scholarly journals Sulfuric acid and Amberlyst-H+ catalyzed condensation reactions of renewable keto acids with paraformaldehyde: synthesis of a new dispiro bis-lactone ring system 2,9,13-trioxadispiro[4.1.4.3]tetradecane-3,6,10-trione

RSC Advances ◽  
2017 ◽  
Vol 7 (39) ◽  
pp. 23917-23923 ◽  
Author(s):  
Ananda S. Amarasekara ◽  
Uyen Ha ◽  
Marina S. Fonari ◽  
Shabari Nath Bejagam ◽  
Davor Margetić
Keyword(s):  
Sulfuric Acid ◽  
Levulinic Acid ◽  
Lactone Ring ◽  
Ring System ◽  
X Ray ◽  
X Ray Crystallography ◽  
Condensation Reactions ◽  
Keto Acids ◽  
Acid Catalyzed

The acid catalyzed condensation of levulinic acid with paraformaldehyde at 80 °C gives 2,9,11,14-tetraoxadispiro[4.1.5.3]pentadecane-3,6-dione, in which the structure was confirmed by X-ray crystallography.

Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

Experimental and Kinetic Modeling Studies on the Sulfuric Acid Catalyzed Conversion of d-Fructose to 5-Hydroxymethylfurfural and Levulinic Acid in Water

2015 ◽  
Vol 3 (12) ◽  
pp. 3024-3034 ◽  
Author(s):  
Boy A. Fachri ◽  
Ria M. Abdilla ◽  
Henk H. van de Bovenkamp ◽  
Carolus B. Rasrendra ◽  
Hero J. Heeres
Keyword(s):  
Sulfuric Acid ◽  
Kinetic Modeling ◽  
Levulinic Acid ◽  
Modeling Studies ◽  
Acid Catalyzed

scholarly journals X-Ray crystallography and the chemistry of the steroids. Part I

1940 ◽  
Vol 239 (802) ◽  
pp. 135-182 ◽  
Keyword(s):  
Crystal Morphology ◽  
Ring System ◽  
Higher Plant ◽  
X Ray ◽  
X Ray Crystallography ◽  
Unit Cell Size ◽  
Molecular Arrangement ◽  
Preliminary Examination ◽  
Optic Orientation ◽  
Shape And Size

A survey has been made of the X-ray crystallography of some eighty sterol derivatives belonging mainly to the cholesterol and ergosterol series but including also calciferol and other photoderivatives of ergosterol and some higher plant and animal sterols. The measurements are recorded in four tables and include determinations of unit cell size, space group and some data on the crystal morphology and optics. In three cases, cholesteryl chloride, bromide and cholesteryl chloride hydrochloride, Patterson projections have also been derived from the intensities of the X-ray reflexions of the hOl planes. These confirm earlier deductions on the shape and size of the sterol molecules, proving that these are roughly lath-shaped, 20 x 7 x 4 A, and the details of the patterns can also to some degree be correlated with the actual arrangement of the carbon atoms in the sterol ring system and with the positions of the chlorine and bromine atoms. The arrangement of the molecules in the crystal units is closely that given by the preliminary examination from the optic orientation, and this has therefore been employed to suggest in each of the remaining sterol crystal structures the probable molecular arrangement

scholarly journals Synthesis of spiroannulated and 3-arylated 1,2,4-trioxanes from mesitylol and methyl 4-hydroxytiglate by photooxygenation and peroxyacetalization

2010 ◽  
Vol 6 ◽  
Author(s):  
Axel G Griesbeck ◽  
Lars-Oliver Höinck ◽  
Jörg M Neudörfl
Keyword(s):  
Singlet Oxygen ◽  
Lewis Acid ◽  
Allylic Alcohols ◽  
Ene Reaction ◽  
X Ray ◽  
X Ray Crystallography ◽  
Homoallylic Alcohols ◽  
Acid Catalyzed ◽  
Benzaldehyde Derivatives

Cycloalkanones were utilized in the Lewis acid catalyzed peroxyacetalization of ß-hydroperoxy homoallylic alcohols (prepared by the ene reaction of the allylic alcohols mesitylol and methyl 4-hydroxytiglate, respectively, with singlet oxygen) to give spiroannulated 1,2,4-trioxanes 5a–5e and 9a–9e, respectively. A second series of 3-arylated trioxanes 10a–10h, that are available from the hydroperoxy alcohol 4 and benzaldehyde derivatives, was investigated by X-ray crystallography.

Addition reactions of a dialkyl- and a diarylsilylene to cyanides RCN: Different pathways? (1)

2000 ◽  
Vol 78 (11) ◽  
pp. 1469-1473 ◽  
Author(s):  
Manfred Weidenbruch ◽  
Frank Meiners ◽  
Wolfgang Saak
Keyword(s):  
Triple Bond ◽  
Ring System ◽  
Addition Reactions ◽  
X Ray ◽  
X Ray Crystallography

Di-tert-butylsilylene, generated by photolysis of hexa-tert-butylcyclotrisilane, reacts with the triple bond of adamantane-1-carbonitrile to furnish the 1,3-diaza-2,5-disilacyclohexa-3,6-diene 5. However, treatment of 2,2-dimethylpropanenitrile with dimesitylsilylene affords the azadisilacyclobutene ring system 6. The structures of 5 and 6 were determined by X-ray crystallography.Key words: silicon, silylene, silaheterocycles, X-ray crystallography.

The Chemistry of Ethyl 2-Ethoxycarbonyl-5,5-Diphenylpenta-2,3,4-Trienoate, a Potential Precursor of Ph2c=C=C=C=C=O

1987 ◽  
Vol 40 (10) ◽  
pp. 1675 ◽  
Author(s):  
NR Browne ◽  
RFC Brown ◽  
FW Eastwood ◽  
GD Fallon
Keyword(s):  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Wittig Reaction ◽  
Cyclization Reactions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Concentrated Sulfuric Acid ◽  
Triphenylphosphonium Bromide ◽  
Hydrolysis Of ◽  
Potential Precursor

The title diester , Ph2C=C=C=C( COOEt )2 (2), has been prepared by a Wittig reaction between (2-bromo-3,3-diphenylprop-2-en-1-yl) triphenylphosphonium bromide and diethyl 2-oxopropane-1,3-dioate ( mesoxalic ester). The diester (2) undergoes cyclization reactions in concentrated sulfuric acid to give diethyl 2-(3'-phenyl-1H-inden-1'-y1idene)propane-l,3-dioate (4) and triethyl 3-oxo-3',9-diphenyl-2,3-dihydrospiro[lH-fluorene-1,l'-[1H]indene]-2,2,4-tricarboxylate (6), the structure of which was determined by X-ray crystallography. The title diester (2)adds cyclopentadiene across the 2,3-C=C bond to give diethyl 3-(2',2'-diphenylethenylidene)bicyclo[2.2.l]hept-5-ene-2,2-dicarboxylate (10). Alkaline hydrolysis of diester (10) gives an unstable colourless acid and a stable yellow crypto acid shown by X-ray crystallography to be 3-(2',2'-diphenylethenyl)bicyclo[2.2.l]hepta-2,5-diene-2-carboxylic acid (12). Attempts to convert diesters (2) and acid (12) into derivatives suitable for pyrolytic generation of Ph2C=C=C=C=C=O failed; The mono-acid chloride (14) yielded a small phenylazulene fraction on pyrolysis at 780-800°/0.02 mm.

The synthesis, separation, and crystal and molecular structures of the three bisphenols, an ethanol solvate of one of them, and of a minor by-product, 6,6′,7,7′-tetrachloro-8,8′-methylenebis(4H-benzo-1,3-dioxin), prepared by condensation of formaldehyde with 3,4-dichlorophenol

1989 ◽  
Vol 67 (5) ◽  
pp. 779-785 ◽  
Author(s):  
George Ferguson ◽  
Robert McCrindle ◽  
Alan James McAlees
Keyword(s):  
Molecular Structures ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ethanol Solvate ◽  
Crystallographic Symmetry ◽  
Molar Equivalent ◽  
Acid Catalyzed ◽  
A Minor ◽  
Hydrogen Bonded

Samples of all three of the expected bisphenols, 4,4′,5,5′-tetrachloro-2,2′-methylenebisphenol (1) and the 3,4,4′,5′-(2) and 3,3′,4,4′-tetrachloro (3) isomers, and of a minor by-product, 5,5′,6,6′-tetrachloro-8,8′-methylenebis(4H-benzo-1,3-dioxin) (4), have been isolated from the mixture formed by acid-catalyzed condensation of 3,4-dichlorophenol with one half of a molar equivalent of formaldehyde. In addition, the structures and solid state conformations of all four compounds, and of an ethanol solvate of 1, have been revealed by X-ray crystallographic studies. The three bisphenols (1, 2, 3) all crystallize in space group [Formula: see text], as centrosymmetric hydrogen-bonded dimers, while the solvate, 1•EtOH, although it also belongs to space group [Formula: see text], forms relatively open infinite bands of hydrogen-bonded molecules. Crystals of 4 belong to space group Fdd2 and the molecules have twofold crystallographic symmetry. Keywords: X-ray crystallography, bisphenols, tetrachloro-2,2′-methylenebisphenols, tetrachloro-8,8′-methylenebis(4H-benzo-1,3-dioxin).

Nucleic Acid Related Compounds. 136. Synthesis of 2-Amino- and 2,6-Diaminopurine Derivatives via Inverse-Electron-Demand Diels-Alder Reactions

2006 ◽  
Vol 71 (7) ◽  
pp. 1029-1041 ◽  
Author(s):  
Xiaoyu Lin ◽  
Morris J. Robins
Keyword(s):  
Nucleic Acid ◽  
Diels Alder ◽  
Curtius Rearrangement ◽  
X Ray ◽  
Inverse Electron Demand ◽  
X Ray Crystallography ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Related Compounds ◽  
Electron Demand

Thermal inverse-electron-demand Diels-Alder reactions of 5-aminoimidazoles and 2,4,6-tris(ethoxycarbonyl)-1,3,5-triazine (2) with spontaneous retro-Diels-Alder loss of ethyl cyanoformate and elimination of ammonia give 2,6-bis(ethoxycarbonyl)purines. A report that selective alkaline hydrolysis followed by acid-catalyzed decarboxylation gave 6-(ethoxycarbonyl)purine products was not in harmony with known reactions in purine chemistry. Our reinvestigation has shown that the 6-(ethoxycarbonyl) group undergoes preferential base-promoted hydrolysis, as expected, but regioselectivity for attack of hydroxide at the carbonyl group at C6 is not high (relative to hydrolysis of both C2 and C6 esters). The structure of 9-benzyl-2-(ethoxycarbonyl)purine was determined by X-ray crystallography and confirmed by Curtius rearrangement of the azidocarbonyl analogue to give 2-amino-6-benzylpurine. Acid-catalyzed decarboxylation of the 2,6-dicarboxylate formed during hydrolysis gave 9-benzylpurine, and Curtius rearrangement of 2,6-bis(azidocarbonyl)-9-benzylpurine gave 2,6-diamino-9-benzylpurine. Attempted applications of inverse-electron-demand Diels-Alder reactions of 2 with nucleoside derivatives were problematic.

scholarly journals Tele-Substitution Reactions in the Synthesis of a Promising Class of Antimalarials

2020 ◽  
Author(s):  
Marat Korsik ◽  
Edwin Tse ◽  
David Smith ◽  
William Lewis ◽  
Peter J. Rutledge ◽  
...  
Keyword(s):  
Heterocyclic Ring ◽  
Ring System ◽  
Substitution Reactions ◽  
Laboratory Notebook ◽  
Polar Solvents ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Core ◽  
Nmr Data

<p></p><p>We have discovered and studied a <i>tele</i>substitution reaction in a biologically important heterocyclic ring system. Conditions that favour the <i>tele</i>-substitution pathway were identified: the use of increased equivalents of the nucleophile or decreased equivalents of base, or the use of softer nucleophiles, less polar solvents and larger halogens on the electrophile. Using results from X-ray crystallography and isotope labelling experiments a mechanism for this unusual transformation is proposed. We focused on this triazolopyrazine as it is the core structure of the <i>in vivo </i>active anti-plasmodium compounds of Series 4 of the Open Source Malaria consortium.</p> <p> </p> <p>Archive of the electronic laboratory notebook with the description of all conducted experiments and raw NMR data could be accessed via following link <a href="https://ses.library.usyd.edu.au/handle/2123/21890">https://ses.library.usyd.edu.au/handle/2123/21890</a> . For navigation between entries of laboratory notebook please use file "Strings for compounds in the article.pdf" that works as a reference between article codes and notebook codes, also this file contain SMILES for these compounds. </p><br><p></p>

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