Approaches to the synthesis of triterpenes. V. An unusual acid-catalysed rearrangement of a β,γ-unsaturated ketone

1978 ◽  
Vol 56 (16) ◽  
pp. 2150-2155 ◽  
Author(s):  
John W. ApSimon ◽  
Satyanand Badripersaud ◽  
Michael L. Post ◽  
Eric J. Gabe
Keyword(s):  
Least Squares ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Unsaturated Ketone ◽  
Geometric Features ◽  
Space Group ◽  
Positional Disorder ◽  
Block Diagonal

The reaction of 2-keto-1β,4aβ-dimethyl-1α-[2-(3-keto-1,4,4-trimethylcyclohexyl)ethyl]-7-methoxy-1,2,3,4,4a,9-hexahydrophenanthrene 1a and b with p-toluenesulphonic acid in boiling xylene yields the rearranged product, 1,10-dimethyl-2-[2-(3-keto-1,4,4-trimethylcyclohexyl)-ethyl]-7-methoxy-3,4-dihydroanthracene (3). Crystals of 3 are monoclinic, space group P21/c, Z = 4, with a = 7.2684(3), b = 30.942(2), c = 10.5544(7) Å, β = 98.24(1)°. The structure was determined by direct methods from diffractometer data and refined by block-diagonal least-squares to an R of 0.043 for 1810 observed reflections. The molecule exhibits no unusual geometric features, although positional disorder is apparent in the cyclohexanone moiety.A possible route for the formation of 3 from 1a and b is presented.

scholarly journals Synthesis and Molecular Structure of cis-Tetracarbonyl[N-(diphenylphosphino-kP)-naphthalen-1-yl-P,P-diphenylphosphinous amide-kP]chromium(0)

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Harbi Tomah Al-Masri
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Direct Methods ◽  
Molar Ratio ◽  
Planar Geometry ◽  
Monoclinic Space Group ◽  
Full Matrix ◽  
Space Group ◽  
Distorted Octahedral ◽  
Least Squares Techniques

The reaction of N,N-bis(diphenylphosphanyl)naphthylamine C10H7-1-N(PPh2)2 with (C5H10NH)2Cr(CO)4 (1 : 1 molar ratio) in dichloromethane afforded cis-[Cr(CO)4{C10H7-1-N(PPh2)2}] (1). This complex was crystallized in the monoclinic space group P21/n. The structure was solved by direct methods and refined by full-matrix least squares techniques to an R factor of 0.0313 for 6488 observed reflections. The Cr-metal is coordinated by four terminal CO molecules and a P,P′-bidentate N,N-bis(diphenylphosphanyl)naphthylamine ligand in a distorted octahedral array. The N-atom adopts a planar geometry with the two P-atoms and C-atom attached to it. The four-membered metallacycle ring P2CrN is nearly planar.

The crystal and molecular structure of 1α,9β-Dichloro-2,2,10,10-tetramethoxy[2,2](2,6)pyridinophane

1978 ◽  
Vol 31 (9) ◽  
pp. 1953 ◽  
Author(s):  
D Taylor
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Title Compound ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Maximum Deviation ◽  
Asymmetric Unit ◽  
Space Group ◽  
Block Diagonal

Crystals of the title compound, C18H20Cl2N2O4, are monoclinic, a 14.706(1), b 17.168(1), c 7.269(1) Ǻ, β 92.72(1)°, space group P21/c with Z = 4. The structure was solved from diffractometer data by direct methods. Block-diagonal least-squares refinement converged at R 0.037, Rw 0.045 for 2103 reflections with I ≥ 3σ(I) which had been corrected for absorption (μ 34.0 cm-1). The asymmetric unit is comprised of two independent half-molecules, each molecule being centrosymmetric. The pyridine rings are distorted from planarity, with a maximum deviation of 0.10 Ǻ at the nitrogen atoms, as a consequence of the short intramolecular N...N contacts of 2.476(4) and 2.473(5) Ǻ.

The crystal structure of N-[[6-methoxy-5-(trifluoromethyl)thio-1-naphthalenyl]thioxomethyl]-N-methylglycine, C16H14F3NO3S2

1983 ◽  
Vol 61 (9) ◽  
pp. 2137-2140 ◽  
Author(s):  
Kottayil I. Varughese ◽  
Maria Przybylska ◽  
Kazimir Sestanj ◽  
Francesco Bellini ◽  
Leslie G. Humber
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Least Squares ◽  
Attractive Interaction ◽  
Monoclinic Space Group ◽  
Intermolecular Hydrogen Bonds ◽  
Space Group ◽  
Block Diagonal ◽  
Oxygen Atoms

The crystals of C16H14F3NO3S2 belong to the monoclinic space group P21/c with a = 11.577(1), b = 12.404(1), c = 12.366(1) Å, β = 90.01(1)°, and Z = 4. The structure was solved by MULTAN 78. The parameters were refined by block-diagonal least-squares to a final R of 0.047 for 2679 observed reflections. Of particular interest is an intramolecular attractive interaction between the sulfur and oxygen atoms with an [Formula: see text] distance of 2.879(2) Å, in which oxygen appears to act as an electrophile. Intermolecular hydrogen bonds between the hydroxyl and keto groups join the molecules related through a centre of symmetry into dimers.

Crystal structures of two lactones of the bicyclo[2,2,2]octane series

1982 ◽  
Vol 35 (2) ◽  
pp. 457 ◽  
Author(s):  
RM Carman ◽  
SS Smith ◽  
CHL Kennard ◽  
G Smith ◽  
AH White ◽  
...  
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Three Dimensional ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
X Ray ◽  
A Cell

The crystal structures of two γ-lactones of the bicyclo[2,2,2]octane series, endo-3-carboxy-exo-5- iodobicyclo[2,2,2]octane-2,6-carbolactone (2; R = CO2H) and exo-3-methoxycarbonyl-endo-5-acetoxybicyclo[2,2,2] octane-2,6-carbolactone (7b), have been determined by direct methods from three-dimensional X-ray data and refined by least-squares to final residuals of 0.033 (2; R = CO2H) and 0.036 (7b) for 1918 and 630 'observed' reflections respectively. Crystals for (2; R = CO2H) are monoclinic, space group P21/c with Z 8 in a cell of dimensions a 7.192(2), b 23.785(8), c 13.199(5) �, β 105.35(2)�, while (7b) crystallizes in the orthorhombic space group P212121 with Z 4 in a cell of dimensions a 13.347(7), b 11.839(7), c 8.227(11) �.

scholarly journals Tetra-n-butylammoniumdicyanoaurat(I), (n-C4H9)4NAu(CN)2 / Tetra-n-butylammonium Dicyanoaurate(I), (n-C4H9)4NAu(CN)2

1990 ◽  
Vol 45 (8) ◽  
pp. 1118-1122 ◽  
Author(s):  
R. J. Schubert ◽  
K.-J. Range
Keyword(s):  
Least Squares ◽  
Single Crystals ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Calculated Density ◽  
Space Group ◽  
Computer Controlled ◽  
R Factors ◽  
Measured Density

Single crystals of (n-C4H9)4NAu(CN)2 were obtained by crystallization using the temperature decreasing method in a newly developed computer-controlled apparatus. The colourless crystals are monoclinic, space group A2/n, with a = 20.216(2) Å, b = 13.130(1) Å, c = 9.328(1) Å, and β = 109.69(1)°. The measured density is 1.45 g/cm3, which agrees with the calculated density of 1.40 g/cm3 for Ζ = 4. The structure was solved by Direct Methods using 674 independent reflections and refined by least-squares procedures to conventional and weighted R factors of 0.068 and 0.058, respectively. The nearly linear [Au(CN)2]--anions form pseudohexagonal layers, in which they are arranged parallel to each other. The shortest Au—Au distance is 8.05 A. The stacking of the layers produces pseudo-trigonal channels, occupied by the cations. The tetra-n-butylammonium cation has four ordered trans chains with idealized D2d symmetry (4̄2 m).

The reaction of tetrasulphur dinitride with norbornadiene; the crystal and molecular structure of S4N2•C7H8, an eight-membered C2S4N2 heterocycle

1983 ◽  
Vol 61 (6) ◽  
pp. 1185-1188 ◽  
Author(s):  
Hans Koenig ◽  
Richard T. Oakley ◽  
A. Wallace Cordes ◽  
Mark C. Noble
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Dihedral Angle ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Crystallographic Analysis ◽  
Monoclinic Space Group ◽  
Full Matrix ◽  
Space Group ◽  
X Ray

The reaction of tetrasulphur dinitride with norbornadiene produces the 1:1 adduct S4N2•C7H8; X-ray crystallographic analysis of this compound reveals that olefin addition cleaves one of the sulphur–sulphur bonds of S4N2, yielding a novel eight-membered C2S4N2 ring. Crystals of S4N2•C7H8 are monoclinic, space group P21/c, a = 6.127(1), b = 17.369(1), c = 9.580(1) Å, β = 106.74(1)°, V = 1003.8(5) Å3Z = 4. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.039. The S—S—N—S—N—S fragment of the C2S4N2 ring is planar to within 0.15 Å. The S—C—C—S unit is folded out of this plane to produce a dihedral angle of 74.5°.

The Crystal and Molecular Structure of the Adduct Formed by the Reaction of Tributylphosphine and p-Chlorobenzylidenemalononitrile

1973 ◽  
Vol 51 (16) ◽  
pp. 2794-2798 ◽  
Author(s):  
George Ferguson ◽  
Colin Alan Fyfe ◽  
Wayne Clifford Marsh
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Phosphorus Atom ◽  
Negative Charge ◽  
Positive Charge ◽  
Crystal And Molecular Structure ◽  
Direct Methods ◽  
Space Group ◽  
Block Diagonal

Crystals of the 1:1 adduct of tributylphosphine with p-chlorobenzylidenemalononitrile are monoclinic, a = 13.719(2), b = 12.557(5), c = 14.229(3) Å, β = 110.59(2)°, Z = 4, space group P21/c. The structure was determined with diffractometer data by direct methods and refined by block-diagonal least-squares calculations to R = 0.10 for 1405 observed reflections. The structure is zwitterionic with the positive charge localized on the phosphorus atom and the negative charge mainly on the terminal —C(CN)2 group.

Studies in aryltin chemistry. Part 6. Crystal and molecular structures of tetra(p-methylsulphonylphenyl)tin(IV) and tetra(p-methylsulphinylphenyl)tin(IV) monohydrate

1990 ◽  
Vol 68 (8) ◽  
pp. 1277-1282 ◽  
Author(s):  
Ivor Wharf ◽  
Michel G. Simard ◽  
Henry Lamparski
Keyword(s):  
Least Squares ◽  
Crystal Structures ◽  
Direct Method ◽  
Molecular Structures ◽  
Water Molecules ◽  
Monoclinic Space Group ◽  
Molecular Symmetry ◽  
Asymmetric Unit ◽  
Full Matrix ◽  
Space Group

Tetrakis(p-methylsulphonylphenyl)tin(IV) and tetrakis(p-methylsulphinylphenyl)tin(IV) n-hydrate have been prepared and their spectra (ir 1350–400 cm−1; nmr, 1H, 13C, 119Sn) and X-ray crystal structures are reported. The first compound is monoclinic, space group C2/c, Z = 4, with a = 21.589(6), b = 6.207(3), c = 22.861(11) Å, β = 93.80(3)° (22 °C); the structure was solved by the direct method and refined by full-matrix least squares calculations to R = 0.043 for 2755 observed reflections. It has 2 molecular symmetry with the methyl group and one oxygen atom completely disordered in both CH3S(O2) groups in the asymmetric unit. The second compound is tetragonal, space group P42/n, Z = 2, with a = b = 15.408(6), c = 6.379(2) Å (−100 °C); the structure was solved by the Patterson method and refined by full-matrix least squares calculations to R = 0.060 for 1209 observed reflections. It has [Formula: see text] molecular symmetry with the whole asymmetric unit disordered. Water molecules occupy positions on parallel 42 axes but molecular packing requirements prevent all sites having 100% occupancy giving n ~ 1 for the hydrate. Keywords: Tetra-aryltins, crystal structures, sulphone, sulphoxide, hydrogen-bonding.

Structure of 3α,4α:5β,6β-Diepoxyandrostan-17-one

1983 ◽  
Vol 36 (11) ◽  
pp. 2333 ◽  
Author(s):  
B Kamenar ◽  
RA Pauptit ◽  
JM Waters
Keyword(s):  
Crystal Structure ◽  
Title Compound ◽  
Direct Methods ◽  
Monoclinic Space Group ◽  
Space Group ◽  
X Ray

The X-ray crystal structure of 3α,4α:5β,6β-diepoxyandrostan-17-one has been determined. Crystals of the title compound (C19H26O3)are monoclinic, space group P21, with a 9.208(2), b 9.620(4), c 9.312(3) �, β 99.14(2)�, V 814.5 Ǻ3 and Z 2. The structure was solved by direct methods and refined to R 0.039 for 887 observed reflexions. The 3α,4α:5β,6β configuration of the epoxide rings confirms the assignment based on proton n.m.r. studies.

The crystal and molecular structure of 1,1-bis(diphenylphosphino)-2,2-dimethylhydrazine

1976 ◽  
Vol 54 (5) ◽  
pp. 738-743 ◽  
Author(s):  
J. Brian Faught
Keyword(s):  
Molecular Structure ◽  
Least Squares ◽  
Crystal And Molecular Structure ◽  
Unit Cell ◽  
Space Group ◽  
Block Diagonal

The structure of 1,1-bis(diphenylphosphino)-2,2-dimethylhydrazine, [(C6H5)2P]2NN(CH3)2 has been determined crystallographically. The compound crystallizes from n-heptane in the space group P21/c with a = 8.910(1), b = 9.686(1), c = 27.489(4) Å, and β = 102.94(2)° with four molecules per unit cell. The structure was solved from 2669 independent reflections with I > 3σ(I) and refined by block diagonal least squares methods to R = 0.032 and Rω = 0.048. Each diphenylphosphino group is bonded to the same hydrazine nitrogen and the geometry about this nitrogen is nearly planar. The average dimensions of the structure are P—C = 1.828 ± 0.005, P—N = 1.715 ± 0.014, N—N = 1.451, and N—C = 1.457 ± 0.003 Å, [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text].

Sign in / Sign up

Export Citation Format

Share Document