Structural Classification of Natural

KochMA, SchuffenhauerA, ScheckM, etfl/. (2005) Charting biologically relevant chemical space A structural classification of natural products (SCONP). Proc. Natl. Acad. Set. 102 11111-11211. 

B. The scaffold tree for structural classification of natural products... 

Koch, M. A., Schuffenhauer, A., Scheck, M., Wetzel, S., Casaulta, M., Odermatt, A., Ertl, P, and Waldmann, H. (2005) Charting biologically relevant chemical space A structural classification of natural products (SCONP). Proc. Natl. Acad. Sci. U.S.A. 102,17272-17277. 

For compound sets with a well defined limit, it is possible to enumerate all the scaffolds in the set and to visualise the chemical relationships. In particular, the Bioactivity guided Scaffold tree method (BIOS) provides a visually compelling means of exploring complex structural relationships. As an example, the Structural Classification of Natural Products (SCONP) arranges the scaffolds of the natural products in this tree-like fashion. This provides a concise and chemistry friendly description of natural product diversity. 

Figure 14.2 The Scaffold tree visualisation of the Structural Classification of Natural Products (SCONP). Reproduced from ref. 61, Waldman et al., Proc. Natl. Acad. Sci. 2005, 102, 17272. Copyright 2005 National Academy of Sciences, U.S.A.

The molecular scaffolds (ring systems) validated by nature or biology can be arranged into hierarchical clusters Structural Classification of Natural Products (SCONP) (Figure 1.2), which could accelerate the design... 

Waldmann et al. have performed a chemoinformatic analysis of all available natural product structures and classified fhe most frequent occurring scaffolds in a hierarchical tree (Structural Classification of Natural Products, SCONP) [115]. This analysis represenfs for fhe first time a quantitative description of privileged structures found among natural products. The Wald-... 

For a long time the structural classification of the mineral todorokite was uncertain, until Turner and Buseck [4] could demonstrate by HRTEM investigations that the crystal structure of that mineral consists of triple chains of edge-sharing octahedra, which form [3 x 3] tunnels by further corner-sharing. These tunnels are partially filled by Mg2+, Ca2+, Na+, K+, and water (according to the chemical analysis of natural todorokites). In 1988 Post and Bish could perform a Rietveld structure determination from XRD data taken for a sample of natural todorokite [25], This diffraction study confirmed the results of Turner and Buseck. The cations... 

Single crystal structure X-ray diffraction analyses and structural classification of synthetic and natural mineral phases have revealed interesting actinide coordination chemistry. " This approach has led to the identification of in CaU(U02)2(C03)04(0H)(H20)7, the mineral wyartite. The structure contains three unique U positions. Two of these are uranyl ions with the typical pentagonal-bipyramidal coordination. The third is also seven-coordinate, but does not contain -yL oxygens and polyhedral geometry and electroneutrality requirements indicate that this site contains U. ... 

PLANT Sources, chemical structures and classifications of natural phthalides Chemical Structure of Phthalide... 

The basic core structure of phthalide is l(3H)-isobenzofuranone, which contains a benzene ring (ring A) fused with a y-lactone (ring B) between carbon atoms 1 and 3 (Fig. (1)). To date, all known natural phthalide compounds have been identified as derivatives of l(3H)-isobenzofiiranone. The structures of these derivatives either have the core structure substituted with one or more groups at different positions or contain a reduced form with one, two or no double bond(s) in ring A and various substitutions at different positions. The detailed structures of the naturally occurring phthalide derivatives identified from plants are discussed in the Classifications of Natural Phthalides Section below. 

Although many structural classifications of minerals have already been proposed, none has focused on rare earth minerals. In view of the importance of the rare earths as natural resources as well as to earth sciences, we have started to review their structures as a series Crystal Structures of Rare Earth Minerals (abbreviated as CSRM) yearly updated in Rare Earths , the Journal of the Rare Earth Society of Japan (Miyawaki and Nakai 1987, 1988, 1989, 1990, 1991). We attempt in this series to provide the complete data necessary for understanding the crystal structures of the rare earth minerals. The present text is based on the CSRM, with permission of the society. In this text, we summarize our most up-to-date knowledge on the crystal structures of rare earth minerals. Thus, this will serve as a structural data base of rare earth minerals. We will continue to publish the CSRM, so that any new data, suggestions, corrections and criticisms are welcome and will be reflected in the next CSRM. Please send all correspondences to R.M. 

Table 10.1 Classification of natural gums on basis of origin, gelation behavior and chemical structure [50,127],...

The wide variation in the structural features of naturally occurring dihydropyra-nones prevents a general, unified classification of the syntheses of the members of this compound class. Accordingly, we will focus first on the methods reported in the literature for the creation of the 5,6-dihydropyran-2-one core. Methods already... 

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