Approaches to the Synthesis of Retronecine From Some Pyrrolidine Precursors

1993 ◽  
Vol 46 (6) ◽  
pp. 805 ◽  
Author(s):  
BW Clare ◽  
V Ferro ◽  
BW Skelton ◽  
RV Stick ◽  
AH White
Keyword(s):  
Structure Determination ◽  
Am1 Calculations ◽  
X Ray ◽  
Bicyclic System ◽  
Alternative Procedures ◽  
Mm2 Calculations

Procedures are described for the attempted conversion of the pyrrolidine (2) into a bicyclic system that would ultimately lead to retronecine (3). The only molecule to be isolated from these attempts was the epimeric ketone (6), and AM1 and MM2 calculations were used to probe this apparently favoured isomerization. Alternative procedures were then investigated that sought to convert the pyrrolidine (1) into precursors to retronecine, and notable successes were obtained with the addition of the amine (21) to both nitroethene and ethyl 2-diethylphosphonoacrylate. However, not only were these precursors resistant to further transformations into retronecine , but also the problem of epimerization again arose. Consequently, AM1 calculations were again employed, and an X-ray structure determination of ethyl (7R,8R)-7-benzyloxy-1-benzyloxymethyl-5,6,7,8-tetrahydro-3H-pyrrolizine-2-carboxylate (39) is reported. Attempts to convert (39) into a diastereoisomer of retronecine were unsuccessful.

Vier- und fünfgliedrige Phosphorheterocyclen, XXXVIII [1] Azaphospholo-benzoxazaphosphole - Synthese, Prototropie und Struktur / Four- and Five - membered Phosphorus Heterocycles, XXXVIII [1] Azaphospholo-benzoaxazaphospholes - Preparation, Proton Shift and Structure

1979 ◽  
Vol 34 (7) ◽  
pp. 906-910 ◽  
Author(s):  
Alfred Schmidpeter ◽  
Josef Helmut Weinmaier
Keyword(s):  
Structure Determination ◽  
Cinnamic Aldehyde ◽  
X Ray ◽  
Proton Shift ◽  
Trigonal Bipyramidal ◽  
Bicyclic Structure ◽  
Bicyclic System ◽  
Methyl Phenyl ◽  
The Ideal

Abstract The o-hydroxyanile of cinnamic aldehyde reacts with methyl, phenyl, oxy-, and aminochlorophosphanes in a combined substitution and oxidative addition to give phosphoranes with the above mentioned bicyclic structure containing phosphorus as bridgehead. For the aminosubstituted species the reaction is followed by a 1.3 proton shift in the C3 moiety from the cinnamic aldehyde. Whether the bicyclic system occupies meridional of facial positions of the phosphorus trigonal bipyramid is shown to depend on the nature of the phosphorus substituents. An X - ray structure determination of a tricyclic derivative with axial annelation shows the deviation from the ideal trigonal bipyramidal geometry to lie on the Berry pseudorotion pathway

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

scholarly journals Radical Ion Salts and Complexes, Part XVII. TCNQ Salts of 1,4-Dimethylpyridine and 2,3-Bis(1-methyl-4-pyridinio)butane

1999 ◽  
Vol 23 (3) ◽  
pp. 196-197
Author(s):  
Timothy J. Houghton ◽  
Stephen C. Wallwork
Keyword(s):  
Structure Determination ◽  
X Ray ◽  
Electrical Conductivities ◽  
Complex Salts ◽  
Radical Ion Salts

X-Ray structure determination of the complex salts [MeNC5H4Me]+[TCNQ2]- [1,4-dimethylpyridinium 2(7,7,8,8-tetracyanoquinodimethane) (1-); I] and [Me(NC5H4)(Me)CH-CH(Me)(C5H4N)Me]2+[TCNQ4]2- [ meso-2,3-bis( N-methyl-4-pyridyl)butane(2+) 4(7,7,8,8-tetracyanoquinodimethane) (2-); II], where TCNQ=(CN)2C(C6H4)C(CN)2, shows that, although in both salts the TCNQ moieties are stacked in columns, lateral shifts break these columns into diads for I and tetrads for II causing their electrical conductivities to be only moderate (Σ = 2–4 × 10−3 ohm−1 cm−1).

Syntheses, X-ray, MSn, NMR and CD structure determination of nickel(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide and aromatic α-amino acids

Polyhedron ◽  
2008 ◽  
Vol 27 (17) ◽  
pp. 3477-3483 ◽  
Author(s):  
Milan Nádvorník ◽  
Vratislav Langer ◽  
Robert Jirásko ◽  
Michal Holčapek ◽  
Tomáš Weidlich ◽  
...  
Keyword(s):  
Amino Acids ◽  
Schiff Bases ◽  
Structure Determination ◽  
X Ray ◽  
Determination Of Nickel

Theoretical Study and X-ray Structure Determination of Dimethyldihydropyrene

1998 ◽  
Vol 63 (9) ◽  
pp. 3125-3127 ◽  
Author(s):  
Richard Vaughan Williams ◽  
W. Daniel Edwards ◽  
Ashwani Vij ◽  
Robert W. Tolbert ◽  
Reginald H. Mitchell
Keyword(s):  
Structure Determination ◽  
Theoretical Study ◽  
X Ray
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