Synthese von Benzo[b]thioxanthenen

Synthesis of Benzo[b]thioxanthenes Benzo[b]thioxanthenes, heterocyclic compounds related to tetracenes and tetracyclines can be obtained by the reaction of 2H-benzo[b]thiete ( 1 ) and 1,4-naphthoquinones ( 3a–g ). The primary cycloadducts 4a–g undergo an autoxidation process leading to the quinones 6a–g . The dihydroxy compound 4e shows an additional isomerization by a tetrafold H transfer ( 4e → 5e ′). Another preparative route to benzo[b]thioxanthenes makes use of the cycloadditon reaction of 1 and 1,4-epoxynaphthalenes ( 7a–d ). The primary adducts can be transformed to the title compounds by catalytic dehydration processes ( 8a–d → 9a-d ). An alternate regioselective opening of the oxygen bridge can be performed by the action of trimethyliodosilane ( 8a → 10a ). Methylation of 9a furnishes the sulfonium salt 14a which rearranges in a strongly alkaline medium to 16a ; in the presence of oxygen ketone 17a is generated.     

Synthesis of Benzo[a]fluorene,Benzo[c]fluorene,and Benzo[j]fluoranthene via a Lewis Acid-Catalyzed Prins-Type Cycloaromatization: Application to the Total Synthesis of Viridistratin A

Synthesis of benzo[a]fluorene, benzo[c]fluorene, and benzo[j]fluoranthene have been accomplished from readily accessible enol ether precursors via a Lewis acid-catalyzed Prins-type cycloaromatization. Mechanistically, it was proposed that Lewis acids catalyze the generation of oxonium species, which accelerate subsequent annulation and aromatization. This protocol offers the benefit of an operationally simple, transition-metal-free, and air-tolerant reaction condition, enabling gram-scale syntheses of the desired products. The total synthesis of viridistratin A further supported this synthetic strategy for establishing polycyclic aromatic hydrocarbon architectures.     

Zur Methodik der Beurteilung von Waschmitteln in der neueren amerikanischen Literatur

Method for the Assessment of Washing Agents in the New American Literature Four test methods from the special literature are treated. The results from these can be employed for a preliminary assessment of washing agents. In three of these test methods soiling of the fabrics with radioactive labelled pigments, synthetic sebum and synthetic sebum plus air-filter impurity respectively are employed. In the fourth method linen soiled in household is used.     

Zur Synthese von 3-Amino-naphth[c]isothiazolen

Synthesis of 3-Amino-naphth[c]isothiazoles 3-Amino-naphthonitrile-2 7 can be readily prepared by ring cleavage of 4-carboxy-methylthio-benzo[g]quinazoline 6 in aqueous medium at pH 9. 1-Amino-naphthonitrile- 2 11 is formed in good yield by thermolysis of 1H-benzo[g]-indoline-2,3-dione-3-oxime 13 (BEDFORD -PARTRIDGE reaction). The scope of both reaction types is studied. Appropriate syntheses of each precursor are reported. By base-catalyzed addition of hydrogen sulfide under pressure 7 and 11 were transformed into amino-thionaphthoic-2-acid amides 17 and 23 . Oxidation of 1-amino-thionaphthoic-2-acid amide 23 with hydrogen peroxide in methanol produced 3-aminonaphth[1,2-c]isothiazole 1b in almost quantitative yield. A similar oxidative cyclization of 3-amino-thionaphthoic-2-acid amide 17 to 3-amino-naphth[2,3-c]isothiazole 3b failed even if the reaction conditions were widely varied. The unsuccessful efforts to synthesize „linear”︁ naphthisothiazoles ( 3a and its 3-amino derivative 3b ) are discussed in terms of the superdelocalizability of these heterocycles. Azo dyes can be obtained from 1b and 7 .     

An Abbreviated Synthesis of 7,12-Dimethylbenz[ a ]anthracene and Benzo[ c ]chrysene Metabolites Using the Suzuki Reaction

Efficient syntheses of important metabolites of 7,12-dimethylbenz[ a ]anthracene (DMBA) and benzo[ c ]chrysene (B[ c ]C), via Suzuki coupling reaction are described. This approach provides an excellent method for the preparation of 3-methoxy-DMBA 5 , 10-methoxy-B[ c ]C 14 and 2-methoxy B[ c ]C 20 , and hence for the corresponding dihydrodiols 6 , 15 , and 21 . Following a similar Suzuki reaction, DMBA-6(5 H )-one 8 was also synthesized in high yield.     

Chinoxaline. XXVI. Synthese von bis-azolo[a,c]kondensierten Chinoxalinen. I. Darstellung aus 4-substituierten 1,2,3-Triazolo[1,5-a]chinoxalinen

Quinoxalines. XXVI. Synthesis of Bis-azolo[a,c]-fused Quinoxalines. I. Synthesis from 4-Substituted 1,2,3-Triazolo[1,5-a]quinoxalines The synthesis of bis-azolo-fused quinoxalines of type. 6 is described. The new bisazolo-fused compounds 9, 10a, b, 12 , and 16 were synthesized from the 4-substituted 1,2,3-triazolo-[1,5-a]quinoxalines 7, 8, 11 , and 13 by intramolecular cyclization reactions. The structures were determined by microanalysis, i.r., ¹H-n.m.r., and mass spectra.     

Darstellung und selektive Komplexbildung von Bisorganylsulfiden auf [2.2.2]Paracyclophan‐Basis

The synthesis of a variety of novel functionalized bisorganyl sulfides 2 – 10 based on the [2.2.2]paracyclophane skeleton is described. The aim was to increase the endohedral silver(I) complexation of the unsubstituted [2.2.2]paracyclophane 1 by combining the cyclophane framework with a sulfur containing pendant arm bearing an additional π‐donor. The complexation behaviour of the new ligands was studied by liquid–liquid extraction from aqueous into organic solution. The new ligands reveal a higher extraction with a decreased selectivity for silver(I) compared to 1 caused by preferential interactions with the sulfur donor atoms in the molecule. Molecular modeling calculations show the different coordination patterns for the 1:1‐, 1:2‐ and 2:1‐complexes (M:L) formed in the organic phase.     

Immunsuppressiva-Antigen-Konjugate. VIII. Darstellung von 6-Mercaptopurin-Protein-Konjugaten nach dem Azid-Verfahren

Immunosuppressant-Antigen Conjugates. VIII. Preparation of 6-Thiopurine-Protein Conjugates by the Azide Method 6-Carboxymethyl-thiopurine was coupled with human serum albumin (HSA) and bovine serum globuline in the presence of a water soluble carbodiimide. Under these conditions, reaction of HSA with the carbodiimide led to electrophoretically detectable changes. Therefore, further conjugates were prepared by the azide method. The used azides, N-(6-benzylthiopurin- and 6-methylthiopurin-9-yl)-acetyl azide, were obtained from the hydrazides. The prepared conjugates contained upto 4.2% thiopurine, determined by spectrophotometry. It was not possible to obtain an azide from purinyl-(6)-thioacethydrazide.     

Eigenschaften von PE-erzeugnissen nach der bewitterung

In the last years in a joint action with Institute of Chemical Industry - Sofia wide research work was completed on lightstabilized (atmospheric resistant) types of polyethylene high density creation and its implementation in transport packaging production. Quite interesting and unexpected result in relevant improvement of tested articles operating properties in the initial stages of the natural ageing after which they regularly change for the worse. Dynamic properties optimum of the polyethylene articles is reached in one to three months of the production date and direct open exhibition. It is found out that main influence on the results got is by some additives existance and concentration in the polyethylene composition. Available data and influences found out are mainly of quality nature but allow assumption that processes as recrystallization and disorientation in unbalanced structure created in treatment process are carried out which in the initial stages of operation predominate over ageing processes. An research is made on determination of exact quantity ratio between composition of the polyethylene (type and quantity of the additives) and treatment conditions (articles configuration and process parameters). Results with essential implementation value are expected.     

Darstellung und Eigenschaften von Pyrazolo[3,2-c]benzo-1,2,4-triazinen und Pyrazolo[3,2-c]pyrido[4,3-e][1,2,4]triazinen

Synthesis and Properties of Pyrazolo[3,2-c]benzo-1,2,4-triazines and Pyrazolo [3,2-c]pyrido[4,3-e] [1,2,4]triazines α,β-Unsaturated β-aminonitriles 1 condensate with 2-nitrophenylhydrazine and with 4-hydrazino-3-nitropyridine to yield the corresponding nitriles of β-keto acids 2 and 3 , respectively. Bases achieve cyclisation of these compounds to pyrazolo[3,2-c]benzo-1,2,4-triazine-5-oxides 7 and pyrazolo[3,2-c]pyrido[4,3-e] [1,2,4]triazine-5-oxides 8 , respectively. The N-oxides are reduced by means of sodium dithionite to the corresponding triazines 9, 10 .