Synthese von α-Methyl-homocysteinthiolacton

Summary A facile high yield large scale methylation procedure affording2c is reported utilizing the N-[bis(methylthio)-methylen-protected derivative4a as an intermediate. The optical resolution of racemic2c is described leading to (S)-2b. In addition the thiolactone2c undergoes oxidative ring opening by bromine to the corresponding sulphonic acid5.

     

Simple synthesis of benzo[f] pyrrolizidine and benzo[g]indolizidine with the use of products of the reductive allylation of indole and quinoline

Benzo[f]pyrrolizidine and benzo[g]indolizidine were synthesized by hydroboration-oxidation-intramolecular cyclization of the corresponding products of the reductive -allylation of indole (2) and quinoline (6) with allylboranes.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No, 11, pp. 2807–2809, November, 1996,     

Die Acetalgruppe, 1. Mitt. Acetale von Halogenmethyl-arylcarbinolen

Several halomethyl-arylcarbinols were prepared, and the influence of substituents on enantiomer selectivity in the acetalisation reaction with [2S-(2,3a,4,7,7a)]-octahydro-7,8,8-trimethyl-4,7-methanobenzofuran-2-ol was examined.

Unserem sehr verehrten Lehrer, Herrn Prof. Dr.Otto Hromatka, mit den besten Wünschen zum 80. Geburtstag gewidmet.     

Amino- und Hydroxylaminosubstituierte α-Azidozimtsäureester und α-Aminozimtsäureester durch kathodische Reduktion ungesättigter Nitroazidoester

Cathodic reduction of nitro-substituted azidocinnamic esters on mercury under aprotic and protic conditions was studied. Nitro and azido groups behave as independent entities so that selectively amino- resp. hydroxylamino--azido compounds are obtained, which could not be synthesised by conventional methods. Under aprotic conditions, with added acetic anhydride, medium yields of acylated 4-hydroxylamino- and 4-amino--cinnamic acid derivatives are isolated. Evidence of homogeneous electron transfer from nitroanion radicals to azido groups is given.

     

Photochromic dihetarylethenes. 7. Synthesis of bis(thienylazoles), photochromic analogs of diarylethenes

Procedures for the synthesis of 4,5-bis[2,5-dimethyl(3-thienyl)]-1,3-azoles based on 1,2-bis[2,5-dimethyl(3-thienyl)]-2-hydroxyethan-1-one, 2-chloro-1,2-bis[2,5-dimethyl(3-thienyl)]ethan-1-one, and 1,2-bis[2,5-dimethyl(3-thienyl)]ethane-1,2-dione were developed. Dithienylethenic compounds in which the thienyl rings are linked through the azole rings exhibit photochromic properties.     

Synthesis of α,ω-dichloropermethyloligosilanes by reactions of polydimethylsilane with metal chlorides

The reactions of high-molecular-weight polydimethylsilane with metal chlorides in variable oxidation states at high temperature in the absence of a solvent afford mixtures of ,-dichloropermethyloligosilanes Cl(Me₂Si) _m Cl (m= 2—9). The influence of the reaction conditions (temperature, reaction time, and the reagent ratio) on the composition and yields of the reaction products was examined.     

Hexafluoroacetone as Protecting and Activating Reagent. Glycosylated Malic, Citramalic, and Thiomalic Acid Derivatives, New Glycosylated Building Blocks for Drug Design [1]

Summary. Glycosylated -hydroxy and -mercapto acids have been synthesized starting from malic/citramalic/thiomalic acid and Ac₄--D-Glc-NH₂/Bzl₄--D-Glc-NH₂ using hexafluoroacetone as protecting and activating reagent.Dedicated to Prof. Dr. Horst Wilde on the occasion of his 65^th birthday     

O-Heterocycles by the cyclization of side-chain bromomethoxylated 2′-acetoxychalcones

Summary The title chalcone derivatives react with aqueous sodium hydroxide of various concentrations to form aurones as the major product, together with small amounts of flavones. However, the introduction of 4-nitro or 4-chloro substituents resulted in the formation of flavones as the major product.

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O-Heterocyclen mittels Cyclisierung von an der Seitenkette brommethoxylierten 2-Acetoxychalconen

Zusammenfassung Die im Titel genannten Chalconderivate reagieren mit Natronlauge in verschiedenen Konzentrationen, wobei Aurone zusammen mit geringen Mengen an Flavonen entstehen. Die Einführung von 4-Nitro- oder 4-Chlor-Substituenten führte jedoch zur bevorzugten Bildung von Flavonen.

     

Condensation of ethyl α-ethoxymethyleneacylacetates withp-bromobenzoyl- and benzylidenehydrazines

Ethyl -ethoxymethyleneacetoacetate and -ethoxymethylenebenzoylacetate react with benzylidenehydrazine andp-bromobenzoylhydrazine to give hydrazones of the corresponding ethyl -formylacylacetates. It was established by¹H NMR and IR spectroscopy that hydrazones, which were obtained from benzylidenehydrazine, andp-bromobenzoylhydrazone of ethyl -formylacetoacetate exist in the ketoenamine (ketoenhydrazine) form, whereasp-bromobenzoylhydrazone of ethyl -formylbenzoylacetate exists in the enolimine (enolhydrazone) form.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2293–2296, September, 1996.     

Thermolytic transformations of polyfluoroorganic compounds

Copyrolysis of 4-chlorotetrafluorobenzotrichloride with chlorodifluoromethane (as the source of difluorocarbene) gave 4-chlorodifluoromethyl--chlorohexafluorostyrene, 1,4-dichlorotetrafluorobenzene, and 4-(chlorodifluoromethyl)chlorotetrafluorobenzene along with 4-chloro--chlorohexafluorostyrene. Possible routes for the formation of these products have been offered.For Part 30, see Ref. 1.Translated fromIzevstiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2199–2202, December, 1994.     

Effects of α-tocopherol and its acetate on the hydrolytic activity of phospholipase D in egg yolk phosphatidylcholine bilayers

Effects of -tocopherol (Toc) and -tocopherol acetate (TocA) on the hydrolysis activity of phospholipase D (fromStreptomyces chromofuscus) were studied in small unilamellar vesicles (SUV) of egg yolk phosphatidylcholine (PC). Choline produced in the reaction was monitored by use of a choline oxidase — oxygen electrode. Addition of 18 mol% Toc into SUV (2 mM PC) brought about a twofold rate of choline production. On the other hand, the effect of 18 mol% TocA in SUV was very small. The apparent maximum velocity,V _max(app), increased by addition of Toc in SUV. The apparent Michaelis constant,K _m(app), was unchanged by addition of Toc and TocA in SUV. The Toc and TocA molecules did not have significant effects when PC was solubilized in the micelles of heptaethylene glycol dodecyl ether. The effects of Toc and TocA are, therefore, not due to specific ones on the enzyme itself, but rather upon the bilayer-organization of the substrate. Measurements of spreading pressure showed complete miscibility of PC and Toc, and limited mutual solubility of PC and TocA, suggesting stronger attractive interactions between Toc and PC than those between TocA and PC in the bilayers.     

Diastereomeric Oxathia[n](1,1′)ferrocenophanes

Zusammenfassung Neue Oxathiaferrocenophane wurden durch Umsetzung von 1,1-Bis(hydroxymethyl)ferrocen mit Dithiolen dargestellt, welche Sauerstoff in den Alkylketten enthalten. Die Reaktion von 1,1-Bis(-hydroxyethyl)ferrocenen mit Dithiolen führte zu Mischungen von Diastereomeren, aus welchen reine Stereoisomere isoliert und charakterisiert wurden. Einige Aspekte des stereochemischen Verlaufes dieser Reaktionen werden diskutiert.

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Diastereomere oxathia[n](1,1)ferrocenophane

Novel oxathiaferrocenophanes have been synthesized by the reaction of 1,1-bis(hydroxymethyl)ferrocene with dithiols bearing oxygen in chains. The reactions of 1,1-bis(-hydroxyethyl)ferrocenes with dithiols afforded mixtures of diastereomeric products from which pure stereoisomers were isolated and characterized. Some aspects concerning a stereochemical course of the reactions described are discussed.

     

Bilirubin conformational enantiomer selection in sodium deoxycholate chiral micelles

Intramolecularly hydrogen-bonded, bichromophoric tetrapyrrole pigments, bilirubin-IX and mesobilirubin-XIII, adopt either of two enantiomeric conformations which are in dynamic equilibrium in solution. InpH 8 aqueous sodium deoxycholate solutions, chiral micelles preferentially select one conformational enantiomer, and the solutions exhibit a bisignate circular dichroism Cotton effect in the vicinity of the bilirubin long wavelength electronic transition. Exciton coupling theory indicates a predominance of the left-handed (or negative) chirality bilirubin conformational enantiomer.     

Dichloromethyl tert-butyl ketone in the Darzens reaction

The condensation of dichloromethyl tert-butyl ketone (1) with benzaldehyde, para-bromobenzaldehyde, and 2,4-dichlorobenzaldehyde under conditions for the Darzens reaction gives 1-aryl-1-chloro-4,4-dimethyl-2,3-pentanediones (2–4). In the case of nitrobenzaldehydes, the reaction products are 1-aryl-2-chloro-1,2-epoxy-4,4-dimethylpentanones (5 and 6), which isomerize to -chloroketones (7 and 8) upon prolonged storage or heating at reflux in benzene.A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Science Center, Russian Academy of Sciences, 420083 Kazan. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 2, pp. 438–441, February, 1992.     

Synthesis and biological activity of yuccagenin bisrhamnoside

The two hydroxyls of yuccagenin can be glycosylated by Koenigs-Knorr condensation with acetobromorhammose in dichloroethane in the presence of mercuric cyanide. The bisrhamnoside of yuccagenin markedly lowers the cholesterol and triglyceride content in blood serum of healthy animals and animals with experimental hyperlipidemia.Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 242–243, May–June, 2000.     

Tetracyclische Imidazole

2-(Phenacyl)-tetrahydro--carboline (2) was transformed to theE/Z-oximes3 and4 and the isolated species cyclodehydrogenated to the nitrone5 and oxadiazine6. These compounds were dehydrated in acidic medium to the imidazole9.

     

Bromination of polyfluorinated α,β-enones

Polyfluoroalkyl-,-enones readily add Br₂ to give ,ß-dibromoketones. The latter are readily and regioselectively dehydrobrominated to -bromo-,-enones on treatment with K₂CO₃ or NEt₃ Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2134–2136, December, 1993.     

Substituierte 3-Amino-thiophene und 3-Amino-selenophene aus β-Chlor-α-cyan-zimtsäurenitril

Summary -Chloro--cyano-cinnamonitrile (1) reacts in one step with -oxo-thioles3 or successively with sodium sulphide and -chlorocarbonyl compounds4 to form the 5-substituted 4-amino-2-phenyl-thiophene-3-carbonitriles5. Analogously, the successive reactions of -chloro cinnamonitrile1 with sodium selenide — produced in situ from selene and sodium boronhydride — and -chlorocarbonyl compounds4 yields the 5-substituted 4-amino-2-phenyl-selenophene-3-carbonitriles6.