Pentatomie heteroaromatic cations. Note II. Chemical properties of 2-phenyl-1,3-benzoxathiolium perchlorate

The reactions of 2-phenyl-1,3-benzoxathiolium perchlorate with common nucleophilic reagents (water, sodium hydroxide, ethanol, thiophenol, morpholine, phenylmagnesium bromide), with reducing agents (zinc, lithium aluminium hydride) and with manganese dioxide, were studied. In every case the reactions proceed by attack of the reagents at the C-2 position of the cationic system, giving rise either to 1,3-benzoxathiole derivatives or to ring-opening products. The 1,3-benzoxathiolium salts were shown to be suitable intermediates for converting the carboxylic acids into aldehydes and ketones.     

On the acylation of 1,3-benzoxathiole systems

The acylation on 1,3-benzoxathiole systems, as well as the effect of the stoichiometry of the catalyst on the yields of ketones and of breaking products of the O C S bonds is here described.     

Metabolites of felbamate; synthesis of 2-(4-hydroxyphenyl)-1,3-propanediol dicarbamate, 2-phenyl-2-hydroxy-1,3-propanediol dicarbamate,and 2-phenyl-1,3-propanediol monocarbamate

Three major metabolites of felbamate, namely 2-(4-hydroxyphyenyl)-1, 3-propanediol dicarbamate. [4], 2-hydroxy-2-phenyl-1,3-propanediol dicarbamat [12], and 2-phenyl-1,3-propanediol monocarbamate [17] were prepared. The first metabolite, 4, was synthesised from p-methoxy-phenylacetic acid [1] via five steps involving carboxylation, reduction, phosgenation, demethylation, and carbonation. The second one, 12, was prepared from 2-phenyl-1,3-propanediol [7] by the following five steps; phosgenation, halogenation, carbonation, dehalogenation, and ammonolysis. The synthesis of the third metabolite, 17, started with 7, via the following five steps: methylation, phosgenation, carbonation, and demethylation.     

Cleavage of the ethereal bond : XI. The reaction of allylic organomagnesium halides with 1,3-benzoxathiole and 1,3-benzodioxole

Some reactions of 1,3-benzoxathiole and 1,3-benzodioxole with allylic Grignard reagents have been examined and found to give cleavage of the ether bond to form substitution products with almost complete allylic rearrangement.     

1,3-Dipolare Cycloadditionen von 2-(Benzonitrilio)-2-propanid mit 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thion und Schwefelkohlenstoff

1,3-Dipolar Cycloadditions of 2-(Benzonitrilio)-2-propanide with 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thione and Carbon Disulfide Irradiation of 2,2-dimethyl-3-phenyl-2H-azirine ( 11 ) in the presence of 4,4-dimethyl-2-phenyl-2-thiazolin-5-thione ( 7 ) yields a mixture of the three (1:1)-ad-ducts 8 , 12 and 13 (Schemes 3 and 6). The formation of 8 and 12 can be explained by 1,3-dipolar cycloaddition of 2-(benzonitrilio)-2-propanide ( 1b ) to the C, S-double bond of 7. Photochemical isomerization of 12 leads to the third isomer 13 (Schemes 3 and 7). Photolysis of the azirine 11 in the presence of carbon disulfide gives a mixture of two (2:l)-adducts, namely 12 and 13 (Scheme 4). A reaction mechanism via the intermediate formation of the 3-thiazolin-5-thione b is postulated. The structure of the heterocyclic spiro compound 13 has been established by single-crystal X-ray structure determination (cf. Fig. 1 and 2).     

Synthesis and Structure of Tris (2′-[2-phenyl-1,3-dioxolano])-chromium(III)

Tris(2′-[2-phenyl-1,3-dioxolano])chromium(III) 3 has been synthesised and has been shown to have the cis (or fac) configuration 3a by X-ray analysis: the Cr? C bond length is 2.037 (10) Å.     

Structure and Conformational Analysis of 5,5-Bis(bromomethyl)-2-methyl-2-phenyl-1,3-dioxane

Russian Journal of General Chemistry - The structure of 5,5-bis(bromomethyl)-2-methyl-2-phenyl-1,3-dioxane 1 has been studied by means of 1H and 13C NMR spectroscopy as well as X-ray diffraction...     

A stereochemical investigation of 2-methyl- and 2,5-dimethyl-3-phenyl-1,3-oxazolidines using NMR

The stereochemical properties of two 2-methyl-3-phenyl-1,3-oxazolidines and two of its 5-methyl substituted and four of its 2,5-dimethyl substituted derivatives have been investigated by pmr and cmr methods. The compounds of 2,5-dimethyl-3-phenyl-1,3-oxazolidines exist in isomeric cis and trans forms at the two methyl groups on the heterocyclic ring.     

Protonation behaviour of 2-phenyl-1,3-diazaazulene derivatives

Three 2-phenyl-1,3-diazaazulene derivatives were synthesized and their protonation behaviours were investigated systematically via UV–vis absorption titration and ¹H NMR titration, as well as theoretical calculations. One of them exhibited a monoprotonation process while the others displayed prominent halochromic diprotonation responses. Interestingly, upon protonation of 2-phenyl-1,3-diazaazulene derivatives, the coplanarity and conjugation of the 16-π-conjugated backbones were well kept, while the electronic structures were controllably adjusted. The response mechanism of 1,3-diazaazulene derivatives towards acid is through the attachment of acid proton to the nitrogen atom in the diazaazulene ring, resulting in the change of the hybridization of protonated-N from sp² to sp³, which differed from that of the well-known azulene (analogue of 1,3-diazaazulene, protonation at carbon atom). This work would provide a new insight into the protonation research of the organic functional molecules.     

Experimental and quantum chemical study on the IR, UV and electrode potential of 6-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-2,3-dihydroxybenzaldehyde

Electrode potential of 6-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-2,3-dihydroxybenzaldehyde (DPDB) in methanol have been calculated theoretically. For the achievement of this task, the density functional theory (B3LYP/6-31G(d)) was employed with the inclusion of the entropic and thermochemical corrections to yield the free energies of the redox reactions. The electrode potential was also obtained experimentally by means of an electrochemical technique (cyclic voltammetry). The geometric parameters, the vibrational frequency values and the UV spectrum of DPDB and 2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-inden-2-yl)-5,6-dioxocyclohexa-1,3-dienecarbaldehyde (DPDD is the oxidized form of DPDB), were computed using the same methods. The calculated IR spectrum of DPDB, used for the assignment of the IR frequencies, was observed in the experimental FT-IR spectrum. The correlation between the theoretical and experimental DPDB vibrational frequencies was 0.996. This agreement mutually verified the accuracy of the experimental method and the validity of the applied mathematical model.     

1,3-Dipolare Cycloadditionen von Nitrilium-Betainen mit 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thion

1,3-Dipolar cycloadditions of Nitrilium Betaines with 4,4-Dimethyl-2-phenyl-2-thiazolin-5-thione Benzonitrile ylides, imines, and oxides undergo smooth 1,3-dipolar cycloaddition reactions with the exocyclic, C,S-double bond of 4,4-dimethyl-2-phenyl-2-thiazolin-5-thione ( 1 ), yielding heterocyclic spiro-compounds. The structure of the cycloadducts 5c, 5c ′, and 3f (Fig.) have been established by x-ray structure analysis. With the benzonitrile ylides, the two regioisomeric cycloaddition modes have been observed, depending on the substituents of the ylide-C-atom. It is questionable, whether the reaction of 1 and the oxazaphosphol 8 (Schemes 8 and 13) proceeds via the corresponding nitrile ylide as an intermediate.     

Synthesis and characterization of [2-(2-phenyl-5,6-dihydro-4H-1,3-oxazinyl)] tellurenyl chloride

The synthesis and characterization of the first examples of two tellurium compounds based on 2-phenyl-5,6-dihydro-4H-1,3-oxazine substrate are described. Intramolecular Te?N interaction in [2-(2-phenyl-5,6-dihydro-4H-1,3-oxazinyl)] tellurenyl chloride is established by single X-ray crystallography.     

Selenium heterocycles. XXXI. Reaction of ethyl propiolate with 5-phenyl-2-thioxo-1,3-thiaselenole and 4-phenyl-2-thioxo-1,3-dithiole

Reaction of ethyl propiolate with 4-phenyl-2-thioxo-1,3-dithiole afforded 4-carbethoxy-2-thioxo-1,3-dithiole in high yield. Reaction of ethyl propiolate with 5-phenyl-2-thioxo-1,3-thiaselenole gave 4-carbethoxy-2-thioxo-1,3-thiaselenone (IX), 4-carbethoxy-2-selenoxo-1,3-dithiole (X) and 5-carbethoxy-2-thioxo-1,3-thiaselenole (XI). A possible mechanism for the formation of these compounds is given.     

Synthesis and X-ray Structural Studies of 2-（2-Benzofuroylimino）-3-aryl-4-phenyl- 1,3-thiazolines

The synthesis for acyliminothiazolines by treatment of N, N□-substituted thioureas with α-bromoacetophenone under aqueous media was described. 2-（2-Benzofuroylimino）-3-aryl- 4-phenyl-1,3- thiazolines were characterized by infrared, NMR spectroscopy and elemental analysis. The single crystals of compounds 4a and 4b were grown by slow evaporation of 80% ethanol solution at room temperature. Compounds 4a and 4b crystallize in triclinic space group P1 and monoclinic space group P21/c, respectively.     

Synthesis and spectral behavior of 5-methyl-3-phenyl-1,3-oxazolidin-2-ones using NMR

Heterocyclic compounds of four 5-methyl-3-phenyl-1,3-oxazolidin-2-ones have been synthesized by the reaction of N-2-hydroxyethyl- or N-2-hydroxypropylanilines with phosgene in the presence of pyridine. From the spectral behavior, the title compounds are found to exist in the trans and cis forms.     

Regioselective electroreduction of 6h-1,3-thiazines. Comparison with chemical reductions I - investigation of 2-phenyl-6H-1,3-thiazines

The electrochemical reduction of 2-phenyl-6H-1,3-thiazines carried out at a mercury cathode in acetate buffer + ethanol (1:1) has been studied : - In the case of compounds monoactivated at carbon 5 (R⁵ = CHO or COCH₃) either hydrodimers (resulting from coupling at C-2), 3,6-dihydro-2H-1,3-thiazines (reduction of the imine bond) or tetrahydrothiazines can be obtained. - Diactivated 6H-1,3- thiazines (R⁴ = CO₂Et, R⁵ = CHO or COCH₃) successively lead to 5,6-dihydro-4H-1,3-thiazines (reduction of the ethylenic bond) and tetrahydrothiazines. - The reduction of a 6H-1,3-thiazine bearing only one withdrawing group at carbon 4 gives rise to a ring opening. At the same time, the action of various chemical reducing agents has been examined : the reduction of the imine bond is performed using NaBH₃CN while NaBH₄ or LiAlH₄ leads to the reduction of the substituents on the heterocyole.     

Cleavage of 2-(1,2,3,4-tetrahydroisoquinolin-1-yl)-2-phenyl-1,3-dithianes with HgO/BF3

Summary The title compounds (5) were prepared by addition of 2-phenyl-1,3-dithiane anion (2-lithiated10) to adequately substituted N-alkyl-3,4-dihydroisoquinolinium salts (7a–7g). Cleavage of compounds5 with HgO/BF₃ affords S-benzoyl-1,3-propanedithiol (4a) and the corresponding disulfide4c, benzaldehyde, and Hg(I) ions. In contrast to the title compounds, 2-(-dialkylaminobenzyl)-2-phenyl-1,3-dithianes (6) yield benzil under these conditions.In commemoration of the late Prof. Dr. Dr. h.c. mult.Horst Böhme, Marburg/Germany, an outstanding representative of Pharmaceutical Chemistry     

Synthesis and polymerization of optically active trans-(R)(–)-5-phenyl-1,3-hexadiene and trans-(R)(–)-6-phenyl-1,3-heptadiene

The monomers trans-(R)(–)-5-phenyl-1,3-hexadiene (I) and trans-(R)(–)-6-phenyl-1,3-heptadiene (II) were prepared by dehydration of (R)(–)-3-acetoxy-5-phenyl-1-hexene and (R)(–)-3-acetoxy-6-phenyl-1-heptene, respectively. Monomers I and II were polymerized in heptane with three catalyst systems: γ-TiCl₃–Al(i-Bu)₃, VCl₃–Alet₃, and nBuLi. Polymers of identical structures were obtained with all three catalysts; according to infrared and NMR spectra, only the 1,4 structure was present. Acetone-insoluble fractions of poly-I and poly-II have higher optical rotations than the corresponding monomers ([M]_D of poly-I, -46.45°, of monomer I, -28.6°: [M]_D of poly-II, -46.8°, of monomer II, -32.55°). There is no difference in the rotation of poly-I and poly-II.     

A convenient synthesis of 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-, 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo-, and 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines

The reactions of 1-alkylamino-1-alkylthio-3-phenylpropene-3-thiones 3 with thiophosgene and phosgene in toluene, followed by treatment of the reaction mixture with triethylamine gave 3-alkyl-2,3-dihydro-4-oxo-6-phenyl-2-thioxo- 4 , 3-alkyl-2,3-dihydro-2,4-dioxo-6-phenyl-4H-1,3-thiazines 5 , respectively in good to excellent yields. Similarly treatment of compounds 3 with N-arylimidoyl dichloride in benzene at room temperature gave 3-alkyl-2-arylimino-2,3-dihydro-4-oxo-6-phenyl-4H-1,3-thiazines 6 in excellent yields. The reactions of compounds 3 with oxalyl chloride in toluene gave also 5 in good yields.     

One-pot synthesis of 2-isopropyl-3-benzyl-1,3-thiazolidin-4-ones and 2-phenyl-3-isobutyl-1,3-thiazolidin-4-ones from valine, arenealdehydes and mercaptoacetic acid

A three-component one-pot synthesis of 2-isopropyl-3-benzyl-1,3-thiazolidin-4-ones and 2-phenyl-3-isobutyl-1,3-thiazolidin-4-ones from valine, arenealdehydes and mercaptoacetic acid with good yields is reported. Characterization of products was generally achieved by NMR techniques and specifically for 2-isopropyl-3-(4-nitrobenzyl)-1,3-thiazolidin-4-one by X-ray crystallography.