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.

Ring Contractions of 3-Azido-4H-quinolizin-4-ones and 3-Azido-4H-azino[1,2 - x]pyrimidin-4-ones: a Novel Approach to 3-Aminoindolizines and their Aza Analogues

2008 ◽  
Vol 61 (2) ◽  
pp. 107 ◽  
Author(s):  
Simon Rečnik ◽  
Anton Meden ◽  
Branko Stanovnik ◽  
Jurij Svete
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Trifluoroacetic Anhydride ◽  
Reaction Products ◽  
Thermal Transformations ◽  
X Ray Diffraction ◽  
Ring Contraction ◽  
X Ray ◽  
Novel Approach

Thermal transformations of 3-azido-4H-quinolizin-4-ones 4a,b and 3-azido-4H-azino[1,2–x]pyrimidin-4-ones 4c,d, available from the corresponding heteroarylamines 2a–d, were studied. The reaction products were mostly dependent on the solvent. Thus, heating of 3-azido-1-cyano-4H-quinolizin-4-one (4a) in toluene afforded 2-(pyridin-2-yl)fumaronitrile 5a, whereas 3-amino-1-cyano-4H-quinolizin-4-one (8) was obtained on treatment of 4a in a mixture of toluene and trifluoroacetic anhydride. However, heating of 4a in acetic anhydride and in acetic acid resulted in a ring contraction to produce 3-(diacetylamino)indolizine-1-carbonitrile 6a and 3-(acetylamino)indolizine-1-carbonitrile 7a, respectively. Similarly, ring contractions took place on heating ethyl 3-azido-4-oxo-4H-quinolizin-1-carboxylate 4b and 3-azido-4H-azino[1,2–x]pyrimidin-4-ones 4c,d in acetic anhydride or acetic acid to produce the N-acetylated 3-aminoindolizine derivatives 6b, 7b and 3-aminoimidazo[1,2–x]azine derivatives 6c,d in 30–89% yields. The structures of compounds 5–8 were determined by NMR spectroscopy and X-ray diffraction.

scholarly journals Tautomerisation in 1-(4-Methylphenylazo)naphthalen-2-ol and 2-(4-Methylphenylazo)-4-methylphenol: A Crystallographic and 13C{1H}NMR Study

1999 ◽  
Vol 23 (3) ◽  
pp. 178-179
Author(s):  
Wendy I. Cross ◽  
Kevin R. Flower ◽  
Robin G. Pritchard
Keyword(s):  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Resonant Frequency ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Study ◽  
Acetic Acid Esters ◽  
Acid Esters ◽  
Equivalent Carbon

The acetic acid esters of 1-(4-methylphenylazo)naphthalen-2-ol 1 and 2-(4-methylphenylazo)-4-methylphenol 3 are prepared and characterised by single crystal X-ray diffraction studies and 13C{1H}NMR spectroscopy; the position of the C(2)13C resonance for the ester is used to predict the position of resonant frequency of the equivalent carbon in the parent alcohols and hence, calculate the position of the azo-hydrazone equilibrium in these compounds.

Protodeborylation of Triorganoboranes

2008 ◽  
Vol 63 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Ezzat Khan ◽  
Rhett Kempe
Keyword(s):  
Molecular Structure ◽  
Acetic Acid ◽  
Nmr Spectroscopy ◽  
Gas Phase ◽  
Appreciable Amount ◽  
Reaction Conditions ◽  
X Ray ◽  
Nmr Parameters ◽  
C Nmr

Protodeborylation of triorganoboranes, usually carried out under mild reaction conditions using an excess of acetic acid, affords 1,5-dialkyl-3,7-dimethyl-4,8,9-trioxa-2,6-dioxonia-1,5-diboratabicyclo [3.3.1]nona-2,6-dienes OB(R)OC(Me)OB(R)OC(Me)O [1 (R = Et), 2 (R = cyclooctyl)]. Acetoxy(dialkyl) boranes and di(acetoxy)alkylboranes were not formed in an appreciable amount. Compounds 1 and 2 were characterized by NMR spectroscopy (1H, 11B, 13C NMR) in solution, the molecular structure of 2 was determined by X-ray analysis. The gas-phase geometry of 1 was optimized by calculations [B3LYP/6-311+G(d, p) level of theory], and its NMR parameters were also calculated at the same level of theory.

scholarly journals Alkylation and 1,3-Dipolar Cycloaddition of 6-Styryl-4,5-dihydro-2H-pyridazin-3-one: Synthesis of NovelN-Substituted Pyridazinones and Triazolo[4,3-b]pyridazinones

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Souad Mojahidi ◽  
Hanan Sekkak ◽  
El Mostapha Rakib ◽  
Maria G. P. M. S. Neves ◽  
Maria A. F. Faustino ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Dipolar Cycloaddition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nitrile Imines ◽  
C Nmr

Some newN-substituted pyridazinones and triazolo[4,3-b]pyridazinones were synthesized, respectively, by simple alkylation and 1,3-dipolar cycloaddition of pyridazin-3-one with nitrile imines. The regioselectivity of the reactions was ascertained by1H,13C NMR spectroscopy and X-ray diffraction of the synthesized compounds.

scholarly journals Nitration of Chitin Monomer: From Glucosamine to Energetic Compound

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7531
Author(s):  
Hui Dou ◽  
Yuxuan Zheng ◽  
Manyi Qu ◽  
Peng Chen ◽  
Chunlin He ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Nitric Acid ◽  
Nmr Spectroscopy ◽  
Acetic Anhydride ◽  
Elemental Analysis ◽  
Specific Impulse ◽  
Solid Propellants ◽  
X Ray Diffraction ◽  
X Ray ◽  
Energetic Compound

The nitration of chitin monomer in a mixture of nitric acid and acetic anhydride was conducted and a highly nitrated (3R,4R,6R)-3-acetamido-6-((nitrooxy)methyl)tetrahydro-2H-pyran-2,4,5-triyl trinitrate (1) was obtained. Its structure was fully characterized using infrared spectroscopy, NMR spectroscopy, elemental analysis, and X-ray diffraction. Compound 1 possesses good density (ρ: 1.721 g·cm−3) and has comparable detonation performance (Vd: 7717 m·s−1; P: 25.6 GPa) to that of nitrocellulose (NC: Vd: 7456 m·s−1; P: 23 GPa; Isp = 239 s) and microcrystalline nitrocellulose (MCNC; Vd: 7683 m·s−1; P: 25 GPa; Isp = 250 s). However, Compound 1 has much lower impact sensitivity (IS: 15 J) than the regular nitrocellulose (NC; IS: 3.2 J) and MCNC (IS: 2.8 J). Compound 1 was calculated to exhibit a good specific impulse (Isp: 240 s), which is comparable with NC (Isp: 239 s) and MCNC (Isp: 250 s). By replacing the nitrocellulose with Compound 1 in typical propellants JA2, M30, and M9, the specific impulse was improved by up to 4 s. These promising properties indicate that Compound 1 has a significant potential as an energetic component in solid propellants.

The structures of indoiyl(alkoxy)carbenium tetrafluoroborates: a new class of highly stabilized carbenium ions

1989 ◽  
Vol 44 (6) ◽  
pp. 659-665 ◽  
Author(s):  
Ulf Pindur ◽  
Ludwig Pfeuffer ◽  
Camran Flo ◽  
Werner Massa ◽  
Karin Seitz
Keyword(s):  
Crystal Structure ◽  
Nmr Spectroscopy ◽  
Crystalline State ◽  
X Ray Diffraction ◽  
Carbenium Ions ◽  
X Ray ◽  
Axial Chirality ◽  
New Class ◽  
Charge Distributions ◽  
C Nmr

The conformations of and charge distributions in indolyl(alkoxy)carbenium tetrafluoroborates 2, a new class of highly stabilized carbenium ions, were investigated by 1H and 13C NMR spectroscopy and the crystal structure of indol-3-yl(methoxy)phenylcarbenium tetrafluoroborate (2e) was determined by X-ray diffraction methods. The phenyl-substituted cation of 2e exhibits axial chirality in the crystalline state

scholarly journals Crystal structure of 2-(2,6-diisopropylphenyl)-N,N-diethyl-3,3-dimethyl-2-azaspiro[4.5]decan-1-amine: a diethylamine adduct of a cyclic(alkyl)(amino)carbene (CAAC)

2021 ◽  
Vol 77 (9) ◽  
Author(s):  
Roxanne A. Naumann ◽  
Joseph W. Ziller ◽  
Allegra L. Liberman-Martin
Keyword(s):  
Crystal Structure ◽  
Nmr Spectroscopy ◽  
Title Compound ◽  
Lithium Diisopropylamide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compound C ◽  
Lithium Diethylamide ◽  
C Nmr

The structure of the title compound, C27H46N2, at 93 K has monoclinic (P21/n) symmetry. The title compound was prepared by treatment of 2-(2,6-diisopropylbenzene)-3,3-dimethyl-2-azaspiro[4.5]dec-1-en-2-ium hydrogen dichloride with two equivalents of lithium diethylamide. Characterization of the title compound by single-crystal X-ray diffraction and 1H and 13C NMR spectroscopy is presented. Formation of the diethylamine adduct of the cyclic(alkyl)(amino)carbene (CAAC) was unexpected, as deprotonation using lithium diisopropylamide results in free CAAC formation.

Partial Reduction of the N–O Functions of Partially Deprotonated Bis(hydroxylamine) Complexes

2009 ◽  
Vol 64 (10) ◽  
pp. 1208-1212
Author(s):  
Patrick Bösing ◽  
Hans-Georg Stammler ◽  
Norbert W. Mitzel
Keyword(s):  
Nmr Spectroscopy ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Elemental Analysis ◽  
Titanium Tetrachloride ◽  
Partial Reduction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amine Function ◽  
C Nmr

The reduction of a partially deprotonated bishydroxylamine complex {(tBu2Ga)2[cyclo-ON(Me)(CH2)2- (Me)NO][HON(Me)(CH2)2(Me)(H)NO]} with a reagent composed of titanium tetrachloride and methyllithium leads to the reduction of one of the N-O groups to an amine function affording the salt {(tBu2Ga)[cyclo- ON(H)(Me)(CH2)2NHMe]}+ {tBu2GaCl2}−. This has been characterised by 1H and 13C NMR spectroscopy, by elemental analysis and by single crystal X-ray diffraction, showing the neutral amine/hydroxylamine ligand to be present in its tautomeric aminoxide form. The molecules form hexameric cyclic aggregates by N-H···Cl hydrogen bonds.

Phenyl-Induced 3,1,11-Rearrangement in the Synthesis of Mixed Pyrrolyl/Dicarbollide Cobaltadicarbaboranes

1997 ◽  
Vol 62 (8) ◽  
pp. 1263-1272 ◽  
Author(s):  
Josep Bertran ◽  
Clara Viñas ◽  
Sílvia Gomez ◽  
Mouad Lamrani ◽  
Francesc Teixidor ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phenyl Rings ◽  
C Nmr

Mixed pyrrolide cobaltadicarbollides have been prepared from the reaction involving potassium pyrrolide, anhydrous CoCl2 and the [7,8-(C6H5)2-nido-7,8-C2B9H10]- anion in dimethoxyethane. An alternative and higher-yield route consists in the reaction between 1,2-(C6H5)2-closo-1,2-C2B10H10 and potassium pyrrolide in the presence of anhydrous CoCl2. As confirmed by the X-ray diffraction analysis of [3-(η5-NC4H4)-1,11-(C6H5)2-closo-3,1,11-CoC2B9H9], the phenyl rings were found to enhance the rearrangement of the metallacarborane cluster carbons to produce the 3,1,11-isomer instead of the expected 3,1,2-derivative. As suggested by 1H and 13C NMR spectroscopy, the electron-withdrawing properties and steric requirements of the phenyl rings facilitate the rearrangement.

scholarly journals Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides

2020 ◽  
Vol 16 ◽  
pp. 1820-1829
Author(s):  
Vladimir P Rybalkin ◽  
Sofiya Yu Zmeeva ◽  
Lidiya L Popova ◽  
Valerii V Tkachev ◽  
Andrey N Utenyshev ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Uv Irradiation ◽  
Molecular Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Highly Efficient ◽  
Shift Reaction ◽  
Photoinduced Rearrangement ◽  
C Nmr

2-Benzo[b]thienyl fulgides and fulgimides containing bulky diphenylmethylene substituents were synthesized in the form of their ring-opened E- or Z-isomers. In contrast to the majority of known fulgides/fulgimides, that form colored ring-closed structures under UV irradiation, the obtained compounds undergo an irreversible transformation leading to decoloration of their solutions. This rearrangement with the formation of the dihydronaphthalene core appeared to be by 2–3 orders of magnitude more efficient than for the known diphenylmethylene(aryl(hetaryl))fulgides. The molecular structures of E- and Z-isomers and of products of the photoinduced rearrangement completed by 1,5-H shift reaction, 3a,4-dihydronaphtho[2,3-c]furans(pyrroles) C, were established based on the data of 1H and 13C NMR spectroscopy and X-ray diffraction studies.

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