Biosynthesis of Corydaline and of Ochotensimine

1974 ◽  
Vol 52 (15) ◽  
pp. 2818-2831 ◽  
Author(s):  
H. L. Holland ◽  
M. Castillo ◽  
D. B. MacLean ◽  
Ian D. Spenser
Keyword(s):  
Carbon Atom ◽  
Schmidt Reaction ◽  
Methyl Group ◽  
Exocyclic Methylene ◽  
Bridge Carbon ◽  
Methylene Group

Radioactivity from [3-14C]tyrosine and from [methyl-14C]methionine is incorporated nonrandomly into predicted positions of corydaline and ochotensimine in Corydalissolida and C. ochotensis, respectively. The methyl group of methionine supplies the C-methyl group of corydaline and the exocyclic methylene group of ochotensimine, as well as the "bridge" carbon atom and the exocyclic O- and N-attached one-carbon units of each alkaloid. Maintenance of the 3H/14C ratio of [methyl-3H,14C]methionine within these units of corydaline is consistent with incorporation of intact CH3 groups.Partial loss of 3H relative to 14C is observed in the course of a Schmidt reaction of [2-3H, 2-14C] acetate.

scholarly journals Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XXXVIII [1]. [4+5]-Cycloaddition von 2,3-Dimethyl-1,3-butadien an Tricarbonyl- η5-2,4-pentadienyl-mangan und Tricarbonyl-η5-dimethyl-2,4-pentadienyl-mangan / Hindered Ligand Motions in Transition Metal Complexes, XXXVIII [1]. [4+5] Cycloaddition of 2,3-Dimethyl-1,3-butadiene to Tricarbonyl(η5 -2 ,4 -pentadienyl)manganese and Tricarbonyl(η5 -2 ,4 -dimethyl-2 ,4 -pentadienyl)manganese

1991 ◽  
Vol 46 (7) ◽  
pp. 941-949 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Klaus Lehr ◽  
Gerhard Heeb
Keyword(s):  
Transition Metal Complexes ◽  
Ambient Conditions ◽  
Temperature Dependent ◽  
Hindered Rotation ◽  
Methyl Group ◽  
X Ray ◽  
H Nmr ◽  
Primary Products ◽  
Exocyclic Methylene ◽  
Methylene Group

Tricarbonyl(η5-2,4-pentadienyl)manganese (1) and tricarbonyl(η5-2,4-dimethyl-2,4-pentadienyl)manganese (2) photochemically add 2,3-dimethyl-1,3-butadiene (3). Mediated by manganese, 6,7-dimethyl-2,6-cyclononadiene-1-yl and 1,3,6,7-tetramethyl-2,6-cyclononadiene-1-yl complexes are formed. Η-shifts from the methyl groups of the substituted CC double bonds convert the primary products into tricarbonyl-η3:CH-l-methylene-2-methyl-6-cyclononen-2-ylmanganese (4), and tricarbonyl-η3:CH-1-methylene-2,5,7-trimethyl-6-cyclononen-2-yl-manganese (6), respectively. In addition tetracarbonyl-η3-1-methylene-2-methyl-6-cyclononen-2-yl-manganese (5), and tetracarbonyl-η3-1-methylene-2,5,7-trimethyl-6-cyclononen-2-ylmanganese (7) are obtained. The latter are also formed from 4 and 6 by addition of CO under ambient conditions. In the complexes 4 and 6 the hydrocarbon ligands are coordinated by enyl units, encompassing C 1, C2, and the exocyclic methylene group, and by a C-H-Mn 2-electron-3-center bond of the 2-methyl group to the manganese. They exhibit temperature dependent 1H NMR spectra due to a hindered rotation of the 2-methyl group with a barrier of activation of AG* = 40-43 kJ ·mol -1. There is evidence for an equilibrium of the complexes 4 and 6 with the isomers tricarbonyl-η3:CH-1-methylene-2-methyl-5-cyclononen-2-yl-manganese (4′), and tricarbonyl-η3:CH-1-methylene-2,5,7-trimethyl-5-cyclononen-2-yl-manganese (6′). At higher temperatures the isomers 4, 4′ and 6, 6′ are interconverted by a 1,4-H shift with a barrier of activation of AG* = 75 kJ · mol-1. The crystal and molecular structure of 4 was determined by X-ray structure analysis. The constitutions of the complexes 4-7 were deduced from IR and 1H NM R spectra.

The biosynthesis of ephedrine

1989 ◽  
Vol 67 (6) ◽  
pp. 998-1009 ◽  
Author(s):  
Gunnar Grue-Sørensen ◽  
Ian D. Spenser
Keyword(s):  
Carbon Atom ◽  
Benzoic Acid ◽  
Pyruvic Acid ◽  
Nmr Spectra ◽  
Carbon Skeleton ◽  
Resonance Spectroscopy ◽  
Methyl Group ◽  
Acid Incorporation ◽  
Group A ◽  
C Nmr

It is shown by 13C nuclear magnetic resonance spectroscopy that the labelled C2 fragment of [2,3-13C2]pyruvic acid is transferred intact into the C-methyl group and the adjacent carbon atom of the Ephedra alkaloids, norephedrine, ephedrine, norpseudoephedrine, and pseudoephedrine, in growing plants of Ephedragerardiana. This finding serves to identify pyruvate as the elusive precursor of the aliphatic C2 terminus of the skeleton of the alkaloids. In earlier experiments with C-labelled substrates, label from [3-14C]pyruvic acid was incorporated mainly, but not exclusively, into the C-methyl group of ephedrine, and label from [2-14C]pyruvate was incorporated similarly into the carbon atom adjacent to the C-methyl group. A C6–C1 unit related to benzaldehyde or benzoic acid has long been known to generate the benzylic fragment of the carbon skeleton of the Ephedra alkaloids. It is likely that the carbon skeleton of ephedrine is generated from pyruvate and either benzaldehyde or benzoic acid, by a reaction analogous to the formation of acetoin or diacetyl from pyruvate and acetaldehyde or acetic acid, respectively. Keywords: biosynthesis of ephedrine, Ephedra alkaloids, 13C NMR spectra, ephedrine, biosynthesis of pyruvic acid, incorporation into ephedrine13C NMR spectra.

Theory of oxygenated polymers with bridge carbon atom. The electronic structure

1997 ◽  
Vol 85 (1-3) ◽  
pp. 1139-1140
Author(s):  
O.A. Ponomarev ◽  
E.S. Shikhovtseva
Keyword(s):  
Electronic Structure ◽  
Carbon Atom ◽  
Bridge Carbon

scholarly journals Relation between Crystal Structures of Precursors and Final Products: Example of Vitamin D Intermediates

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1802
Author(s):  
Monika Wanat ◽  
Maura Malinska ◽  
Andrzej Kutner ◽  
Krzysztof Woźniak
Keyword(s):  
Vitamin D ◽  
Crystal Structures ◽  
Theoretical Calculations ◽  
Geometrical Parameters ◽  
Space Groups ◽  
Vitamin D Analogues ◽  
Vitamin D Analog ◽  
Exocyclic Methylene ◽  
Solid Form ◽  
Methylene Group

In this paper, we proved that the solid-state structure of vitamin D analog is well represented by the structures of its structural fragments. This is important in predicting the biological activity of vitamin D analogs that are not available in the solid form. The previously published crystal structure of advanced vitamin D intermediate provided additional insights into vitamin D properties. A similar analysis based on simple vitamin D intermediate analogues showed that precursors crystallized in the space groups typical for vitamins D; geometrical parameters were related to the corresponding parameters in the vitamin D analogues; and crystal structures of the basic intermediates and their final products contained similar intermolecular interactions, essential for the infinite hydrogen bond motif observed in the vitamin D analogues. The energy of these interactions is related as shown by theoretical calculations, that is, energy frameworks analysis. Moreover, analysis of the hydrogen bonds motifs revealed a relation between these motifs and the absolute configuration of basic intermediates as well as the space orientation of the exocyclic methylene group in the final structures.

THE STRUCTURE AND STEREOCHEMISTRY OF ATISINE

1964 ◽  
Vol 42 (1) ◽  
pp. 137-149 ◽  
Author(s):  
D. Dvornik ◽  
O. E. Edwards
Keyword(s):  
Long Range ◽  
Rigorous Proof ◽  
Polar Groups ◽  
Detailed Explanation ◽  
Exocyclic Methylene ◽  
Derivatives Of ◽  
Methylene Group ◽  
Absolute Stereochemistry ◽  
Basic Strength

A stereospecific hydration of the exocyclic methylene group of a derivative of the alkaloid atisine has been observed. The product was used to degrade the alkaloid to a tetracyclic phenol. This enabled rigorous proof of the structure and relative and absolute stereochemistry of atisine and related alkaloids. A detailed explanation of the abnormal basic strength and the isomerization of atisine is given. Long-range influence of polar groups on the basic strength of derivatives of the alkaloid is reported.

The stereospecific hydrogenation of an exocyclic methylene group

1966 ◽  
pp. 128 ◽  
Author(s):  
J. E. Anderson ◽  
F. G. Riddell ◽  
J. P. Fleury ◽  
J. Morgen
Keyword(s):  
Exocyclic Methylene ◽  
Methylene Group

The Origin of the Unusual C4ν Structure Predicted for SH4

1994 ◽  
Vol 47 (8) ◽  
pp. 1431 ◽  
Author(s):  
CJ Marsden ◽  
BA Smart
Keyword(s):  
Carbon Atom ◽  
Theoretical Calculations ◽  
Structural Parameters ◽  
Binding Energies ◽  
Molecular Orbital Calculations ◽  
Electrostatic Model ◽  
Net Charge ◽  
Methyl Group ◽  
Steric Factors ◽  
Net Charges

Ab initio molecular orbital calculations have been performed on C2v and C4v isomers of SH4, SF4 and S(CH3)4 to investigate the origin of the different structures adopted by these molecules. We propose an electrostatic model similar in spirit to the VSEPR approach; this implies that the net charges on the ligands L in SL4 compounds can control the geometry of these compounds. Steric factors may also be significant. Even though the net charges on hydrogen and on the CH3 group are similar when these act as ligands towards sulfur, the carbon atom in the methyl group bears a substantial negative net charge, which has important structural consequences. Binding energies and structural parameters are presented for SH4 which are obtained from more complete theoretical calculations than those previously reported.

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