Chemistry of 1,2-diphospholide anions and 1,2-diphospholes

The main trends in the chemistry of 1,2-diphosphacyclopentadienes (1,2-diphospholes) and their derivatives 1,2-diphosphacyclopentadienide anions (1,2-diphospholide anions) were systematized, analyzed, and generalized. Methods for the generation of 1,2-diphospholide anions and their reactions with organic and organoelement electrophiles, as well as with transition metal complexes, were considered. Particular attention was paid to the cycloaddition reactions of 1-alkyl-1,2-diphospholes to obtain polycyclic chiral phosphines. A comparative analysis of the reactivity of 1,2-diphospholes and 1,2-diphospholide anions with respect to other representatives of phosphacyclopentadienes and phosphacyclopentadienide anions was carried out. The potential of application of 1,2-diphosphacyclopentadiene derivatives for the design of materials with magnetic, catalytic, and optical properties was shown.

     

Reactions of azoles with tetrachloro-1,2-difluoroethane and 1,2-dichlorodifluoroethylene

Tetrachloro-1,2-difluoroethane reacted with pyrazole and imidazole sodium salts to give mixtures of the corresponding N-(1,2,2-trichloro-1,2-difluoroethyl) derivatives and (E)-1,2-difluoro-1,2-dihetarylethenes. (E)-1,2-Difluoro-1,2-di(3,5-dimethyl-1H-pyrazol-1yl)ethene was also obtained as a result of replacement of chlorine atoms in 1,2-dichloro-1,2-difluoroethene. Analogous reaction with more nucleophilic imidazole involved replacement of not only chlorine but also fluorine atoms in 1,2-dichloro-1,2-difluoroethene, yielding tetraimidazolyl-substituted ethylene.     

Synthesis of disubstituted 1,2-dioxolanes, 1,2-dioxanes, and 1,2-dioxepanes

A route to cyclic peroxides containing 1,2-dioxolane, 1,2-dioxane or 1,2-dioxepane rings is described. These compounds present simpler structures related to the bicyclic core of stolonoxides, metabolites with marked cytotoxicity against several mammalian tumor cell lines, isolated from the marine tunicate Stolonica socialis. The key synthetic step consists in the intramolecular Michael addition of a secondary hydroperoxide group to an α,β-unsaturated ester.     

Acidity constants of 1,2-cycloheptane- and 1,2-cyclo-octanedione dioximes

Summary The acidity constants of 1,2-cycloheptanedione dioxime and 1,2-cyclo-octanedione dioxime have been determined potentiometrically and spectrophotometrically. Derivation of the acidity constants and molar absorptivities from the spectrophotometric data is discussed.

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Zusammenfassung Die sauren Dissoziationskonstanten des 1,2-Cykloheptandiondioxims und des 1,2-Cyklooctandiondioxims wurden potentiometrisch bzw. spektrophotometrisch bestimmt. Die Ableitung der sauren Dissoziationskonstanten und der molaren Absorptionskoeffizienten aus spektrophotometrischen Daten wurde diskutiert.

     

The synthesis of 1,2-diacetyl- and 1,2-diethylferrocenes

A method is described for the preparation of 1,2-diacetylferrocene, in which ferrocene is acetylated with acetyl chloride in the presence of AlCl₃ in methylene chloride. Addition of the ferrocene to an excess of the acetylation mixture over a prolonged period was found to be most favourable. The 1,2-diacetylferrocene formed proved to be free of the 1,3-isomer. It was reduced with LiAlH₄/AlCl₃ to 1,2-diethylferrocene.     

Reduction of 1,2-diaroyl-1,2-diazetidines by lithium aluminum hydride

Reaction of a series of four-membered ring hydrazides (1,2-diaroyl-1,2-diazetidines) with lithium aluminum hydride at 80° results in reductive saturation of both carbonyl groups affording 1,2-diaryl-1,2-diazetidines in modest yield. Reactions at 22° result in reductive fragmentation at one carbonyl moiety, producing a monoaroyl-1,2-diazetidine as the exclusive product. A mechanism similar to that postulated for the temperature-dependent reduction of amides by lithium aluminum hydride is proposed for the reduction of these 1,2-diazetidines.     

Synthesis of 1,2-disubstituted naphth [1,2-d]imidazole-4,5-diones

A convenient synthesis of 3-acylamino-1,2-naphthoquinones (I) is presented. The addition of aromatic and aliphatic amines to I followed by exposure to oxygen gives the corresponding 4-arylamino- or 4-alkylamino-3-acylamino-1,2-naphthoquinones (II). The addition of 4-cyclo-hexylbutylamine to 3-trichloroacetamino-1,2-naphthoquinone took an anomalous course and 1-(4′-cyclohexylbutyl)-3(H)-naphth[1,2-d]imidazoline-2,4,5-trione (VII) was obtained. Treatment of II with refluxing acetic acid gave 1,2-disubstituted naphth[1,2-d]imidazole-4,5-diones (III). The reaction was successful with a variety of 4-substituted amino-3-acylamino-1,2-naphthoquinones (II) and usually occurred in excellent yield. However, the cyclization of II to III is subject to steric limitation and attempts to cyclize 4-tert-butylamino-3-acetamino-1,2-naphthoquinone to the corresponding imidazole derivative was unsuccessful. The infrared, ultraviolet and nuclear magnetic resonance spectra of I, II, and III are discussed in relation to their structures.     

Reducing properties of 1,2-diaryl-1,2-disodiumethanes

1,2-Diphenyl- and 1-phenyl-2-(2-pyridyl)-1,2-disodiumethane efficiently dehalogenate vic-dibromoderivatives, affording the corresponding alkenes. The reaction proceeds rapidly, under mild conditions and is tolerant of a variety of functional groups (alcohol, carboxylic acid, ester and amide). This procedure was successfully extended to similar vic-disubstituted compounds.     

Synthesis of 1,2 difluoro-1,2-bis(pentafluorophenyl)dichlorane

1,2-Difluoro-1,2-bis(pentafluorophenyl)dichlorane is a new class of organic polyvalent chlorine compound. The closeness of the retention time of this compound and that of chloropentafluoro- benzene made its purification difficult. All attempts to obtain this compound in high yield have failed. 1,2-Difluoro-1,2-bis- (pentafluorophenyl)dichlorane is prepared by fluorination of chloropentafluorobenzene at 128°C with elemental fluorine. It has been characterized by ¹⁹F n.m.r., i.r., mass spectroscopy and elemental analysis.     

1,2-Epoxycarotinoide. 3. Mitteilung. Isolierun von 1,2-Epoxy-1,2-dihydrolycopin aus Tomaten

1,2-Epoxycarotenoids: Isolation of 1,2-Epoxy-1,2-dihydrolycopene from Tomatoes The optically active, 1,2-epoxy-1,2-dihydrolycopene was isolated from tomatoes. Its constitution was established by comparison with the racemic synthetic compound.     

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.     

A novel one-pot isocyanide-based four-component reaction: synthesis of highly functionalized 1H-pyrazolo[1,2-b]phthalazine-1,2-dicarboxylates and 1H-pyrazolo[1,2-a]pyridazine-1,2-dicarboxylates

A new protocol has been developed for the efficient synthesis of structurally diverse 1H-pyrazolo[1,2-b]phthalazine-1,2-dicarboxylates and 1H-pyrazolo[1,2-a]pyridazine-1,2-dicarboxylates via a four-component reaction of hydrazine hydrate, dialkyl acetylenedicarboxylates, isocyanides and various cyclic anhydrides such as succinic anhydride, maleic anhydride and phthalic anhydride in ethanol/acetone (1:1) at room temperature in good to moderate yields.     

Heterogeneous platinum catalytic aerobic oxidation of cyclopentane-1,2-diols to cyclopentane-1,2-diones

A method for the aerobic oxidation of cyclopentane-1,2-diols to the corresponding diketones over a commercial heterogeneous Pt/C catalyst is described. Unsubstituted and 3- or 4-substituted cyclopentane-1,2-diols are oxidized to 1,2-dicarbonyl compounds in good yields under the reported optimized reaction conditions (atmospheric air, 1 mol % of catalyst, 1 equiv of LiOH, aqueous solvents and 60 °C temperature). The method is applicable for producing cyclopentane-1,2-diketones in a scalable manner.     

1,2-Dichalcogenins: Simple Syntheses of 1,2-Diselenins, 1,2-Dithiins,and 2-Selenathiin

Ring opening of titanacyclopentadienes 1 with (SCN)₂ or (SeCN)₂ followed by bis(thiocyanate) or bis(selenocyanate) cyclization affords 1,2-dithiin ( 2 a ) or 1,2-diselenin ( 2 b ), respectively. Compound 1 gives 2 a directly on reaction with S₂Cl₂. Unsubstituted 1,2-diselenin is prepared by reaction of PhCH₂SeNa with 1,4-bis(trimethylsilyl)-1,3-butadiyne followed by reductive cleavage of the benzyl group and oxidation. The unsubstituted 2-selenathiin is prepared in an analogous manner, but from a mixture of PhCH₂SeNa and PhCH₂SNa.     

Mild template synthesis of copper(II)-containing macrocyclic compounds in the CuII–1,2-diaminoethanedithione-1,2–ethanedione-1,2 and CuII–1,2-diamino-ethanedithione-1,2–butanedione-2,3 triple systems into Cu2[Fe(CN)6]-gelatin-immobilized matrix implantates

The complexing processes in the Cu^II–1,2-diaminoethanedithione-1,2–ethanedione-1,2 and Cu^II–1,2-diaminoethanedithione-1,2–butanedione-2,3 triple systems occuring in the copper(II)hexacyanoferrate(II) gelatin-immobilized matrix in contact with aqueous alkaline solutions (pH~12) containing 1,2-diaminoethanedithione-1,2 and ethanedione-1,2 or butanedione-1,2 under room temperature, and between MCl₂, 1,2-diaminoethanedithione-1,2 and ethanedione-1,2 or butanedione-1,2 in the ethanol solutions, upon heating up to ~80 °C, have been studied. In both systems indicated, template synthesis occurs in the gelatin-immobililized matrix but does not occur in the ethanol solution. As a result of template synthesis, macrocyclic Cu^II chelates with 2,7-dithio-3,6-diazaoctadien-3,5-dithioamide-1,8 and its 4,5-dimethylsubstituted derivative are formed in the gelatin-immobililized matrix. 1,2-diaminoethanedithione-1,2 and ethanedione-1,2 or butanedione-2,3 are the ligand synthons in the processes indicated.     

Synthesis of vinyl 1,2-diketones

A new route is outlined for preparation of vinyl 1,2-diketones via a three-step sequence. First, allylic alcohols are photooxidized by ¹O₂ to hydroperoxides, which are reduced to vinyl 1,2-diols. These vinyl 1,2-diols are oxidized to vinyl 1,2-diketones with oxoammonium salts, which are prepared in situ from organic nitroxyl radicals. The new route is short, avoids the use of protecting groups, and is generally applicable to obtain aliphatic or aromatic vinyl 1,2-diketones.     

Macrocycles with 1,2-dicyano-1,2-dithioethene units

Abstract

The new unsaturated macrocyclic tetrathioethers (Z,Z)-4 (n = 0), (Z,Z)-5 (n = 1), (Z,Z)-6 (n = 2) and (Z,Z)-7 (n = 3) were synthesized by the cyclization of (Z)-disodium-1,2-dicyanoethene-1,2-dithiolate (Z)-3 with ω,ω'-dibromoalkanes BrCH₂CH₂(CH₂)nCH₂Br (n = 0;1;2;3) on refluxing in dioxane in yields up to 15%. By reaction of the dithiolate (Z)-3 with 1,3-dibromopropane the unsaturated hexathioether (Z,Z,Z)-6 was also obtained. By the cyclization of dithiolate (Z)-3 with 1,5-dibromopentane and 1,6-dibromohexane the (Z,E)- and (E,E)-isomers, respectively, were formed in addition to the (Z,Z)-isomers. The (E,E)- and (Z,E)-isomers are photochemically convertable to the corresponding themodynamically more stable (Z,Z)-isomers by irradiation with UV-light. The (E,E)-isomers can be synthesized in a straightforward manner using the (E)-disodium-1,2-dicyanoethene-1,2-dithiolate (E)-3. Crystal structures of (Z,Z)-5, (Z,Z)-6, (E,E)-6, (Z,E)-7 and (E,E)-7 are reported.     

Organocatalysis using protonated 1,2-diamino-1,2-diphenylethane for asymmetric Diels-Alder reaction

Bisammonium salts of mono-N-alkylated chiral 1,2-diamino-1,2-diphenylethane (DPEN) were employed in the catalytic and asymmetric Diels-Alder reaction between cyclopentadiene and crotonaldehyde. The N-3-pentyl diamine·2HCl catalyst shows high endo/exo selectivity and endo-enantioselectivity for the cycloaddition, and this organocatalysis is the first example of the use of a chiral 1,2-diamine to generate an imine intermediate which is activated by an internal ammonium Brønsted acid for the cycloaddition in a wet solvent.     

Lipase-catalyzed desymmetrization of meso-1,2-diaryl-1,2-diaminoethanes

The synthesis and enzyme-catalyzed desymmetrization of meso-1,2-diaryl-1,2-diaminoethanes have been investigated. A family of aromatic meso-1,2-diamines, containing different substitution patterns in the aromatic ring, was first prepared and then desymmetrized enantioselectively using lipases as biocatalysts. Selective alkoxycarbonylation of one of the amino groups was achieved using allyl carbonates, isolating the corresponding allyl monocarbamates with moderate to high enantiomeric excess at 45 °C. Candida antarctica lipase types A (CAL-A) and B (CAL-B) displayed the best activities and stereopreferences, with a dramatic influence being observed depending on the diamine structure. Non substituted and para-substituted aryldiamines led to the formation of allyl carbamates with good enantiomeric excess, using CAL-A for the less hindered substrates and CAL-B for the more hindered ones. On the other hand meta- and ortho-derivatives afforded low or negligible conversions and selectivities, respectively.     

1,2-Dimethyl-1,2-diphenyidisilane-1,2-diol and its K,Na, and FeII derivatives. Molecular structure of the all-trans-isomer, 2,3,5,6-tetra-methyl-2,3,5,6-tetraphenyl-1,4-dioxa-2,3,5,6-tetrasilacyclohexane

Hydrolysis of 1,2-dimethyl-1,2-diphenyl-1,2-dichlorodisilane yields 1,2-dimethyl-1,2diphenyldisilane-1,2-diol, which undergoes dimerization into stereoisomeric 2,3,5,6-tetramethyl-2,3,5,6-tetraphenyl-1,4-dioxa-2,3,5,6-tetrasilacyclohexanes under the action of H₂SO₄. Pure all-trans-isomer has been isolated and characterized by¹H NMR and IR spectroscopy and X-ray analysis. The reaction of sodium disilanediolate with FeBr₂ results in the formation of 1,2-dimethyl-1,2-diphenyl-4-ferra(ii)-3,5-dioxa-1,2-disilacyclopentane.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2550–2556, October, 1996.