, multicomponent reaction of bis‐aldehydes, malononitrile, and dimedone in the presence of a catalytic amount of piperidine is reported. Bis(2‐benzylidene‐1H‐indene)‐1,3‐(2H )‐dione derivatives were obtained as the main products as a result of reaction of the bis(arylidenemalononitriles) with indandione. The anti‐influenza H5N1 virus activities of the newly prepared bis‐chromene derivatives are also investigated.     

Struktur eines Blei(II)‐Komplexes mit verknüpften Monothioquadratationen als Liganden

A Lead(II) Complex with Linked Monothiosquarate Ions as Ligands The thiosquarate ligand bis‐1,2‐(2‐hydroxy‐3,4dione‐cyclobut‐1‐enylsulfanyl)‐ethane and its lead(II) complex have been prepared. According to the crystal structure analysis the complex has a unique layer structure in the solid state. The layers consist of a superposition of cyclic dimeric complexes and of chain like polymeric complexes. The shortest nonbonding Pb…Pb distances are 4.0 Å.     

An Efficient One‐Pot,Four‐Component Synthesis of {[(1H‐1,2,3‐Triazol‐4‐yl)methoxy]phenyl}‐1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione Derivatives

The 1‐{[(1H‐1,2,3‐Triazol‐4‐yl)methoxy]phenyl}‐1H‐pyrazolo[1,2‐b]phthalazine‐5,10‐dione derivatives 5 were synthesized by a simple and efficient method, i.e., by the four‐component, one‐pot condensation reaction of phthalohydrazide 4 , a (propargyloxy)benzaldehyde 1 , an active methylene compound 3 (malononitrile or ethyl cyanoacetate), and an azide 2 in the presence of Cu(OAc)₂/sodium L ‐ascorbate as catalyst and 1‐methyl‐1H‐imidazolium trifluoroacetate ([Hmim](CF₃COO)) as an ionic‐liquid medium in good to excellent yields (Scheme 1).     

DPPH (= 2,2‐Diphenyl‐1‐picrylhydrazyl = 2,2‐Diphenyl‐1‐(2,4,6‐trinitrophenyl)hydrazyl) Radical‐Scavenging Reaction of Protocatechuic Acid Esters (= 3,4‐Dihydroxybenzoates) in Alcohols: Formation of Bis‐alcohol Adduct

Protocatechuic acid esters (= 3,4‐dihydroxybenzoates) scavenge ca. 5 equiv. of radical in alcoholic solvents, whereas they consume only 2 equiv. of radical in nonalcoholic solvents. While the high radical‐scavenging activity of protocatechuic acid esters in alcoholic solvents as compared to that in nonalcoholic solvents is due to a nucleophilic addition of an alcohol molecule at C(2) of an intermediate o‐quinone structure, thus regenerating a catechol (= benzene‐1,2‐diol) structure, it is still unclear why protocatechuic acid esters scavenge more than 4 equiv. of radical (C(2) refers to the protocatechuic acid numbering). Therefore, to elucidate the oxidation mechanism beyond the formation of the C(2) alcohol adduct, 3,4‐dihydroxy‐2‐methoxybenzoic acid methyl ester ( 4 ), the C(2) MeOH adduct, which is an oxidation product of methyl protocatechuate ( 1 ) in MeOH, was oxidized by the DPPH radical (= 2,2‐diphenyl‐1‐picrylhydrazyl) or o‐chloranil (= 3,4,5,6‐tetrachlorocyclohexa‐3,5‐diene‐1,2‐dione) in CD₃OD/(D₆)acetone 3 : 1). The oxidation mixtures were directly analyzed by NMR. Oxidation with both the DPPH radical and o‐chloranil produced a C(2),C(6) bis‐methanol adduct ( 7 ), which could scavenge additional 2 equiv. of radical. Calculations of LUMO electron densities of o‐quinones corroborated the regioselective nucleophilic addition of alcohol molecules with o‐quinones. Our results strongly suggest that the regeneration of a catechol structure via a nucleophilic addition of an alcohol molecule with a o‐quinone is a key reaction for the high radical‐scavenging activity of protocatechuic acid esters in alcoholic solvents.     

Voltammetric Anion Sensors based on Redox‐active Ferrocene‐bearing Macrocyclic Amides

Reactions between 5‐ferrocenylisophthalic dichloride and 1,2‐bis(o‐aminophenoxy)ethane yield 1:1‐ and 2:2‐cyclization products with amide linkages, which are marked as L1 and L2 , respectively. The crystal structure of the 2:2‐macrocycle L2 is determined by X‐ray single crystal structure analysis. Interestingly, L2 affords a folded conformation due to the intermolecular π–π interaction between two isophthaloyl groups, so as to stabilize the marcocylic conformation. The electrochemical anion sensing studies of L1 and L2 show that they have a good ability to recognize H₂PO₄^–, and the 2:2‐cyclization products ( L2 ) with two ferrocene groups, more anion binding sites, and larger cavities, give better electrochemical anion recognition results than L1 .     

[Hg2(μ‐bpe)(μ‐OAc)2(μ‐SCN)2]n,a New Two‐Dimensional Coordination Polymer Involving Three Simultaneously Bridging Ligands: 1,2‐Bis(4‐pyridyle)ethene,Acetate, and Thiocyanate

A new mercury(II) complex of 1,2‐bis(4‐pyridyle)ethene (bpe) with anionic acetate and thiocyanate ligands has been synthesized and characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectroscopy. The single crystal X‐ray analysis shows that the complex is a two‐dimensional polymer with simultaneously bridging 1,2‐bis(4‐pyridyle)ethane, acetate and thiocyanate ligands and basic repeating dimeric [Hg₂(μ‐bpe)(μ‐OAc)₂(μ‐SCN)₂] units. The two‐dimensional system forms a three‐dimensional network by packing via π‐π stacking interactions.     

Synthesis of original benzo[g]quinoxaline‐5,10‐diones by bis‐SRN1 methodology

A new heterocyclic bioreductive bis‐alkylating agent, 2,3‐bis(chloromethyl)benzo[g]quinoxaline‐5,10‐dione, was prepared in a four‐steps synthesis. It was shown to react under electron transfer conditions with 2‐nitropropane anion by an bis‐S_RN1 mechanism to give three C‐alkylation products in excellent yields. Extension of this bis‐S_RN1 reaction to various nitronate or malonate anions and S‐centered anions led to a new class of potentially active benzo[g]quinoxaline‐5,10‐dione derivatives.     

<Emphasis Type="Italic">o</Emphasis>-Semiquinone metal complexes as derivatives of sterically hindered di-<Emphasis Type="Italic">o</Emphasis>-quinone

ESR spectroscopy was used to study a series of mono- and binuclear o-semiquinone metal complexes, viz., derivatives of sterically hindered di-o-quinone 1,2-bis(2,5-di-tert-butylcyclohexadiene-1,5-dion-3,4-yl)ethane (1). Hindered rotation was found in the o-semiquinone moiety of the generated complexes. Magnetochemical measurements for polymeric bis(o-semiquinolate)copper(II) based on di-o-quinone 1 showed two antiferromagnetic channels of interaction between the paramagnetic centers. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1580–1584, July, 2005.     

A New Chiral Quinoxaline Derivative with Ferroelectric Property

Reaction of 1,2‐di(thiophen‐2‐yl)ethane‐1,2‐dione and (1R,2R)‐(−)‐diaminocyclohexane afforded a homochiral quinoxaline derivative (4aR,8aR)‐2,3‐di(thiophen‐2‐yl)‐decahydroquinoxaline ( 1 ). Fluorescent analysis exhibits an intense blue emission band at 386 nm. Crystallographic analysis showed that it belongs to chiral space group P2₁ with ferroelectric behavior, and a typical ferroelectric feature of electric hysteresis loop was obtained. The dielectric constant of compound 1 was measured at room temperature.     

Facile Chemoselective synthesis of 2‐(2‐(Methoxycarbonyl)‐3‐oxo‐2,3‐dihydrobenzofuran‐2‐yl)benzoic acids and 3H,3’H‐Spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives

Oxidation of some derivatives of 4b,9b–dihydroxyindeno[1,2‐b]benzofuran‐10‐one have been investigated in detail using lead(IV) acetate in acetic acid under reflux conditions and periodic acid in aqueous ethanol at room temperature. We realized that during the first 5–15 minutes of the oxidation reactions in lead(IV) acetate/acetic acid system, 3H,3’H‐spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives have been synthesized chemo selectively, while, if the reaction mixtures stirred for additional 3 hours, the main products would be 2‐(2‐(Methoxycarbonyl)‐3‐oxo‐2,3‐dihydrobenzofuran‐2‐yl)benzoic acids. Moreover, room temperature oxidation of 4b,9b–dihydroxyindeno[1,2‐b]benzofuran‐10‐ones by periodic acid (H₅IO₆), leads to the formation of 3H,3’H‐spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives in good to excellent yields.     

Synthesis of heterocyclic nitrogen derivatives from aryl‐1,4‐benzoquinones

Treatment of 2‐aryl‐3,6‐bis(arylamino)‐1,4‐benzoquinones 2a‐h with different acid chlorides, namely acetyl, phenylacetyl and chloroacetyl chloride yields 3a,7a‐dihydropyrrolo[2,3‐f]indole‐2,6‐dione 3, 5‐(N‐phenylacetylarylamino)‐3‐phenylindole‐2,6‐dione 4 and 3‐chloro‐5‐(N‐chloroacetylarylamino)indole‐2,6‐dione 5 respectively. Stirring 2‐aryl‐1,4‐benzoquinones ( 1 ) with ethylenediamine and/or o‐phenyl‐enediamine in methylene chloride gives pyrazino[2,3‐g]quinoxalines derivative 6 and/or tetrapentacene derivative 7 respectively. The products 5‐aryl‐ and 6‐aryl‐1/H‐indazole‐4,7‐diones 8 and 9 were obtained in the 1,3‐dipolar cycloaddition of diazomethane to ( 1 ).     

Enantioselective Allylic Alkylation Catalyzed by Novel C2‐Symmetric Bisphosphinites

In this article, we present our results concerning new C₂‐symmetric bisphosphinites with a (1R,2R)‐1,2‐bis([1,1′: 3′,1″‐terphenyl]‐5′‐yl)ethane backbone. For the given chirality of the backbone, derivatives with aromatic and aliphatic substituents at the donor P‐atoms were synthesized with moderate yields in a straightforward manner. These compounds were evaluated in the Pd⁰‐catalyzed enantioselective allylic alkylations (up to 67% ee).