THE REACTION OF UNSATURATED CARBOHYDRATES WITH CARBON MONOXIDE AND HYDROGEN: V. ABSOLUTE STEREOCHEMISTRY OF ANHYDRODEOXYHEPTITOLS FROM 3,4,6-TRI-O-ACETYL-D-GLUCAL. STEREOCHEMISTRY OF HYDROFORMYLATION. CONFORMATIONAL ANALYSIS

1965 ◽  
Vol 43 (5) ◽  
pp. 1375-1381 ◽  
Author(s):  
Alex Rosenthal ◽  
Hans J. Koch
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Carbon Monoxide ◽  
Absolute Configuration ◽  
Sodium Iodide ◽  
Crystallographic Analysis ◽  
X Ray ◽  
Dicobalt Octacarbonyl ◽  
The Absolute ◽  
Compound Ii ◽  
Absolute Stereochemistry

3,4,6-Tri-O-acetyl-D-glucal reacted with carbon monoxide and hydrogen in the presence of dicobalt octacarbonyl to yield a mixture of two epimeric anhydrodeoxyheptitols, namely, 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-D-manno-heptitol (I) and 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-D-gluco-heptitol (II). De-O-acetylation of the mixture, followed by chromatographic separation, yielded crystalline 2,6-anhydro-3-deoxy-D-manno-heptitol (III) and 2,6-anhydro-3-deoxy-D-gluco-heptitol (IV). Reaction of the mixture of heptitols (I) and (II) with p-bromobenzenesulfonyl chloride, followed by fractional crystallization of the brosylates, gave pure 4,5,7-tri-O-acetyl-2,6-anhydro-1-O-(p-bromophenylsulfonyl)-3-deoxy-D-gluco-heptitol (VII). The absolute configuration of (VII) has been previously established by X-ray crystallographic analysis. The absolute configuration of (III) was established by correlation with that of (VII). The conversion of compound (II) into various derivatives is described.Reaction of 3,4,6-tri-O-acetyl-D-glucal with carbon monoxide and deuterium afforded 2,6-anhydro-3-deoxy-D-manno-heptitol-1,1,3-2H3 (XIII) and 2,6-anhydro-3-deoxy-D-gluco-heptitol-1,1,3-2H3 (XIV). Examination of the nuclear magnetic resonance (n.m.r.) spectra of the normal and deuterated anhydrodeoxyheptitols confirmed the structural assignments and showed that cis addition to the double bond took place to give (XIV).Comparison of the exchange reaction of sodium iodide with 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-1-O-tosyl-D-gluco-heptitol (VIII) and with 4,5,7-tri-O-acetyl-2,6-anhydro-3-deoxy-1-O-tosyl-D-manno-heptitol (XV) revealed that the equatorial primary tosyloxy group of (VIII) was exchanged by iodine twice as readily as the axial primary tosyloxy group of (XV).

Absolute Stereochemistry of (-)-Wieland-Miescher Ketone as Established by the X-ray Crystallographic and CD Exciton Chirality Methods

1992 ◽  
Vol 57 (7) ◽  
pp. 1459-1465 ◽  
Author(s):  
Nobuyuki Harada ◽  
Tatsuo Sugioka ◽  
Hisashi Uda ◽  
Takeo Kuriki
Keyword(s):  
Structure Analysis ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The 8aR absolute stereochemistry of Wieland-Miescher ketone (-)-I was established by the X-ray structure analysis of its bis(4-bromobenzoate) derivatives (1R,6R,8aR)-(+)-IV and (1R,6S,8aR)-(-)-V. The absolute configuration of (-)-I was corroborated further by the application of the CD exciton chirality method to bis(4-bromobenzoates) (+)-IV and (-)-V.

Étude conformationnelle de cétopipérazines: (I) 3R-méthyl-6-carbéthoxy-2 oxopipérazine, (II) 3R-[p-hydroxybenzyl]-6-carbéthoxy-2 oxopipérazine: I, II en solution et structure cristalline de II

1987 ◽  
Vol 65 (6) ◽  
pp. 1308-1312 ◽  
Author(s):  
André Michel ◽  
Guy Evrard ◽  
B. Norberg
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Absolute Configuration ◽  
Structure Determination ◽  
Opiate Receptor ◽  
Receptor Level ◽  
X Ray ◽  
Diastereomeric Mixture ◽  
The Absolute

The synthesis of the title compounds has been described recently. It was anticipated that the product would be a diastereomeric mixture. Surprisingly, only one isomer was obtained. The present work is an attempt to find the conformationnal properties accounting for those observations. X-ray structure determination of 3R-[p-hydroxybenzyl]-6-carbethoxy-2-oxopiperazine shows that the molecule adopts a folded conformation and that the absolute configuration at C6 is [R]. Investigation in solution using 1H nuclear magnetic resonance shows the existence of three conformers and discusses the relative populations. Those findings are also relevant in terms of the activity of such compounds at the opiate receptor level.

scholarly journals 2,4-Dimethyl-3,4-O-isopropylidene-L-arabinono-1,5-lactone

2007 ◽  
Vol 63 (3) ◽  
pp. o1128-o1130 ◽  
Author(s):  
Kathrine V. Booth ◽  
David J. Watkin ◽  
Sarah F. Jenkinson ◽  
George W. J. Fleet
Keyword(s):  
Absolute Configuration ◽  
Crystallographic Analysis ◽  
Starting Material ◽  
Relative Configuration ◽  
X Ray ◽  
Boat Form ◽  
The Absolute

The relative configuration at C-2 of 2,4-dimethyl-3,4-O-isopropylidene-L-arabinono lactone, C10H16O5, which exists in the boat form, was unequivocally established by X-ray crystallographic analysis. The absolute configuration was determined by the use of 2-C-methyl-D-ribonolactone as a starting material.

Sterically Crowded Heterocycles. XIII. An Insight Into the Absolute Stereochemistry of Atropisomeric (Z)-3-(Imidazo[1,2-a]pyridin-3-yl)prop-2-en-1-ones

2000 ◽  
Vol 65 (10) ◽  
pp. 1643-1652
Author(s):  
Radek Pohl ◽  
Jan Sýkora ◽  
Petr Maloň ◽  
Stanislav Böhm ◽  
Bohumil Kratochvíl ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Heats Of Formation ◽  
Cd Spectra ◽  
X Ray ◽  
Space Analysis ◽  
The Absolute ◽  
Absolute Stereochemistry ◽  
Insight Into

The absolute configuration of the atropisomeric (Z)-3-(5-methyl-2-phenylimidazo[1,2-a]pyridin-3-yl)-1,3-diphenylprop-2-en-1-one was evaluated to be R for the dextrorotatory and S for the laevorotatory enantiomers. The assignment is based on their two-step syntheses via atropodiastereoisomeric carbamates prepared from the corresponding atropodiastereoisomeric alcohols with (R)-(+)-α-phenylethyl isocyanate and by a complete X-ray space analysis of the quaternary triiodide obtained from the (R)-(+)-enantiomer. CD spectra and PM3 calculated heats of formation for selected compounds are discussed in relation to the found molecular configurations.

Metabolites produced by the scleroderris canker fungus, Gremmeniellaabietina. Part 2. The structure of scleroderolide

1987 ◽  
Vol 65 (4) ◽  
pp. 748-753 ◽  
Author(s):  
William A. Ayer ◽  
Yumiko Hoyano ◽  
M. Soledade Pedras ◽  
Jon Clardy ◽  
Edward Arnold
Keyword(s):  
Absolute Configuration ◽  
Temperature Dependent ◽  
X Ray ◽  
Triclinic System ◽  
R Factor ◽  
Racemic Form ◽  
Crystallographic Study ◽  
Acetyl Group ◽  
The Absolute ◽  
Absolute Stereochemistry

Scleroderolide, a yellow pigment produced by the Scleroderris canker fungus Gremmeniellaabietina (Lagerb.) Morelet, is shown to possess structure 1. The structure was determined by an X-ray crystallographic study of the racemic monoacetate 1a. The crystal of 1a belongs to the triclinic system space group, P1, the R-factor converged to 0.047 for the 1957 observed reflections. Scleroderolide occurs mainly as the levorotatory enantiomer (S configuration at C-2′) although on one occasion it was obtained in partially racemic form. The absolute stereochemistry of the levorotatory form was determined by transformation of (−)-sclerodione (5) of known absolute configuration into (−)-scleroderolide. The absolute configuration of (−)-sclerodione was established by correlation with (−)-sclerodin (3). The diacetyl derivative of scleroderolide (1b) shows interesting temperature dependent nuclear magnetic resonance spectral properties due to restricted rotation of the C-4 O-acetyl group. Oxidation of the red pigment sclerodione (5) with m-chloroperbenzoic acid provides both sclerodin (3) and scleroderolide (1). Scleroderolide (1) is the first natural product to be reported that contains a phenylglyoxylate lactone functionality.

The Absolute Stereochemistry of the Galbulimima Alkaloids

2006 ◽  
Vol 59 (9) ◽  
pp. 629 ◽  
Author(s):  
Anthony C. Willis ◽  
Patrick D. O'Connor ◽  
Walter C. Taylor ◽  
Lewis N. Mander
Keyword(s):  
Crystal Structures ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The X-ray crystal structures have been determined for three alkaloids isolated from the bark of the rainforest tree Galbulimima belgraveana, namely himbosine, himandrine, and himgaline, thereby allowing the absolute configuration to be established for these three compounds and 15 further alkaloids from this source.

Revised Absolute Configurations of Latifolic Acid and the Pyrrolizidine Alkaloid Latifoline

1988 ◽  
Vol 41 (11) ◽  
pp. 1781 ◽  
Author(s):  
JN Roitman ◽  
RY Wong
Keyword(s):  
Carboxylic Acid ◽  
Single Crystal ◽  
Pyrrolizidine Alkaloid ◽  
Crystallographic Analysis ◽  
Side Chain ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of (+)- latifolk acid has been determined by single-crystal X-ray crystallographic analysis to be (2S,3R,4R)-3- hydroxy-2,4-dimethyl-5-oxotetrahydrofuran-3-carboxylic acid. The configuration of the three chiral centres is opposite to that presently recorded in the literature. Accordingly, the configuration of the pyrrolizidine alkaloid, latifoline, which includes a latifolic acid side chain, must be revised.

Metabolites of Lachnellula fuscosanguinea (Rehm). Part 2. The structure of lachnellulone

1988 ◽  
Vol 66 (3) ◽  
pp. 506-512 ◽  
Author(s):  
William A. Ayer ◽  
J. Daniel Figueroa Villar ◽  
Barbara S. Migaj
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Absolute Configuration ◽  
Mass Spectra ◽  
Antifungal Metabolite ◽  
X Ray ◽  
Crystallographic Study ◽  
Nuclear Magnetic Resonance Spectra ◽  
The Absolute ◽  
Nuclear Magnetic

Lachnellulone, an antifungal metabolite produced by Lachnellula fuscosanguinea (Rehm) Dennis is shown to possess structure 8. The structure was determined by consideration of the ultraviolet, infrared, 1H and 13C nuclear magnetic resonance, and mass spectra of 8 and its derivatives and was confirmed by an X-ray crystallographic study of lachnellulone p-nitrobenzoate. In solution lachnellulone undergoes facile isomerization to isolachnellulone (9a), which explains the observed mutarotation of 8. The 13C nuclear magnetic resonance spectra of lachnellulone and the related lachnelluloic acid (1) are discussed in some detail. The absolute configuration of lachnellulone has not been determined.

scholarly journals Punctaporonins N–S, New Caryophyllene Sesquiterpenoids from Cytospora sp.

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Yan Li ◽  
Qingbin Wang ◽  
Xingzhong Liu ◽  
Yongsheng Che
Keyword(s):  
Nmr Spectroscopy ◽  
Absolute Configuration ◽  
Hela Cells ◽  
Crystallographic Analysis ◽  
X Ray ◽  
The Absolute

Six new caryophyllene sesquiterpenoids, punctaporonins N–S (1–6), and three known ones, 6-hydroxypunctaporonins B (7), A (8), and E (9), have been isolated from solid cultures of Cytospora sp. The structures of 1–6 were elucidated primarily by NMR spectroscopy. The absolute configuration of 1 was assigned by X-ray crystallographic analysis of its S-MTPA ester. Compounds 2, 5, and 6 showed modest cytotoxicity against HeLa cells.

scholarly journals 5-Amino-5-deoxy-2-C-hydroxymethyl-2,3-O-isopropylidene-L-lyxono-1,5-lactam

2007 ◽  
Vol 63 (3) ◽  
pp. o1409-o1411
Author(s):  
Michela Simone ◽  
George W. J. Fleet ◽  
Richard Bream ◽  
David J. Watkin
Keyword(s):  
Absolute Configuration ◽  
Catalytic Hydrogenation ◽  
Title Compound ◽  
Crystallographic Analysis ◽  
Starting Material ◽  
Relative Configuration ◽  
X Ray ◽  
Compound C ◽  
The Absolute

The relative configuration of the title compound, C9H14NO5, formed by catalytic hydrogenation of an azidolactone, has been established by X-ray crystallographic analysis. The absolute configuration was determined by the use of 2,3-O-isopropylidene-L-lyxono-1,4-lactone as the carbohydrate starting material.

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