Structure and Absolute Configuration of the Ansamycin Antibiotic Awamycin

1992 ◽  
Vol 45 (1) ◽  
pp. 309 ◽  
Author(s):  
AJ Herlt ◽  
RW Rickards ◽  
GB Robertson
Keyword(s):  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
Biologically Active ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Tertiary Structures ◽  
X Ray ◽  
Parameters Analysis ◽  
Solvent Molecules ◽  
Absolute Stereochemistry

The structure and absolute configuration (3) of the biologically active ansamycin antibiotic awarnycin have been determined from X-ray diffraction data recorded at 129 K. Crystals are monoclinic, space group P2′2′2′, with a 25.426(3), b 30.823(2), c 13.592(1) A, and contain two molecules of the antibiotic and eleven solvent molecules (two water and nine ethanol) in each asymmetric scattering unit. The structure was solved with SHELXS and refined by full-matrix least-squares analysis to R 0.076 ( Rw 0.090) for 7308 reflections and 1174 refined parameters. Analysis of observed and calculated Bijvoet differences with the statistic Χ2 defines the absolute configuration of awamycin as 20R,21R,22R,23R,24R,25R,26R,27S,28S and the helicity as P. This is the first crystal structure analysis of an underivatized ansamycin antibiotic of the subgroup possessing an 18-membered ansa chain, and the first such analysisof an underivatized ansarnycin antibiotic in which it has been possible to assign absolute stereochemistry by the Bijvoet method. The constitution and absolute configuration of awamycin are compared with those of related ansarnycins carrying 18- and 19-membered ansa chains, and the tertiary structures of awarnycin and of several rifamycins and variants are analysed in relation to the arrangement of oxygen functions required for antibiotic activity.

Crystal-to-Crystal Diastereoselective Transformation of 2,4,6-Triisopropyl-4'-(S)-phenylalaninocarbonylbenzophenone Methyl Ester

1998 ◽  
Vol 54 (6) ◽  
pp. 907-911 ◽  
Author(s):  
H. Hosomi ◽  
Y. Ito ◽  
S. Ohba
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Methyl Ester ◽  
Absolute Configuration ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
Pass Filter ◽  
X Ray ◽  
Ultra High Pressure ◽  
Phenylalanine Methyl Ester

Dissymmetry of the photoproduct was induced by using a chiral substituent, (S)-methylphenylalanine, in the title compound {N-4-(2,4,6-triisopropylbenzoyl)benzoyl]-(S)-phenylalanine methyl ester (I)}. On irradiation with light from a 250 W ultra-high-pressure Hg lamp for 7 h through a long-pass filter, the photoreaction in a crystal was 100% complete without the loss of crystallinity. The crystal structures (I), before, and (II) {N-[4-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoyl]-(S)-phenylalanine methyl ester}, after photocyclization, have been determined by X-ray diffraction. For comparison, a crystal structure analysis has also been carried out for the photoproduct (III) of the 3′-COOMe derivative after recrystallization {methyl 3-(7-hydroxy-3,5-diisopropyl-8,8-dimethylbicyclo[4.2.0]octa-1,3,5-trien-7-yl)benzoate}. The dihedral angle between the central carbonyl plane and the triisopropylphenyl ring deviates from 90° by 10 (1)° in (I), which makes an imbalance in the intramolecular O(carbonyl)...H(methine) distances of the isopropyl groups at positions 2 and 6. The crystal structure of (II) indicates that the nearer methine H was predominantly abstracted by the carbonyl O atom in the reaction. The absolute configuration around the asymmetric C atom in the cyclobutenol ring of the product is S.

Weak interactions observed in ruthenium and iridium complexes containing hydride, amine, and bulky phospyhine ligands

1997 ◽  
Vol 75 (5) ◽  
pp. 475-482 ◽  
Author(s):  
Wei Xu ◽  
Alan J. Lough ◽  
Robert H. Morris
Keyword(s):  
Molecular Structure ◽  
Crystal And Molecular Structure ◽  
Weak Interactions ◽  
Crystal Structure Analysis ◽  
Monoclinic Space Group ◽  
Iridium Complexes ◽  
X Ray Diffraction ◽  
Full Matrix ◽  
X Ray ◽  
Van Der Waals Contacts

New amineruthenium and amineiridium hydride derivatives have been synthesized and characterized with the objective of observing intramolecular [Formula: see text] or [Formula: see text] interactions. These include RuHCl(CO)(L)(PPri3)2 (1a, L = NH2NH2; 1b, L = NH3) and IrCl2(L)(H)(PCy3)2 (2a, L = SC(NH2)2; 2b, L = NH3; 2c, L = NH2NH2; 2d, L = NH2(CH2)3NH2; 2e, L = NH2OH). Instead, weak [Formula: see text] van der Waals contacts have been detected in the solid state by X-ray analysis and in solution by NMR T1 measurements and nOe techniques. Both X-ray crystal structure analysis and minimum T1 measurements indicate that the [Formula: see text] distances in the [Formula: see text] interactions are ca•2.0–2.2 Å. The weak interactions might influence the course of deuteration of these complexes under D2 gas. The crystal and molecular structure of IrCl2(NH3)(H)(PCy3)22a has been determined by X-ray diffraction at 173 K: monoclinic, space group P21/n, a = 14.859(2) Å, b = 18.579(3) Å, c = 18.548(3) Å, β = 97.29(1)°, V = 5079.1(13) Å3, Z = 4, full-matrix least-squares refinement on F2 for 10 953 independent reflections; R[F2 > 4σ(F2)] = 0.0283, wR(F2) = 0.0704. Keywords: ruthenium, iridium, hydride, dihydrogen, complexes, hydrogen bond, NMR, X-ray.

The Constituents of Marine Sponges. VII. The Absolute Stereochemistry of Aplyroseol-1.

1997 ◽  
Vol 50 (4) ◽  
pp. 391 ◽  
Author(s):  
Trevor W. Hambley ◽  
Walter C. Taylor ◽  
Stephen Toth
Keyword(s):  
Crystal Structure ◽  
Marine Sponges ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
The Absolute ◽  
Absolute Stereochemistry

The absolute stereochemistry of aplyroseol-1 (1), a diterpenoid isolated from Aplysillarosea Barrois, has been established as (5S; 7R; 8S; 9R; 10S; 13R; 14R; 15R) by determining the crystal structure of the p-bromobenzoyl derivative (3) by X-ray diffraction methods. The structure was refined to a residual of 0·032 for 1451 independent observed reflections. The crystals are monoclinic, space group P 21, a 6·668(8), b 20·04(1), c 10·974(3) Å, β 98·04(7)°.

scholarly journals 4- and 5-Coordinate Dinuclear Copper(II) Complexes with the Tetraacetylethanediide and an N-Alkylated Diamine or a Triamine

1995 ◽  
Vol 50 (4) ◽  
pp. 536-544 ◽  
Author(s):  
Hide Kambayashi ◽  
Junko Yuzurihara ◽  
Yuichi Masuda ◽  
Hiroko Nakagawa ◽  
Wolfgang Linert ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Esr Spectra ◽  
Crystal Structure Analysis ◽  
Dinuclear Complex ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Dinuclear Copper ◽  
X Ray ◽  
Final Agreement

Six dinuclear copper(II) complexes have been prepared, Cu2(taet)(plam)2X2 where taet = 1,1,2,2-tetraacetylethanediide, plam = N-alkylated polyamine such as tmen = N,N,N′,N′-tetramethylethylenediamine or pmdt = N,N,N′,N′,N′-pentamethyldiethylenetriamine, X = a monovalent anion such as ClO4- , NO3- or Cl-. These complexes are classified into two categories from the results of electronic spectra, IR spectra, and X-ray single crystal structure analysis as follows: (1) 4-coordinate-4-coordinate dinuclear, [Cu2(taet)(tmen)2]X2 (where X = ClO4- or NO3-), (2) 5-coordinate-5-coordinate dinuclear, [Cu2(taet)(tmen)2Cl2], and [Cu2(taet)(pmdt)2]X2 (where X = ClO4-, NO3- , or Cl- ). The crystal structure of Cu2(taet)(tmen)2(ClO4)2 · H2O (1) has been determined by the single crystal X-ray diffraction technique; monoclinic space group P21/a with a = 26.478(3), b = 8.744(1), c = 15.601(3) Å, β = 106.195(9)°, and V = 3468.9(8) Å3 for Z = 4. The final agreement factors are R = 0.097 ( Rw = 0.099). The geometry of each Cu(II) moiety in the dinuclear cation (1) is 4-coordinate square planar with a N2O2 donor set. This tmen-dinuclear complex exhibits a very weak C u (II)-Cu (II) interaction (J = -0.5 cm-1), and shows characteristic ESR spectra with seven hyperfine peaks in 1,2-dichloroethane solution at room temperature. This is not found for the corresponding pmdt-dinuclear complex. All complexes obtained in this study are very soluble in many organic solvents. The tmen-dinuclear complexes show pronounced solvatochromic behavior-dependent on the solvent donor properties. This is not found for the corresponding pmdt-dinuclears, which are stable as 5-coordinated species.

Heterocladol, a halogenated selinane sesquiterpene of biosynthetic significance from the red alga Laurencia filiformis: Its isolation, crystal structure andabsolute configuration

1977 ◽  
Vol 30 (12) ◽  
pp. 2679 ◽  
Author(s):  
R Kazlauskas ◽  
PT Murphy ◽  
RJ Wells ◽  
JJ Daly ◽  
WE Oberhansli
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Absolute Configuration ◽  
Red Alga ◽  
Ring Closure ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Annular Ring

The structure and absolute configuration of heterocladol, C15H26BrClO (6), have been determined by single-crystal X-ray diffraction methods. This compound is the first example of a selinane skeleton reported from Laurencia species and its structure can be rationalized in terms of a trans-annular ring closure of a germacradiene. The colourless crystals are monoclinic, space group P21, with a 11.852, b 14.486, c 10.932 Ǻ, β 119.6�, Z4.

scholarly journals Indole alkaloids from Vinca erecta type of sarpagine and ajmaline

2019 ◽  
Vol 10 (4) ◽  
pp. 409-416 ◽  
Author(s):  
Shahobiddin Adizov ◽  
Bakhodir Tashkhodjaev
Keyword(s):  
Conformational Changes ◽  
Absolute Configuration ◽  
Indole Alkaloids ◽  
Diffraction Method ◽  
Monoclinic Space Group ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray

The single crystal X-ray diffraction method established the absolute configuration of the Vinca erecta indole alkaloids of the akuammidine sarpagine type (3S, 5S, 15R, 16R) and its o-acyl derivative, as well as the type of ajmaline, quebrachidine (2S, 3S, 5S, 7R, 15S, 16R, 17S) and majoridine (2R, 3S, 5S, 7R, 15R, 16S, 17R). Crystal data for C21H24N2O3 (1): orthorhombic, space group P212121 (no. 19), a = 6.3949(5) Å, b = 13.5009(10) Å, c = 22.461(3) Å, Z = 4, 7694 reflections measured (7.64° ≤ 2Θ ≤ 152.294°), 3813 unique (Rint = 0.0798) which were used in all calculations. The final R1 was 0.0680 (I > 2σ(I)) and wR2 was 0.1650 (all data). Crystal data for C23H26N2O4 (2): orthorhombic, space group P212121 (no. 19), a = 9.9730(13) Å, b = 10.2090(10) Å, c = 20.409(3) Å, Z = 4, 7959 reflections measured (8.666° ≤ 2Θ ≤ 151.998°), 4212 unique (Rint = 0.0386) which were used in all calculations. The final R1 was 0.0477 (I > 2σ(I)) and wR2 was 0.1171 (all data). Crystal data for C42H48N4O6 (3): monoclinic, space group P21 (no. 4), a = 8.9320(10) Å, b = 21.515(5) Å, c = 9.5420(10) Å, β = 97.103(10)°, Z = 2, 16677 reflections measured (9.34° ≤ 2Θ ≤ 151.836°), 7393 unique (Rint = 0.0278) which were used in all calculations. The final R1 was 0.0366 (I > 2σ(I)) and wR2 was 0.1037 (all data). Crystal data for C23H28N2O3 (4): orthorhombic, space group P212121 (no. 19), a = 10.636(2) Å, b = 11.208(12) Å, c = 16.725(13) Å, Z = 4, 1650 reflections measured (9.498° ≤ 2Θ ≤ 119.97°), 1650 unique (Rint = 0.0436) which were used in all calculations. The final R1 was 0.0608 (I > 2σ(I)) and wR2 was 0.1720 (all data). In alkaloids such as sarpagine and ajmaline exo, the substituents of alkaloids do not lead to conformational changes of a stable polycyclic framework. In the series of sarpagine, alkaloids form mono-salts in the tetrahedral nitrogen N4, and in indolines of the ajmaline type, the tetrahedral hybridization of the N1 and N4 atoms favors the formation of disols. In V. erecta alkaloids, the exomethylene fragment (C18-C19=C20-C21) of the polycyclic backbone always takes on the E-state.

Synthesis and crystal structure of a novel hexaborate, Na2ZnB6O11

2010 ◽  
Vol 25 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Y. Q. Chen ◽  
J. K. Liang ◽  
Y. X. Gu ◽  
J. Luo ◽  
J. B. Li ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Structure Type ◽  
Crystal Structure Analysis ◽  
Monoclinic Space Group ◽  
Chemical Formula ◽  
X Ray Diffraction ◽  
Calculated Density ◽  
Synthesis And Crystal Structure ◽  
X Ray

A novel hexaborate, Na2ZnB6O11, has been successfully synthesized by solid-state reaction and ab initio crystal-structure analysis has been completed using powder X-ray diffraction data. The compound crystallizes in the monoclinic space group Cc with lattice parameters a=10.7329(2) Å b=7.4080(3) Å, c=11.4822(2) Å, and β=112.16(2)°. The number of chemical formula per unit cell is Z=4 and the calculated density is 2.768(3) g/cm3. It represents a new structure type in which double-bridge-ring [B6O11]4− groups were found as fundamental building units. The infrared spectrum confirms the presence of both [BO3]3− groups and [BO4]5− groups.

Crystal Structure Analysis and Antinociceptive Property of Lappaconitine Hydrochloride

2011 ◽  
Vol 343-344 ◽  
pp. 1049-1052
Author(s):  
Wen Xiu Sun ◽  
Tun Galag Dong ◽  
Chun Ming Ding
Keyword(s):  
Crystal Structure ◽  
Mouse Model ◽  
Absolute Configuration ◽  
Acute Pain ◽  
Analgesic Effect ◽  
Crystal Structure Analysis ◽  
Gansu Province ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray

An alkaloid compound, lappaconitine Hydrochloride, was synthesized with lappaconitine which was isolated from the root ofAconitum sinomontanum Nakaiin Gansu province in China. The structures were elucidated by IR,NMR, Anal. and X-ray diffraction analysis. Crystal data: C32H47ClN2O9,Mr= 639.17, space group monoclinic, P21; a=10.665 (7) Å, b=12.178 (7) Å and c=12.214 (7) Å; β=91.003 (10)°, Z=2, Dx= 1.338 mg/m-3,F(000)= 684,µ=0.18.00 mm-1, V=1586.1 (16) Å3; R1=0.038,wR2=0.087, Flack parameter x= -0.12 (7). RingA, B, C, D, EandFrespectively present boat, chair, envelope, boat, boat and envelope forms. The absolute configuration was determined as 1S, 4S, 5S, 7S, 8S, 9S, 10S, 11S, 13R, 14S, 16S, 17 R. And the analgesic potential has been investigated in a mouse model of acute pain. The result exhibited that the analgesic effect of the compound is worse than lappaconitine hydrobromide.

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