Structural studies of N-(2′-substituted phenyl)-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximides by X-ray diffraction and NMR spectroscopy—proofs for CH/π interactions in liquid and solid phases

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

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

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19912917 ◽

1991 ◽

Vol 56 (12) ◽

pp. 2917-2935 ◽

Cited By ~ 1

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.

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Unusual Rearrangement of Naphthalene in the Synthesis of a Novel B8-B8-Bridged Derivative in the [(1,2-C2B9H11)2-3-Co]- Series. X-Ray Structure and 11B NMR Spectra of [8,8'-μ-(CH2-C9H6)-(1,2-C2B9H10)2-3-Co]- (CH3)4N+

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19970746 ◽

1997 ◽

Vol 62 (5) ◽

pp. 746-751 ◽

Cited By ~ 7

Author(s):

Andreas Franken ◽

Jaromír Plešek ◽

Christiane Nachtigal

Keyword(s):

Nmr Spectroscopy ◽

Single Crystal ◽

Nucleophilic Substitution ◽

Nmr Spectra ◽

X Ray Diffraction ◽

X Ray ◽

Unusual Rearrangement ◽

Multinuclear Nmr Spectroscopy ◽

11B Nmr ◽

Isolated Compound

On treatment of the [(1,2-C2B9H11)2Co]- ion with naphthalene in presence of AlCl3 a remarkably bridged [8,8'-μ-(CH2-C9H6)-(1,2-C2B9H10)2-3-Co]- ion is obtained as a single isolated compound. The triatomic -CH2-C9H6- bridge is derived from the rearranged naphthalene nucleus. The mechanism of this reaction is obscure but it does resemble the "Electrophile-Induced Nucleophilic Substitution" reported earlier. The structure of the compound was established by multinuclear NMR spectroscopy and by single crystal X-ray diffraction.

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Ten-Vertex Polyhedral Monocarbaborane Chemistry. The Novel High-Yield Formation of the Ten-Vertex closo Compound [6-(PMe2Ph)-closo-1-CB9H9] from the Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11]

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19932924 ◽

1993 ◽

Vol 58 (12) ◽

pp. 2924-2935 ◽

Cited By ~ 8

Author(s):

Jane H. Jones ◽

Bohumil Štíbr ◽

John D. Kennedy ◽

Mark Thornton-Pett

Keyword(s):

Nmr Spectroscopy ◽

Diffraction Analysis ◽

High Yield ◽

Monoclinic Space Group ◽

The Novel ◽

X Ray Diffraction ◽

Metal Centre ◽

X Ray ◽

Yield Formation ◽

Boiling Toluene

Thermolysis of [8,8-(PMe2Ph)2-nido-8,7-PtCB9H11] in boiling toluene solution results in an elimination of the platinum centre and cluster closure to give the ten-vertex closo species [6-(PMe2Ph)-closo-1-CB9H9] in 85% yield as a colourles air stable solid. The product is characterized by NMR spectroscopy and single-crystal X-ray diffraction analysis. Crystals (from hexane-dichloromethane) are monoclinic, space group P21/c, with a = 903.20(9), b = 1 481.86(11), c = 2 320.0(2) pm, β = 97.860(7)° and Z = 8, and the structure has been refined to R(Rw) = 0.045(0.051) for 3 281 observed reflections with Fo > 2.0σ(Fo). The clean high-yield elimination of a metal centre from a polyhedral metallaborane or metallaheteroborane species is very rare.

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