Assignment of Local Conformation in Medium-Ring Unsaturated Lactones Derived From Labda-8(17),14-dien-13-Ol (Manool)

1991 ◽  
Vol 44 (7) ◽  
pp. 897 ◽  
Author(s):  
PK Grant ◽  
LR Hanton ◽  
GP Lynch ◽  
J Simpson ◽  
GC Slim
Keyword(s):  
Membered Ring ◽  
Asymmetric Induction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unsaturated Lactone ◽  
Local Conformation ◽  
Unsaturated Lactones ◽  
Medium Ring

The unsaturated lactone (2) derived from manool (1) has a particularly rigid 10-membered ring which gives rise to high asymmetric induction in epoxidation with m-chloroperoxybenzoic acid. The corresponding 11-membered lactone (14) shows greater flexibility. The conformations of lactone (2) and epoxy lactones (12) and (13) have been determined by X-ray diffraction studies.

Crystal structures of medium ring compounds. Part III. The crystal and molecular structure of trans-anti-trans-4,5:9,10-biscyclohexano-1,3,6,8-tetraoxecane

1979 ◽  
Vol 57 (16) ◽  
pp. 2154-2158 ◽  
Author(s):  
Aris Terzis ◽  
T. Bruce Grindley
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Chair Conformation ◽  
Membered Ring ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ring Compounds ◽  
R Value ◽  
Medium Ring

The crystal structure of trans-anti-trans-4,5:9,10-biscyclohexano-1,3,6,8-tetraoxecane (3) has been determined by X-ray diffraction. The crystals are monoclinic, a = 11.919(3), b = 17.330(7), c = 7.019(2) Å, β = 98.91(1)°, P21/c, with Z = 4. The structure was solved by application of the tangent formula and refined by large block least squares to a final R value of 0.060 (Rw = 0.058).The ten-membered ring is present in the crystal in a twist-chair-boat-chair conformation — one which has been calculated to be relatively unstable for cyclodecane. Possible reasons why 3 adopts this conformation are discussed.

An unusual reaction of a bridged triterpenoid α-diketone with acetic anhydride

1991 ◽  
Vol 56 (12) ◽  
pp. 2917-2935 ◽  
Author(s):  
Eva Klinotová ◽  
Václav Křeček ◽  
Jiří Klinot ◽  
Miloš Buděšínský ◽  
Jaroslav Podlaha ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Spectral Methods ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mild Conditions ◽  
Condensation Products ◽  
Unsaturated Lactones ◽  
C Nmr

3β-Acetoxy-21,22-dioxo-18α,19βH-ursan-28,20β-olide (IIIa) reacts with acetic anhydride in pyridine under very mild conditions affording β-lactone IVa and γ-lactones Va and VIIa as condensation products. On reaction with pyridine, lactones Va and VIIa undergo elimination of acetic acid to give unsaturated lactones VIIIa and IXa, respectively. Similarly, the condensation of 20β,28-epoxy-21,22-dioxo-18α,19βH-ursan-3β-yl acetate (IIIb) with acetic anhydride leads to β-lactone IVb and γ-lactone Vb; the latter on heating with pyridine affords unsaturated lactone VIIIb and 21-methylene-22-ketone Xb. The structure of the obtained compounds was derived using spectral methods, particularly 1H and 13C NMR spectroscopy; structure of lactone IVa was confirmed by X-ray diffraction.

Synthesis, crystal structure and molecular conformation of (±)-1-oxoferruginol and (±)-shonanol

2004 ◽  
Vol 219 (10) ◽  
Author(s):  
Swastik Mondal ◽  
Monika Mukherjee ◽  
Arnab Roy ◽  
Debabrata Mukherjee
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Diffraction Data ◽  
Molecular Conformation ◽  
Membered Ring ◽  
Methyl Groups ◽  
Single Bond ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Structures

Abstract(±)-1-oxoferruginol and (±)-shonanol, two potential intermediates in the synthesis of tricyclic diterpenoid ferruginol, have been prepared and crystal structures of the compounds have been investigated using single-crystal X-ray diffraction data. The methyl groups of the isopropyl moiety in (±)-shonanol are disordered over two positions with occupation factors 0.65(1) and 0.35(1), respectively. Although the chemical structures of two compounds are very similar, a C—C single bond in the terminal six-membered ring of (±)-1-oxoferruginol is replaced by a C=C bond in (±)-shonanol, the quantitative isostructurality index calculations indicate that the structures are not isostructural. Intermolecular O—H…O hydrogen bonds between pairs of molecules in the compounds related by center of inversion lead to characteristic dimers forming R

scholarly journals Synthesis of Cationic Pd(II) Complexes with 5-Membered Ring Chelating Iminoylcarbene Ligand and Its Catalytic Activity on Norbornene Polymerization

2019 ◽  
Vol 31 (3) ◽  
pp. 637-641
Author(s):  
Roushown Ali ◽  
Jubaraj Chandra ◽  
Tariqul Hasan
Keyword(s):  
Catalytic Activity ◽  
Nmr Spectra ◽  
Membered Ring ◽  
Moderate Activity ◽  
13C Nmr Spectra ◽  
X Ray Diffraction ◽  
1H And 13C Nmr ◽  
X Ray ◽  
Addition Polymerization ◽  
Norbornene Polymerization

Iminoyl N-heterocyclic carbine ligand with cationic allyl Pd(II) complex (3) was successfully synthesized by transmetallation of corresponding Ag complex with one equivalent of [Pd(allyl)(COD)]+SbF6–. A slightly distorted square planer structure of the Pd(II) complex 3 was confirmed by single crystal X-ray diffraction analysis. The Pd(II) complex 3 is stable in air and found to show moderate activity in the polymerization of norbornene without any activator. The polynorbornene produced with Pd(II) complex 3 was obtained to be stable up to 440 °C. The 1H and 13C NMR spectra of the polymer indicated addition polymerization of norbornene and the presence of the vinylene group at the end of polymer chain.

The X-Ray Crystal Structure of 1,2-3,4-Di-O-isopropylidene-4-C-methylthiomethoxy-β-L-arabino-hexoseptanos-5-ulose

1990 ◽  
Vol 43 (12) ◽  
pp. 2083 ◽  
Author(s):  
DC Craig ◽  
VJ James ◽  
JD Stevens
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Membered Ring ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray

The crystal structure of the title compound (1) has been determined by X-ray diffraction. Crystals of (1) are orthorhombic, space group P21212 with a 11.425(1), b 24.916(1), c 5.8952(3)Ǻ, Z 4. Refinement on 1675 observed reflections measured with Cu Kα radiation converged at R 0.034. The seven- membered ring adopts a boat conformation in which the pseudo plane of symmetry passes through the ring oxygen.

Synthesis and characterization of the new tin borate SnB8O11(OH)4

2018 ◽  
Vol 73 (5) ◽  
pp. 337-348 ◽  
Author(s):  
Sandra Schönegger ◽  
Klaus Wurst ◽  
Gunter Heymann ◽  
Andreas Schaur ◽  
Andreas Saxer ◽  
...  
Keyword(s):  
Hydrothermal Process ◽  
Building Blocks ◽  
Membered Ring ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermoanalytical Investigations ◽  
Hydrogen Bond Interactions ◽  
Simple Hydrothermal Process

AbstractA new tin(II) borate with the composition SnB8O11(OH)4 was synthesized by a simple hydrothermal process. It crystallizes in the centrosymmetric monoclinic space group P21/n (no. 14) with the lattice parameters a=790.1(1), b=1402.2(2), c=994.8(1) pm, and β=90.40(5)° (Z=4). The new compound SnB8O11(OH)4 is isotypic to PbB8O11(OH)4 and isostructural to BaB8O11(OH)4. The borate layers are built up from fundamental building blocks (FBBs) with the composition [B8O11(OH)4]2−. Four of these FBBs form a nine-membered ring wherein the Sn2+ cations are located. These boron-oxygen layers are further connected by O–H···O hydrogen bond interactions. The characterization of SnB8O11(OH)4 is based on single-crystal X-ray diffraction data, vibrational spectroscopy, DFT calculations, and thermoanalytical investigations including high temperature powder XRD.

scholarly journals Synthesis of Trithia-Borinane Complexes Stabilized in Diruthenium Core: [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BR}] (R = H or SMe)

Inorganics ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 21 ◽  
Author(s):  
Koushik Saha ◽  
Urminder Kaur ◽  
Rosmita Borthakur ◽  
Sundargopal Ghosh
Keyword(s):  
Mass Spectrometry ◽  
1H Nmr Spectroscopy ◽  
Chair Conformation ◽  
Membered Ring ◽  
Molecular Structures ◽  
Boat Conformation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Butterfly Cluster ◽  
Tellurium Powder

The thermolysis of arachno-1 [(Cp*Ru)2(B3H8)(CS2H)] in the presence of tellurium powder yielded a series of ruthenium trithia-borinane complexes: [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BH}] 2, [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3B(SMe)}] 3, and [(Cp*Ru)2(η1-S)(η1-CS){(CH2)2S3BH}] 4. Compounds 2–4 were considered as ruthenium trithia-borinane complexes, where the central six-membered ring {C2BS3} adopted a boat conformation. Compounds 2–4 were similar to our recently reported ruthenium diborinane complex [(Cp*Ru){(η2-SCHS)CH2S2(BH2)2}]. Unlike diborinane, where the central six-membered ring {CB2S3} adopted a chair conformation, compounds 2–4 adopted a boat conformation. In an attempt to convert arachno-1 into a closo or nido cluster, we pyrolyzed it in toluene. Interestingly, the reaction led to the isolation of a capped butterfly cluster, [(Cp*Ru)2(B3H5)(CS2H2)] 5. All the compounds were characterized by 1H, 11B{1H}, and 13C{1H} NMR spectroscopy and mass spectrometry. The molecular structures of complexes 2, 3, and 5 were also determined by single-crystal X-ray diffraction analysis.

Phosphanchalkogenide und ihre Metallkomplexe. IV. Halogenierungsprodukte der Gold(I)halogenidkomplexe einiger Diphosphanmonochalkogenide

2016 ◽  
Vol 71 (3) ◽  
pp. 249-265 ◽  
Author(s):  
Christina Taouss ◽  
Peter G. Jones
Keyword(s):  
Membered Ring ◽  
Quantitative Yield ◽  
X Ray Diffraction ◽  
Central Ring ◽  
X Ray ◽  
Hydrolysis Products ◽  
Related Product ◽  
Hydrolysis Of ◽  
By Products

AbstractDiphosphanegold(I) complexes of the form dppmEAuX [dppm = bis(diphenylphosphano)methane, E = S, Se; X = Br, I], dppeEAuX [dppe = 1,2-bis(diphenylphosphano)ethane; E = O, S; X = Br, I] and dppbzEAuX [dppbz = 1,2-bis(diphenylphosphano)benzene; E = S, Se, X = Br, I] were treated with elemental X2. With dppm, the three products [dppmEAuX2]+X3– (E = S, X = Br (1), I (2); E = Se, X = I (3) were obtained in quantitative yield. These are gold(III) complexes involving a five-membered ring . With dppe, the only related product was [dppeEAuBr2]+Br3– (4), in which the central ring is six-membered with two carbon atoms. These dppe systems are very sensitive to oxidation/hydrolysis of the ligand, and several such unintended products were isolated and identified. The reaction of dppbzSAuBr with bromine leads to [dppbzS]2+[AuBr4]–Br– (5), the dication of which is formally 1,1,3,3-tetraphenylbenzo[d]-2-thia-1, 3-diphosphol-1,3-diium and contains a central five-membered ring . The dications are associated with the bromide anions via S…Br contacts of ca. 3.1 Å to form inversion-symmetric S2Br2 rings. The halogenation of the dppbzSe derivatives leads to loss of selenium and formation of dppbzAuBr3 (6), with [4+1] coordination at gold, or the known compound [dppbzAuI2]+I3– (7). All products 1–6 were subjected to X-ray diffraction analyses, as were four hydrolysis products 4a–d and two further by-products [5(thtBr+)·2Br3–·3(AuBr4–)] (1a) and (tht)AuBr3 (1b). Compound 1a displays unusually short Br…Br contacts of 3.2398(8) Å between neighbouring tetrabromidoaurate(III) ions.

Soluble Pyridine Complexes Of The Ternary Gallium(III) Chalcogenide Halides (GaEX)3, With E = S, Se And X = Cl, Br

2001 ◽  
Vol 56 (8) ◽  
pp. 711-718 ◽  
Author(s):  
Stefan D. Nogai ◽  
Annette Schier ◽  
Hubert Schmidbaur
Keyword(s):  
Single Crystal ◽  
Molecular Complexes ◽  
Membered Ring ◽  
New Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pyridine Ligands ◽  
Ring Molecules ◽  
Gallium Metal ◽  
Convenient Preparation

The four ternary gallium(III) chalcogenide halides GaEX with E = S, Se and X = Cl, Br can be prepared a) from the binary gallium(III) chalcogenides Ga2E3 and halides Ga2X6, b) from gallium(I) tetrahalogallates(III) GafGaX4] and the chalcogen E, and c) from gallium metal and the dichalcogen dihalides E2X2. The new method c) was shown to be the most convenient preparation. The products are readily soluble in pyridine to give trinuclear molecular complexes [GaEX·Py]3 which are not volatile without decomposition, but can be purified by crystallization. The structures have been determined by single crystal X-ray diffraction techniques. The two chlorides are isostructural and show twisted tub-form six-membered ring molecules with the pyridine donors in axial positions. The two bromides are also isostructural, but with the pyridine ligands in two axial and one equatorial positions

Cobalt(III) Complexes of the 10-Membered Macrocycle 1,4,7-Triazacyclodecane. The Structure of trans-Bis(1,4,7-triazacyclodecane)cobalt(III) Perchlorate

1993 ◽  
Vol 46 (12) ◽  
pp. 1955 ◽  
Author(s):  
TW Hambley ◽  
TW Hambley ◽  
GH Searle ◽  
GH Searle
Keyword(s):  
Crystal Structure ◽  
Membered Ring ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths

The crystal structure of trans-[Co( tacd )2](ClO4)3 has been determined by X-ray diffraction methods and refined to a residual of 0.054 for 2477 independent observed reflections. The crystals are monoclinic, P 21/c, a 18.627(2), b 9.3438(5), c 16.057(2)Ǻ, β 119.45(2)°. Two complex cations are located at centres of symmetry and the ligands adopt λ,δ,chair conformations. Bond lengths from cobalt to nitrogen atoms in the six- membered ring (average 1.995 Ǻ) are significantly longer than those only associated with five- membered rings (average 1.961 Ǻ).

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