Flavanones chemistry

Grayer RJ and Veitch NC. Flavanones and dihydroflavonols. In Anderson OM, Markham KR. editors. Flavonoids Chemistry, Biochemistry and Applications. Boca Raton, FL CRC Press/Taylor Francis Group, pp. 918—1002. 

PHYSICAL ORGANIC CHEMISTRY NOMENCLATURE FLAVANONE 3/3-HYDROXYLASE FLAVINS AND DERIVATIVES Flavokinase,... 

From a chemosystematic point of view, it is interesting to note that prenylated flavonoids such as microfolione (56) have been found in a species of the family Ptaeroxylaceae, because the relationships of this family with other families were disputed in the past. Most taxonomists considered the Ptaeroxylaceae closely related to families in the order Rutales to which the Rutaceae and Meliaceae belong, whereas others considered it related to the Sapindaceae. Flavonoid chemistry supports a close relationship to the Rutaceae and Meliaceae, as iso-prenylated flavanones also occur in these families, e.g., 58 and 98 in Boronia coerulescens ssp. spinescens, the farnesyl-bearing 121 (Figure 15.3) in B. ramosa (Rutaceae)," and flowerine (59) and flowerone (60) in Azadirachta indica (Meliaceae). Microfolione is one of the few new flavanones for which the (2i )-configuration has been determined. 

Almost every class of natural phenolic compounds contains examples of substances with a 2,2-dialkylchromene ring, and the number of those that are discovered increases every year. It would be difficult to give an exhaustive list of these compounds. Their chemistry will be discussed here only when it is related to some particular behavior of the benzo-pyran ring. Examples include simple chromenes substituted in the aromatic ring,3,4,35-44 benzodipyrans,3,39 dimers of chromenes,45 naphthopyrans,46,47 quinones,48 flavones,49 flavonols,49 chalcones,49 flavanones,49 isoflavonoids,50 rotenoids,50 pterocarpans,50 couma-rins,17,51-53 3-arvl-4-hydroxycouniarins,50 4-phenylcoumarins,54 chroma-... 

Often used in concert with mass spectrometry, NMR spectroscopy remains an invaluable structural diagnostic tool of particular importance to tricyclic natural products chemistry. For example, the tricyclic phenolic compound moracin P (3) was one of eight previously known compounds identified together with two new isoprenoid-substituted flavanones in isolates of the root bark of mulberry trees <89H(29)807>. In a series of studies of 6-7-5 tricyclic natural products, ID and 2D H and l3C NMR spectroscopy were employed extensively in the structure determination of sesquiterpene lactones (4)—(8) found among the aerial natural products of toxic plants (85P1378,90P551, 90P3875). 

Jannie P. J. Marais studied at the University of the Free State, Bloemfontein, South Africa where he obtained his Ph.D. in organic chemistry in 2002. His research focused on characterization of the free phenolic profile of South African red wine, and the stereoselective synthesis of flavonoids, for example, flavan-3,4-diols and flavanones. He joined the National Center for Natural Products Research at the University of Mississippi as a postdoctoral associate in July of 2002, where he worked with Dr. Ferreira on the stereoselective synthesis of flavonoid precursors, the semi-synthesis of proanthocyanidin oligomers, characterization of proanthocyanidin profiles of selected transgenic plants, and the synthesis of radioactive antimalarial 8-aminoquinolines. He was promoted to associate research scientist in 2005, where his main area of research still remains the synthesis of A- and B-type proanthocyanidins, starting at the monomeric level and continuing through the tri- and tetra-meric, to the deca-mer level. 

Contents P. LEFRANCIER and E. LEDERER Chemistry of Synthetic Immunomodulant Muramyl Peptides. — SUKH DEV The Chemistry of Longifolene and Its Derivatives. — W. HELLER and CH.TAMM Homoiso-flavanones and Biogenetically Related Compounds. — R. G. COOKE and J. M. EDWARDS Naturally Occurring Phenalenones and Related Compounds. — C. W. JEFFORD and P. A. CADBY Molecular Mechanisms of Enzyme-Catalyzed Dioxygenation (An Interdisciplinary Review). 

They are also interesting compounds because they are the obligate intermediates in flavonoid biosynthesis. Although flavanones are minor chemical constituents of plants, they have attracted a lot of attention in chemistry and biological sciences. 

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