Über Pterinchemie. 85. Mitteilung. Polyacetylierte 5,6,7,8-Tetrahydro-D- und -L-neopterine. Ein besonderer Fall von N(5)-Alkylierung des 5,6,7,8-Tetrahydroneopterin-Gerüstes

Polyacetylated 5,6,7,8-Tetrahydro-D - and L -neopterins. A Special Case of N(5)-Alkylation of 5,6,7,8-Tetrahydroneopterins Improved conditions are reported for the preparation of the earlier described (6R)- and (6S)-1′-O,2′-O,3′-O,2-N,5-pentaacetyl-5,6,7,8-tetrahydro-L -neopterins, one of which could be obtained as pure crystals. Its structure, determined by X-ray-diffraction analysis, corresponds to the (6R)-enantiomer. The method has also been used to make the corresponding D -diastereoisomers. Further acetylation of (6RS)-1′-O,2′-O,3′-O,2-N-tetraacetyl-5,6,7,8-tetrahydro-D -neopterin under drastic conditions yields a mixture of several polyacetylated D -neopterin derivatives and a polyacetylated ethyl-tetrahydro-D -neopterin which was isolated in crystalline form and established by X-ray-diffraction analysis to be (6R)-1′-O,2′-O,3′-O,4-O,2-N,2-N,8-heptaacetyl-5-ethyl-5,6,7,8-tetrahydro-D -neopterin.     

Utilisation d'ylides du phosphore non stabilisés en chimie des sucres. V. Sucres ramifiés dérivés du méthyl α-D-lyxo-hexopyrannosul-4-oside. Communication préliminaire

Cis and trans-methyl-4-deoxy-2, 3-O-isopropylidene-6-O-methyl-4-methylthio-methylene-α-D -lyxo-hexopyra-nosides are prepared by a Wittig reaction. Methods are described for the determination of the configuration of the geometrical isomers whose Raney-Nickel reduction leads to derivatives of 4-deoxy-4-methyl-hexoses of the D -manno and D -talo series.     

Utilisation d'ylides du phosphore non stabilisés en chimie des sucres VI. Sucres ramifiés dérivés des di-O-isopropylidène-1,2:5,6-α-D-ribo-et-α-D-xylo-hexofurannosul-3-oses

The cis and trans isomers of 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-methylthiomethylene-α-D -xylo- and -α-D -ribo-hexofuranoses have been prepared by treatment of 1,2:5,6-di-O-isopropylidene-α-D -xylo- and -α-D -ribo-hexofuran-3-uloses with methylthiomethylene-triphenylphosphorane. Configurations are assigned by NMR. A new type of ⁴J is described. Hydrogenation-desulfurization of the methylthiovinylic sugars affords 3-deoxy-3-methyl sugars of the D -allo, D -gulo, and D -galacto series. Derivatives of 3-deoxy-3-methyl-D -lyxose and 3-deoxy-3-methyl-D -ribose are prepared by chain-shortening of derivatives of the corresponding 3-deoxy-3-methyl-hexoses.     

Die massenspektrometrische Retro-Diels-Alder-Reaktion: 1,2,3,4-Tetrahydrocarbazol. 30. Mitteilung über massenspektrometrische Untersuchungen

The mass spectral retro Diels-Alder-reaction: 1,2,3,4-tetrahydrocarbazole 1,2,3,4-Tetrahydrocarbazole undergoes a retro Diels-Alder-reaction under electron impact. C(2) and C(3) are eliminated as ethylene. This is shown by measuring the deuterated derivatives 1a , 1b and 1c . Furthermore the oxo-1,2,3,4-tetrahydrocarbazole derivatives 3 and 4 are investigated in respect to the mass spectral retro Diels-Alder reaction too.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXXV. Structure of cyclomacroside E

The structure of a new cycloartane-type triterpene glycoside, cyclomacroside E, which was isolated from roots of Astragalus macropus Bunge (Leguminosae), was established as 3-O-α-L-rhamnopyranoside,24-O[(β-D-xylopyranosyl)(1→2)-β-D-xylopyranoside]-24R-cycloartan-1α,3β,7β,24,25-pentaol.     

Nucleotide. XV. Synthese und Eigenschaften von 2′-O-t-Butyldimethylsilyl-5′-O-monomethoxytritylribonucleosid-3′-phosphotriestern,Ausgangssubstanzen für Oligonucleotid-Synthesen

Nucleotides. XV. Synthesis and Properties of 2′O-t-Butyldimethylsilyl-5′-O-monomethoxytritylribonucleoside-3′-phosphotriesters, Starting Materials for Oligonucleotide Syntheses The syntheses of two types of fully blocked ribonucleoside 3′-phosphotriesters 6–14 have been achieved in excellent yields from 2′-O-t-butyldimethylsilyl-5′-O-monomethoxytrityl-ribonucleosides 1–5 by phosphorylation with 2-chloro- and 2,5-dichlorophenylphosphorodichloridate respectively and subsequent treatment by cyanoethanol to 6 , 8 , 10 , 12 and 14 and by p-nitrophenylethanol to 7 , 9 , 11 and 13 . These phosphotriesters are valuable starting materials for oligonucleotide syntheses due to the fact that the corresponding phosphotriesters 15–23 with free HO? C(5′) could be obtained by detritylation and the 3′-phosphodiester triethylammonium salts 24–32 by deblocking of the cyanoethyl and the 2,5-dichlorophenyl group respectively. All newly synthesized compounds have been characterized by UV.-and NMR.-spectra as well as C, H, N elementary analyses.     

Interactions intramoléculaires. XXVI—Constantes de couplage et hétérogénéités conformationnelles dans une série de R-3 et R-5 cyano-4 cyclohexènes deutériés (R=méthyl ou t-butyl)

For trans-3-R- and 5-R-1-acetoxy-4-cyanocyclohexene-6,6-d₂ the molar fractions of diequatorial conformers are 0.83 (3-methyl), 0.68 (5-methyl), 0.57 (3-tert-butyl) and 0.55–0.69 (5-tert-butyl). For the last two compounds the values of the coupling constants are in agreement with the hypothesis of an ee?aa equilibrium. For the cis isomers, the molar fractions of equatorial alkyl conformers are 0.76 (3-methyl and 5-methyl) and 1.0 (3-tert-butyl and 5-tert-butyl). The cis-1-acetoxy-3-tert-butyl-4-methoxycarbonyl-cyclohexene presents a conformational heterogeneity. The conformational free energy of the methyl group in position 4 has been evaluated as ?0.6 kcal mol^?1 (2.5 kJ mol^?1).     

Nouveaux types de sucres acétyléniques. Communication préliminaire

Novel types of acetylenic sugars The coupling, following Cadiot's procedure, of a 6-bromo-5,6-dideoxy-1,2-O-isopropylidène-3-O-methyl-α-D -xylo-hex-5-yno-1, 4-furanose (1) with phenylacetylene, 2-propyn-1-ol or terminal acetylenic sugars gave with excellent yields the expected diynes (an enediyne when the terminal acetylene was the 3,5, 6-trideoxy-1,2-O-isopropylidene-α-D -glycero-hex-3-en-5-yno-1,4-furanose 7 ). The chloro analogue 8 of 1 on treatment with lithium thiophenate gave the corresponding phenylthio-acetylenic sugar 9 . An acetylene was also formed by reacting the gem-difluoro-olefinic sugar 10 with butyllithium whereas the same olefinic sugar and its 3-O-benzyl analogue 11 gave only a gem-fluoro-arylthio-olefinic sugar (13–15) as a mixture of the Z and E isomers (Z/E > 4) when treated with the conjugate base of an arylmercaptan.     

Recherches dans la série des cyclitols XLII. Synthèses de cyclitols tout-cis dérivés du cyclopentane; préparation des cyclopentane-tétrol et - pentol tout-cis

All-cis cyclitols derived from cyclopentane have been prepared in two ways: (i) by LiAlH₄ reduction of all-cis epoxypolyos; (ii) by dimethyl sulfoxide treatment, in the presence of sodium hydrogencarbonate, of brominated derivatives containing a neighbouring benzoyloxy group; under these conditions, the halogen is replaced by a cis-oriented hydroxyl group. Thus all-cis cyclopentane-tetrol and -pentol have been prepared; their configuration has been confirmed by NMR. spectroscopy.     

Dérivés C-Glycosyliques XXXII. Synthèse de dérivés spiro-C-glycosylidéniques par cyclisation nucléophile. Communication préliminaire

C -Glycosylic derivatives XXXII. Synthesis of spiro-C -glycosylidenic derivatives via nucleophilic cyclization. On treatment with compounds bearing two nucleophilic groups as ethylenediamine, o-phenylenediamine or their monooxa or monothia analogues, 1,2:5, 6-di-O-isopropylidene-α-D -ribo-hexofuranos-3-ulose gave with excellent yields the corresponding spiro-C-glycosylidenic derivative; for example, when using o-phenylenediamine, a spirobenzimidazoline ( 5 ) was obtained. The latter compound underwent, on oxidation, a ring expansion to a morpholinobenzimidazole ( 8 ). Spirobenzodiazepines, spirobenzooxazepines and spirobenzothiazepines were formed when applying the same type of cyclization reaction to 3-C-acetylmethylene-3-deoxy-1,2:5,6-di-O-isopropylidene-α-D -ribo- and α-D -xylo-hexofuranoses.     

Triterpene glycosides from <Emphasis Type="Italic">Astragalus</Emphasis> and their genins. LXXXII. Cyclomacroside B,a new glycoside

The structure of the new cycloartane glycoside cyclomacroside B that was isolated from Astragalus macropus Bunge (Leguminosae) was shown to be 1,7-di-O-acetyl-24R-cycloartan-1α,3β,7β,24,25-pentaol 3-O-α-Lrhamnopyranoside-24-O-β-D-xylopyranoside.     

Circulardichroismus. 62. Mitteilung. Chiroptische Eigenschaften einiger Trimethylcyclohexen-Derivate: Die Jonone,Irone und Abszisinsäuren

The absolute configuration of (+)-α-ionone 3 (R), the absolute configurations at C(6) of (+)-cis-α-irone 5 (6S) and (?)-trans-α-irone 6 (6R), and the absolute configurations of (+)-cis-abscisic acid 10 (S) and (+)-trans-abscisic acid 11 (S) are deduced from the CD.-spectra.     

Die Kristallstruktur der 2,4, 6-Trimethylpimelinsäuren 1. Mitteilung

The crystal structure of the stereoisomer m.p. 130° of 2,4,6-trimethylpimelic acid has been determined by three-dimensional X-ray analysis. The cristals are monoclinic, a = 10.35, b = 10.70, c = 11.61 Å, β = 110°12′, Z = 4, space group P_{2 1/c}, the structure has been solved by direct methods and refined by least-squares methods. The configuration of the acid is given by formula I; the chirality of the asymmetric centres is (2-R, 4-r, 6-S).     

Synthese von threo-cis/threo-trans- und erythro-cis/erythro-trans-Dihydropalustrin. 17. Mitteilung über Schachtelhalmalkaloide

Synthesis of threo-cis/threo-trans- and erythro-cis/erythro-trans-dihydropalustrin The first synthesis of a threefold protected spermidine, namely ³-benzyloxycarbonyl-N¹-phthaloyl-N²-tosylspermidin ( 9 ) is presented. Each of the protecting groups can be removed selectively. After hydrazinolysis the resulting N³-benzyloxy-carbonyl-N²-tosylspermidine ( 10 ) has been condensed with methyl (2 E)-cis-7,8-epoxy-2-decenoate to the threo-cis/trans piperidines 17 , and with methyl (2 E)-trans-7,8-epoxy-2-decenoate to the erythro-cis/trans piperidines 17 , respectively. After catalytic removal of the Z group, the resulting aminoesters 13 and 18 , in a melt with imidazole, underwent ring closure to the 13-membered lactames 14 and 19 , respectively. reductive deprotection of the N-tosyl group with sodium/ammonia led to the stereoisomeric palustrines 15 and 20 , respectively.     

Die Herzglykoside des Pfeilgiftes von Lophopetalum toxicum LOHER. 13. Mitteilung über Celastraceen-Inhaltsstoffe

The Heart Glycosides of the Arrow Poison of Lophopetalum toxicum LOHER From the cytotoxic and positive inotropic acting bark extract of the Philippinan Lophopetalum toxicum eight heart glycosides have been isolated and their structures have been elucidated mainly by field-desorption-MS- and ¹- and ¹³C-NMR spectroscopy. Besides the known k-Strophanthidin ( 1 ), Antiarigenin ( 6 ) and β-Antiarin (Antiarigenin-3-β-O-α-L -rhamnoside, 10 ) the following mono- and diglycosides could be identified: strophanthidin-3-β-O-α-6-desoxy-D -allopyranoside (strophalloside, 2 ), strophanthidin-3-β-O-β-6-desoxy-D -glucopyranoside (= Strophanthidin chinovoside, 3 ), strophanthidin-3-β-O[-4Oβ-D -allopyranosyl-β-6-desoxy-D -allopyranoside] ( 4 ), strophanthidin-3-β-O-[3-O-β-D -glucopyranosyl-β-6-desoxy-D -talopyranoside] ( 5 ), antiarigenin-3-β-O-[3-O-β-D -gulopyranosyl-β-6-desoxy-D -talopyranoside] ( 7 ), antiarigenin-3-β-O-[4O-β-D -allopyranosyl-β-6-desoxy-D -allopyranoside] ( 8 ), and antiarigenin-3-β-O-β-6-desoxy-D -allopyranoside (antiallosid) ( 9 ). The structure of strophanthidinchinovoside ( 3 ) could be confirmed by synthesis.     

Synthèse de spiro-pyrazolines par cycloaddition du diazométhane sur des sucres insaturés ramifiés. Influence de l'isomérie géométrique sur l'orientation de la réaction Communication préliminaire

The orientation of the cycloaddition of diazomethane on unsaturated branchedchain sugars has been studied. For 3-C-cyanomethylidene-3-deoxy-1,2-O-isopropylidene-α-D-glycero-tetrofuranose the orientation was ‘normal’ and did not depend on the configuration at the double bond. The same situation prevailed with derivatives of 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-methylidene-α-D-xylo-hexofuranose. For the 3-C-acylmethylidene- and the 3-C-cyanomethylidene-3-deoxy-1,2:5,6-di-O-isopropylidene-α-D-ribo-hexofuranoses, the trans-(H–C(3′)–C(2))-isomer gave the ‘normal’ cycloadduct whereas the cis-isomer gave predominantly the αabnormal spiro-pyrazoline. This observation represents the first instance where the regioselectivity of a cycloaddition reaction is affected by the geometrical isomerism of the dipolarophile. The most probable explanation of the phenomenon is the conformational perturbation about the C(4)--C(5) bond of the unsaturated sugars induced by a change in the configuration at C(3). The consequence of that ‘conformational transmission’ of a difference in configuration at C(3) is that the steric crowding on the cis- than in the trans-isomer. Several novel examples of a new series of C-glycosylidenic derivatives, the spiro-pyrazolines, are described.     

Identification et Etude en Résonance Magnétique Nucléaire du Carbone-13 des Produits de la Réaction de Quaternisation en Série Thiazolo[3,2-d]tétrazolique

We have demonstrated that the compounds obtained by quaternization of thiazolo[3,2-d]tetrazole, and two of its derivatives, 3-phenyl-thiazolo[3,2-d]tetrazole and tetrazolo[5,1-b]benzothiazole, are tetrazolium salts. The quaternization effects are discussed as a function of the ¹³C NMR results.     

Reductive Acylamination of Pyridine <Emphasis Type="Italic">N</Emphasis>-Oxide with Aminopyridines and Their <Emphasis Type="Italic">N</Emphasis>-<Emphasis Type="Italic">p</Emphasis>-Tolylsulfonyl Derivatives

Pyridine N-oxide reacts with 2- and 3-aminopyridines and their N-p-tolylsulfonyl derivatives in alkaline medium in the presence of p-toluenesulfonyl chloride to give N-p-tolylsulfonyl-2,2′- and 2,3′-dipyridylamines, respectively, as a result of reductive acylamination. In the reactions with 4-aminopyridine and 4-p-tolylsulfonyl-aminopyridine, their N-p-tolylsulfonyl- and N,N-bis(p-tolylsulfonyl) derivatives are formed, while reductive acylamination does not occur.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 128–130.Original Russian Text Copyright © 2005 by Solekhova, Kurbatov.     

Vibrational spectroscopic studies of conformation of poly(oxyethylene). II. Conformation–spectrum correlations

Detailed normal-coordinate analysis has been carried out on a large number of conformers of model molecules of poly(oxyethylene); the model molecules treated are CH₃(OCH₂CH₂)_nOCH₃ with n = 2,3, and 6. The systematic treatment provides well-defined correlations between conformation and vibrational spectra of poly(oxyethylene). The vibrations in the region 1050–800 cm^?1, which are associated with the C? O and C? C stretching and CH₂ rocking modes, are highly dependent on the conformation of the polymer chain. On the basis of these correlations, the infrared and Raman spectra of the molten state and of the aqueous solution are interpreted in terms of the conformational states. The analysis indicates that the following conformational fragments are present in these phases: GT-TG (T: trans; G: gauche), TT-TG, GT-GG, TT-TT, and TT-GG for the CH₂? CH₂? O? CH₂? CH₂ group, and TGT and TGG for the O? CH₂? CH₂? O group. Conformational fragments GT-TG′ and GT-G′G′ are also possible in the analogy to GT-TG and GT-GG.     

Zur Photodimerisierung von 3-Phenyl-2H-azirinen. Vorläufige Mitteilung

Irradiation of 3-phenyl-2H-azirine ( 2 ) in benzene solution with a high-pressure mercury lamp yields 4,5-diphenyl-1,3-diazabicyclo[3,1,0]hex-3-ene ( 4 ) and not 3-phenylimino-4-phenyl-1-azabicyclo[2,1,0]pentane ( 1 ), as had been reported previously by others [2]. 2-Methyl-3-phenyl-2H-azirine ( 3 ) yields on irradiation a 2:1 mixture of 2-exo, 6-exo- and 2-exdo, 6-exo-dimethyl-4,5-diphenyl-1,3-diazabicyclo[3,1,0]hex-3-ene (2-exo,6-exo- and 2-endo, 6-exo- 5 ). Irradiation of 2,3-diphenyl-2H-azirine ( 8 ) leads to the formation of 2,4,5-triphenyl-imidazole ( 9 ) and tetra-phenylpyrazine ( 10 ). The suggested reaction path for the generation of 9 and 10 is shown in Scheme 2.