Synthesis, characterization and coordination properties of bis(alkyl)selenosalen ligands

New bis (alkyl) selenosalen podand ligands having Se2N2 donor sites have been synthesized by the condensation of unsymmetrical o-formylphenyl alkyl selenide (1-3) with ethylenediamine. The reaction of bis(alkyl)selenosalen podands with Pd(II) and Pt(II) afforded selenoether-selenolate coordination complexes 7-10via cleavage of one of the two Se-C(alkyl) bonds of bis(alkyl)selenosalen podands upon complexation. DFT calculations revealed that the cleavage of Se-C(alkyl) bonds occurred possibly via S(N)2 mechanism instead of a sequence of oxidative addition and reductive elimination reactions. The spectral data and elemental analyses confirmed the formation of selenoether-selenolate complexes. The structures of the podands N,N'-bis[(2-methylseleno)phenylmethylene]-1,2-ethanediamine (4), N,N'-bis[(2-decylseleno)phenylmethylene]-1,2-ethanediamine (5) and the selenoether-selenolate complex 8 have been determined by single crystal X-ray diffraction analysis. The crystal structure of 5 showed SeH interaction with a ladder like 3D supramolecular arrangement via interdigitation of long alkyl chains. Comparison of crystal packing of podands 4 and 5 indicates that the alkyl chain length has significant impact on the crystal packing. The platinum selenolate complex 8 shows a square planar arrangement around the Pt centre, where the Se atoms in the selenolate and the selenoether have nearly equal Pt-Se bond length.     

Halophilic reaction of N-sodium-substituted azoles with polyhaloperfluoroethanes containing different vicinal halogen atoms

The reactions of N-sodium-substituted azoles with 2-chloro-1-iodo- tetrafluoroethane, 1,2-dichloro-1-iodotrifluoroethane, and 1,2-dibromo-1-chlorotrifluoroethane have been investigated. As shown for iodo derivatives, it is the chlorine rather than the iodine atom that is substituted by the heterocyclic residue, which is consistent with the halophilic reaction mechanism. In the case of indole, the products of simultaneous N-iodopolyfluoroalkylation and ring-iodination have been isolated. The reaction with 1,2-dibromo-1-chlorotrifluoroetane yields N-(2-bromo-2-chlorotrifluoroethyl)azoles accompanied by minor amounts of N-(2,2-dibromotrifluoroethyl) derivatives as by-products.     

TBAF-mediated reactions of 1,1-dibromo-1-alkenes with thiols and amines and regioselective synthesis of 1,2-heterodisubstituted alkenes

An efficient synthesis of trisubstituted alkenes including 1,2-heterodisubstituted alkenes has been described. Reactions of thiols and amines with 1,1-dibromo-1-alkenes in the presence of TBAF·3H(2)O afford (Z)-2-bromovinyl sulfides and (Z)-2-bromovinyl amines regio- and stereoselectively. The reaction proceeds under catalyst-free conditions with high efficiency. The coupling reactions of the obtained products bearing bromine atoms with phenylacetylene and phenylboronic acid gave trisubstituted alkenes in good to excellent yields. Cross-coupling with various N, O, S, and P nucleophiles selectively generated 1,2-N,O, 1,2-N,S, 1,2-S,P, 1,2-S,S, and 1,2-S,O heterodisubstituted alkenes.     

A Base-Mediated Alternative to the Orthoester Claisen Rearrangement

The bromo-acetals (2), which may be prepared from allylic alcohols by reaction with 1,2-dibromo-1-ethoxyethane, may be converted in HMPA-Et³N to allyl 1-ethoxyvinyl ethers (1, R⁵ = Et) which undergo Claisen rearrangement.     

Regiospecific metalation of oligobromobenzenes

The metalation of selected oligobromobenzenes with lithium diisopropylamide (LDA) was investigated. 1,3-Dibromo-substituted benzenes were metalated without special precautions since the resultant 2,6-dibromophenyllithium intermediates are relatively stable under reaction conditions: corresponding benzaldehydes were obtained in good or moderate yields after subsequent quench with N,N-dimethylformamide (DMF). Aryllithium compounds derived from 1,4- and 1,2-dibromobenzene are much less stable, but they could be trapped by the in situ use of chlorotrimethylsilane. The one-pot metalation/disilylation of 1,4-dibromo- and 1,2-dibromobenzene afforded 1,4-dibromo-2,5-bis(trimethylsilyl)benzene and 2,3-dibromo-1,4-bis(trimethylsilyl)benzene, respectively.     

Building block synthesis of predominantly (E) symmetrical and unsymmetrical 1,2-difluorostilbenes from 1,2-dibromo-1,2-difluoroethene

An efficient synthesis of predominantly (E) symmetrical or unsymmetrical 1,2-difluorostilbenes based on the Suzuki–Miyaura palladium-catalyzed cross-coupling reaction of arylboronic acids with predominantly (E)-1,2-dibromo-1,2-difluoroethene in the presence of Cs₂CO₃ in toluene is described. The reaction preserved the stereochemistry of the building block and performed in good yield independently of the electron-withdrawing or electron-donating character of the substituents.     

Efficient Routes for the Synthesis of Dinaphthosulfide (BINOL Derivatives) and Dibenzosulfide Aza Podands Containing Ethanolamine

Four new dinaphthosulfide and dibenzosulfide aza podands were synthesized. The synthesis of these podands was performed under three different reaction conditions: 1) diester, K ₂ CO ₃ , methanol, and RT; 2) diester, ethanolamine, and microwave (MW); and 3) diacid dichloride, ethanolamine, Et ₃ N, CH ₂ Cl ₂ , RT. Two kinds of diester (dinaphthosulfide and dibenzosulfide) were used for the preparation of dihydroxy podands. These dihydroxy podands were reacted with thionyl chloride to afford dichloro podands. The second route gave excellent yields of dihydroxy podands. Dichloro podands are more soluble than dihydroxy podands in conventional solvents such as methanol, chloroform, and acetonitrile.     

Synthesis of glyco-1-ynitols via 1,1-dibromo-1-alkenes from partially and unprotected aldoses

We report the synthesis of 1,1-dibromo-1-alkenes from partially and unprotected aldoses and the synthesis of glyco-1-ynitols from these dibromocompounds. The 1,1-dibromo-1-alkenes were obtained by the reaction of dibromomethyl-triphenylphosphonium bromide in the presence of zinc in refluxing 1,4-dioxane. As an example, when the reaction is performed on 2-deoxy-5-O-trityl-d-ribofuranose (1) the corresponding 1,1-dibromo-1-olefin, (2R,3S)-6,6-dibromo-1-O-trityl-hex-5-ene-1,2,3-triol (12), is obtained in 89% yield. These smooth reaction conditions led also to the achievement of the other olefins from other sugars with good yields (44-90%). The reaction of these olefins with n-butyllithium in THF at low temperature afforded the corresponding alkynes. So the reaction of (2R,3S)-6,6-dibromo-1-O-trityl-hex-5-ene-1,2,3-triol (12) with this alkyllithium reagent led to (2R,3S)-1-O-trityl-hex-5-yne-1,2,3-triol (23) in 87% yield. Other glyco-1-ynitols were obtained with satisfying yields (64-87%).     

Reaction of N-substituted 2-oxochromen-3-carboxamides with bromoderivatives of zinc enolates prepared from alkyl 2,2-dialkyl-4,4-dibromo-3-oxoalkanoates and zinc

Zinc enolates obtained from ethyl 2,2-dialkyl-4,4-dibromo-3-oxobutanoates and zinc react with N-substituted 2-oxochromen-3-carboxamides forming ethyl 3-{1a-(R³-carbamoyl)-2-oxo-1a,7b-dihydrocyclopropa[c]chromen-1-yl}-2,2-dialkyl-3-oxopropanoate isomer with a Z-position of methine hydrogens. Zinc enolates prepared from alkyl 2,2-dialkyl-4,4-dibromo-3-oxopentanoates and-hexanoates and zinc react with N-substituted 2-oxochromen-3-carboxamides to give rise to esters of 3-{1-alkyl-1a-(R³-carbamoyl)-2-oxo-1a,7b-dihydrocyclopropa-[c]chromen-1-yl}-2,2-dialkyl-3-oxopropanoic acid as isomers with the E-position of the methine proton and the alkyl substituent. The reaction carried out in the presence of small quantities of THF and HMPA leads to the formation of 9c-alkyl-2-R³-9b,9c-dihydro-5-oxa-2-azacyclopenta[2,3]-cyclopropa[1,2-a]naphthalene-1,3,4-triones. Zinc enolates from alkyl 2,2-dialkyl-4,4-dibromo-3-oxopentanoates and-hexanoates and zinc with the secondary amides of 2-oxochromen-3-carboxylic acid form alkyl 3-{2-oxo-1a-(piperidinocarbonyl)-and 3-{6-R¹-1a-(morpholinocarbonyl)-2-oxo-1a,7b-dihydrocyclopropa[c]chromen-1-yl}-2,2-R²,R²-3-oxopropanoates as single geometrical isomers.     

Reaction of zinc enolates prepared from 2,2-dibromoindan-1-one or 2,2-dibromo-1-tetralone and zinc with 2-oxochromen-3-carboxylic acid derivatives

Zinc enolates obtained from 2,2-dibromonidan-1-one or 2,2-dibromo-1-tetralone and zinc reacted with alkyl esters and amides of 2-oxochromen-3-carboxylic acid giving the corresponding derivatives of 2,1′-dioxo-spiro(1a,7b-dihydrocyclopropa[c]chromen-1,2′-indan)-or 1′,2′,3′,4′-tetrahydro-2,1′-dioxospiro(1a,7b-dihydrocyclopropa[c]chromen-1,2′-naphthalene)-1a-carboxylic acids prevailingly in the form of a single geometric isomer.     

Reaction of trihalo(phenylenedioxy)phosphoranes with acetylenes: X. specific features of the reactions of substituted 2,2,2-trichloro-1,3,2λ5-benzodioxaphospholes with 3-chloro(bromo, iodo)propynes

It was shown for the first time that 3-chloro-, 3-bromo-, and 3-iodopropynes can react with 2,2,2-trichloro-, 2,2,2-trichloro-5-methyl-, and 5,6-dibromo-2,2,2-trichloro-1,3,2λ⁵-benzodioxaphospholes to give derivatives of 4-(halomethyl)-2-chloro-2H-1,2λ⁵-benzoxaphosphinin-2-ones. The reaction involves nonselective chlorination of the phenylene substituent in different positions, and the resulting isomer ratio is temperature-dependent. In the reactions of 3-bromo-and 3-iodopropynes with 2,2,2-trichloro-1,3,2λ⁵-benzo-dioxaphosphole, a side process takes place, viz. nucleophilic substitution of bromine and iodine with chlorine. The structure of some of the prepared 4-(chloromethyl)-1,2-benzoxaphosphinines was studied by means of X-ray diffraction.     

Unexpected redox processes in the reactions of 1-bromo- and 1,2-epoxy-9-(<Emphasis Type="Italic">p</Emphasis>-tolylsulfonyl)-1,2,3,4,4a,9a-hexahydrocarbazoles with acetyl bromide

1,2-Epoxy-9-(p-tolylsulfonyl)-1,2,3,4,4a,9a-hexahydrocarbazole reacted with acetyl bromide on heating to give 1-acetoxy-2-bromo-9-(p-tolylsulfonyl)-1,2,3,4,4a,9a-hexahydrocarbazole and 1-acetoxy-9-acetyl-2,6-dibromo-1,2,3,4,4a,9a-hexahydrocarbazole. The structure of the latter was proved by X-ray analysis. Analogous reaction of 1-bromo-9-(p-tolylsulfonyl)-1,2,3,4,4a,9a-hexahydrocarbazole with acetyl bromide led to the formation of 9-acetyl-1,6-dibromo-1,2,3,4,4a,9a-hexahydrocarbazole.     

Synthesis and ion-selective properties of 1,2-bis[2-((2-diphenylphosphorylmethyl)phenoxy)ethoxy]cyclohexane (L) and its structural analogs. Crystal structure of L

Potentially hexadentate phosphoryl podands 1,2-bis[2-((2-diphenylphosphorylmethyl)phenoxy) ethoxy]cyclohexane (L), 1,2-bis[2-((2-diphenylphosphoryl)phenoxy)ethoxy]cyclohexane (L¹), and 1,2-bis[2-((2-diphenylphosphorylmethyl)phenoxy)ethoxy]benzene (L²) are synthesized. Stability constants of complexes formed by L, L¹, and L² with alkali-metal 2,4-dinitrophenolates in mixed THF—CHCl₃ solutions (4: 1 by volume) are determined. Electroanalytical characteristics of ion-selective electrodes with hexadentate phosphoryl podands having different structures used as active components of their plasticized membranes are compared for cations of alkali and alkaline-earth metals. The IR spectra are described. The crystal structure of L is studied by X-ray diffraction.     

Chromium-mediated fluoroalkenylation reactions of 1,1-dibromo-1-fluoroalkane and 1-bromo-1-fluoroalkene derivatives

CrCl₂- and NiCl₂-mediated coupling reactions of E/Z mixture of 1-bromo-1-fluoroalkenes with aldehydes proceeded in a high stereoselectivity to give the corresponding (Z)-2-fluoroallylic alcohol derivatives. On the other hand, in the reaction of 1,1-dibromo-1-fluoroalkane with CrCl₂, (Z)-fluoroalkene derivative was formed via α-elimination reaction of the chromium carbenoid intermediate accompanying the concomitant 1,2-shift of β-hydrogen.     

Reaction of organozine reagents derived from dialkyl 2,2-dibromomalonates and methyl 4,4-dibromo-3-oxoalkanoates with 2-oxochromene-3-carboxamides

Organozinc compounds obtained by treatment of dialkyl 2,2-dibromomalonates with zinc reacted with N-substituted 2-oxochromene-3-carboxamides to give dialkyl 1a-R-carbamoyl-2-oxo-1a,7b-dihydro-2H-cyclopropa[c]chromene-1,1-dicarboxylates or alkyl 2-R-1,3,4-trioxo-2,3-dihydro-1H,9bH-chromeno[3′,4′:1,3]-cyclopropa[1,2-c]pyrrole-9c-carboxylates. Reactions of N-substituted 2-oxochromene-3-carboxamides with zinc enolates derived from methyl 4,4-dibromo-3-oxoalkanoates led to the formation of the corresponding 9c-alkyl-2-R-2,3-dihydrochromeno[3′,4′:1,3]cyclopropa[1,2-c]pyrrole-1,3,4-triones.     

Multicomponent reactions in the synthesis of dihydropyrimidine-containing podands having tuberculostatic activity

Dihydropyrimidinethione podands, as well as podands containing 2-thienyl substituents have been synthesized via the multicomponent Biginelli reaction. Tuberculostatic activity of the novel podands was shown to depend on the polyether unit length. In particular, activity of dihydropyrimidinethione podands against laboratory strains of Mycobacterium tuberculosis, H₃₇Rv, M. avium, M. terrae, and the clinical strain of multi-drug resistant M. tuberculosis (MDR), increases with a shortening of the polyether unit length.     

Synthesis of imidazo[1,5-a]pyridines from 1,1-dibromo-1-alkenes

An efficient method is developed for the synthesis of imidazo[1,5-a]pyridine from the reaction of 1,1-dibromo-1-alkenes with 2-aminomethylpyridines. The reaction requires an inorganic base, such as Na₂CO₃, and moderate heating in DMF to proceed. Moderate to good yields are obtained. As demonstrated by the authors and others, 1,1-dibromo-1-alkenes are employed as synthons for activated carboxyl groups.     

Copper-catalyzed C–N coupling/C–H functionalization: A tandem approach to azole-fused quinazoline derivatives

A Cu-catalyzed tandem synthesis of azole-fused pyrimido[1,2-c]quinazolines and imidazo[1,2-c]quinazolines has been developed. The reaction is based on a C–N cross-coupling/C–H functionalization reaction of 2-(2-bromophenyl)-1,4,5,6-tetrahydropyrimidines with azoles. A variety of the desired polycyclic products were obtained in moderate to excellent yields.     

Synthesis and fluorescent properties of europium complexes with amide-type podand ligands of methyl salicylate

Amide-type podands derived from N,N′-(ethane-1,2-diyl)bis(2-hydroxybenzamide) and 2-chloro-N-phenylacetamide (substituted with methyl, methoxy, chlorine, nitrogen) were synthesized. Solid complexes of europium nitrate with podands were also synthesized and characterized by elemental analysis, ethylenediaminetetraacetic acid (EDTA) titrimetric analysis, thermal analysis, molar conductivity analysis, and infrared (IR) and ultraviolet–visible (UV–Vis) spectra analysis. The fluorescent properties of the europium(III) [Eu(III)] complexes in a solid state were also investigated. Under excitation of UV light, target Eu(III) complexes exhibited characteristic europium ion emissions. The influence of the substituent on the fluorescence intensity was discussed. Electrochemical properties were also investigated and discussed.     

Synthesis, transport and ionophore properties of α,ω-diphosphorylated aza podands: III. Liquid ion-selective electrodes based on phosphorylated aza podands

Aza podands having side α-aminomethylphosphine oxide groups were prepared and used as electrode-active agents in liquid membrane ion-selective electrodes. A series of liqiud membrane electrodes sensitive to Cu²⁺ and Hg²⁺ cations were prepared on the basis of N,N-bis[di(n-hexyl)phosphorylmethyl]piperazine. The electrodes containing copper complexes with aza podands as ionophores exhibit anionic function toward lipophilic anions. Potentiometric and argentometric determination of iodide ions was performed with an iodide-selective electrode based on the mercury complex.