On the synthesis of cryptosporiopsin: stereochemistry of early intermediates

1982 ◽  
Vol 60 (16) ◽  
pp. 2062-2064
Author(s):  
George M. Strunz ◽  
Peter S. White
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Single Crystal ◽  
Acid Methyl Ester ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Synthetic Route ◽  
Space Group ◽  
X Ray ◽  
Acid Methyl

The relative configurations of two intermediates in the synthetic route to cryptosporiopsin are clarified through the structure of 3,5-dichloro-1,4-dihydroxy-2-methylcyclopent-2-ene-1-carboxylic acid methyl ester, which was determined by single crystal X-ray techniques. The crystal was monoclinic, space group P21/c, a = 7.352(1), b = 8.868 (3), c = 16.300(7) Å; β = 96.49(2)°. The structure was solved by direct methods and refined to a final R of 0.057.

Synthese neuer optisch aktiver Rh-Komplexe: Die Kristallstruktur von [(5S)-3,4-Bis(diphenylphosphino)-5-menthoxy-2(5H)-furanon](1,5-cyclooctadien)rhodium-hexafluorophosphat / Synthesis of New Optically Active Rh-Complexes: The Crystal Structure of [(5S)-3,4-Bis(diphenylphosphino)-5-menthoxy-2(5 H)-furanone](1,5-cyclooctadiene)rhodium-hexafluorophosphate

1989 ◽  
Vol 44 (8) ◽  
pp. 884-888 ◽  
Author(s):  
Dieter Fenske ◽  
Kurt Merzweiler
Keyword(s):  
Crystal Structure ◽  
Methyl Ester ◽  
Single Crystal ◽  
Enantiomeric Excess ◽  
Optically Active ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants

The chiral diphosphine 1 reacts with [(diolefin)Rh(THF)2]PF6 (diolefine: 1.5-cyclooctadiene, norbornadiene) to form the complexes 4 and 5. The structure of 4 was determined by single crystal X-ray analysis. 4 crystallizes in the monoclinic space group P21. The lattice constants (at 180 K) are: a = 974.0(6); b = 3889.2(29); c = 1309.4(5) pm; β = 105.25(4)°. The hydrogenation of methyl-α-acetamidocinnamate in the presence of 5 yields (R)-N-acetylphenylalanine methyl ester with 33% enantiomeric excess.

Structure and degree of charge transfer of two polymorphs of a 1:1 molecular complex: [2,2′-bis-1,3-dithiole][9-dicyanomethylene-4,5,7-trinitrofluorene-2-carboxylic acid methyl ester] (TTF-MeDC2TNF)

2003 ◽  
Vol 59 (4) ◽  
pp. 505-511 ◽  
Author(s):  
Amparo Salmerón-Valverde ◽  
Sylvain Bernès ◽  
Juan Gerardo Robles-Martínez
Keyword(s):  
Charge Transfer ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Acid Methyl Ester ◽  
Structural Features ◽  
Space Group ◽  
Acid Methyl ◽  
Organic Complexes ◽  
Crystal Packings ◽  
Degree Of Charge Transfer

A new organic charge-transfer complex, C18H7N5O8·C6H4S4, has been prepared using TTF (tetrathiafulvalene) as a donor (D) and MeDC2TNF (9-dicyanomethylene-4,5,7-trinitro-fluorene-2-carboxylic acid methyl ester) as an acceptor (A). Two monoclinic polymorphs of the 1:1 salt were crystallized and characterized by X-ray diffraction. Form α crystallizes in space group P21/n with Z′ = 1, while form β crystallizes in space group C2/c with Z′ = 1\over 2 and the MeDC2TNF moiety disordered across a twofold axis. Both phases have mixed-stack crystal packings, which are characteristic of semiconducting one-dimensional organic complexes. However, the observed crystal packings are significantly different, with a single D...A interlayer separation of 3.452 Å for the disordered β polymorph and interlayer separations of 3.378 and 3.483 Å in the case of the ordered α form. These variations are reflected in the degree of charge transfer, δ, which was estimated on the basis of the b 2u stretching-mode frequency shift observed in the IR spectra for the cyano groups of the MeDC2TNF radical anion. The fact that the charge transfer is more efficient for α-(TTF-MeDC2TNF) than for β-(TTF-MeDC2TNF) (δ = 0.35 and 0.31, respectively) is consistent with the structural features observed for each crystalline form.

The cytotoxic effect of Ru(II) complexes with 5-(2-hydroxyphenyl)-3-methyl-1-(2-pyridyl)-1H-pyrazole-4-carboxylic acid methyl ester: Synthesis, X-ray structure and DNA damage potential

Polyhedron ◽  
2019 ◽  
Vol 169 ◽  
pp. 228-238 ◽  
Author(s):  
Anna Skoczyńska ◽  
Beata Pasternak ◽  
Magdalena Małecka ◽  
Urszula Krajewska ◽  
Marek Mirowski ◽  
...  
Keyword(s):  
Dna Damage ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Cytotoxic Effect ◽  
Acid Methyl Ester ◽  
Ester Synthesis ◽  
Damage Potential ◽  
X Ray ◽  
Acid Methyl

Clemmensen Reduction. IX. Structure and Reactions of a Cyclopropane-1,2-diol

1988 ◽  
Vol 41 (8) ◽  
pp. 1191 ◽  
Author(s):  
GR Clark ◽  
BR Davis ◽  
MG Hinds ◽  
CEF Rickard
Keyword(s):  
Single Crystal ◽  
Direct Methods ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray ◽  
R Factor ◽  
Clemmensen Reduction

The β-keto aldehyde , 1-methyl-2-oxocyclododecanecarbaldehyde (4), was converted into a mixture of two cyclopropane-1,2-diyl diacetates , 12- methyl- cis-bicyclo [10.1.0]tridecane-cis-1,13-diyl diacetate (6) and 12- methyl-trans- bicyclo [10.1.0]tridecane-trans-1,13-diyl diacetate (8). The structure of (6) was established by means of a single-crystal X-ray study. The crystals are monoclinic, space group P21/c, with four molecules in a unit cell of dimensions a 12.326(1), b 14.998(2), c 10.388(3) Ǻ, β 108.33(1)°. The structure was solved by direct methods, and refined to an R factor of 0.059. Protonolysis of the corresponding diols leads to compounds not normally encountered in such systems but the genesis of the major products can be rationalized.

Crystal structure of 9-Oxofluorene-4-carboxylic acid

1981 ◽  
Vol 34 (5) ◽  
pp. 1143 ◽  
Author(s):  
CHL Kennard ◽  
G Smith ◽  
GF Katekar
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Diffraction Data ◽  
Three Dimensional ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
A Cell

The crystal structure of 9-oxofluorene-4-carboxylic acid has been determined by direct methods using three-dimensional X-ray diffraction data, and refined to R0·068 for 1323 'observed' reflections. Crystals are monoclinic, space group P21/c with 24 in a cell of dimensions a 3·843(3), b 7·986(5), c 3269(2) �, β 96·64(4)�. The molecules form centrosymmetric hydrogen-bonded cyclic dimers [O···O 2·642(3) �] with the plane of the carboxylic acid making an angle of 26·5� with that of the 9-oxofluorene group. Stacks of molecules form down the a axis with 3.843 �. separation.

A NovelC2-Symmetric 2,6-Diallylpiperidine Carboxylic Acid Methyl Ester as a Promising Chiral Building Block for Piperidine-Related Alkaloids†

2002 ◽  
Vol 4 (20) ◽  
pp. 3459-3462 ◽  
Author(s):  
Hiroki Takahata ◽  
Hidekazu Ouchi ◽  
Motohiro Ichinose ◽  
Hideo Nemoto
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Building Block ◽  
Acid Methyl Ester ◽  
Acid Methyl ◽  
Chiral Building Block

scholarly journals Thermodynamic Properties of Three Pyridine Carboxylic Acid Methyl Ester Isomers

2007 ◽  
Vol 52 (2) ◽  
pp. 580-585 ◽  
Author(s):  
Maria D. M. C. Ribeiro da Silva ◽  
Vera L. S. Freitas ◽  
Luís M. N. B. F. Santos ◽  
Michal Fulem ◽  
M. J. Sottomayor ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Thermodynamic Properties ◽  
Acid Methyl Ester ◽  
Pyridine Carboxylic Acid ◽  
Acid Methyl ◽  
Pyridine Carboxylic

Structure of 3α,4α:5β,6β-Diepoxyandrostan-17-one

1983 ◽  
Vol 36 (11) ◽  
pp. 2333 ◽  
Author(s):  
B Kamenar ◽  
RA Pauptit ◽  
JM Waters
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray

The X-ray crystal structure of 3α,4α:5β,6β-diepoxyandrostan-17-one has been determined. Crystals of the title compound (C19H26O3)are monoclinic, space group P21, with a 9.208(2), b 9.620(4), c 9.312(3) �, β 99.14(2)�, V 814.5 Ǻ3 and Z 2. The structure was solved by direct methods and refined to R 0.039 for 887 observed reflexions. The 3α,4α:5β,6β configuration of the epoxide rings confirms the assignment based on proton n.m.r. studies.

3β-(4-Ethyl-3-iodophenyl)nortropane-2β- carboxylic Acid Methyl Ester as a High-Affinity Selective Ligand for the Serotonin Transporter

1997 ◽  
Vol 40 (24) ◽  
pp. 3861-3864 ◽  
Author(s):  
Bruce E. Blough ◽  
Philip Abraham ◽  
Andrew C. Mills ◽  
Anita H. Lewin ◽  
John W. Boja ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Methyl Ester ◽  
Serotonin Transporter ◽  
Acid Methyl Ester ◽  
High Affinity ◽  
Acid Methyl ◽  
Selective Ligand

Stereochemistry and Tautomerism of Amino Acid Antagonists: α,γ-Diketo Acids and Esters and their Cyclisation Products

1983 ◽  
Vol 38 (2) ◽  
pp. 220-225 ◽  
Author(s):  
W. S. Sheldrick ◽  
W. Trowitzsch
Keyword(s):  
Amino Acid ◽  
Methyl Ester ◽  
Glyoxylic Acid ◽  
Acid Methyl Ester ◽  
Acid Ethyl Ester ◽  
Enolic Form ◽  
X Ray ◽  
Acid Methyl ◽  
Acid Proton ◽  
Amino Acid Antagonists

Abstract X-ray structural analyses of two α,γ-diketo esters and one α,γ-diketo acid, which are amino acid antagonists, have shown them all to be present in the solid state in the α,β-unsaturated γ-keto enolic form. The structures of the esters β-acetyl-pyruvic acid methyl ester (1) and 2-oxo-cyclopentyl-glyoxylic acid ethyl ester (3) are stabilized by intra-molecular O···H(-O) hydrogen bonds involving the enol proton. In the case of camphor oxalic acid (4) an intramolecular O···H-O hydrogen bond between the γ-keto oxygen and the acid proton is observed. The bond lengths and angles in 1 indicate a significant contribution from the mesomeric β,γ-unsaturated enol form. For comparison purposes the structure of the γ-enol methyl ether of 1, (4-methoxy-2-oxo-pentene)carboxylic acid methyl ester (2) has also been determined. The X-ray structures of the cyclization products of respectively an α,γ-diketo acid and an α,γ-diketo ester are reported.

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