Peptide coupling reactions of the mycotoxin sporidesmin: synthesis of sporidesmin hemisuccinates, x-ray crystal structure of sporidesmin A 11-hemisuccinate, and its coupling with Na-t-Boc-L-lysine methyl ester

1992 ◽  
Vol 40 (4) ◽  
pp. 701-706 ◽  
Author(s):  
Rex T. Gallagher ◽  
Stephen J. Eichler ◽  
Patrick T. Holland ◽  
Alistair L. Wilkins ◽  
Brian K. Nicholson
Keyword(s):  
Crystal Structure ◽  
Methyl Ester ◽  
Coupling Reactions ◽  
Peptide Coupling ◽  
X Ray

scholarly journals Preparation of pyridine-3,4-diols, their crystal packing and their use as precursors for palladium-catalyzed cross-coupling reactions

2010 ◽  
Vol 6 ◽  
Author(s):  
Tilman Lechel ◽  
Irene Brüdgam ◽  
Hans-Ulrich Reissig
Keyword(s):  
Crystal Structure ◽  
Crystal Packing ◽  
Cross Coupling ◽  
Crystal Structure Analysis ◽  
Coupling Reactions ◽  
X Ray ◽  
Cross Coupling Reactions ◽  
Fluorescence Measurements ◽  
Subsequent Conversion ◽  
Palladium Catalyzed

A series of trifluoromethyl-substituted 3-alkoxypyridinol derivatives has been deprotected to furnish pyridine-3,4-diol derivatives in good yields. The X-ray crystal structure analysis proved that a 1:1 mixture of pyridine-3,4-diols and their pyridin-4-one tautomers exist in the solid state. Subsequent conversion into bis(perfluoroalkanesulfonate)s were smoothly achieved. The obtained compounds were used as substrates for palladium-catalyzed coupling reactions. Fluorescence measurements of the biscoupled products showed a maximum of emission in the violet region of the spectrum.

Crystal-to-Crystal Diastereoselective Transformation of 2,4,6-Triisopropyl-4'-(S)-phenylalaninocarbonylbenzophenone Methyl Ester

1998 ◽  
Vol 54 (6) ◽  
pp. 907-911 ◽  
Author(s):  
H. Hosomi ◽  
Y. Ito ◽  
S. Ohba
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Methyl Ester ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
Pass Filter ◽  
X Ray ◽  
Ultra High Pressure ◽  
Phenylalanine Methyl Ester

Dissymmetry of the photoproduct was induced by using a chiral substituent, (S)-methylphenylalanine, in the title compound {N-4-(2,4,6-triisopropylbenzoyl)benzoyl]-(S)-phenylalanine methyl ester (I)}. On irradiation with light from a 250 W ultra-high-pressure Hg lamp for 7 h through a long-pass filter, the photoreaction in a crystal was 100% complete without the loss of crystallinity. The crystal structures (I), before, and (II) {N-[4-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoyl]-(S)-phenylalanine methyl ester}, after photocyclization, have been determined by X-ray diffraction. For comparison, a crystal structure analysis has also been carried out for the photoproduct (III) of the 3′-COOMe derivative after recrystallization {methyl 3-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoate}. The dihedral angle between the central carbonyl plane and the triisopropylphenyl ring deviates from 90° by 10 (1)° in (I), which makes an imbalance in the intramolecular O(carbonyl)...H(methine) distances of the isopropyl groups at positions 2 and 6. The crystal structure of (II) indicates that the nearer methine H was predominantly abstracted by the carbonyl O atom in the reaction. The absolute configuration around the asymmetric C atom in the cyclobutenol ring of the product is S.

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.

Geminal bis(hypersilyl) compounds — the synthesis and structure of bis[tris(trimethylsilyl)silyl]silanes

2000 ◽  
Vol 78 (11) ◽  
pp. 1399-1404
Author(s):  
Thoralf Gross ◽  
Helmut Reinke ◽  
Hartmut Oehme
Keyword(s):  
Crystal Structure ◽  
Key Words ◽  
Trifluoromethanesulfonic Acid ◽  
Molar Ratio ◽  
Coupling Reactions ◽  
Subsequent Reaction ◽  
X Ray ◽  
A Value ◽  
Spatial Demand

Protodesilylation of diphenylsilane with trifluoromethanesulfonic acid and subsequent reaction of the obtained bis(trifluoromethanesulfonyloxy)silane with tris(trimethylsilyl)silyllithium (1) (molar ratio 1:2) afforded bis[tris(trimethylsilyl)silyl]silane (8). Methyl-bis[tris(trimethylsilyl)silyl]silane (3) and phenyl-bis[tris(trimethylsilyl)silyl]silane (10) were obtained by coupling reactions of 1 with MeHSiCl2 or PhHSiCl2, respectively, (2:1). By treatment with HCBr3, the H-silanes 3, 8, and10 were converted into the bromosilanes [(Me3Si)3Si]2SiR1R2 (9: R1 = R2 = Br; 11: R1 = Me, R2 = Br; 12: R1 = Ph, R2 = Br). X-ray crystal structure analyses, performed for 3, 10 and 12, confirmed the expected distortions of the molecular skeletons of the compounds. Thus, e.g., in 10, the spatial demand of the two extended hemispherical hypersilyl groups forces a widening of the Si-Si-Si angle at the central Si atom to a value of 128.3°.Key words: silanes, sterically congested, bis(hypersilyl)silanes, hypersilylsilanes, bis(hypersilyl)germanes, tris(trimethylsilyl)silylsilanes.

ChemInform Abstract: Pigments of Fungi. Part 48. Clavorubin (Ia) from Two Australasian Toadstools of the Genus Cortinarius and the X-Ray Crystal Structure of the Methyl Ester of 6-O-Methylclavorubin (Ib).

ChemInform ◽  
2010 ◽  
Vol 29 (36) ◽  
pp. no-no
Author(s):  
M. S. BUCHANAN ◽  
M. GILL ◽  
N. M. MILANOVIC ◽  
S. PHONH-AXA ◽  
P. J. STEEL
Keyword(s):  
Crystal Structure ◽  
Methyl Ester ◽  
X Ray

The Structure of Polyisoprenes. IV. Double-Bond Interaction in Certain Carbalkoxy-Substituted 1,5-Dienes

1946 ◽  
Vol 19 (1) ◽  
pp. 14-22
Author(s):  
L. Bateman ◽  
G. A. Jeffrey
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Methyl Ester ◽  
X Ray ◽  
Bond Interaction ◽  
Carbon Framework ◽  
New Interpretation ◽  
Related Compounds ◽  
Ray Methods ◽  
Crystallization From Solution

Abstract A peculiar lack of olefinic reactivity, combined with a facility for cyclization of methyl and ethyl Δ1,5-hexadiene-1, 1, 3, 3, 4, 4, 6, 6-octacarboxylates, has been attributed by Ingold, Parekh, and Shoppee to ring-chain mesomerism. A reinvestigation of these and related compounds has now been made by using x-ray methods, and it is shown that the crystal structure of the methyl ester is incompatible with the cis-configuration required for such interspatial double-bond saturation. A radical disruption of a mesomeric system by crystallization from solution is improbable and, an earlier formulation incorporating a bicyclobutane nucleus being rejected on chemical grounds, it is necessary to seek a new interpretation of the anomalous reactivity. We suggest that the determinative condition is hyperconjugation throughout the carbon framework of the molecule, and discuss this in relation to 1,5-dienes generally.

Synthesis and Characterization of Rhenium(V) Oxo Complexes withN-[N-(3-Diphenylphosphinopropionyl)glycyl]cysteine Methyl Ester. X-ray Crystal Structure of {ReO[Ph2P(CH2)2C(O)-Gly-Cys-OMe(P,N,N,S)]}

2003 ◽  
Vol 42 (4) ◽  
pp. 950-959 ◽  
Author(s):  
Roberta Visentin ◽  
Raffaella Rossin ◽  
Maria Cecilia Giron ◽  
Alessandro Dolmella ◽  
Giuliano Bandoli ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Methyl Ester ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Oxo Complexes

The Minor Iridoid Glucosides of Barleria lupulina: Isolation, Crystal Structure and Plant Growth-Inhibiting Properties of 6-O-Acetylshanzhiside Methyl Ester

1987 ◽  
Vol 40 (5) ◽  
pp. 785 ◽  
Author(s):  
LT Byrne ◽  
JM Sasse ◽  
BW Skelton ◽  
A Suksamrarn ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Methyl Ester ◽  
Plant Growth ◽  
Structure Determination ◽  
Chemical Methods ◽  
X Ray ◽  
Aerial Parts ◽  
Iridoid Glucosides ◽  
Wheat Embryos ◽  
Growth Inhibiting

The minor iridoid glucosides present in the aerial parts of Barleria lupulina Lindl. ( Acanthaceae ) have been identified as ipolamiidoside (7) and the new compound 6-O-acetylshanzhiside methyl ester (3). The structure of (3) was determined by spectroscopic and chemical methods, and was confirmed by a single-crystal X-ray structure determination. Crystals of (3) are orthorhombic P212121, a 43.75(1), b 8.151(3), c 5.695(2) �, Z 4. The crystal structure was determined at 295 K from diffractometer data [I528 reflections with I > 3σ(I)] and refined to a residual of 0.043. Shanzhiside methyl ester (1) and its 6-Oacetyl (3), 8-Oacetyl (2) and 6,8-O,O-diacetyl (4) derivatives, all of which occur in Barleria lupulina, have been found to inhibit the growth of wheat embryos.

scholarly journals Synthetic Studies on Potent Marine Drugs: Synthesis and the Crystal Structure of 6-tert-butyl-4-phenyl-4H-chromene-2-carboxylic Acid

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Hui-Jing Li ◽  
Jun-Li Wang ◽  
Rui Wang ◽  
Dong-Hui Luo ◽  
Yan-Chao Wu
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Crystallographic Analysis ◽  
Antitumor Antibiotic ◽  
Stacking Interactions ◽  
X Ray ◽  
Structural Activity Relationship ◽  
Derivatives Of

4H-Chromene-2-carboxylic acid ester derivatives of renieramycin M might be of use for the structural-activity relationship studies of antitumor antibiotic tetrahydroisoquinoline natural products. Accordingly, 6-tert-butyl-4-phenyl-4H-chromene-2-carboxylic acid, one key intermediate, was synthesized via the condensation of (3E)-2-oxo-4-phenylbut-3-enoate methyl ester with 4-tert-butylphenol in the presence of AuCl3/3AgOTf (5 mol%), followed by cyclodehydration and aqueous hydrolysis. The product was unambiguously shown to the 4H-chromene-2-carboxylic acid by spectroscopy and X-ray crystallographic analysis. A packing diagram of the crystal structure shows that aromaticπ-stacking interactions and O–H⋯O hydrogen bond stabilize the structure in the solid.

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