Deacetylation effect of N,N-dimethylvancosamine in saptomycins D and E.

A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15 940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts.

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“…In the latter case, rhamnosylation was found to be detrimental to the observed anticancer activity of the parental aglycon. 592 …”

Section: Indoles and Indolocarbazolesmentioning

confidence: 99%

A comprehensive review of glycosylated bacterial natural products

et al. 2015

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“…Calculation of Specific Rotation The specific rotation [a] 11,12) of a chiral molecule was obtained from the frequency n as: (1) where N A is Avogadro's constant, c is the light velocity, g s is the solvent effect frequently approximated using the Lorentz factor (g s ϭ(n 2 ϩ2)/3; n: the refractive index of the medium). bϭTr[b ab ]/3ϭ[b xx ϩb yy ϩb zz ]/3, where b ab is the electric dipole-magnetic dipole polarizability.…”

Section: )mentioning

confidence: 99%

“…G324 together with two related oxopropalines E and G, which produce lavendamycin, by Abe and co-workers in 1993 (Chart 1). 1,2) This new b-carboline alkaloid possessing an acyl group and a methyl group at the 1-and 4-positions exhibits cytocidal activity. Oxopropalines A (1) and B (2) have been converted into oxopropaline D (3) by acidic methanolysis.…”

mentioning

confidence: 99%

The Absolute Configuration of (+)-Oxopropaline D by Theoretical Calculation of Specific Rotation and Asymmetric Synthesis.

Kuwada

Fukui

Hata

et al. 2003

CHEMICAL & PHARMACEUTICAL BULLETIN

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The cytocidal b-carboline alkaloids, oxopropalines A (1), B (2), and D (3), were isolated from Streptomyces sp. G324 together with two related oxopropalines E and G, which produce lavendamycin, by Abe and co-workers in 1993 (Chart 1). 1,2) This new b-carboline alkaloid possessing an acyl group and a methyl group at the 1-and 4-positions exhibits cytocidal activity. Oxopropalines A (1) and B (2) have been converted into oxopropaline D (3) by acidic methanolysis. Natural oxopropaline D (3) has positive rotation, but the absolute stereochemistry of both 3a and 3b has not been determined yet (Chart 2). Recently we reported the total syntheses of (ϩ)-and (Ϫ)-oxopropaline D (3) by the construction of a new b-carboline framework based on a thermal electrocyclic reaction of a 1-azahexatriene system involving an indole 2,3-bond, followed by enantioselective 1,2-dihydroxylation.3) We described in the report 3) that absolute configurations of (ϩ)-3 and (Ϫ)-3 are presumed to have S and R, respectively, in accordance with the Sharpless rule. 4)In the present study, we describe here the determination of the absolute configuration of (ϩ)-oxopropaline D (3). We initially estimated whether the (R)-oxopropaline D refers to either the plus or minus sign of a specific optical rotation calculated by an ab initio MO method that was previously reported by the Kondru group. 5) Based on the absolute configuration estimated as R, an asymmetric synthesis of (R)-oxopropaline D acetonide (4a) was carried out in order to compare the results with those of previously synthesized (ϩ)-oxopropaline D acetonide (4). 3) Results and DiscussionTheoretical Calculations of the Specific Optical Rotation for (R)-Oxopropaline D It is well known that the theoretical specific rotations for enantiomers show the same value and different signs. This fact indicates that only the sign of the theoretical specific rotation for R-or S-configurations can be used to determine the absolute configuration. We attempted to determine the sign of the specific rotation for (R)-oxopropaline D (3a) by theoretical calculations.Since the specific optical rotation obtained by the theoretical calculations showed basis set and geometry dependencies, the conformational searches by MNDO-AM1 6) (Method A) and HF/3-21G* (Method B) methods were carried out at first. Next, the conformers showing larger probability than 1%, obtained by respective conformational searches, were optimized by the HF/6-31G* ab initio MO method. The basis set dependence of the computed rotation angles was evaluated by 6-31G* and 6-31G**.The specific rotations of (R)-oxopropaline D (3a) obtained by all of the methods used are shown in Table 1 Fukuyama University; Fukuyama, Hiroshima 729-0292, Japan: and b Process Chemistry Laboratory, Medicinal Research Laboratory, Taisho Pharmaceutical Co. Ltd.; 1-403 Yoshino-cho, Saitama, Saitama 330-8530, Japan. Received July 17, 2002; accepted September 25, 2002 The specific optical rotations of (R)-oxopropaline D calculated by two ab initio MO methods were ؉52؎31°a ...

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“…Accordingly, compound 220 exhibited close structural similarity to the hydroxyquinone mentioned above. Based on the spectroscopic data, a search in AntiBase, as well as by comparison with authentic spectra and the literature, compound 220 was established as saptomycin A [332] .…”

Section: β β β β-Indomycinonementioning

confidence: 99%