Studies on the chemistry of 2-(2-oxo-3-phenylpropyl)-benzaldehydes: novel total synthesis of 3-phenylnaphthalen-2-ols and 2-hydroxy-3-phenyl-1,4-naphthoquinones

We describe the first studies on the chemistry of 2-(2-oxo-3-phenylpropyl)benzaldehydes, which were converted into 3-benzylisochromen-1-ones via the corresponding 2-(2-oxo-3-phenylpropyl)benzoic acid. The 2-(2-oxo-3-phenylpropyl)benzaldehydes proved to be convenient starting materials for the synthesis of 3-phenyl-2-naphthols. Oxidation of the latter compounds resulted in a novel, efficient synthesis of 3-phenyl-1,2-naphthoquinones, which were efficiently transformed into 2-hydroxy-3-phenyl-1,4-naphthoquinones.     

Electropolymerized Pyrrole‐Substituted Manganese Phthalocyanine Films for the Electroassisted Biomimetic Catalytic Reduction of Molecular Oxygen

We report for the first time on the electroassisted biomimetic activation of molecular oxygen by a newly prepared electropolymerized polypyrrole‐manganese phthalocyanine film. The prepared films and their intervention in the electroassisted catalytic reduction of molecular oxygen were analyzed by cyclic voltammetry and UV‐visible spectrophotometry on optically transparent electrodes. The obtained results demonstrate the probable existence of the key‐steps responsible for the suggested formation of the highly reactive manganese oxo intermediate.     

Reaction of ferrocenecarboxylic acid with N,N-disubstituted carbodiimides: synthesis, spectroscopic and X-ray crystallographic analysis of N,N-disubstituted N-ferrocenoylureas and identification of a one-pot coupling reagent for the formation of ferrocenecarboxamides in a non-aqueous solvent

N,N^′-dicyclohexyl-N-ferrocenoylurea 2, N,N^′-diisopropyl-N-ferrocenoylurea 3, N,N^′-di-p-tolyl-N-ferrocenoylurea 4 and N,N^′-di-tert-butyl-N-ferrocenoylurea 5 were obtained by reaction of ferrocenecarboxylic acid 1 with N,N^′-dicyclohexylcarbodiimide (DCC), N,N^′-diisopropylcarbodiimide (DIC), N,N^′-di-p-tolylcarbodiimide 10 and N,N^′-di-tert-butylcarbodiimide 11, respectively. Both N-tert-butyl-N^′-ethyl-N-ferrocenoylurea 6 and N^′-tert-butyl-N-ethyl-N-ferrocenoylurea 7 were obtained by reaction of 1 with N-tert-butyl-N^′-ethylcarbodiimide 12. In all cases a small amount of ferrocenecarboxylic anhydride 8 was formed as a by-product. All compounds were characterized by ¹H NMR, ¹³C NMR, IR and MS. Single crystal X-ray structural analyses were made of 2, 3 and 4. From the consistent results, the reaction products of 1 with carbodiimides appear different from those proposed by some earlier workers. With N-(3-dimethylaminopropyl)-N^′-ethylcarbodiimidehydrochloride 9 ferrocenoylurea was not isolated, but the main product was rather 8. The suitability of 8 as acylation reagent was applied by using 9 to obtain N-(3-triethoxysilyl)-propylferrocenecarboxamide in a one-pot reaction from 1 and 3-(triethoxysilyl)-propylamine.     

A New Approach to α—Bromochalcones

α-Bromo benzolymethylene triphenylphosphorane 3 has been synthesized by the reaction of benzoylmethylene triphenylphosphorane 1 with N-bromosuccinimide in the yield of 87% and can react with aromatic aldehydes 4 to give α-bromochalcones 5 in good yields.     

The detection of oxygen in magneto-optical layers with SIMS

The detection of oxygen in magneto-optical layers is of fundamental importance for the characterization of the stability of RE-TM material. The magnetic properties are directly influenced by oxide formation. Oxygen depth profiles are carried out by using the SIMS technique. A comparison with magnetic measurements showed a clear conformity. We were able to study the oxidation behaviour of various layers at room temperature and at higher values up to 250° C for several hours. It could be shown that aluminum is a successful material for the protection of RE-films against oxidation. The difficulties of translating SIMS counting rates into concentration values were overcome by using EPMA. Specially prepared reference samples were measured by this technique and could then be used as standard samples for SIMS.     

Oxidation of mandelic acid derivatives catalysed by Bi(0)/O2 systems: mechanistic considerations

Mandelic acid and some aryl substituted derivatives were oxidised under molecular oxygen and a catalytic amount of Bi(0). The corresponding aldehydes and/or the carboxylic acids were obtained selectively depending on the nature of the substituent. Aldehydes and α-keto acids were oxidised under the same Bi(0)/O₂ system and α-keto acids were proposed as intermediates in the formation of benzoic acid derivatives.     

Synthese von „Dithio-Oxolinsäure“

5-Amino-benzo-1,3-dithiol, available by reduction of 5-amino-benzo-1,3-dithiol-2-thion, was elaborated into dithio-oxolinic Acid (6 a).

     

Cathodic reduction of SO2 in the presence of organic dihalides

The reaction of the electrolytically generated SO ₂ ^– anion radical with 1,-dihalides is used for the synthesis of sulfur containing heterocycles like oxathiolane-, oxathiane-, thiane- and thiepane-oxides. 1,2-Dihalides are reductively deblocked to give olefines.

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Kathodische Reduktion von SO₂ in Gegenwart organischer Dihalogenide

Zusammenfassung Die Reaktion des elektrolytisch erzeugten SO ₂ ^– -Anionradikals mit 1,-Dihalogeniden führt zu schwefelhaltigen Heterocyclen wie Oxathiolan-, Oxathian-, Thian- und Thiepanoxiden. 1,2-Dihalogenide geben durch reduktive Eliminierung Olefine.

     

Electrocatalytic dehalogenation of α-bromoketones in the presence of Cp2TiCl2

Processes of direct and electrocatalytic (in the presence of electrochemically reduced Cp₂TiCl₂) reduction of three α-bromoketones containing the C(sp³)-Br or C(sp²)-Br bond, viz., 2-bromo-and 2,6-dibromo-4,4-dimethylcyclohexa-2,5-dien-1-ones and α-bromo-acetophenone, were studied by cyclic voltammetry and preparative electrolysis. In all cases, the dissociative electron transfer proceeds via the concerted mechanism. Preparative electrolysis of these α-bromoketones in the presence of Cp₂TiCl₂ affords the reductive debromination products in 40–80% yield at low cathodic potentials (−0.85 V vs. Ag/AgCl/KCl). In the case of 2,6-dibromo-4,4-dimethylcyclohexa-2,5-dien-1-one in the potentiostatic regime, only one bromine atom can be eliminated selectively. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 977–983, May, 2007.     

新型Zhuo酚酮类糖苷化合物的合成

根据Zhuo酮的结构特点，对Zhuo酚酮类化合物与半乳糖的Kenigs-Knorr反应进 行了研究。探索出一种具有较高立体选择性的合成方法，从而制得四种具有β－构 型的单一端基异构体的Zhuo酚酮半乳糖苷新化合物。生成的新化合物不但保持了原 有的生理活性，而且降低了毒性、提高了药效，为人工合成Zhuo酚酮类增添新化合 物的同时，也扩展了此类化合物的应用领域。应用元素分析、核磁共振、红外光谱 表征了它们的结构。