Synthesis and X-Ray Analysis of the (S) Enantiomer of Methyl 5-Hydroxy-3,11-di-2-pyridyl-4,5-dihydro-1H,3H-2,6-methano- 6-benz[c]azocinecarboxylate C24H23N3O3 and of the Corresponding Camphanic Acid Ester C34H35N3O6

1988 ◽  
Vol 43 (7) ◽  
pp. 901-910 ◽  
Author(s):  
K.-F. Hesse ◽  
Ulrike Holzgrabe ◽  
Barthold Piening
Keyword(s):  
Absolute Configuration ◽  
Acid Chloride ◽  
Acid Ester ◽  
Oxidative Cyclization ◽  
X Ray ◽  
Space Groups ◽  
Cell Parameters ◽  
The Absolute ◽  
Camphanic Acid

Abstract Methyl 5-hydroxy-3,11-di-2-pyridyl-4,5-dihydro-1H,3H-2,6-methano-6-benz[c]azocinecarb-oxylate (-)-3 is synthesized by oxidative cyclization of an N-benzyl-4-piperidone, reduction and resolution with (-)-camphanic acid chloride.The structures of C24H23N3O3 (-)-3 and of the corresponding camphanic acid ester C34H35N3O6 (-)-5 are orthorhombic and monoclinic with space groups P212121 ((-)-3) and P21 ((-)-5). The respective cell parameters are a = 9.758(3), b = 12.815(2), c = 16.584(4) Å, Z = 4 and Dx = 1.29 g cm-3 ((-)-3) and a = 11.189(1), b = 10.591(1), c -12.84(1) Å, β = 92.53(1)°, Z = 2, Dx = 1.27 g cm-3 ((-)-5). They were refined to R (unweighed) -0.037 ((-)-3), 0.069 ((-)-5) and R (weighed) = 0.035 ((-)-3), 0.061 ((-)-5) using 965, 1722 non-equivalent reflections, respectively. The absolute configuration of (-)-3 was determined as 2S, 3R. 5R, 6R, 11 R.

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.

scholarly journals Preparative-scale HPLC Resolution of Metallacyclic η3-Allyltricarbonyliron Complexes and Determination of the Absolute Configuration by X-Ray Crystal Structure Analysis

1999 ◽  
Vol 23 (9) ◽  
pp. 578-579
Author(s):  
Rainer Schobert ◽  
Hermann Pfab ◽  
Jutta Böhmer ◽  
Frank Hampel ◽  
Andreas Werner
Keyword(s):  
Crystal Structure ◽  
Silica Gel ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Preparative Scale ◽  
X Ray ◽  
The Absolute

Racemates of (η3-allyl)tricarbonyliron lactone complex Fe(CO)3{η1:η3-C(O)XCH2CHCMeCH2} 1a (X = O) and (η3-allyl)tricarbonyliron lactam complex 2a (X = NMe) are resolved on a preparative scale by HPLC on cellulose tris(3,5-dimethylphenyl)carbamate/silica gel RP-8 and the absolute configuration of (-)-2a is determined by X-ray crystal structure analysis.

Alkaloids of Rauvolfia salicifolia GRISEB species

1982 ◽  
Vol 47 (11) ◽  
pp. 2912-2921 ◽  
Author(s):  
Patricia Sierra ◽  
Ladislav Novotný ◽  
Zdeněk Samek ◽  
Miloš Buděšínský ◽  
Ladislav Dolejš ◽  
...  
Keyword(s):  
Absolute Configuration ◽  
Cd Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute

From the endemic Cuban species Rauvolfia salicifolia GRISEB nine alkaloids were isolated of which the following seven had been already described: (+)-ajmalidine (I), (-)-reserpiline (II), (-)-isoreserpiline (III), (-)-isocarapanaubine (IV), (-)-ajmalicine (V), (+)-vellosimine (VI), and (+)-yohimbine (VII). The structure of (-)-raucubaine (VIII) had been previously determined by X-ray diffraction and the structure of the alkaloid (-)-raucubainine (IX) was suggested on the basis of its conversion to (-)-raucubaine (VIII). The absolute configuration of (-)-raucubaine and (-)-raucubainine was elucidated by CD spectroscopy.

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.

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).

The structures of marialite (Me6) and meionite (Me93) in space groups P42/n and I4/m, and the absence of phase transitions in the scapolite series

2011 ◽  
Vol 26 (2) ◽  
pp. 119-125 ◽  
Author(s):  
Sytle M. Antao ◽  
Ishmael Hassan
Keyword(s):  
Phase Transitions ◽  
High Resolution ◽  
Crystal Structures ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Space Groups ◽  
Cell Parameters ◽  
The Mean

The crystal structures of marialite (Me6) from Badakhshan, Afghanistan and meionite (Me93) from Mt. Vesuvius, Italy were obtained using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and Rietveld structure refinements. Their structures were refined in space groups I4/m and P42/n, and similar results were obtained. The Me6 sample has a formula Ca0.24Na3.37K0.24[Al3.16Si8.84O24]Cl0.84(CO3)0.15, and its unit-cell parameters are a=12.047555(7), c=7.563210(6) Å, and V=1097.751(1) Å3. The average ⟨T1-O⟩ distances are 1.599(1) Å in I4/m and 1.600(2) Å in P42/n, indicating that the T1 site contains only Si atoms. In P42/n, the average distances of ⟨T2-O⟩=1.655(2) and ⟨T3-O⟩=1.664(2) Å are distinct and are not equal to each other. However, the mean ⟨T2,3-O⟩=1.659(2) Å in P42/n and is identical to the ⟨T2′-O⟩=1.659(1) Å in I4/m. The ⟨M-O⟩ [7]=2.754(1) Å (M site is coordinated to seven framework O atoms) and M-A=2.914(1) Å; these distances are identical in both space groups. The Me93 sample has a formula of Na0.29Ca3.76[Al5.54Si6.46O24]Cl0.05(SO4)0.02(CO3)0.93, and its unit-cell parameters are a=12.19882(1), c=7.576954(8) Å, and V=1127.535(2) Å3. A similar examination of the Me93 sample also shows that both space groups give similar results; however, the C–O distance is more reasonable in P42/n than in I4/m. Refining the scapolite structure near Me0 or Me100 in I4/m forces the T2 and T3 sites (both with multiplicity 8 in P42/n) to be equivalent and form the T2′ site (with multiplicity 16 in I4/m), but ⟨T2-O⟩ is not equal to ⟨T3-O⟩ in P42/n. Using different space groups for different regions across the series implies phase transitions, which do not occur in the scapolite series.

scholarly journals Absolute Configuration of Cembrane Diterpenoids from Bursera multijuga

2014 ◽  
Vol 9 (9) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Juan D. Hernández-Hernández ◽  
Hugo A. García-Gutiérrez ◽  
Luisa U. Román-Marín ◽  
Yunuen I. Torres-Blanco ◽  
Carlos M. Cerda-García-Rojas ◽  
...  
Keyword(s):  
Molecular Modeling ◽  
Absolute Configuration ◽  
2D Nmr ◽  
Vibrational Circular Dichroism ◽  
Conformational Preference ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Absolute ◽  
First Time ◽  
Good Agreement

The stems of Bursera multijuga afforded (-)-(1 S,3 E,7 R,8 R,11 E)-7,8-epoxycembra-3,11-dien-1-ol (1) and its acetate 2, together with cembrene A (3), nephthenol (4), and cembrenol (5). The structures of 1 and 2 were elucidated by 1D and 2D NMR, HRESIMS, and X-ray diffraction. The conformational preference of flexible 1 was studied by molecular modeling at the DFT B3LYP/DGDZVP level of theory. Good agreement between calculated and experimental vibrational circular dichroism curves established the absolute configuration of 1. This is the first time that cembrane derivatives have been isolated from the genus Bursera.

Enantioselective Arylation of 3-Carboxamide Oxindoles with Quinone Monoimines and Synthesis of Chiral Spirooxindole-benzofuranones

Synlett ◽  
2019 ◽  
Vol 30 (09) ◽  
pp. 1067-1072
Author(s):  
Hui Chen ◽  
Hui Liu ◽  
Si-Han Zhao ◽  
Shao-Bing Cheng ◽  
Xiao-Ying Xu ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Absolute Configuration ◽  
Tertiary Amine ◽  
The Other ◽  
X Ray ◽  
Quaternary Center ◽  
Crystal Structural ◽  
The Absolute

A highly enantioselective arylation of 3-carboxamide oxoindoles with quinone monoimines is described. Various 3-aryl-3-carboxamide oxindoles with an all-carbon quaternary center were obtained in moderate to good yields (up to 99%) with moderate to good enantioselectivities (up to 98%) in the presence of a bifunctional thiourea-tertiary amine catalyst. The absolute configuration of one product was determined by an X-ray crystal structural analysis and the absolute configurations of the other products can be assigned by analogy. Moreover, several chiral spirooxindole-benzofuranones were synthesized from the 3-aryl-3-carboxamide oxindoles in moderate yields with moderate to good enantioselectivities.

Die absolute Konfiguration der Juglomycine/The Absolute Configuration of the Juglomycins

1989 ◽  
Vol 44 (3) ◽  
pp. 345-352 ◽  
Author(s):  
Johann Krupa ◽  
Helmut Lackner ◽  
Peter G. Jones ◽  
Karen Schmidt-Bäse ◽  
George M. Sheldrick
Keyword(s):  
Single Crystal ◽  
Structure Analysis ◽  
Absolute Configuration ◽  
X Ray ◽  
The Absolute ◽  
Dibromo Derivative

The absolute configurations of the known juglomycins A (1) and B (2) have been elucidated by single crystal X-ray structure analysis of 1 and its 6,8-dibromo derivative (1b). The structure of 2 has been corrected; it differs from 1 in its configuration at C-4', and not at C-3' as previously assumed. Relationships with the closely related isochromanquinone antibiotics are discussed.

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