scholarly journals The first spontaneous resolution of a sulfoxide: Dianin's compound analogue, (R)-4-(4-hydroxyphenyl)-2,2,4-trimethylthiachroman-1-oxide

2018 ◽  
Vol 74 (11) ◽  
pp. 1633-1636
Author(s):  
James H. Gall ◽  
J. Derek White ◽  
David D. MacNicol ◽  
Christopher S. Frampton
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Glacial Acetic Acid ◽  
Crystal Structure Analysis ◽  
Spontaneous Resolution ◽  
Orthorhombic Space Group ◽  
Aromatic Substituent ◽  
Methyl Group ◽  
Dianin's Compound ◽  
Initial Crystal

The title sulfoxide, C18H20O2S, was prepared by controlled oxidation of thia-Dianin's compound using hydrogen peroxide in glacial acetic acid. On recrystallization from glacial acetic acid, it was found to form unsolvated, spontaneously resolved crystals, the initial crystal structure analysis revealing the presence of both sulfoxide epimers in the crystal. On multiple recrystallization a single epimer was observed, with crystallization occurring in the unchanged orthorhombic space group P212121, with Z′ = 1. The molecule possesses a distal conformation, referring to the juxtaposition of the p-hydoxyphenyl substituent with respect to its syn-related methyl group, with the sulfoxide oxygen atom anti to the aromatic substituent. The molecular packing features O—H...O hydrogen bond chains running parallel to the b axis of the unit cell.

Isomerizations akin to the Dimroth rearrangement. IV. Formation of simple s-Triazolo[1,5-c]pyrimidines via their [4,3-c] isomers

1978 ◽  
Vol 31 (11) ◽  
pp. 2505 ◽  
Author(s):  
DJ Brown ◽  
T Nagamatsu
Keyword(s):  
Acetic Acid ◽  
Glacial Acetic Acid ◽  
Methyl Groups ◽  
Dimroth Rearrangement ◽  
Methyl Group ◽  
Alkyl Groups ◽  
Ring Fission

Pyrimidin-4-ylhydrazines and simple orthoesters are used in combination (1) to give N-ethoxyalkyl-idene-N'-pyrimidinylhydrazines (2) and thence s-triazolo[4,3-c]pyrimidine (3a) and its 3-, 5-, 7- or 8-alkylated derivatives (3b-s). In glacial acetic acid, these undergo rearrangement into the corresponding s-triazolo[1,5-c]pyrimidines (5) via the acylaminoalkenyltriazoles (4); in aqueous buffers, these reactions stop at the triazoles (4) except in the presence of a 7-methyl group which stimulates completion of the sequence. The ring-fission step, (3) → (4), is retarded markedly by 5- and/or 8-methyl groups but accelerated slightly by 3- and/or 7-alkyl groups; the slower ring-fission of triazolo[1,5-c]-pyrimidines (5) to the same triazoles (4) is retarded by 2-, 5- or 8-alkylation and precluded totally by a 7-methyl group. The recorded u.v. and N.M.R. spectra afford a ready means of distinguishing between the systems (3)-(5).

Condensation of Schiff bases with 2-oxazolin-5-ones: simultaneous introduction of arylidene and amino moieties

1982 ◽  
Vol 60 (3) ◽  
pp. 317-322 ◽  
Author(s):  
Arya K. Mukerjee ◽  
Pradeep Kumar
Keyword(s):  
Acetic Acid ◽  
Schiff Bases ◽  
Sodium Acetate ◽  
Glacial Acetic Acid ◽  
Methyl Group

Schiff bases condense with 2-oxazolin-5-ones having a C-4 methylene and/or C-2 methyl group, and the reaction in glacial acetic acid, containing freshly fused sodium acetate, produces 4-arylidene- and/or 2-styryl-2-imidazoline-5-ones as a result of simultaneous introduction of arylidene and amino moieties.

(Se,O)-Koordinierte Komplexe niedervalenter Hauptgruppenmetalle: Die Kristallstruktur von Bis(N,N-Diethyl-N′-benzoylselenoureato)blei(II) / (S e,O)-Coordinated Complexes of Subvalent Main Group Metals: The Crystal Structure of Bis(N ,N -diethyl-N′-benzoylselenoureato)lead(II)

1994 ◽  
Vol 49 (12) ◽  
pp. 1615-1619 ◽  
Author(s):  
M. Schuster ◽  
W. Bensch
Keyword(s):  
Crystal Structure ◽  
Lone Pair ◽  
Polar Axis ◽  
Crystal Structure Analysis ◽  
Equatorial Position ◽  
Orthorhombic Space Group ◽  
Cell Parameters ◽  
Main Group Metals ◽  
Single Crystal Structure Analysis ◽  
Neighboring Molecule

Bis(N,N-diethyl-N′-benzoylselenoureato)lead(II) has been prepared and characterized by single-crystal structure analysis. Pb(C12H15N2OSe)2 crystallizes in the non-centrosymmetric orthorhombic space group Iba2. The cell parameters are a = 13.206(3), b = 20.542(4), c = 10.089(2) A and Z = 4. R = 0.025. The direction of the polar axis was determined unambig­ uously. Pb(II) is bidentally coordinated to two N,N-diethyl-N′-benzoylselenourea molecules. The coordination polyhedron is a distorted pseudo-trigonal bi-pyramid with one equatorial position occupied by an electron lone-pair. The Pb-Se and Pb-O bond lengths are 2.876(1) and 2.444(4) Å, respectively. In the crystal lattice, each Pb atom also shows interactions with two Se atoms of a neighboring molecule. The Pb-Se distance of that interaction is 3.643 Å.

The crystal and molecular structure of bis(2,3-butanedione dioximato)chloro-(hydroxodiphenylarsine)cobalt(III): assignment of the nature of the arsenic-based ligand

1984 ◽  
Vol 62 (2) ◽  
pp. 285-288 ◽  
Author(s):  
Monica Pizzey ◽  
Lynn Mihichuk ◽  
Richard J. Barton ◽  
Beverly E. Robertson
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares Method ◽  
Crystal And Molecular Structure ◽  
Crystal Structure Analysis ◽  
Arsenic Compound ◽  
Single Bond ◽  
Orthorhombic Space Group ◽  
Cl Atom

The Co(II) cobaloximes, (B)Co(dmgH)2 (where B = phosphine or phosphite; dmgH = dimethylglyoximato monoanion) react with (C6H5)2AsCl to form ClCo(dmgH)2B and a compound of formula C20H25AsClCoN4O5. A crystal structure analysis of the arsenic compound indicated it to be bis(2,3-butanedione dioximato)chloro(diphenylhydroxoarsine)cobalt(III), [(C6H5)2As(OH)Co(dmgH)2Cl]. The crystals are orthorhombic, space group Pna21, a = 15.334(2), b = 11.173(2), c = 13.745(4) Å at 19(2) °C with Z = 4. The structure has been refined by the least-squares method to a weighted residual of 0.071 using 2345 independent reflections. The Co atom is bonded equatorially to two dmgH ligands (average [Co—N] = 1.89(1) Å) with a Cl atom above this plane ([Co—Cl] = 2.252(2) Å) and the As atom of the (C6H5)2As(OH) group below it ([Co—As] = 2.322(1) Å). The [As—O] bond length is 1.781(7) Å, corresponding to a single bond and is consistent with the observed H atom on the oxygen atom.

The chlorination of some 2,6-substituted 4-chlorophenols; X-ray crystal structure of (E)-(2RS,5RS)-2,4,5,6,6-Pentachloro-2-methyl-6-nitrohex-3-enoic acid

1984 ◽  
Vol 37 (9) ◽  
pp. 1963 ◽  
Author(s):  
MP Hartshorn ◽  
RJ Martyn ◽  
J Vaughan
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Hydrochloric Acid ◽  
Carboxylic Acids ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Enoic Acid ◽  
X Ray

Chlorination of 4-chloro-2-methyl-6-nitrophenol (4) with chlorine in acetic acid containing concentrated hydrochloric acid gives the epimeric acyclic carboxylic acids (6) and (7). The structure of compound (6) was determined by X-ray crystal structure analysis. No such acyclic compounds are formed in similar chlorinations of 2,4-dichloro-6-nitrophenol (13a) or 2,4-dichloro-6-methylphenol (13b). The mode of formation of compounds (6) and (7) is discussed.

Synthesis, characterization and biological activity of Pyrazoline derivatives

2021 ◽  
pp. 6223-6227
Author(s):  
Saras Kumar Jain ◽  
Rohit Singhal ◽  
Neetesh K. Jain
Keyword(s):  
Crystal Structure ◽  
Antimicrobial Activity ◽  
Antibacterial Activity ◽  
Acetic Acid ◽  
Biological Activity ◽  
Spectroscopic Data ◽  
Glacial Acetic Acid ◽  
Retardation Factor ◽  
Physical Parameters ◽  
Pyrazoline Derivative

Pyrazoline is dihydropyrazole having only one endocyclic double bond. Synthesis of pyrazoline derivatives from chalcones is an active arena of investigation due to established pharmacological result. In present study, chalcones were prepared by reacting of acetophenone with benzaldehyde. Then prepared chalcones react with isoniazid in the presence of glacial acetic acid results pyrazoline derivative. Physical parameters such as color, crystal structure, solubility, melting point, retardation factor (Rf) and % yield was evaluated. Confirmations of structures of all synthesized derivatives, were done by spectroscopic data of IR, 1HNMR and Mass spectroscopy. Also, all synthesized compounds were evaluated for antibacterial activity against B. subtilis, S. aureus, P.aeruginosa and E.coli, and antifungal activity was accomplished against C. albicans and A. niger at the different conc. and concluded that some compounds have excellent antimicrobial activity and most of the synthesized compounds exhibits moderate antimicrobial activity.

The Chlorination of Some Substituted 2,4-Dimethylphenols

1994 ◽  
Vol 47 (2) ◽  
pp. 289 ◽  
Author(s):  
JLM Gordon ◽  
MP Hartshorn ◽  
RJ Martyn ◽  
AJ Morgan ◽  
WT Robinson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Carbon Tetrachloride ◽  
Acetic Anhydride ◽  
Methyl Group ◽  
X Ray

Chlorination reactions of 2-chloro-3,4,6-trimethylphenol (4), 2-chloro-4,6-dimethylphenol (5) and 3-chloro-2,4,6-trimethylphenol (6) are described. In acetic acid or acetic anhydride solution, chlorinations yield predominantly the corresponding 4-chlorocyclohexa-2,5-dienones (8), (17a) and (29), but in carbon tetrachloride containing pyridine products are formed which result from the modification of the 4-methyl group in each substrate. X-Ray crystal structure analyses are reported for compounds (7), (14), (28) and (31).

Investigation of the Cs x Rb1−x TiOAsO4 Series. I. Crystal Structure Analysis and Pseudo-symmetry

1998 ◽  
Vol 54 (5) ◽  
pp. 635-644 ◽  
Author(s):  
M. N. Womersley ◽  
P. A. Thomas ◽  
D. L. Corker
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Low Temperature ◽  
Room Temperature ◽  
Structural Changes ◽  
Crystal Structure Analysis ◽  
Orthorhombic Space Group ◽  
Acta Cryst ◽  
Space Group ◽  
Structural Framework

Refinements of five crystals in the Cs2x Rb2−2x Ti2O2As2O8 series, caesium rubidium titanyl arsenate, with x = 0.07, 0.31, 0.58, 0.71 and 0.86, which are compositional analogues of KTiOPO4 (KTP), have been completed at 293 K and two (x = 0.71, 0.86) at low temperature. All the structures are found to be orthorhombic (space group Pna21) and are isostructural with KTP, although there is evidence of some Cs disorder over additional sites in the framework, particularly at the Cs-rich end of the series, as discussed in Part II [Thomas & Womersley (1998). Acta Cryst. B54, 645–651]. Unusually large U 33 parameters for shared Cs/Rb sites are observed and are shown to be the result of the existence of separate sites for Cs and Rb within the structural framework, although the coordinates of these sites cannot be resolved convincingly. The structural changes in the TiO6/AsO4 framework required to accommodate an increasing fraction of the larger Cs cation across the series and under cooling to 120 K are elucidated. Finally, the deviations of the room-temperature and low-temperature structures from the high-temperature prototypic structure (space group Pnan) are examined and suggest that the phase-transition temperature should increase linearly from CsTiOAsO4 to RbTiOAsO4.

scholarly journals 1,3-Propanediammonium [μ4-1,2,4,5-benzenetetracarboxylato(4-)]copper(II)dihydrate with a microporous structure

2005 ◽  
Vol 70 (12) ◽  
pp. 1441-1450 ◽  
Author(s):  
Dejan Poleti ◽  
Ljiljana Karanovic
Keyword(s):  
Crystal Structure ◽  
Crystal Structure Analysis ◽  
Title Complex ◽  
Microporous Structure ◽  
Dsc Analysis ◽  
Orthorhombic Space Group ◽  
Open Framework ◽  
Carboxylate Groups ◽  
Square Planar ◽  
Final Agreement

Crystal structure analysis of the title complex, (H3NC3H6NH3)[Cu{C6H2(COO)4}] ?2H2O, showed that the structure is built up from Cu(II) and tetradentate 1,2,4,5-benzenetetracarboxylate( 4-)(btc) ions forming a 3D open-framework with two different channels extending parallel to the [110]/[1,-1,0] and [001] directions. The first, wider channels accommodate 1,3-propanediammonium cations, whereas the second ones are filled with H2O molecules. The Cu(II) ions are in a tetrahedrally distorted square-planar environment consisting of four carboxylate O atoms from four different btc ligands. The four uncoordinated O atoms from the same carboxylate groups are placed around Cu(II) at longer distances (?2.8?), forming a distorted sphenoid. The complex crystallizes in the orthorhombic space group Cc2m with a=8.887(1) b=11.493(2), c=16.457(3)?, V=1680.9(5)?3 and Z=4. Final agreement indices are: R1=0.0303 for 1012 reflections with I>2?(I), wR2=0.0493 for 1317 independent reflections and 123 refined parameters. The compound was also characterized by IR spectroscopy and TG/DSC analysis.

scholarly journals Novel Ansa-Chain Conformation of a Semi-Synthetic Rifamycin Prepared Employing the Alder-Ene Reaction: Crystal Structure and Absolute Stereochemistry

Chemistry ◽  
2021 ◽  
Vol 3 (3) ◽  
pp. 734-743
Author(s):  
Christopher S. Frampton ◽  
James H. Gall ◽  
David D. MacNicol
Keyword(s):  
Crystal Structure ◽  
Rna Synthesis ◽  
Crystal Structure Analysis ◽  
Orthorhombic Space Group ◽  
Ene Reaction ◽  
X Ray ◽  
Diethyl Azodicarboxylate ◽  
Hydroxy Groups ◽  
Absolute Stereochemistry ◽  
Predominant Product

Rifamycins are an extremely important class of antibacterial agents whose action results from the inhibition of DNA-dependent RNA synthesis. A special arrangement of unsubstituted hydroxy groups at C21 and C23, with oxygen atoms at C1 and C8 is essential for activity. Moreover, it is known that the antibacterial action of rifamycin is lost if either of the two former hydroxy groups undergo substitution and are no longer free to act in enzyme inhibition. In the present work, we describe the successful use of an Alder-Ene reaction between Rifamycin O, 1 and diethyl azodicarboxylate, yielding 2, which was a targeted introduction of a relatively bulky group close to C21 to protect its hydroxy group. Many related azo diesters were found to react analogously, giving one predominant product in each case. To determine unambiguously the stereochemistry of the Alder-Ene addition process, a crystalline zwitterionic derivative 3 of the diethyl azodicarboxylate adduct 2 was prepared by reductive amination at its spirocyclic centre C4. The adduct, as a mono chloroform solvate, crystallized in the non-centrosymmetric Sohnke orthorhombic space group, P212121. The unique conformation and absolute stereochemistry of 3 revealed through X-ray crystal structure analysis is described.

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