6236-09-5Relevant academic research and scientific papers
Glycosides of polyenoic branched fatty acids from myxomycetes
?ezanka, Tomá?
, p. 639 - 646 (2007/10/03)
The determination of chemical structures of five novel compounds, i.e. one multibranched polyunsaturated fatty acid ((2E,4E,7S,8E,10E,12E,14S)-7,9,13,17-tetramethyl-7,14-dihydroxy-2, 4,8,10,12,16-octadecahexaenoic acid) and its four glycosides from seven different myxomycetes is described. The absolute configuration of both hydroxyl groups was determined. The glycosides containing glucose, mannose and rhamnose. These compounds were identified by means of 1H and 13C NMR, MS, UV and IR spectra. Three of them were identified in Arcyria cinerea (Bull.) Pers., two in A. denudata (L.) Wetts., and A. nutans (Bull.) Grev., Fuligo septica (L.) Wigg., Lycogala epidendrum (L.) Fries, Physarum polycephalum Schwein., and Trichia varia Pers. contained one of the identified glycosides each.
Pigments of Fungi. LIX - Synthesis of (1S,3S)- and (1R,3R)-austrocortilutein and (1S,3S)-austrocortirubin from citramalic acid
Gill, Melvyn,Harte, Michael F.,Ten, Abilio
, p. 245 - 256 (2007/10/03)
The naturally occurring tetrahydroanthraquinone (1S,3S)-austrocortilutein (1) is synthesized for the first time in enantiomerically pure form by Diels-Alder cycloaddition between the functionalized butadiene derivative (8) and the chiral 1,3-dihydroxy-1,2,3,4-tetrahydro-5,8-naphthoquinone (9), the latter being derived from (R)-citramalic acid (3). The natural products (1S,3S)-austrocortirubin (2) and (1R,3R)-austrocortilutein (5) were also prepared for the first time by using the same strategy. CSIRO 2000.
Asymmetric Allylation of Carbonyl Compounds with Tartrate-Modified Chiral Allylic Tin Reagents
Yamada, Koji,Tozawa, Takashi,Nishida, Minoru,Mukaiyama, Teruaki
, p. 2301 - 2308 (2007/10/03)
Chiral allylating reagents, readily generated in situ from tin(II) catecholate [SnII(O2C6H4)], allyl halides, chiral dialkyl tartrates, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), reacted smoothly with aldehydes or reactive ketones at - 78 °C in the presence of a catalytic amount of copper salts to afford the corresponding optically active homoallyl alcohols. Allylation of aromatic aldehydes and pyruvates by the present chiral tin reagents proceeded in high yields (81-99%) with high enantioselectivities (89-94%ee). In addition, both enantiomers of dimethyl citramalate were prepared from the allylation products of benzyl pyruvate.
Preparation of Both Enantiomers of Malic and Citramalic Acid and Other Hydroxysuccinic Acid Derivatives by Stereospecific Hydrations of cis or trans 2-Butene-1,4-dioic Acids with Resting Cells of Clostridium formicoaceticum
Eck, Richard,Simon, Helmut
, p. 13641 - 13654 (2007/10/02)
(R)-Malic, (S)-malic, (R)-citramalic, (S)-citramalic, (2R,3S)-2-hydroxy-3-methylsuccinic and (2R,3S)-2,3-dimethyl-2-hydroxysuccinic acid were prepared on scales up to 25 mmol by stereospecific addition of water to different 2-butene-1,4-dioic acid derivatives catalyzed by resting cells of Clostridium formicoaceticum (Scheme 1).The (3R)-monodeuterio (R)- and (S)-malic acid as well as (R)- and (S)-citramalic acid were prepared using freeze-dried cells in 2H2O-buffer.The stereochemical purity of the products was in most cases >/= 99percent.
Stereochemistry of Enzymic Cyclisation of 3-Methyl-cis,cis-muconic Acid to form 3- and 4-Methylmuconolactone
Cain, Ronald B.,Kirby, Gordon W.,Rao, Ghanakota V.
, p. 1629 - 1631 (2007/10/02)
Enzyme-catalysed cyclisation of 3-methyl-cis,cis-muconic acids proceeds by syn addition of carboxyl groups to double bonds to form (4S)-3-methylmuconolactone in Aspergillus niger and (4S)-4-methylmuconolactone in Pseudomonas putida.
A highly efficient synthesis of (R)- and (S)-citramalic acid
Staring, Emiel G. J.,Moorlag, Henk,Wynberg, Hans
, p. 374 - 375 (2007/10/02)
An efficient multigram synthesis of optically pure (S)- and (R)-citramalic acid is described.
163. Asymmetrische Michael-Additionen Stereoselektive Alkylierung chiraler, nicht racemischer Enolate durch Nitroolefine. Herstellung enantiomerenreiner γ-Aminobuttersaeure- und Bernsteinsaeure-Derivative
Calderari, Giorgio,Seebach, Dieter
, p. 1592 - 1604 (2007/10/02)
Chiral, non-racemic lithium-enolates (E,F,G) of 1,3-dioxolan-4-ones, methyl 1,3-oxazolidin-4-carboxylates, methyl 1,3-oxazolin-4-carboxylates, 1,3-oxazolidin-5-ones, and 1,3-imidazolidin-4-ones derived from (S)-lactic acid (2a), (S)-mandelic acid (2b), and (S)-malic acid (2c), or from (S)-alanine (10), (S)-proline (11), (S)-serine (12), and (S)-threonine (13), are added to nitroolefins.Michael adducts (3-9, 14-18) are formed (40-80percent) with selectivities generally above 90percent ds of one of the four possible stereoisomers.Conversions of these nitroalkylated products furnish the α-branched α-hydroxysuccinic acids 28 and 29, the α-hydroxy-γ-amino acid 25, the α,γ-diamino acid 32, the substituted γ-lactames 19-22, and the pyrrolidine 23.The relative and absolute configuration of the products from dioxolanones and nitropropene are derived by chemical correlation and NOE measurements indicating that the steric course of reaction is to be specified as 1k, ul-1,3.The mechanism is discussed.
α-ALKYLATION OF α-HETEROSUBSTITUTED CARBOXYLIC ACIDS WITHOUT RACEMIZATION; EPC-SYNTHESES OF TERTIARY ALCOHOLS AND THIOLS
Seebach, Dieter,Naef, Reto,Calderari, Giorgio
, p. 1313 - 1324 (2007/10/02)
α-Hydroxy- and α-mercapto-carboxylic acids are condensed with pivalaldehyde to give 2-t-butyl-5-substituted-1,3-dioxolanones or 1,3-oxathiolanones (2); the predominate cis-isomers are separeted by crystallization.The cis-disubstituted heterocycles 2 derived from lactic, mandelic and malic acid funish, after deprotonation with LDA, reaction with electrophiles such as alkyl halides, aldehydes and ketones, and hydrolysis α-branched α-hydroxy-carboxylic acids (3, 6, 8, 9, 10).These result from an overall substitution of the proton in the α-CO position with retention of configuration.The optically active carboxylic acids are α-alkylated without racemization and without employment of a chiral auxiliary ("self-reproduction of chirality", Scheme 1).The diastereoselectivities (ds) are generally >95percent (Table 1, 2, and 20-25).
The Use of Grignard Reagents in the Synthesis of Carbohydrates. I. The Synthesis of Deoxy and Branched-chain Deoxy Sugars
Kawana, Masajiro,Emoto, Sakae
, p. 222 - 229 (2007/10/02)
Two branched-chain deoxy sugars, methyl 5,6-O-cyclohexylidene-3-deoxy-2-C-methyl-β-D-arabino-hexofuranoside and its α-D-ribo isomer, were easily prepared by the one-step reaction of methyl 5,6-O-cyclohexylidene-3-O-mesyl-β-D-allofuranoside (3a) with methylmagnesium iodide.Similarly, the corresponding α-mesylate (4a) gave methyl 5,6-O-cyclohexylidene-3-deoxy-2-C-methyl-α-D-ribo-hexofuranoside.It was demonstrated that these reactions involved 1,2-hydride shifts.The reactions of 3a and 4a with t-butylmagnesium bromide yielded two deoxy sugars, methyl 5,6-O-cylohexylidene-3-deoxy-β-D-arabino-hexofuranoside and the corresponding α-D-ribo isomer, respectively.Under certain reaction conditions with the Grignard reagents, the sulfonate (3a) afforded dimeric compounds, in which two furanose rings were directly bound with a carbon-carbon bond.A convenient method for the preparation of the sulfonates (3a and 4a) is also reported.
