Carotinoid-Glycosylester 4. Mitteilung. Synthese von 8′-Apo-β-carotin-8′-säure-(β-D-glucosyl)ester und Vitamin-A-säure-(β-D-glucosyl)ester

Carotenoid Glycosyl Esters Synthesis of β-D -Glucosyl 8′-Apo-β-carotene-8′-oate and β-D -Glucosyl Vitamin-A-oate (β-D -Glucosyl Retionate) β-D -glucosyl 8′-apo-β-carotene-8′-oate (III) and β-D -glucosyl vitamin-A-oate (VI) were regio- and stereoselectively synthesized in high yields from the N-acylimidazoles I and IV, respectively, or from the N-acyltriazoles II and V, respectively, and unprotected β-D -glucose, according to the method described for the synthesis of di(β-D -glucosyl) 8,8′-diapo-carotene-8,8′-dioate [1]. It seems that this method can generally be applied for the synthesis of β-D -glucosyl esters of polyene carboxylic acids.     

C45- und C50-Carotinoide. 3. Mitteilung. Synthese von (S)-Trisanhydrobacterioruberin

C₄₅-and C₅₀-Carotenoids: Synthesis of (S)-Trisanhydrobacterioruberin The Synthesis of (S)-trisanhydrobacterioruberin ((S)- 1 ) is reported.     

Synthese und Strukturaufklärung von Merucathinon und Synthese von Cathinon. Inhaltsstoffe von Catha edulis FORSK

Synthesis and Structure Elucidation of Merucathinone and Synthesis of Cathinone. Constituents of Catha edulis FORSK . Starting from L-alanine, two constituents of Catha edulis FORSK ., (S)-4-amino-1-phenylpent-1-en-3-on ((S)- 3 ; merucathinone) and (S)-2-amino-1-phenylpropan-1-on ((S)- 1 ; cathinone) were synthesized.     

Compound set enrichment: a novel approach to analysis of primary HTS data

The main goal of high-throughput screening (HTS) is to identify active chemical series rather than just individual active compounds. In light of this goal, a new method (called compound set enrichment) to identify active chemical series from primary screening data is proposed. The method employs the scaffold tree compound classification in conjunction with the Kolmogorov-Smirnov statistic to assess the overall activity of a compound scaffold. The application of this method to seven PubChem data sets (containing between 9389 and 263679 molecules) is presented, and the ability of this method to identify compound classes with only weakly active compounds (potentially latent hits) is demonstrated. The analysis presented here shows how methods based on an activity cutoff can distort activity information, leading to the incorrect activity assignment of compound series. These results suggest that this method might have utility in the rational selection of active classes of compounds (and not just individual active compounds) for followup and validation.     

Oxidative Coupling of αω,-Di(cyclopentadienyl)alkane-diides

The Cu^II-induced oxidative coupling of αω,-di(cyclopentadienyl)alkane-diides 6 (n = 2–5) has been shown to proceed mainly by an intermolecular pathway to give polymers 8 , while the yield of intramolecular coupling 6 → 7 strongly decreases with increasing number n of C-atoms of the alkyl chain (Scheme 3). For n = 2, intramolecular coupling may be considerably enhanced by replacing the H-atoms of the CH₂CH₂ bridge of 6a (n = 2) by Me groups. In this case, intramolecular couplings 11 → 20 (Scheme 7) and 22 → 23 + 24 (Scheme 8) are accomplished with a total yield of 59% and 54%, respectively. All the intramolecular couplings investigated so far proceed stereoselectively to give the C₂-symmetrical cyclohexanes 7a, 20 and 23 with a fixed chair conformation. These results are easily explained, if a conformational equilibrium E ? F is operative in which large substituents R are assumed to enhance the gauche-conformation F which is the favored conformation for intramolecular couplings. Bridged dihydropentafulvalenes 20 and 23 are quantitatively rearranged to the thermodynamically favored bridged pentafulvenes 27 and 28 under base or acid catalysis, respectively (Scheme 9).     

Säurekatalysierte Umsetzungen von 2- Vinylanilin-Derivaten mit 1-Benzyl- und 1-Methylpiperidin-4-on: Eine Elegante Synthese Neuer Polycyclischer Indol-Derivate

Acid-Catalyzed Reactions of 2-Vinylaniline Derivatives with 1-Benzyl- and 1-Methylpiperidin-4-one: An Elegant Synthesis of New Polycyclic Indole Derivatives The reaction of 2-vinylaniline derivatives with 1-benzylpiperidin-4-one or 1-methylpiperidin-4-one in toluene at temperatures between 115 and 120° with toluene-4-sulfonic acid as catalyst leads in good yields to a new class of polycyclic indole derivatives (Scheme 1, Table 1). The structure of the new diastereoisomerically pure racemic compounds 1–5 is determined by NMR-spectroscopic methods. A reaction mechanism proceeding via cyclization of enamine 9 , leading to a racemic, tricyclic reactive intermediate 10 , and subsequent intramolecular 1,5-dipolar cyclization as key steps in proposed for the formation of octahydropyrido[4′,3′:4]cyclobut[1,2-b]indoles 1–5 . The scope and limitations of the new method are discussed (see Table 2).     

Synthesis of (all-E,2R,2′R)-oscillol

Optically active (all-E,2R,2′R)-oscillol (= (all-E,2R,2′R)-3,4,3′,4′-tetradehydro-1,2,1′,2′-tetrahydro-ψ,ψ-carotene-1,2,1′,2′-tetrol; 1 ) was synthesized according to the C₁₀ + C₂₀ + C₁₀ = C₄₀ strategy, applying the Wittig reaction to couple the synthons 4 and 6 . The chiral centre was introduced by a Sharpless dihydroxylation of 3-methylbut-2-enyl 4-nitrobenzoate ( 8 ).     

Über den Einfluss der pK-Werte von Anilinen auf die Bildung und Folgereaktionen von substituierten Butadienen aus Cumalinsäure-methylester

The Influence of Aniline pK Values on the Formation and Reactivity of Substituted Butadienes from Methyl Coumalate The product of the reaction between 2 equiv. of methyl coumalate ( 1 ) and 1 equiv. of a substituted aromatic amine depends on the pK value of the latter. Aromatic amines with pK values between 1.05 and 2.8 produce bicyclic lactones 4 , whereas those with higher pK values also give 2-azabicyclo[3.3.1]nona-3,7-diene-9-carboxylic acids 9 . The latter, products of the intramolecular Diels-Alder reaction 8 → 9 , may in certain cases even prevail.     

The Synthesis and Liquid-Crystal Transition Temperatures of Some Fluoro-Substituted Benzonitriles

Various laterally fluoro-substituted benzonitriles have been prepared containing a trans-4-(n-alkyl)cyclohexane ring linked to the 4-position of the benzonitriles either through a methyleneoxy (? CH₂O–) or an ethylene (? CH₂CH₂-) bridge. The bridging group links the benzonitrile and cyclohexane rings either directly or through an additional 1,4-bonded cyclohexane or benzene ring. The synthesis and liquid-crystal transition temperatures of these new compounds are described. In several cases the nematic-isotropic transition temperatures of F-substituted benzonitriles are found to be higher than those of the non-laterally substituted analogues.     

Arc-smooth generalized universal covering spaces

Let Y be a path-connected subset of a CAT(0) space Z, allowing for a map to a 1-dimensional separable metric space X, such that the nontrivial point preimages of f form a null sequence of convex subsets of Z. Such Y need not be homotopy equivalent to a 1-dimensional space.

We prove that Y admits a generalized universal covering space, which we equip with an arc-smooth structure by consistently and continuously selecting one tight representative from each path homotopy class of Y. It follows that all homotopy groups of Y vanish in dimensions greater than 1.