The geometry of 4-(1-ethoxyethylidene)-5-oxazolones and thiazolones: 1H and 13C studies and the crystal structure of 4-[(Z)-1-ethoxyethylidene]-2-phenyl-5-oxazolone

1985 ◽  
Vol 63 (12) ◽  
pp. 3618-3630 ◽  
Author(s):  
R. A. Bell ◽  
R. Faggiani ◽  
C. J. L. Lock ◽  
R. A. McLeod
Keyword(s):  
Crystal Structure ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Side Chain ◽  
Oxazole Ring ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cell Dimensions ◽  
Ring Nitrogen ◽  
E And Z Isomers

A series of E and Z isomers of substituted 4-(1-ethoxyethylidene)-5-oxazolones and thiazolones have been prepared and their 1H and 13C spectra recorded. The vinylic methyl 1H chemical shifts showed minimal differences between E and Z isomers whereas the vinylic OCH21H signals differed by 0.15–0.43 ppm, with the Z isomer being consistently the more deshielded. Both vinylic methyl and OCH2 groups showed different 13C resonances for each isomer, with the Z isomers being the more deshielded. The Z geometry was conclusively defined for one isomer of 4-(1-ethoxyethylidene)-2-phenyl-5-oxazolone, 5, by X-ray crystallography and this was sufficient to assign the geometry of the remaining pairs of E and Z isomers. Oxazolone 5 has the space group P21/n and cell dimensions a = 9.219(3), b = 19.899(5), c = 7.459(1) Å, β = 118.01(2)°, and has four formula units in the unit cell. Intensities were measured with use of MoKα radiation and a Nicolet P3 diffractometer. The crystal structure was determined by standard methods and refined to R1 = 0.0709, R2 = 0.0696 based on 1419 independent reflections. The molecule is essentially planar and most bond lengths and angles are normal. Exceptions are the very short C(olefin)—O(ether) bond (1.339(4) Å) and the large ether C—O—C angle (122.1(3)°) caused by extreme delocalization in the O(ether)CCCO(carbonyl) system. The planarity causes a number of strong intramolecular repulsive interactions, causing an exceptionally small external olefin angle, O(ether)CC(methyl), of 108.1(4)°. The ethoxyl side chain of 5 adopts a conformation in the solid state which places the methylene of the OCH2 group adjacent to the oxazole ring nitrogen. This conformation is proposed to persist in solution phases and is consistent with the observed 13C chemical shifts and known γ and δ substituent effects.

Synthesis of the cyclopropa[c]benzofuran system of mycorrhizin A and of gilmicolin from a benzofuranol. Crystal structure of a 5,8-Methanocyclopropa-[c]naphtho[2,3-b]furan derivative

1982 ◽  
Vol 35 (8) ◽  
pp. 1665 ◽  
Author(s):  
RFC Brown ◽  
GD Fallon ◽  
BM Gatehouse ◽  
CM Jones ◽  
ID Rae
Keyword(s):  
Crystal Structure ◽  
Ultraviolet Irradiation ◽  
Room Temperature ◽  
Cyclopropane Ring ◽  
Structural Features ◽  
Side Chain ◽  
Furan Derivative ◽  
Methoxy Derivative ◽  
X Ray ◽  
X Ray Crystallography

The cyclopropa[c]benzofuran derivative (17), which contains the structural features of methyl ethers of mycorrhizin A and gilmicolin save for the C3 side chain, has been synthesized from the benzofuranol (4) through the benzofuran-4,7-dione (5) and the 7a-methoxy derivative (8). The cyclopropane ring of (17) was introduced by ultraviolet irradiation of a 1-pyrazoline (13) at -78�; irradiation at room temperature gave mainly a profoundly rearranged acidic product for which the methanoindenone structure (18) is proposed. The stereochemistry of the penultimate cyclopropane (16) has been established by X-ray crystallography.

X-Ray structure determination of 1,2-anhydro-3,4:5,6-di-O-isopropylidene-1-C-nitro-D-mannitol

1988 ◽  
Vol 66 (7) ◽  
pp. 1600-1604 ◽  
Author(s):  
Walter A. Szarek ◽  
George W. Hay ◽  
Ramesh K. Sood ◽  
Konia Trouton ◽  
Suzanne Fortier
Keyword(s):  
Crystal Structure ◽  
Hydrogen Peroxide ◽  
Direct Methods ◽  
Major Product ◽  
Calculated Density ◽  
Aqueous Sodium ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cell Dimensions

The structure of the major product of the reaction of 1,2-dideoxy-3,4:5,6-di-O-isopropylidene-1-C-nitro-D-arabino-hex-1-enitol with 30% hydrogen peroxide and aqueous sodium hydrogencarbonate has been confirmed by X-ray crystallography to be that of 1,2-anhydro-3,4:5,6-di-O-isopropylidene-1-C-nitro-D-mannitol (2). The crystal structure of 2, C12H19NO7, is orthorhombic, P212121, with cell dimensions a = 10.269(3), b = 15.115(7), c = 9.295(8) Å, and Z = 4. The calculated density is Dx = 1.336 gcm−3. The structure was solved by direct methods and refined to a residual R = 0.052. The molecule has a 2G− conformation having bond lengths and angles in agreement with those observed in related structures, except for the C(1)—C(2), C(2)—C(3), and O(2N)—N bond distances which were found to be unusually small.

Appendix. Crystallographic measurements on the anti-pernicious anaemia factor

1950 ◽  
Vol 136 (885) ◽  
pp. 609-613 ◽  
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Pernicious Anaemia ◽  
Aqueous Acetone ◽  
Crystal Habit ◽  
Side Chain ◽  
Solvent Content ◽  
X Ray ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

Since May 1948, five different samples of crystalline anti-pernicious anaemia factor have been examined in Oxford by various crystallographic techniques. These all, from their general characteristics, particularly the intensities of a number of X-ray reflexions, contain the same molecular structure. But the different samples have shown small variations in unit-cell dimensions and in crystal habit, which are probably due mainly to differences in solvent content, combined with traces of different impurities. Small changes in, for example, some side chain in the molecule, might also conceivably contribute to these effects. The crystals, as grown both from water and from aqueous acetone, are dark red and show marked pleochroism . They vary in habit from long thin needles to short thick prisms on which different crystal faces appear (figures A 1 and A 2). They all contain solvent, probably water, of crystallization, part at least of which they lose slowly on exposure to the air. Crystals kept in their mother-liquor are transparent and show beautifully clear reflecting faces; they give sharp X-ray reflexions extending to spacings of 1·1Å. On removal from the liquid they tend to crack and to become opaque; the faces are distorted and the X-ray reflexions become first multiple, and then blurred, corresponding to the presence of disorder within the dried crystal structure. But the rate of loss of solvent appears to vary both with the size of crystals and with the different samples studied. Individual air-dried crystals for example, have been observed which have given good and sharp X-ray reflexions some weeks after exposure to the atmosphere.

The crystal structure of bis(triphenyltin)telluride and the interpretation of the 119Sn Mössbauer and nuclear magnetic resonance data of the bis(triphenyltin) and bis(trimethyltin) chalcogenides

1983 ◽  
Vol 61 (11) ◽  
pp. 2611-2615 ◽  
Author(s):  
F. W. B. Einstein ◽  
C. H. W. Jones ◽  
T. Jones ◽  
R. D. Sharma
Keyword(s):  
Crystal Structure ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Solution Nmr ◽  
Fold Axis ◽  
X Ray ◽  
X Ray Crystallography ◽  
Magnetic Resonance Data ◽  
Resonance Data

The structure of (Ph3Sn)2Te has been determined by X-ray crystallography. The compound crystallizes in the space group C2/c with a = 18.578(3) Å, b = 7.731(1) Å, c = 25.272(4) Å, β = 117.17(1)°, ρc = 1.702 g cm−3, ρo(CHCl3/CH2I2) = 1.69 g cm−3, and Z = 4. Intensities were measured for 2853 independent reflections (2θ ≤ 50°) of which 2044 were observed (I ≤ 2.3σ(I)) and used in subsequent refinement (final R values were R = 0.034 and Rw = 0.045). The (Ph3Sn)2Te molecule exhibits a "bent" structure in which Sn—Te—Sn = 103.68(2)° and Te—Sn = 2.7266(6) Å and in which the Te atom lies on a crystallographic two-fold axis. Comparison of the present structure with corresponding selenide and sulphide analogues indicates that in all three cases the environment about tin corresponds to that of sp3 hybridisation. The 119Sn Mössbauer quadrupole splittings of (Ph3Sn)3E and (Me3Sn)2E, where E = S, Se, or Te, show a correlation with the 119Sn solution nmr chemical shifts and this correlation is discussed.

Kinetic benzylidenation. Part I. The selective formation of five-membered ring benzylidene acetals from aldose diethyl dithioacetals

1986 ◽  
Vol 64 (12) ◽  
pp. 2388-2396 ◽  
Author(s):  
T. Bruce Grindley ◽  
Srihari Kusuma ◽  
T. Stanley Cameron
Keyword(s):  
Crystal Structure ◽  
Phenyl Ring ◽  
Dimethyl Acetal ◽  
Membered Ring ◽  
Sugar Chain ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cell Dimensions ◽  
Intermolecular Reaction ◽  
Selective Formation

Reaction of D-arabinose diethyl dithioacetal with one equivalent of benzaldehyde dimethyl acetal in the presence of p-toluenesulfonic acid at −40 °C gave a mixture of the two epimers of 5-O-methoxyphenylmethyl-D-arabinose diethyl dithioacetal initially. After 14 h at −20 °C, the major products were R- and S-4,5-O-benzylidene-D-arabinose diethyl dithioacetal. The structure of the S isomer was determined by X-ray crystallography. The crystal was orthorhombic, with space group P212121, cell dimensions a = 5.179(4), b = 12.469(3), c = 27.150(4) Å, and Z = 4. The crystal structure was solved using the SHELX (76) system and refined to R = 0.060 for 714 reflections. The sugar chain was in a zigzag conformation, the 4,5-O-benzylidene ring in a 0−5Tc conformation, and the plane of the phenyl ring was nearly perpendicular to the plane of the five-membered ring (88° angle). There were two short OH—S hydrogen bonds, one intramolecular and one intermolecular. Reaction of the diethyl dithioacetals of D-glucose, D-galactose, D-mannose, and D-ribose at −20 °C as above also gave mixtures of the terminal five-membered ring O-benzylidene diastereomers.

Reaktionen von Re2O7 mit Iminophosphoranen - Kristallstruktur von ( O3ReN = PPh2)2C2H4/Reactions of Re2O7 with Iminophosphoranes - Crystal Structure of (O3ReN = PPh2)2C2H4

1990 ◽  
Vol 45 (1) ◽  
pp. 72-76 ◽  
Author(s):  
Herbert W. Roesky ◽  
Detlev Hesse ◽  
Mathias Rietzel ◽  
Mathias Noltemeyer
Keyword(s):  
Crystal Structure ◽  
Unit Cell ◽  
Space Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

AbstractRe2O7 reacts with (Me3SiN = PPh2)2CH2, (Me3SiN = PPh2)2C2H4 and Me3SiN = PPh3 to give (O3ReN = PPh2)2CH2 (3), (O3ReN = PPh2)2C2H4 (6) and Ph3P= NReO3 (7). 6 has been characterizedby X-ray crystallography. The complex crystallizes in the space group P 1̄ with unit cell dimensions a = 837.4(4), b = 873.0(5), c = 1102.5(6) pm, ɑ = 112.53(4), β = 98.54(4), γ = 100.59(4)°, and Z = 1. The structure demonstrates that the bis(diphenylphosphinimino)-ethane group is bridging two ReO3 units.

Verfeinerung der Kristallstruktur von Tripalladium-di-tetrathiophospliat Pd3(PS4)2 Refinement of the Crystal Structure of Tripalladium-di-tetrathiophosphate Pda3(PS4)2

1983 ◽  
Vol 38 (4) ◽  
pp. 426-427 ◽  
Author(s):  
Arndt Simon ◽  
Karl Peters ◽  
Harry Hahn
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Title Compound ◽  
Type Structure ◽  
Tetrahedral Symmetry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Planar Environment

Abstract The structure of the title compound has been determined by X-ray crystallography. The title compound is synthesized from the elements at 600 °C. Its crystal structure, derived from powder data [3] is refined by single crystal diffractometer data. The structure is trigonal (P3̅ml, α = 684.1(1), c = 724.4(1) pm); Pd2+ cations and PS43- anions form a network with an anti-Claudetite (AS2O3) type structure. The PS4 units are distinctly distorted from ideal tetrahedral symmetry. The Pd atoms have a planar environment of 4 S atoms.

Configurational and conformational studies on condensation products of biogenic amines with 2,5-anhydro-D-mannose

1985 ◽  
Vol 63 (11) ◽  
pp. 2915-2921 ◽  
Author(s):  
Ian M. Piper ◽  
David B. MacLean ◽  
Romolo Faggiani ◽  
Colin J. L. Lock ◽  
Walter A. Szarek
Keyword(s):  
Hydrogen Bond ◽  
Intermolecular Hydrogen Bond ◽  
Direct Methods ◽  
Conformational Studies ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Twist Conformation ◽  
Cell Dimensions ◽  
Internal Hydrogen Bond

The products of a Pictet–Spengler condensation of tryptamine and of histamine with 2,5-anhydro-D-mannose have been studied by X-ray crystallography to establish their absolute configuration. 1(S)-(α-D-Arabinofuranosyl)-1,2,3,4-tetrahydro-β-carboline (1), C16H20N20O4, is monoclinic, P21 (No. 4), with cell dimensions a = 13.091(4), b = 5.365(1), c = 11.323(3) Å, β = 115.78(2)°, and Z = 2. 4-(α-D-Arabinofuranosyl)imidazo[4,5-c]-4,5,6,7-tetrahydropyridine (3), C11H17N3O4, is orthorhombic, P212121 (No. 19), with cell dimensions a = 8.118(2), b = 13.715(4), c = 10.963(3) Å, and Z = 4. The structures were determined by direct methods and refined to R1 = 0.0514, R2 = 0.0642 for 3210 reflections in the case of 1, and to R1 = 0.0312, R2 = 0.0335 for 1569 reflections in the case of 3. Bond lengths and angles within both molecules are normal and agree well with those observed in related structures. In 3 the base and sugar adopt a syn arrangement, which is maintained by an internal hydrogen bond between O(2′) and N(3). The sugar adopts a normal 2T3 twist conformation. The sugar has the opposite anti arrangement in the β-carboline 1 and the conformation of the sugar is unusual; it is close to an envelope conformation with O(4′) being the atom out of the plane. This conformation is caused by a strong intermolecular hydrogen bond from O(5′) in a symmetry-related molecule to O(4′). Both compounds are held together in the crystal by extensive hydrogen-bonding networks. The conformations of the compounds in solution have been investigated by 1H nmr spectroscopy, and the results obtained were compared with those obtained by X-ray crystallography for 1 and 3.

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