Polarographische Untersuchungen an symmetrischen Triazacarbocyaninen in Acetonitril

Polarographic Investigations on Symmetrical Triazacarbocyanine Dyes in Acetonitrile Solution The reduction behaviour of thirteen symmetrical triazacarbocyanine dyes with different heterocycles in acetonitrile solution has been investigated by means of dc- and ac-polarography, cyclic oscillopolarography and coulometry. The reduction mechanism has been found to be of the type eec with the first step being reversible and the second step being reversible to irreversible. Reduction potentials, transfer coefficients and specific currents of both steps have been measured (E_1/2: ?0,110 to ?1.025 V vs. Ag/AgCl for the first step) and compared with known properties of carbocyanines and triazenium salts and to HMO calculations. The effect of substituents X has been studied on the compounds 1,3-diethyl-2-[(1,3-diethyl-5-X-benzimidazolin-2-yliden)triazenyl]-5-X-benzimidazolium-tetra-fluoroborate ( 1a (X)) and 3-ethyl-2-[(3-ethyl-5-X-Δ⁴-1,3-triazolin-2-yliden)triazenyl]-5-X-1,3-thiazolium-tetrafluoroborate ( 1g (X)), and p-values of 0,36 and 0,72 V, respectively, have been found.     

Functiaonalization of 2-(1-Cyclohexen-1-yl)aniline Derivatives

The reaction of 2-(1-cyclohexen-1-yl)aniline and -6-methylaniline with phthalic anhydride has afforded 2-(2-cyclohex-1-en-1-ylphenyl)- and 2-(2-cyclohex-1-en-1-ylphenyl)-6-methylphenyl)-1H-isoindole-1,3(2H)-diones. The reaction of the obtained isoindole-1,3-diones with bromine in dichloromethane in the presence of sodium bicarbonate has led to the formation of the product of pseudo-allylic halogenation. Replacement of the halogen atom by methoxy group has been performed by keeping 2-[2-(6-bromocyclohex-1-en-1-ylphenyl)-6-methylphenyl)]-1H-isoindole-1,3(2H)-dione in a methanolic solution in the presence of NaHCO₃. The reaction of 2-(2-cyclohex-1-en-1-yl-6-methylphenyl)-1H-isoindole-1,3(2H)-dione with molecular bromine in the presence of methanol has given a co-halogenation product, whereas the dibromination product has been obtained in the presence of octyl alcohol.

     

1,3-Adamantanyl dimethylsiloxane copolymers. Preparation and properties

1,3-bis(Dimethylhydroxysilyl)adamantane(I) has been prepared. Thermal condensation polymerization of this monomer yields poly-1,3-adamantyl-1,1,3,3-tetramethyldisiloxane. Condensation of I with bis(dimethylamino)dimethylsilane or 1,3-bis(dimethylamino)-1,1,3,3-tetramethyldisiloxane gave the expected 1,3-adamantyl dimethylsiloxane copolymers (II and III) respectively. These polymers have been characterized by ¹H,¹³C, and ²⁹SiNMR as well as GPC and TGA. They have unusually high thermal stability.     

Voltammetrische Untersuchungen der Oxydation der symmetrischen Triazacarbocyanine in Acetonitril

Voltammetric Investigations on the Oxidation Step of Symmetrical Triazacarbocyanine Dyes in Acetonitrile Solution The oxidation behaviour of twelve symmetrical triazacarbocyanine dyes with different heterocycles in MeCN (containing tetrabutylammonium perchlorate) has been investigated by means of dc-, ac- and cyclic triangular wave voltammetry. The oxidation mechanism has been found to be of the type ec, with the electrochemical step being reversible to irreversible. Oxidation potentials and transfer coefficients have been measured (E_1/2 1.60 to 2.12 V vs. Ag/AgCl) and compared with known properties of carbocyanines. The effect of substituents X has been studied on the compounds 1,3-diethyl-2-[3-(1,3-diethyl-5-X-benzimidazolin-2-ylidene)-1-triazeno]-5-X-benzimidazolium tetrafluoroborate ( (1a(X)) and 3-ethyl-2-[3-ethyl-5-X-Δ⁴-1,3-thiazolin-2-ylidene)-1-triazeno]-5-X-1,3-thiazolium tetrafluoroborate ( 1g(X)) , and ρ-values of 0.425 and 0.565 V, respectively, have been found.     

Cobalt(II) complexes with aminopolycarboxylate 1,3-pdta-type ligands: synthesis and characterization of trans(O6)-[Mg(H2O)6][CoII(1,3-pddadp)]·H2O

Starting from Ba₂(1,3-pddadp)·8H₂O (1,3-pddadp=1,3-propanediamine-N,N′-diacetate-N,N′-di-3-propionate ion) and CoSO₄, a new hexadentate [Co^II(1,3-pddadp)]²⁻ complex has been prepared. The trans(O₆) geometry of this complex was confirmed by comparison of its i.r. and u.v.–vis. spectra with those of [Co^II(1,3-pdta)]²⁻ (1,3-pdta is the 1,3-propanediaminetetraacetate ion) and trans(O₆)-[Co^III(1,3-pddadp)]⁻ complexes of known X-ray crystal structure. Magnetic and electrolytic conductivity properties of these complexes have also been discussed.     

Crystal structure of polyamides containing 1,3-cyclohexane rings

The effect of 1,3-cyclohexane rings in the chain backbone on the crystal structure of polyamides has been studied using polyamides (denoted 1,3-CBMA-n) obtained from 1,3-cyclohexane-bis(methylamine) (1,3-CBMA) and n-carbon dicarboxylic acids. The crystallinity of the 1,3-CBMA-n polymers changes greatly with variation in the value of n. This is attributed to hydrogen-bond changes associated with the relative length of the diacid moiety to the diamine moiety in the monomeric unit of each polymer. In 1,3-CBMA-6, the cis-1,3-cyclohexane rings are readily accommodated in the molecular chains to form crystals in a manner similar to the m-benzene rings in poly(m-xylylene adipamide) (MXD-6). The crystal lattice, however, is more expanded than in MXD-6 since the 1,3-cyclohexane rings is bulkier than the m-benzene ring. The crystal structure of the 1,3-CBMA-n polymers is essentially the same as that of MXD-6.     

Gold(III) amine complexes in aqueous alkali solutions

The gold(III) 1,3-diaminopropane complex [Au(1,3-pn)(1,3-pn-H)]Cl₂ has been synthesized. Its dissociation constant has been determined: Au(1,3-pn)₂³⁺ = Au(1,3-pn-H)²⁺ + H⁺, logK _a1 = −7.03 ± 0.05 (I = 0.1 mol/L NaClO₄). Considerable spectral changes are observed for strong alkali solutions (pH 11–14) containing the monoamido forms of the gold(III) ethylenediamine, 1,3-diaminopropane, and diethylenetriamine complexes (Au(en)(en-H)²⁺, Au(1,3-pn)(1,3-pn-H)²⁺, Au(dien-H)OH⁺). These changes are attributed to the formation of the diamido species Au(en-H)₂⁺, Au(1,3-pn-H)₂⁺, and Au(dien-2H)OH⁰. The dissociation constants of the monoamido complexes have been determined: Au(en)(en-H)²⁺ (logK _a2 = −10.9 ± 0.1 at I = 0.001–0.01 mol/L NaCl); Au(1,3-pn)(1,3-pn-H)²⁺ (logK _a2 = −11.3 ± 0.1 at I = 0.1 mol/L NaCl); Au(dien-H)OH⁺ (logK _a2 = −12.4 ± 0.1 at I = 0.1 mol/L NaCl).     

Pteridine. Teil LXXXI. Mechanismus der Photooxidation von 5,6-Dihydro-1,3-dimethyl-6-thioxopteridin-2,4(1H,3H)-dion

Mechanism of the Photooxidation of 5,6-Dihydro-1,3-dimethyl-6-thioxopteridine-2,4(1H,3H)-dione The mechanism of the photooxidation of 5,6-dihydro-1,3-dimethyl-6-thioxopteridine-2,4(1H,3H)-dione ( 9 ) has been investigated in dependence of the pH. Photooxidation of the anion species in weak alkaline solution takes place by singlet oxygen as well as the superoxide radical anion forming 1,2,3,4-tetrahydro-1,3-dimethyl-2,4-dioxopteridine-6-sulfinate ( 5 ) as the first detectable reaction product. In acidic medium, a more complex photooxidation process is observed leading, in a radical-chain mechanism, to 6,6′-dithiobis[1,3-dimethylpteridine-2,4(1H,3H)-dione] ( 6 ).     

Synthesis of 3‐(ω‐Hydroxyalkoxy)isobenzofuran‐1(3H)‐ones by Trifluoroacetic Acid‐Mediated Lactonization of tert‐Butyl 2‐(1,3‐Dioxol‐2‐yl)‐ or 2‐(1,3‐Dioxan‐2‐yl)benzoates

An efficient two‐step method for the preparation of 3‐(2‐hydroxyethoxy)‐ or 3‐(3‐hydroxypropoxy)isobenzofuran‐1(3H)‐ones 3 has been developed. Thus, the reaction of 1‐(1,3‐dioxol‐2‐yl)‐ or 1‐(1,3‐dioxan‐2‐yl)‐2‐lithiobenzenes, generated in situ by the treatment of 1‐bromo‐2‐(1,3‐dioxol‐2‐yl)‐ or 1‐bromo‐2‐(1,3‐dioxan‐2‐yl)benzenes 1 with BuLi in THF at ?78°, with (Boc)₂O afforded tert‐butyl 2‐(1,3‐dioxol‐2‐yl)‐ or 2‐(1,3‐dioxan‐2‐yl)benzoates 2 , which can subsequently undergo facile lactonization on treatment with CF₃COOH (TFA) in CH₂Cl₂ at 0° to give the desired products in reasonable yields.     

Synthesis and characterization of polymerizable β-diketone-based liquid crystalline metal chelates

Two novel square-planar palladium chelating liquid crystals, bis(p-n-(l-undecenoxyphenyl-3-dodecyloxyphenyl)-propane-1,3-dionato)palladium(II) (Pd-C₁₁-C₁₂) and bis(1,3-di(p-n-tetradecyloxphenyl)-propane-1,3-dionato) palladium (II) (Pd-C₁₄-C₁₄) have been synthesized. Moreover, the copper chelating liquid crystal bis(p-n-(l-undecynoxylphenyl-3-dodecyloxylphenyl)-propane-1,3-dionate)copper (II) (Cu-Cu₁₁-C₁₂) has been synthesized by heterogeneous ligand-exchange reaction. These β-diketone metal chelates have been characterized by elementary analysis, differential scanning calorimetry, polarizing microscopy, X-ray diffraction analysis and temperature-variable IR. It was found that these chelates were discotic lamellar-(D_L) mesophase liquid crystals. In particular, the temperature-variable IR study indicates that the central chelating ring and the surrounding benzene rings would form a co-planar conjugated structure in the liquid crystalline (LC) state.     

A Facile Synthesis of Oxoindenothiazine and Dioxospiro(indene‐2,4′‐thiazine) Derivatives from (Substituted ethylidene)hydrazinecarbothioamides

(E)‐2‐[2‐(1‐Substituted ethylidene)hydrazinyl]‐5‐oxo‐9b‐hydroxy‐5,9b‐dihydroindeno[1,2‐d][1,3]‐thiazine‐4‐carbonitriles and (E)‐5‐oxo‐[(E)‐(1‐substituted ethylidene)hydrazinyl]‐2,5‐dihydroindeno[1,2‐d][1,3]thiazine‐4‐carbonitriles have been obtained from the reaction of 2‐(substituted ethylidene)hydrazinecarbothioamides with 2‐(1,3‐dioxo‐2,3‐dihydro‐1H‐inden‐2‐ylidene)propanedinitrile ( 1 ) in ethyl acetate solution. However, (Z)‐6′‐amino‐1,3‐dioxo‐3′‐substituted‐2′‐[(E)‐(1‐phenylethylidene)hydrazono]‐1,2′,3,3′‐tetrahydrospiro(indene‐2,4′‐[1,3]thiazine)‐5′‐carbonitriles were observed during the reaction of N‐substituted‐2‐(1‐phenylethylidene)hydrazinecarbothioamides with ( 1 ). The structure assignment of products has been confirmed on the basis of ¹H‐, ¹³C‐NMR, and mass spectrometry, as well as theoretical calculations.     

Microwave‐assisted synthesis and diels–alder reactions of 1,3‐azaphospholo[5,1‐a]isoquinolines

The application of microwave technique has been extended successfully for the first time to the synthesis of a representative class of azaphospholes, viz. 1,3‐bis(alkoxycarbonyl)‐1,3‐azaphospholo[5,1‐a]isoquinolines ( 2 ), which occurs rapidly giving higher yields. Stereoselectivity is observed in the reaction with 2,3‐dimethyl‐1,3‐butadiene, and isoprene reacts regioselectively as well. 1‐Methyl‐3‐ethoxycarbonyl‐1,3‐azaphospholo[1,5‐a]pyridine ( 4 ) remains inert toward [2+4] cycloaddition. The nonoccurrence of the Diels–Alder reaction in the latter case has been supported by semiempirical PM3 calculations. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:560–563, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10193     

Preparation,configurational and DFT–NBO analysis of nickel(II) complexes with edta-type ligands containing six-membered backbone ring: crystal structure of [Ni(H2O)6][Ni(1,3-pdta)]·2H2O

New hexadentate nickel(II) complex Mg[Ni(1,3-pd3ap)]·10H₂O containing unsymmetrical edta-type ligand, 1,3-propanediamine-N,N,N′-triacetate-N′-3-propionate (1,3-pd3ap), has been prepared, chromatographically separated, and characterized. Only one [trans(O₅)] of the two possible geometrical isomers was isolated. In this isomer, the two five-membered glycinate rings (R rings) occupy trans-axial sites while the one glycinate ring and one β-alaninate ring lie in the equatorial plane with the two diamine nitrogens (G rings). This result confirms the assignment made on the basis of the density functional theory (DFT), IR, and UV–Vis spectral data analysis. In order to see cation influence on the structural and electronic behavior, [Ni(H₂O)₆][Ni(1,3-pdta)]·2H₂O complex has also been prepared and its structure verified by an X-ray analysis. Spectral data and electronic transition assignment, DFT–natural bonding orbital, and an extensive strain analysis are discussed in comparison with those of other [Ni(edta-type)]^2? complexes of known configuration.     

On the syntheses of 1,3-disubstituted dithieno[3,4-b:3′,2′-d]pyridines via halogen-metal exchange of 1,3-dibromodithieno[3,4-b:3′,2′-d]pyridine

Halogen-metal exchange of 1,3-dibromodithieno[3,4-b:3′,2′-d]pyridine with butyllithium under different conditions has been studied. Upon reaction with iodine, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl carbonate, dimethyl disulfide and thiuram disulfide, the 1,3-diiodo-, 1,3-diacetyl-, 1,3-diformyl-, 1,3-dicarbomethoxy, 1,3-di(thiomethyl)- and 1,3-di(N,N-dimethyldithiocarbamoyl)dithieno[3,4-b:3′,2′-d]-pyridines, respectively, were obtained in varying yields. 3-Monosubstituted derivatives were obtained in some cases. The formation of 3,7-disubstituted derivatives was sometimes also observed.     

Synthesis and Structure of Carbonyliron Complexes of Allenecarboxylates and Allenic Lactones

On irradiation in the presence of Fe(CO)₅, the allenecarboxylates 1 afforded binuclear carbonyliron complexex 6 (Scheme 3), whereas the allenic lactone 7 under similar conditions gave a mixture of one binuclear and two mononuclear carbonyliron complexes ( 9 , 8 , and 10 ; Scheme 4). The structure of the complexes has been elucidated by X-ray crystallography. The structure of the binuclear complex 9 corresponds to that of 6 , while 8 has been shown to be a 1,3-butadiene(tricabonyl)iron complex. The unique structure of the 10 represents a new type of allenic complex. A stepwise formation of the complexes via intermediate allene(tetracarbonyl) iron complexes type 11 and 13 is suggested. Treatment of the binuclear complex 6b with FeCl₃ led to the formation of the free ligand and a mixture of mononuclear complexes 13 and 14 (Scheme 5). On heating, the 1,3-diene complex 8 yielded the free ligand 15 , the prouduct of a (1,3) H shift in the allene 7 ; the complex 10 on the other hand liberates 7 on treatment with ethylenetracarbonitrile (TCNE) (Scheme 6).     

INVESTIGATION OF THE THIAZOLE SERIES 7. SYNTHESIS,STRUCTURE AND PROPERTIES OF 2-HYDROXIMINO-1,3-THIAZOLIDINE-4-ONES

Abstract

Several 2-hydroximino-1,3-thiazolidine-4-ones have been prepared by reaction of the respective α-thiocyanatocarbonic acid esters with hydroxylamine. They have been characterized by ir, uv and ¹H-nmr. The chemical structure was determined unequivocally by the crystal structure analysis of 5-ethyl-2-hydroximino-1,3-thiazolidine-4-one, space-group: P2₁/c, a = 10.0382(7), b = 5.2903(4), c = 19.305(1) Å, β = 134.233(4) at T = 24(1)°C. The structural model was refined with 3196 data to give R = 0.044. Analysis of the bonding geometry has lead to characterization of the 2-amino-1,3-thiazolidine-4-ones as cyclic N-thiaiminoamides.     

Heterocycles from substituted amides. VI. A new carbostyril synthesis from alpha-substituted acetamides and the vilsmeier reagent

Reaction of tertiary α-substituted acetanilides with Vilsmeier reagent has been found to give 1,3-disubstituted-carbostyrils, 1. α-Chloro-N-(1-cyclohexen-1-yl) acetamides are similarly converted to tetrahydro carbostyrils 2 and 3. The method appears useful for the preparation of a variety of 1,3-substituted 2(1H) quinolinones. The scope and mechanism of the reaction has been investigated, with evidence presented to indicate the ring-closure proceeds via electrophilic attack of Vilsmeier reagent on intermediate chlorenamine.     

Reaktion von 3-(Dimethylamino)-2H-azirinen mit 1,3-Thiazolidin-2-thion

Reaction of 3-(Dimethylamino)-2H-azirines with 1,3-Thiazolidine-2-thione Reaction of 3-(dimethylamino)-2H-azirines 1 and 1,3-thiazolidine-2-thione ( 6 ) in MeCN at room temperature leads to a mixture of perhydroimidazo[4,3-b]thiazole-5-thiones 7 and N-[1-(4,5-dihydro-1,3-thiazol-2-yl)alkyl]-N′,N′-dimethylthioureas 8 (Scheme 2), whereas, in i-PrOH at ca. 60°, 8 is the only product (Scheme 4). It has been shown that, in polar solvents or under Me₂NH catalysis, the primarily formed 7 isomerizes to 8 (Scheme 4). The hydrolysis of 7 and 8 leads to the same 2-thiohydantoine 9 (Scheme 3 and 5). The structure of 7a, 8c , and 9b has been established by X-ray crystallography (Chapt. 4). Reaction mechanisms for the formation and the hydrolysis of 7 and 8 are suggested.     

Reaction of 4-(2′-Hydroxyaryl)-1,3-dithiolium Salts with Sodium Sulfide. A Selective Synthesis of 2′-Hydroxyacetophenones

Abstract

The treatment of 4-(2′-hydroxyaryl)-2-(N,N-dialkylamino)-1,3-dithiolium perchlorates (1a–g) with sodium sulfide nonahydrate in ethanol at room temperature affords the corresponding 1,3-dithiole-2-thiones (2a–g). When these reactions are conducted in boiling ethanol, 2′-hydroxyacetophenones (3a–g) have been obtained in good to excellent yield. A tentative mechanism for the formation of 3a–g shows that this reaction is regioselective, this being established by the presence of hydroxyl group in 2′-position. That has been confirmed in a control experiment, 4-phenyl-2-(piperidin-1-yl)-1,3-dithiolium perchlorate affording a mixture of condensation products of acetophenone and phenylacetaldehyde, under similar reaction conditions.