Tetracyanoethylene pi-complex chemistry. Indirect spectrophotometric determination of Diels-Alder-active 1,3-dienes

An indirect spectrophotometric method, based on the rapid Diels-Alder reaction between cisoid 1,3-dienes and tetracyanoethylene (TCNE) and the destruction of an aromatic-TCNE pi-complex, was developed to determine eleven 1,3-dienes in the 0.05-1.00 x 10(-3)M range. These dienes were: cyclopentadiene; 1,3-cyclohexadiene; trans-1,3-pentadiene; 2,4-dimethyl-1,3-pentadiene; trans-2-methyl-1,3-pentadiene; 2-methyl-1,3-butadiene; 9-methylanthracene; 9,10-dimethylanthracene; 1,6-diphenyl-1,3,5-hexatriene; 2,3-dimethyl-1,3-butadiene; and 1,4-diphenyl-1,3-butadiene. Three 1,3-dienes were determined in the 0.05-1 x 10(-4)M range: cyclopentadiene, trans-2-methyl-1,3-pentadiene, and anthracene. The limit of detection for cyclopentadiene in carbon tetrachloride solutions is 0.11 microg/ml. Fourteen 1,3-dienes were found to form stable pi-complexes and could not be determined by the proposed method. For these 1,3-dienes, the spectra of some of the complexes are reported; in addition, relative equilibrium constants for the pi-complexes of 2,5-dimethyl-2,4-hexadiene, cis-1,3-pentadiene, 4-methyl-1,3-pentadiene, and 1,3-cyclo-octadiene were estimated. An explanation of the transient colour in the 1,3-diene-TCNE Diels-Alder reaction is suggested.     

Synthesis of New 1,3-Thiazolecarbaldehydes

H-Lithiation and Br-lithiation reactions of 1,3-thiazole were studied in order to obtain new thiazole derivatives. Four isomeric chloromethyl derivatives of 1,3-thiazole containing a protected aldehyde group like 2-(1,3-dioxolan-2-yl)-5-(chloromethyl)-1,3-thiazole, 5-(1,3-dioxolan-2-yl)-2-(chloromethyl)-1,3-thiazole, 4-(1,3-dioxolan-2-yl)-2-(chloromethyl)-1,3-thiazole, and 2-(1,3-dioxolan-2-yl)-4-(chloromethyl)-1,3-thiazole were synthesized. Their nucleophilic substitution reactions with dimethylamine and sodium methylthiolate were studied. New aldehydes of 1,3-thiazole series of low-molecular weight were obtained.     

Oxidation of 1,3-Dioxacyclanes with Oxone and Potassium Persulfate Catalyzed by 2,2,5,5-Tetramethyl-4-Phenyl-3-Imidazoline-3-Oxide-1-Oxyl

The catalytic effect of 2,2,5,5-tetramethyl-4-phenyl-3-imidazoline-3-oxide-1-oxyl on the oxidation of 2-isopropyl-1,3-dioxolane, 2-phenyl-1,3-dioxolane, 2-phenyl-4-chlormethyl-1,3-dioxolane, 2-isopropyl-1,3-dioxane, 2-isopropyl-4-methyl-1,3-dioxane, 2-phenyl-1,3-dioxane, 2-phenyl-4-methyl-1,3-dioxane with oxone and potassium persulfate is reported. The corresponding glycol monoesters were obtained with yields of 90-100%.     

Condensation of 1,3-diketones with 1,8-diaminonaphthalene: Synthesis ofbis(2,3-dihydroperimidine-2-spiro)cycloalkanes

Summary Cyclic 1,3-diketones like cyclopentane-1,3-dione, cyclohexane-1,3-dione, and 5,5-dimethylcyclohexane-1,3-dione react with 1,8-diaminonaphthalene to afford new condensed heterocyclic spiro systems.

---

Kondensation von 1,3-Diketonen mit 1,8-Diaminonaphthalin: Synthese vonBis(2,3-dihydroperimidin-2-spiro)cycloalkanen

Zusammenfassung Cyclische 1,3-Diketone wie Cyclopentan-1,3-dion, Cyclohexan-1,3-dion und 5,5-Dimethylcyclohexan-1,3-dion reagieren mit 1,8-Diaminonaphthalin zu neuen kondensierten heterocyclischen Spiranen.

     

Skeletal isomerism within 1,3-disilabicyclo[1.1.0]butane and 2,3-disilabuta-1,3-diene derivatives

A bis-adamantane-spiro-fused 1,3-bis(triisopropylsilyl)-1,3-disilabicyclo[1.1.0]butane equilibrates with the corresponding 2,3-bis(triisopropylsilyl)-1,3-disilabuta-1,3-diene with a ratio of 1:19. The 1,3-disilabuta-1,3-diene was fully characterized by a combination of multinuclear NMR and UV-VIS spectroscopies, elemental analysis, and single-crystal X-ray diffraction analysis.     

Photocyclization of 2-chloro-substituted 1,3-diarylpropan-1,3-diones to flavones

The photochemical behavior of 2-halo-substituted 1,3-diarylpropan-1,3-dione strongly depends on the nature of the halogen atom bonded and the presence of electron-donor groups on the phenyl ring. In the case of 2-chloro-1,3-diphenylpropan-1,3-dione and 1-(3,5-dimethoxyphenyl)-3-phenylpropan-1,3-dione, cyclization to flavones was the sole reaction pathway, whereas in the case of 2-chloro-1,3-di(4-methoxyphenyl)propan-1,3-dione, only products derived from alpha-cleavage were observed. 2-Fluoro derivatives of 1,3-diarylpropan-1,3-diones were photostable; on the other hand, 2-chloro-2-fluoro derivates resulted in 3-fluoroflavones.     

A convenient one-pot synthesis of substituted 2-pyrone derivatives

2-Pyrone derivatives were prepared in a one step procedure from readily available (chlorocarbonyl)phenyl ketene and 1,3-diketones such as 2,4-pentanedione, 1,3-diphenyl-1,3-propanedione, 1-phenyl-1,3-butanedione, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dimethyl-pyrimidine-2,4,6-trione and ethyl 2,4-dioxopentanoate. A mechanism is presented to account for the formation of the products. This method provides an easy route to prepare 3,4,5,6-tetrasubstituted 2-pyrones in good to excellent yields and in a short experimental time.     

New chemical access for pyran core embedded derivatives from bisalkenylated 1,3-diketones and 1,3-diketoesters via tandem C-dealkenylation and cyclization

New chemical access has been developed for the synthesis of pyran core embedded derivatives from 1,3-diketones and 1,3-diketoesters, in which the active methylene group of 1,3-diketone or 1,3-diketoester was alkenylated with three equivalents of alkenyl bromides in presence NaH to give bisalkenyl 1,3-diketones or 1,3-diketoesters and the resultant bisalkenyl 1,3-diketones or 1,3-diketoesters were reacted with AlCl₃ at room temperature to furnish pyran core embedded derivatives in good to excellent yields.     

Synthesis and photoluminescence properties of BF2 complexes with 1,3-diketone ligands

BF₂ complexes with 1,3-diketone ligands were synthesized, and their optical and electrochemical properties were studied. The colors of the complexes varied depending on the structures of the 1,3-diketone ligands. The absorption and emission maxima of the complexes with 1,3-diaryl-1,3-diketone ligands were considerably red shifted as compared to those of the complexes with 1-aryl-3-trifluoromethyl-1,3-diketone ligands, suggesting an extended π-conjugation of the 1,3-diaryl-1,3-diketone moieties. The molar absorption coefficients and quantum yields of the complexes with 1,3-diaryl-1,3-diketone ligands were larger than those of the complexes with 1-aryl-3-trifluoromethyl-1,3-diketone ligands. Cyclic voltammetry measurements revealed that the reduction potentials of the BF₂ complexes were higher than those of the free ligands. These complexes exhibited various emission colors in the solid states due to the intermolecular interactions.     

Condensation of aldehydes and ketones

The Mannich reaction with methylene- and benzylidenediacetophenones has given: 1,3-dibenzoyl-4-piperidinobutane, 1,3-dibenzoyl-4-morpholinobutane, 1,3-dibenzoyl-4-diethylamino-2-phenylbutane, 1,3-dibenzoyl-2-phenyl-4-piperidinobutane, 1,3-dibenzoyl-4-diethylaminobutane, and 1,3-dibenzoyl-4-dimethylamino-2-phenylbutane. From the latter two compounds, 3-diethylaminomethyl-2,6-diphenylpyridine and 3-dimethylaminomethyl-2,4,6-triphenylpyridine have been obtained.For part XVII, see [7].     

3(1,3-Heterazolidin-3-yl-methyl)-1,3-oxazolidines and their reduction with borane–THF

Preparation of bis-heterazolidines bonded by a CH₂, CH₂–S–CH₂ or CH₂SCH₂SCH₂ groups through their nitrogen atoms is reported: 3-(1,3-oxazolidin-3-ylmethyl)-1,3-oxazolidine 1, 3-(4,4-dimethyl-1,3-oxazolidin-3-ylmethyl)-1,3-oxazolidine 2, 3-(1,3-diazolidin-3-ylmethyl)-1,3-diazolidine 3, 3-(1,3-thiazolidin-3-ylmethyl)-1,3-thiazolidine 4, 3-(1,3-thiazolidin-3-ylmethylsulfanylmethyl)-1,3-thiazolidine 5 and 3-(1,3-oxazolidin-3-ylmethylsulfanylmethyl-sulfanylmethyl)-1,3-oxazolidine 6. The solid state structures of 4 and 5 were determined by X-ray diffraction analyses. BH₃–THF reduction reactions of compounds 1–6 were investigated. N→BH₃ mono- and di-adducts of 1–6 were prepared and their structures calculated (ab initio 3-21G*).     

1,3-Dimethoxy-1,3-dimethyl-1,3-diphenyl- and 1,3-dimethoxy-1,3-tetraphenyldisiloxanes: synthesis and structure

Russian Chemical Bulletin - 1,3-Dimethoxy- 1,3-dimethyl- 1,3-diphenyl- and 1,3-dimethoxy- 1,3-tetraphenyldisiloxanes were synthesized. Their structures were confirmed by IR and NMR spectroscopy....     

Assessment of the in vivo genotoxicity of new lead compounds to treat sickle cell disease

The compounds 1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)methyl nitrate (C1), (1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)ethyl nitrate (C2), 3-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)benzyl nitrate (C3), 4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-N-hydroxy-benzenesulfonamide (C4), 4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)benzyl nitrate (C5), and 2-[4-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)phenyl]ethyl nitrate (C6) were evaluated with a micronucleus test using mouse peripheral blood to identify new candidate drugs for the treatment of sickle cell disease (SCD) that are safer than hydroxyurea. The compounds induced an average frequency of micronucleated reticulocytes (MNRET) of less than six per 1,000 cells at 12.5, 25, 50, and 100 mg/kg, whereas hydroxyurea induced an average MNRET frequency of 7.8, 9.8, 15, and 33.7 per 1000 cells respectively, at the same concentrations. Compounds C1-C6 are new non-genotoxic in vivo candidate drugs for the treatment of SCD symptoms.     

Steerochemistry of heterocycles.

The stereochemical peculiarities of substituted 1,3-dioxanes and 1,3-dithianes are discussed. The high probability of the existence of flexible conformations in these series, the considerable energy preference of the 5-C-axial position in the chair conformation of 1,3-dioxanes and 1,3-dithianes, and the definite preference of the 2-C-axial position in the chair conformation of 1,3-dithianes as compared with the axial conformations of the cyclohexane type are noted. The PMR spectra of stereoisomeric 2,5-dimethyl-5-isopropyl-1,3-dioxanes, 2-methy-l5-isopropyl-1,3-dithianes, and 2,2,5-trimethyl-1,3-dithiane are described, and their configurations and preferred conformations are proved. The results of a study of the epimerization of stereoisomers of substituted 1,3-dioxanes and 1,3-dithianes are examined, and the conformational energies of individual substituents in the 5-position of these cyclic systems are calculated on the basis of this examination.See [48] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 582–592, May, 1971.     

Radical Cyclization of Fluorinated 1,3‐Dicarbonyl Compounds with Dienes Using Manganese(III) Acetate and Synthesis of Fluoroacylated 4,5‐Dihydrofurans

Radical cyclizations of fluorinated 1,3‐dicarbonyl compounds with dienes mediated by Mn(OAc)₃ afforded 4,5‐dihydrofurans containing difluoroacetyl, trifluoroacetyl, or heptafluorobutanoyl groups in good‐to‐excellent yields. Additionally, 2‐(difluoromethyl)‐4,5‐dihydrofurans and a 4,7‐dihydrooxepin derivative were obtained as unexpected products in the reaction of 4,4‐difluoro‐1‐phenylbutane‐1,3‐dione with 1,3‐diphenylbuta‐1,3‐diene. The radical cyclization of symmetrical dienes such as 2,3‐dimethylbuta‐1,3‐diene and 1,4‐diphenylbuta‐1,3‐diene with 1,3‐diketones furnished the corresponding products in low yields. However, treatment of 1‐phenylbuta‐1,3‐diene with 1,3‐dicarbonyl compounds afforded 4,5‐dihydrofurans containing fluoroacyl groups. The radical cyclizations with 3‐methyl‐1‐phenylbuta‐1,3‐diene and 1,3‐diphenylbuta‐1,3‐diene led to 4,5‐dihydrofurans in good yields, since Me and Ph groups at C(3) of these dienes increase the stability of the radical intermediate.     

Synthesis and Thermal Reaction of 1,3-Bis(alkylseleno)allenes

Reactions of Ph(2)C(3) dianion, prepared from 1,3-diphenylpropyne and n-butyllithium, with dimethyl diselenide and benzylselenocyanate yielded 1,3-bis(methylseleno)-1,3-diphenylpropadiene and 1,3-bis(benzylseleno)-1,3-diphenylpropadiene, respectively, and the reaction with a mixture of dimethyl diselenide and benzylselenocyanate gave 1-benzylseleno-3-methylseleno-1,3-diphenylpropadiene together with the symmetric products. Thermal reactions of the 1,3-bis(alkylseleno)allenes afforded (E)- and (Z)-1,3,4,6-tetraphenyl-3-hexene-1,5-diynes along with compounds derived from cyclic dimer of the allene or diselenide via radical pathway.     

New Approach to the Synthesis of 1,3-Chloroisothiocyanatoalkanes. Synthesis of Tetrahydro-1,3-thiazine-2-thiones and 2-Alkylamino-5,6-dihydro-1,3-thiazines

A method was developed to prepare 1,3-chloroisothiocyanatoalkanes by reducing 1,3-isothiocyanato ketones using sodium borohydride at pH ~7 and subsequent treatment of the resultant 1,3-isothiocyanato alcohols with thionyl chloride. The reaction of 1,3-chloroisothiocyanatoalkanes with sodium hydrosulfide or amines gives substituted tetrahydro-1,3-thiazine-2-thiones or 2-amino-5,6-dihydro-1,3-thiazines.     

Synthesis of new electron-donor compounds: Bis(2-thia-1,3-propylenedithio)teterathiafulvalene and bis(2-oxo-1,3-propylenedithio)tetrathiafulvalene

1,3-Dithiole-2-thione derivatives, which are starting compounds for the synthesis of new electron donors of the tetrathiafulvalene class, viz., bis(2-thia-1,3-propylendithio)tetrathiafulvalene and bis(2-oxo-1,3-propylendithio)tetrathiafulvalene, were obtained by the reaction of bis(tetraalkylamonium) bis(1,3-dithiole-2-thione-4,5-dithiolato)zincates with 1,3-dichlorodimethyl sulfide and 1,3- dibromoacetone.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 471–474, April, 1990.     

Synthesis of 1,3-dialkyl-5-(hetaryl-1-yl)-1,3-dihydrobenzimidazol-2-ones

Reactions of 5-amino-1,3-dialkyl-1,3-dihydrobenzimidazol-2-ones with 2,5-dimethoxytetrahydrofuran and 2,6-dimethyl-γ-pyranone led to the formation of 1,3-dialkyl-1,3-dihydro-5-(pyrrol-1-andл)benzimidazol-2-ones and 1-(1,3-dialkyl-2-oxo-1,3-dihydrobenzimidazol-5-yl)-2,6-dimethylpyridin-4-ones.     

Theoretical and spectroscopic study of 2-substituted indan-1,3-diones: a coherent picture of the tautomeric equilibrium

The structures of some 2-substituted indan-1,3-diones are investigated in the gas phase and solution using quantum chemical calculations and spectral (NMR, IR, and UV) measurements. The influence of the substituent at the 2-position on the tautomeric equilibrium of 2-substituted indan-1,3-diones in solvents with different polarity is evaluated. It is shown that the equilibrium in 2-formyl-indan-1,3-dione and 2-acetyl-indan-1,3-dione is shifted to the 2-hydroxyalkylidene-indan-1,3-dione tautomer, while 2-carboxyamide-indan-1,3-dione exists as a mixture of two tautomers, 2-(hydroxyaminomethylidene)-indan-1,3-dione and 2-carboamide-1-hydroxy-3-oxo-indan, with extremely fast proton transfer between them. The situation for 2-carboxy-indan-1,3-dione is quite different - on the basis of the analysis of the obtained results, the possible existence of an anionic form of 2-carboxy-indan-1,3-dione in solution can be inferred.