An Expansion of the Role of the Corey - Link Reaction for the Synthesis of α-Substituted Carboxylic Acid Esters

2006 ◽  
Vol 59 (7) ◽  
pp. 426 ◽  
Author(s):  
Adrian Scaffidi ◽  
Brian W. Skelton ◽  
Robert V. Stick ◽  
Allan H. White
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Single Crystal ◽  
X Ray ◽  
Structure Determinations ◽  
Acid Esters

The treatment of 1,2:5,6-di-O-isopropylidene-α-d-ribo-hexos-3-ulose with chloroform under basic conditions has yielded the normal 3-C-trichloromethyl-α-d-allofuranose derivative. Under the conditions of the modified Corey–Link reaction but with a nucleophile different from the usual azide, a range of α-substituted carboxylic acid esters (and one amide) has been obtained. A similar addition of bromoform to the ulose has formed the α-bromo methyl ester. Two attempts at forming an ‘inositol α-amino acid’ from a polyhydroxylated cyclohexanone failed. Single-crystal X-ray structure determinations are reported for (3S)-1,2:5,6-di-O-isopropylidene-3-C-methoxycarbonyl-3-S-phenyl-3-thio-α-d-ribo-hexose, (3S)-1,2:5,6-di-O-isopropylidene-3-S-phenyl-3-C-(phenylthio)carbonyl-3-thio-α-d-ribo-hexose, 3-deoxy-1,2:5,6-di-O-isopropylidene-3-C-methoxycarbonyl-α-d-erythro-hex-3-enofuranose, 4,6-di-O-benzyl-2-C-trichloromethyl-scyllo-inositol 1,3,5-orthoformate, 2,2'-anhydro-4,6-di-O-benzyl-2-C-dichlorohydroxymethyl-scyllo-inositol 1,3,5-orthoformate, 1,3,4,5,6-penta-O-benzyl-2-C-trichloromethyl-myo-inositol, and 2-amino-1,3,4,5,6-penta-O-benzyl-2-C-cyano-2-deoxy-myo-inositol.

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.

scholarly journals Potential photoacid generators based on oxime sulfonates

2019 ◽  
Vol 43 (1-2) ◽  
pp. 26-33
Author(s):  
M John Plater ◽  
William TA Harrison ◽  
Ross Killah
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystal Structure ◽  
Fragmentation Pathways ◽  
X Ray ◽  
Photoacid Generators ◽  
Structure Determinations ◽  
Secondary Reactions

The bis-oxime of acenaphthenequinone and the mono-oxime of benzil have been sulfonated by reaction with 4-methylbenzenesulfonyl chloride and propylsulfonyl chloride. The four sulfonated oximes were characterised by X-ray single-crystal structure determinations. Some photochemical decompositions were studied using a 6-W 254-nm immersion well lamp in dichloromethane. The 4-methylbenzenesulfonate bis-oxime of acenaphthenequinone and the 4-methylbenzenesulfonate mono-oxime of benzil both give 4-methylbenzenesulfonic acid upon irradiation but not 4-methylbenzenesulfinic acid. Fragmentation pathways are discussed. The possible use of these compounds as photoacid generators in polymer resists and the role of secondary reactions to liberate acid is discussed.

Pigments of Fungi. XLVIII Clavorubin from Two Australasian Toadstools of the Genus Cortinarius and the X-Ray Crystal Structure of the Methyl Ester of 6-O-Methylclavorubin

1998 ◽  
Vol 51 (5) ◽  
pp. 347 ◽  
Author(s):  
Melvyn Gill ◽  
Malcolm S. Buchanan ◽  
Peter J. Steel ◽  
Nives M. Milanovic ◽  
Somphone Phonh-Axa
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Methyl Ester ◽  
Single Crystal ◽  
Natural Product ◽  
Structure Analysis ◽  
Claviceps Purpurea ◽  
Chemical Methods ◽  
X Ray ◽  
First Time

Clavorubin (1,5,6,8-tetrahydroxy-3-methyl-9,10-dioxoanthracene-2-carboxylic acid) (1), previously known only from the ascomycetious rye fungus Claviceps purpurea (‘ergot’), has been isolated from the fruit bodies of two Australasian basidiomycetes belonging to the genus Cortinarius and characterized by spectroscopic and chemical methods. A single-crystal X-ray structure analysis of the methyl ester (4) of 6-O-methylclavorubin establishes unequivocally, for the first time, the structure of the natural product.

scholarly journals The role of silver in the crystal structure of pyrargyrite: single crystal X-ray diffraction study

2012 ◽  
pp. 161-167 ◽  
Author(s):  
F. Laufek ◽  
J. Sejkora ◽  
M. Dušek
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Study ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Modeling of magneto-conductivity of bismuth selenide: a topological insulator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Field Range ◽  
X Ray ◽  
Bulk Carriers ◽  
Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

Isolation from atelia herbert-smithii pittier (sophoreae, leguminosae) and x-ray structure of cis-1-amino-3-hydroxymethyl-cyclobutane-1-carboxylic acid, an achiral non-protein amino acid

Tetrahedron ◽  
1987 ◽  
Vol 43 (8) ◽  
pp. 1857-1861 ◽  
Author(s):  
Geoffrey N. Austin ◽  
Peter D. Baird ◽  
Hak-Fun Chow ◽  
L.E. Fellows ◽  
G.W.J. Fleet ◽  
...  
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Protein Amino Acid ◽  
X Ray

Comparative Structural Studies on Three-Coordinate Copper(I) Halide Complexes With Tertiary Phosphines. Crystal Structures of [(PPh2Mes)CuX]2 and [(PPhMes2)CuX]2 (Mes = Mesityl X = Cl, Br, I)

1992 ◽  
Vol 45 (7) ◽  
pp. 1155 ◽  
Author(s):  
GA Bowmaker ◽  
D Camp ◽  
RD Hart ◽  
PC Healy ◽  
BW Skelton ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Copper Atom ◽  
Structural Studies ◽  
Coordination Environment ◽  
X Ray ◽  
Tertiary Phosphines ◽  
Structure Determinations ◽  
Halide Complexes ◽  
The Subject

The 1 : 1 complexes of the substituted triphenylphosphine ligands mesityldiphenylphosphine and dimesitylphenylphosphine with copper(1) chloride, bromide and iodide have been the subject of single-crystal X-ray structure determinations at 295 K. All six complexes crystallize as air-stable dimeric molecules, [(PPh2Mes)CuX]2 and [ (PPhMes2)CUX]2 with each copper atom in a distorted trigonal PCuX2. coordination environment. Crystals of [(PPh2Mes)CuCl]2 (1) are monoclinic, P21/n, a 9.961(3), b 18.687(6), c 11.009(7) Ǻ, β 114.63(4)°; R was 0.049 for 2450 'observed' reflections. [(PPh2Mes)CuBrI2 (2) is monoclinic, P21/n, a 9.939(2), b 18.832(6), c 11.238(6) Ǻ, β 115.36(3)°; R was 0.046 for 1803 'observed' reflections. [(PPh2Mes)CuI]2.4/3 C6H6 (3) is rhornbohedral, R3, a 36.877(8), c 9.047(5) A; R was 0.039 for 2537 'observed' reflections. Crystals of [(PPhMes2)CuCl]2.2MeCN (4) are triclinic, Pi, a 15.783(7), b 9.570(4), c 8.914(4) Ǻ, α 72.43(3), β 76.37(3), γ 74.03(3)°; R was 0.045 for 3341 'observed' reflections. [(PPhMes2)CuBr]2.3C6H6 (5) is monoclinic, C2/c, a 9.694(6), b 30.15(2), c 20.66(2) Ǻ, β 98.00(7)°; R was 0.047 for 2117 'observed' reflections. [(PPhMes2)CuI]2.2MeCN (6) is orthorhombic, PP1nb, a 11.694(8), b 14.77(1), c 29.76(3) Ǻ; R was 0.049 for 3447 'observed' reflections. Cu-P bond lengths are: 2.196(2) A (1); 2.198(3) Ǻ (2); 2.222(5) and 2.226(5) Ǻ (3); 2.202(1) Ǻ (4); 2.197(3) A (5); 2.201(4) and 2.264(5) Ǻ (6). The geometries of the LCuX2 and CuX2Cu units are compared with data reported for other monomeric and dimeric compounds for both phosphorus- and nitrogen-based ligands L.

Approaches to the Synthesis of Lincosamine, a Derived Portion of the Antibiotic Lincomycin

1990 ◽  
Vol 43 (10) ◽  
pp. 1657 ◽  
Author(s):  
LM Engelhardt ◽  
BW Skelton ◽  
RV Stick ◽  
DMG Tilbrook ◽  
AH White
Keyword(s):  
Nitrogen Atom ◽  
Single Crystal ◽  
Structure Elucidation ◽  
X Ray ◽  
Structure Determinations

A variety of approaches towards the synthesis of lincosamine, a derived portion of the antibiotic lincomycin , are reported. Initial approaches involved the intramolecular delivery of a nitrogen atom ( trichloroacetimidate , trichloroacetylcarbamate , carbamate, 2-amino-2- phenylacetate ) attached to O4 onto C6 of a 6,7-anhydrooctoside. Later approaches, albeit more direct but again largely unsuccessful, involved the Sharpless titanium(IV)-mediated nucleophilic opening of a suitable 6,7-anhydrooctose, and the Sharpless oxyamination and the aziridination of suitable octenoses . As an aid to the structure elucidation of several compounds encountered in this work, single-crystal X-ray structure determinations are reported for methyl 6,7-anhydro-2,3-di-O-benzyl-8-deoxy-α-D-threo-D-galacto-octopyranoside , methyl 6,7-anhydro-2,3-di-O-benzyl-8-deoxy-α-D-threo-D-gluco-octopyranoside and 7-azido-7-deoxy-1,2:3,4-di-O-isopropylidene-β-L-erythro-Dgalacto-octose.

Sign in / Sign up

Export Citation Format

Share Document