The Chemistry of Laurenene. VI. An Investigation of the Widely Differing Reactivity of a Pair of Epimeric Keto Esters

1987 ◽  
Vol 40 (9) ◽  
pp. 1591
Author(s):  
LR Hanton ◽  
SD Lorimer ◽  
RT Weavers
Keyword(s):  
Lithium Aluminium Hydride ◽  
Two Dimensional ◽  
X Ray ◽  
X Ray Crystallography ◽  
Keto Esters ◽  
Lithium Aluminium

X-ray crystallography and two-dimensional n.m.r. techniques have been used to establish the conformations of the epimeric keto esters (1) and (3), derived from cleavage of ring A of lauren-1-ene (2). This information has been used to rationalize the disparate reactivity of the keto functions of (1) and (3) in acid-catalysed carbocation rearrangements and with lithium aluminium hydride. The structures of two new rearranged ethers derived from (1) are also discussed.

Selective O-Methyloxime Formation From 6-Methoxy-2-[(1'-methyl-2',5'-dioxocyclopentyl)-methyl]-3,4-dihydronaphthalen-1(2H)-one

1994 ◽  
Vol 47 (4) ◽  
pp. 649 ◽  
Author(s):  
DJ Collins ◽  
GD Fallon ◽  
CE Skene
Keyword(s):  
Lithium Aluminium Hydride ◽  
X Ray ◽  
X Ray Crystallography ◽  
Lithium Aluminium ◽  
Major Isomer ◽  
Toluenesulfonic Acid ◽  
Ester Formation ◽  
Diastereomeric Mixture ◽  
A Minor

Reaction of 6-methoxy-2-[(1′-methyl-2′,5′-dioxocyclopentyl)methyl]-3,4-dihydronaphthalen-1(2H)-one (4a) with 1 or 2 moles of O- methylhydroxylamine hydrochloride in pyridine gave (1′SR,2RS)-6-methoxy-2-[(1′-methyl-2′,5′-dioxocyclopentyl)methyl]-3,4-dihydronaphthalen-1(2H)-one (E)-2′-O-methyloxime (5a), or the corresponding 2′,5′-bis(O-methyloxime ) (6), respectively. A minor product from the formation of the bis (O- methyloxime ) (6) was the (Z) isomer (5b) of the mono(O- methyloxime ) (5a); the structure and stereochemistry of (5a) and (5b) were established by X-ray crystallography. Reduction of the keto bis (O-methyloxime ) (6) with 0.25 mole of lithium aluminium hydride gave a diastereomeric mixture of the corresponding alcohols (7a), of which the major isomer was characterized by ester formation. The bis (O-methyloxime ) (6) could be hydrolysed to the parent triketone (4a), but it resisted deprotection with cetyltrimethylammonium permanganate. Reaction of the triketone (4a) with 1 mole of 4-anisidine in the presence of 4-toluenesulfonic acid resulted in retro Michael cleavage with formation of 3-(4′-methoxyphenyl)amino-2-methylcyclopent-2-en-1-one (1).

Some oxidation products of lycoctonine revisited

2006 ◽  
Vol 84 (9) ◽  
pp. 1167-1173 ◽  
Author(s):  
Doaa Abdelrahman ◽  
Michael Benn ◽  
Ryan Hellyer ◽  
Masood Parvez ◽  
Oliver E Edwards
Keyword(s):  
Oxidation Product ◽  
Chromic Acid ◽  
Oxidation Products ◽  
Acid Oxidation ◽  
Lithium Aluminium Hydride ◽  
X Ray ◽  
X Ray Crystallography ◽  
Chromic Acid Oxidation ◽  
Lithium Aluminium ◽  
Norditerpenoid Alkaloid

The structure of a chromic acid oxidation product of the norditerpenoid alkaloid lycoctonine (1) was established as hydroxylycoctonal (3) by spectrometric analyses and X-ray crystallography of its reduction product, hydroxylycoctonine (5); the structure of lycoxonine, a chromic acid oxidation product of the lactam, lycoctonam (7), was similarly confirmed as N-ethyl-4,7,8-trihydroxy-1α,6β,14α,16β-tetramethoxy-19-oxoaconitane (8). Reduction of lycoxonine with lithium aluminium hydride gave the 1,14-di-O-methyl ether (12) of the bisnorditerpenoid alkaloid delbine (9).Key words: norditerpenoid, bisnorditerpenoid, alkaloids, lycoctonine, lycoctonam, hydroxylycoctonal, lycoxonine. 1,14-di-O-methyldelbine, semisynthesis.

Assembly of C-propyl-pyrogallol[4]arene with bipyridine-based spacers and solvent molecules

2020 ◽  
Vol 75 (4) ◽  
pp. 341-345
Author(s):  
Xiao-Li Liu ◽  
Jing-Long Liu ◽  
Hong-Mei Yang ◽  
Ai-Quan Jia ◽  
Qian-Feng Zhang
Keyword(s):  
Mixed Solvent ◽  
Polymer Structure ◽  
Brick Wall ◽  
Two Dimensional ◽  
One Dimensional ◽  
X Ray ◽  
X Ray Crystallography ◽  
Wave Trough ◽  
Hydrogen Bonding Networks ◽  
Solvent Molecules

AbstractCo-crystallization of C-propyl-pyrogallol[4]arene (PgC3) with 4,4′-bipyridine (bpy) in ethanol afforded a multi-component complex (PgC3) · 3(bpy) ·(EtOH) (1) that consists of a one-dimensional brick-wall framework, which was formed by four pyrogallol[4]arene molecules and two juxtaposed bpy molecules, entrapping two other bpy molecules as guests within each cavity. Heating a mixture of PgC3 and trans-1,2-bis-(4-pyridyl)ethylene (bpe) in an ethanol-water mixed solvent allowed the isolation of a multi-component complex (PgC3) ·(bpe) · 2(EtOH) ·(H2O) (2), which has a two-dimensional wave-like polymer structure with the bpe molecules embedded in the wave trough between two PgC3 molecules. Single-crystal X-ray crystallography was utilized to investigate the hydrogen bonding networks of the multi-component complexes 1 and 2.

scholarly journals Low-Zpolymer sample supports for fixed-target serial femtosecond X-ray crystallography

2015 ◽  
Vol 48 (4) ◽  
pp. 1072-1079 ◽  
Author(s):  
Geoffrey K. Feld ◽  
Michael Heymann ◽  
W. Henry Benner ◽  
Tommaso Pardini ◽  
Ching-Ju Tsai ◽  
...  
Keyword(s):  
Protective Antigen ◽  
Three Dimensional ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Fixed Target ◽  
X Ray ◽  
X Ray Crystallography ◽  
Transmission Electron ◽  
Linac Coherent Light Source ◽  
Efficient Alternative

X-ray free-electron lasers (XFELs) offer a new avenue to the structural probing of complex materials, including biomolecules. Delivery of precious sample to the XFEL beam is a key consideration, as the sample of interest must be serially replaced after each destructive pulse. The fixed-target approach to sample delivery involves depositing samples on a thin-film support and subsequent serial introductionviaa translating stage. Some classes of biological materials, including two-dimensional protein crystals, must be introduced on fixed-target supports, as they require a flat surface to prevent sample wrinkling. A series of wafer and transmission electron microscopy (TEM)-style grid supports constructed of low-Zplastic have been custom-designed and produced. Aluminium TEM grid holders were engineered, capable of delivering up to 20 different conventional or plastic TEM grids using fixed-target stages available at the Linac Coherent Light Source (LCLS). As proof-of-principle, X-ray diffraction has been demonstrated from two-dimensional crystals of bacteriorhodopsin and three-dimensional crystals of anthrax toxin protective antigen mounted on these supports at the LCLS. The benefits and limitations of these low-Zfixed-target supports are discussed; it is the authors' belief that they represent a viable and efficient alternative to previously reported fixed-target supports for conducting diffraction studies with XFELs.

Synthesis, Characterization and Crystal Structure of Coordination Polymers Developed as Anion Receptor

2018 ◽  
Vol 273 ◽  
pp. 134-139
Author(s):  
M.A. Kadir ◽  
Christopher J. Sumby
Keyword(s):  
Coordination Polymer ◽  
Coordination Polymers ◽  
Cadmium Nitrate ◽  
Two Dimensional ◽  
Anion Receptor ◽  
Slow Evaporation ◽  
One Dimensional ◽  
X Ray ◽  
X Ray Crystallography ◽  
Good Potential

Reaction of diamide ligand, namelyN,N’-2,6-bis (4-pyridylmethyl) pyridine dicarboxamide (L) with cadmium nitrate and cadmium perchlorate has given rise to the formation of two types coordination polymers. Compound (CP1-Cd) with formula molecule {[Cd (L)2(H2O)2](NO3)2·6H2O}nis a one-dimensional coordination polymer while compound (CP2-Cd), with formula molecule {[Cd (L)2(H2O)2](ClO4)2·31⁄2H2O.CH3OH}n, is a two dimensional coordination polymer. These coordination polymers were preparedviaslow evaporation methods and completely characterized by combination of solid state techniques such as Fourier Transform Infrared (FTIR) spectroscopy, elemental analysis and X-ray crystallography. This study revealed that coordination polymers derived fromN,N’-2,6-bis (4-pyridylmethyl) pyridine dicarboxamide can accommodate anions with different sizes, showing good potential as anion receptor.

Tuning of crystallization method and ligand conformation to give a mononuclear compound or two-dimensional SCO coordination polymer based on a new semi-rigid V-shaped bis-pyridyl bis-amide ligand

2020 ◽  
Vol 76 (5) ◽  
pp. 412-418
Author(s):  
Xiaoyun Hao ◽  
Yong Dou ◽  
Tong Cao ◽  
Lan Qin ◽  
Lu Yang ◽  
...  
Keyword(s):  
Coordination Polymer ◽  
Single Crystal ◽  
Rational Design ◽  
High Spin State ◽  
Structure Type ◽  
Two Dimensional ◽  
Thermally Induced ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ligand Conformation

With the new semi-rigid V-shaped bidentate pyridyl amide compound 5-methyl-N,N′-bis(pyridin-4-yl)benzene-1,3-dicarboxamide (L) as an auxiliary ligand and the FeII ion as the metal centre, one mononuclear complex, bis(methanol-κO)bis[5-methyl-N,N′-bis(pyridin-4-yl)benzene-1,3-dicarboxamide-κN]bis(thiocyanato-κN)iron(II), [Fe(SCN)2(C19H16N4O2)2(CH3OH)2] (1), and one two-dimensional coordination polymer, catena-poly[[[bis(thiocyanato-κN)iron(II)]-bis[μ-5-methyl-N,N′-bis(pyridin-4-yl)benzene-1,3-dicarboxamide-κ2 N:N′]] methanol disolvate dihydrate], {[Fe(SCN)2(C19H16N4O2)2]·2CH3OH·2H2O} n (2), were prepared by slow evaporation and H-tube diffusion methods, respectively, indicating the effect of the method of crystallization on the structure type of the target product. Both complexes have been structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray crystallography. The single-crystal X-ray diffraction analysis shows that L functions as a monodentate ligand in mononuclear 1, while it coordinates in a bidentate manner to two independent Fe(SCN)2 units in complex 2, with a different conformation from that in 1 and the ligands point in two almost orthogonal directions, therefore leading to a two-dimensional grid-like network. Investigation of the magnetic properties reveals the always high-spin state of the FeII centre over the whole temperature range in 1 and a gradual thermally-induced incomplete spin crossover (SCO) behaviour below 150 K in 2, demonstrating the influence of the different coordination fields on the spin properties of the metal ions. The current results provide useful information for the rational design of functional complexes with different structure dimensionalities by employing different conformations of the ligand and different crystallization methods.

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