Nucleophilic Displacements of Imidazoles. I. Oxygen, Nitrogen and Carbon Nucleophiles

1987 ◽  
Vol 40 (8) ◽  
pp. 1399 ◽  
Author(s):  
S Kulkarni ◽  
MR Grimmett ◽  
LR Hanton ◽  
J Simpson
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
X Ray ◽  
Carbon Nucleophiles ◽  
Nucleophilic Displacement ◽  
Ray Methods

4(5)- Bromo - and - iodo-imidazoles, activated by an adjacent nitro substituent, undergo nucleophilic displacement with methoxide, phenoxide , cyclic secondary chines and cyanide. The regiochemistry of the reactions of 5-iodo-4-nitroimidazole with methoxide has been confirmed by spectroscopic and X-ray methods, and a number of erroneous structures from the literature have been revised. Some apparently anomalous reactions of methoxide with 5-halo-1,2-dimethyl-4- nitroimidazoles, and of cyanide with 4-halo-1-methyl-5-nitroimidazole have been noted. The crystal and molecular structure of 5-methoxy-1-methyl-4-nitroimidazole has been determine: by direct methods. Crystals are monoclinic, P21/c, a 10.929(3), b 8 899(2), c 7.290(2) �; β 92.87(2)�; Z 4. The structure was refined to R = 0.095 for 818 reflections (I > 2σI).

Chalkogenolat-Ionen und ihre Derivate, V Kristall- und Molekülstruktur von 2.8-Dimethyldibenzo [c.g] [1.2.5.6] tetrathiacyclooktadien, einem Oxidationsprodukt von 4-Methylbenzol-1.2-dithiol/Chalcogenolates and their Derivatives, V Crystal and Molecular Structure of 2.8-Dimethyldibenzo[c,g][1,2,5,6]tetrathiaocin, an Oxidation Product of 4-Methylbenzene-1,2-dithiol

1979 ◽  
Vol 34 (1) ◽  
pp. 48-51 ◽  
Author(s):  
Jürgen Kopf ◽  
Klaus von Deuten ◽  
Bahman Nakhdjavan ◽  
Günter Klar
Keyword(s):  
Molecular Structure ◽  
Dihedral Angle ◽  
Oxidation Product ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
The Mean ◽  
Ray Methods ◽  
Anti Form

Abstract The structure of 2,8-dimethyldibenzo[c,g][1,2,5,6]tetrathiaocin (1b) has been determined by X-ray methods and discussed in connection with the preferred conformations of diaryl disulfides. The compound has the anti-form I. The SS-distance is 205.8 pm, the mean CSS-angle 104.1°, and the CSS/SSC-dihedral angle 111.1°.

A Ring Destruction Approach to Some Benzo-Fused Medium-Sized Heterocycles by Means of Cyanogen-Bromide Under Solvolytic Conditions - X-Ray Structure of a '1h-2,6-Benzoxazecine-6-Carbonitrile and a '2h-3,6-Benzoxazecine-6-Carbonitrile Derivative

1986 ◽  
Vol 39 (6) ◽  
pp. 893 ◽  
Author(s):  
JB Bremner ◽  
CL Raston ◽  
GL Rowbottom ◽  
AH White ◽  
KN Winzenberg
Keyword(s):  
Molecular Structure ◽  
Tertiary Amine ◽  
Cyanogen Bromide ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
Concomitant Reduction ◽  
Heterocyclic Derivatives ◽  
Isoquinoline Derivatives ◽  
Ray Methods ◽  
Medium Ring

Reaction of the reduced pyrrolo [2,1-a] isoquinoline amine (1a) with cyanogen bromide in the presence of methanol gave the medium-ring cyanamide derivative 7,9,10-trimethoxy-2,3,4,5,6,7-hexahydro-1H-3- benzazonine-3-carbonitrile (2a). Analogous products were also obtained from reaction of the reduced 5H-oxazolo[2,3-a] isoquinoline , 2H- benzo [a] quinolizine , 2H,6H-[1,3] oxazino [2,3-a] isoquinoline and [1,4] oxazino [3,4-a] isoquinoline derivatives (1b-e), whereas the reduced 3H-oxazolo[4,3-a] isoquinoline and 5H-oxazolo[2,3-a] isoquinoline derivatives (1f) and (8) gave 1-(2,4-dioxapentyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-2-carbonitrile (5a) and N-[2-(2-benzoyl-4,5-dimethoxyphenyl)ethyl]-N- methylcyanamide (9) respectively, the latter in low yield. The medium-sized heterocyclic derivatives (2f-h) were also obtained from cyanogen -bromide-mediated water solvolysis reactions of (1a), (1c) and (1e). The cyanamides (2a-h), (5a) and (9) have been converted into the respective tertiary amine derivatives (3a- h), (5c) and (11), with concomitant reduction of the carbonyl group in the last case. The crystal and molecular structure of 1,10,11- trimethoxy-3,4,5,6,7,8-hexahydro-1H-2,6-benzoxazecine-6-carbonitrile (2d) and 1-hydroxy-10,11-dimethoxy-1,4,5,6,7,8-hexahydro-2H-3,6- benzoxazecine-6-carbonitrile (2h) have been determined by single- crystal X-ray methods.

The crystal and molecular structure of 1,4-diphenyl-2,2′,3,3′,5,5′,6,6′-octamethylcyclo-1,4-diphospha-2,3,5,6-tetrasilahexane, a phosphorus–silicon heterocycle

1979 ◽  
Vol 57 (2) ◽  
pp. 174-179 ◽  
Author(s):  
A. Wallace Cordes ◽  
Paul F. Schubert ◽  
Richard T. Oakley
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Chair Conformation ◽  
Monoclinic Space Group ◽  
Single Bond ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Bond Lengths

The crystal structure of 1,4-diphenyl-2,2′,3,3′,5,5′,6,6′-octamethylcyclo-1,4-diphospha-2,3,5,6-tetrasilahexane, (PhPSi2Me4)2, has been determined by single crystal X-ray diffraction. The crystals are monoclinic, space group P21/c, with a = 9.866(1), b = 11.921(1), and c = 11.324(2) Å, β = 104.31(1)°, Z = 2, and ρcalcd = 1.15 g/cm3. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to a final R of 0.060 and Rw of 0.078, for 1173 reflections with intensities greater than 3σ. The (PhPSi2Me4)2 molecule lies on a crystallographic centre of symmetry, and the six-membered P2Si4 ring has a chair conformation with equatorial phenyl groups. The endocyclic angles at P (104.4(1)°) and Si (104.9(2)°) are intermediate between those found in cyclic hexaphosphine and hexasilane molecules, and the Si—Si and P—Si distances of 2.345(3) and 2.252(4) Å, respectively, correspond to single bond lengths, with no appreciable evidence for secondary pπ → dπ bonding between phosphorus and silicon. The Si—C (1.867(8) Å) and P—C (1.828(7) Å) bond lengths are also normal. The variations in the Si—P—C (101.6(2)°, 108.6(2)°), P—Si—C (range 106.2(3)–120.0(3)°), and Si—Si—C (range 105.8(3)–113.7(3)°) angles indicate that the positions of the exocyclic methyl and phenyl groups are influenced by both intra- and intermolecular steric forces.

Nitrones and oximes of bifunctional carbonyl compounds and their reaction products with diarylborinic acids. Crystal and molecular structure of examples of five-, six-, and seven-membered boron chelates

2000 ◽  
Vol 78 (10) ◽  
pp. 1325-1344
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Jens O Pokriefke ◽  
Steven J Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Carbonyl Compounds ◽  
Spectroscopic Data ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Reaction Products ◽  
Boron Chelates ◽  
Full Matrix ◽  
Space Group ◽  
X Ray

Synthesis has been carried out of diarylboron chelates of 2- and 3-hydroxynitrones, of 2- and 3-hydroxyoximes, and of 2-carboxynitrones and a 2-carboxyoxime. The structures have been determined from spectroscopic data and from X-ray analyses of 5d, 9a, 11b, and 19. Crystals (at 180 K) of 5d are monoclinic, a = 10.543(2), b = 19.085(4), c = 10.2667(3) Å, β = 90.4978(7)°, Z = 4, space group P21/c; those of 9a are orthorhombic, a = 10.9913(5), b = 14.9329(7), c = 10.2460(13) Å, Z = 4, space group P212121; those of 11b are monoclinic, a = 11.227(2), b = 9.967(2), c = 17.0537(4) Å, β = 105.4179(5)°, Z = 4, space group P21/n; those of 19 are monoclinic, a = 11.1847(15), b = 13.715(3), c = 11.5559(5) Å, β = 104.8730(10)°, Z = 4, space group P21/n. The structures were solved by direct methods and refined by full-matrix least-squares procedures to R(F, I [Formula: see text] 3σ(I)) = 0.049, 0.047, 0.042, and 0.047, respectively, for CCD data for 5d, 9a, 11b, and 19. The four molecules contain five-, seven-, six-, and five-membered rings, respectively, with O-B-N groups in the 5d, 11b, and 19, and O-B-O in 9a; the rings exhibit various deviations from planarity, particularly the seven-membered ring.Key words: diarylboron chelates, hydroxyoximes, hydroxynitrones, carboxyoximes, carboxynitrones, organoboron compounds, crystal structure.

Structural studies of organoboron compounds. LX. Reaction of sterically hindered arylboronic acids with 2-(hydroxyamino)alkanols. Crystal and molecular structure of 2-mesityl-6,6-pentamethylene-1,3-dioxa-4-aza-2-boracyclohexane

1994 ◽  
Vol 72 (4) ◽  
pp. 1154-1161 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Structural Studies ◽  
Full Matrix ◽  
Space Group ◽  
X Ray ◽  
Arylboronic Acids ◽  
Sterically Hindered

Three 2-(hydroxyamino)alkanols have been reacted with sterically hindered arylboronic acids, ArB(OH)2. When Ar = o-tolyl, 1:2 condensates having bicyclic structures are formed but when Ar = mesityl (2,4,6-(CH3)3C6H2), 1:1 condensates having six-membered cycloboronate structures result. These 1:1 condensates represent the first examples of N-unsubstituted 1,3-dioxa-4-aza-2-boracyclohexane derivatives. An X-ray analysis of one example provides unambiguous proof of the structure. Crystals of 2-mesityl-6,6-pentamethylene-1,3-dioxa-4-aza-2-boracyclohexane, 3c, are monoclinic, a = 11.076(9), b = 23.94(2), c = 13.414(9) Å, β = 109.40(5)°, Z = 8, space group P21/n. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.051 and Rw = 0.058 for 2037 reflections with I ≥ 3σ(F2).

Diphenylboron complexes of the enol tautomers of arylpyruvic acids. Crystal and molecular structure of triethylammonium (2-nitrophenyl)pyruvato-diphenylboron(1-)

2000 ◽  
Vol 78 (5) ◽  
pp. 546-552 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Jens O Pokriefke ◽  
Steven J Rettig ◽  
James Trotter
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bond ◽  
Least Squares ◽  
Spectroscopic Data ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Full Matrix ◽  
X Ray

Synthesis has been carried out of 15 examples of anionic diphenylboron complexes of arylpyruvic acids, and the structures of the compounds have been determined from spectroscopic data and from X-ray analysis of one of the compounds. Crystals of5j are monoclinic, P21/n,a = 9.5566(10), b = 15.961(3), c = 16.6382(6) Å, beta = 99.3239(10)°, and Z = 4, at 180 K. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R(F2) = 0.056 for 6662 CCD data. 5j contains a triethylammonium cation and an anion containing a planar five-membered OBOCC ring, with cation and anion linked by an N-H···O hydrogen bond. Spectroscopic data and bond distances establish that the pyruvate ligand is the enol-tautomeric state.

Synthesis of 2,3-Dihydro-1,4,5-benzodioxazocines. X-ray structure of 6-Phenyl-2,3-dihydro-1,4,5-benzodioxazocine

1983 ◽  
Vol 36 (12) ◽  
pp. 2555 ◽  
Author(s):  
EJ Browne ◽  
LM Engelhardt ◽  
AH White
Keyword(s):  
Molecular Structure ◽  
Single Crystal ◽  
Crystal And Molecular Structure ◽  
Ring System ◽  
Cyclic Dimer ◽  
X Ray ◽  
Ray Methods ◽  
By Products

Derivatives (6a-c) of the 1,4,5-benzodioxazocine ring system have been prepared in low-to-moderate yields by hydrazinolysis of {2-[2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)oxyethyloxy]aryl}phenylmethanones(5a-c), and cyclization of the products at pH c. 4. Only in the case of (6b) was a trace of a cyclic dimer (7b) detected, in contrast to the analogous preparations of the 2H-1,5,6-benzodioxazonine derivatives (1a-c) where 18-membered cyclic dimers (8a-c) formed as by-products. The crystal and molecular structure of 6-phenyl-2,3-dihydro-1,4-5-benzodioxazocine (6a) has been determined by single-crystal X-ray methods.

Radical Cation Salts of an Unsymmetrical BEDT-TTF Derivative: Molecular Structure and Physical Properties of (DIMET*)2CIO4 X THF

1985 ◽  
Vol 40 (12) ◽  
pp. 1703-1710 ◽  
Author(s):  
R. Heid ◽  
H. Endres ◽  
H. J. Keller
Keyword(s):  
Molecular Structure ◽  
Electrical Conductivity ◽  
Physical Properties ◽  
Crystal And Molecular Structure ◽  
Average Charge ◽  
Two Dimensional ◽  
X Ray ◽  
Radical Cation Salts ◽  
Solvent Molecules ◽  
Ray Methods

Abstract 4.5-Dimethyl-4'.5'-ethylenedithiolotetrathiafulvalene (DIMET) was obtained by reacting 4.5- ethylenedithiolo-1.3-dithioliumtetrafluoroborate with 4.5-dimethyl- 1.3-dithiolium-tetrafluoroborate in the presence of diisopropylethylamine or triethylamine. Electrocrystallization of this donor in different solvents like dichloromethane or tetrahydrofurane (THF) and with varying supporting electrolytes, like tetrabutylammonium hexafluorophosphate, triiodide, nitrate, perrhenate or perchlorate, results in a large number of well crystallizing compounds. The crystal and molecular structure of one of the isolated solids was elucidated by X-ray methods. (C10)H10S6)2CIO4 x C4H8O, Mr = 816.66, is triclinic, P1̄ , a = 6.731(5), b - 7.632(3), c = 33.32(3) Å , α = 96.53(5), β = 92.99(6), γ = 103.13(5)°, V - 1650.7 Å3, Z = 2, dc = 1.64 gem-3, final Rw = 0.077 for 1844 observed independent reflections. Sheets of cations with an average charge of 1/2+ are separated by sheets of anions and THF solvent molecules. Intermolecular S···S contacts result in two-dimensional physical properties. Electrical conductivity and thermopower measurements indicate two broad phase transitions at around 200 K and 80 K

Studies of the rhenium–oxygen bond. II. The crystal and molecular structure of µ-oxobis(cis-dichloro-cis-di(pyridine)-trans-oxorhenium(V)), ORe(C5H5N)2Cl2ORe(C5H5N)2Cl2O

1978 ◽  
Vol 56 (2) ◽  
pp. 179-188 ◽  
Author(s):  
Colin James Lyne Lock ◽  
Graham Turner
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Single Crystal ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
The Other ◽  
Full Matrix ◽  
X Ray ◽  
Ray Methods ◽  
Oxygen Bond

The crystal structure of µ-oxobis(cis-dichloro-cis-di(pyridine)-trans-oxorhenium(V)), ORe(C5H5N)2Cl2•O•Re(C5H5N)2Cl2O bas been studied by single crystal X-ray methods. The crystals were orthorhombic with lattice parameters a = 15.367(2), b = 10.283(2), c = 16.685(2) Å. The space group was Pna21 and there were four formula weights per unit cell. A total of 3339 reflections, of which 2990 were observed, were examined, and the structure refined by full matrix least squares (treating the pyridine rings as groups) to an R2 value of 0.0449. The dimer had a roughly rectilinear O—Re—O—Re—O backbone with pairs of chlorine atoms and pyridine molecules arranged cis in each half of the dimer. The two halves of the dimer were arranged such that the pairs of cis atoms in one half were rotated about the Re(1)–Re(2) axis almost 113 ° when compared to the corresponding pair in the other half. Important bond lengths (Re—O(terminal), 1.715(16), 1.764(16); Re—O(bridging), 1.943(16), 1.903(16); Re—Cl, 2.356(5)–2.390(5); Re—N, 2.116(16)–2.180(16)) were close to previously observed values. The molecule was markedly disturbed from the idealized structure and this was caused by intramolecular non-bonded interactions.

The preparation and the crystal and molecular structure of S3N2NH2+BF4−; a molecular orbital study of the protonation of the trisulphur trinitride anion

1984 ◽  
Vol 62 (9) ◽  
pp. 1822-1827 ◽  
Author(s):  
Clifford G. Marcellus ◽  
Richard T. Oakley ◽  
A. Wallace Cordes ◽  
William T. Pennington
Keyword(s):  
Molecular Structure ◽  
Molecular Orbital ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Membered Ring ◽  
Molecular Orbital Calculations ◽  
X Ray Diffraction ◽  
Triclinic Space Group ◽  
X Ray ◽  
Molecular Orbital Study

Protonation of the trisulphur trinitride ion, S3N3−, with tetrafluoroboric acid yields the ring-contracted S-amino thiodithiazyl salt, S3N2NH2+BF4−. The crystal and molecular structure of this salt has been determined by X-ray diffraction. The crystals are triclinic, space group P1, with a = 5.445(2), b = 7.346(3), c = 9.473(5) Å, α = 85.89(4), β = 83.92(3), γ = 82.13(3)°, V = 372.6(4) Å3, Dc = 2.02 g cm−3, and Z = 2. The structure was solved by direct methods and refined by full-matrix least-squares procedures to give a final R = 0.060. The structure of the five-membered ring with a single exocyclic NH2 group bonded to sulphur is discussed in relation to other S3N2NR derivatives. The reasons for the instability of six-membered rings of the type S3N3R are discussed in the light of MNDO molecular orbital calculations on an S3N3H model.

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