The biosynthesis of the new tremulane sesquiterpenes isolated from Phellinustremulae

1997 ◽  
Vol 75 (6) ◽  
pp. 834-839 ◽  
Author(s):  
Elizabete R. Cruz
Keyword(s):  
Spectral Analysis ◽  
Sodium Acetate ◽  
Labelling Pattern ◽  
Farnesyl Pyrophosphate ◽  
Fungal Metabolites ◽  
Methyl Group ◽  
Liquid Cultures ◽  
C Nmr

The tremulane sesquiterpenes isolated from the wood-rotting fungus Phellinustremulae are irregular isoprenoids derived from the cyclization and rearrangement of farnesyl pyrophosphate (FPP). The most interesting feature in the formation of the tremulane skeleton seems to involve the migration of a methyl group from one of the isoprene units. To investigate the biosynthetic origin of this unique sesquiterpene skeleton, labelling experiments were carried out by adding 13C-labelled sodium acetate to liquid cultures of Phellinustremulae. The labelling pattern was determined by 13C NMR spectral analysis of labelled tremulenediol A, which was purified as its di-p-bromobenzoate. A possible route to the tremulane skeleton, which accounts for the observed labelling pattern, proceeds from FPP, via humulene. The stereochemical course of the tremulane biosynthesis is discussed. Keywords: fungal metabolites, aspen, perhydroazulene sesquiterpenes, labelling experiments.

Synthesis and characteristics of ethylenediamine-N,N'-di-S-α-isovalerate and isomers of its cobalt(III) complexes

1982 ◽  
Vol 47 (1) ◽  
pp. 210-216 ◽  
Author(s):  
Milan Strašák ◽  
František Bachratý ◽  
Jaroslav Majer
Keyword(s):  
Amino Acids ◽  
Absolute Configuration ◽  
Electronic Absorption ◽  
Electronic Absorption Spectra ◽  
Chemical Parameters ◽  
Methyl Group ◽  
Nmr Data ◽  
Physico Chemical ◽  
Natural Amino Acids ◽  
C Nmr

The synthesis and physico-chemical parameters are described of a new complexone based on natural amino acids, viz. ethylenediamine-N,N'-di-S-α-isovalerate (SS-EDDIV). 1H- and 13C-NMR data revealed that the methyl group in the substance are not equivalent. The isomers of the cobalt(III) complex with the asymmetric tetradentate SS-EDDIV ligand were prepared and separated; their characteristics are given. The absolute configuration of two of the five theoretically feasible isomers was determined based on their electronic absorption spectra and circular dichroism data.

A New Dimeric Derivative of Ethoxyquin from Its Reaction with Alkylperoxy Radicals

1993 ◽  
Vol 58 (8) ◽  
pp. 1914-1918 ◽  
Author(s):  
Jaroslav Kříž ◽  
Luděk Taimr
Keyword(s):  
Mass Spectrometry ◽  
Nmr Spectroscopy ◽  
Peroxy Radicals ◽  
Methyl Group ◽  
Alkylperoxy Radicals ◽  
C Nmr

The structure of a new compound formed in the reaction of ethoxyquin with alkylperoxy radicals was resolved by 1H and 13C NMR spectroscopy (including COSY, NOESY, HHC RCT and SSLR INEPT techniques) and confirmed by mass spectrometry. The structure suggest participation of 4-methyl group of ethoxyquin in the deactivation of peroxy radicals. A mechanism of this reaction is proposed.

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.

The rotational barrier for methyl group dynamics in anhydrous sodium acetate

2002 ◽  
Vol 74 (0) ◽  
pp. s1351-s1353
Author(s):  
A.J. Moreno ◽  
A. Alegr�a ◽  
J. Colmenero ◽  
B. Frick
Keyword(s):  
Group Dynamics ◽  
Sodium Acetate ◽  
Rotational Barrier ◽  
Anhydrous Sodium Acetate ◽  
Methyl Group ◽  
Methyl Group Dynamics

scholarly journals Synthesis of Some Novel Fused Imidazo [2, 1-b] [1, 3] Thiazole and Imidazo [2, 1-b] Thiazolo [5, 4-d] Isoxazole Derivatives

2012 ◽  
Vol 9 (3) ◽  
pp. 1518-1525 ◽  
Author(s):  
Hamid Reza Jaberi ◽  
Hadi Noorizadeh
Keyword(s):  
Acetic Acid ◽  
Sodium Acetate ◽  
Carbon Disulphide ◽  
Thiazole Derivatives ◽  
H Nmr ◽  
Nmr Data ◽  
Elemental Analyses ◽  
New Compounds ◽  
Isoxazole Derivatives ◽  
C Nmr

In this work we describe the synthesis of some novel fused imidazo [2, 1-b] [1, 3] thiazole derivatives. The reaction of 1, 2-diaminoethane 1 with carbon disulphide in H2O/ETOH as solvent furnishes 4, 5-dihydro-1H-imidazol-2-thiol 2 under reflux condition. the reaction of 4,5-dihydro-1H-imidazol-2-thiol on treatment with ethylchloro acetate and aromatic aldehyde in presence of anhydrous sodium acetate and acetic acid as solvent to give (Z)-2-(arylidene)-5,6-dihydroimidazo [2,1-b] [1,3] thiazol-3(2H)-one 3a-j. Compounds 3a-j was condensed with hydroxylamine to give 3-(aryl)-2, 3, 6, 7-tetrahydroimidazo [2, 1-b] [1,3] thiazolo [5, 4-d] isoxazole 4a-j. The structures of the new compounds were established by elemental analyses, IR,1H NMR and13C NMR data.

scholarly journals Flavonol Triglycosides from the Leaves of Silphium Albiflorum

2006 ◽  
Vol 1 (11) ◽  
pp. 1934578X0600101 ◽  
Author(s):  
Małgorzata Wojcińska ◽  
Jeffrey Williams ◽  
Tom J. Mabry ◽  
Ahmed A. Ahmed ◽  
Barry D. Davis ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Flavonol Glycosides ◽  
H Nmr ◽  
C Nmr

In the course of chemotaxonomic studies of the genus Silphium two new and six known flavonol glycosides were isolated from the leaves of S. albiflorum. The structures of the new flavonoids were established by spectral analysis (1H NMR, 13C NMR, HMQC, HMBC, ROESY, TOCSY, MS) as isorhamnetin 3-O-α-L-rhamnosyl (1′“→6″)-O-β-D-galactopyranoside 7-O-β-D-apiofuranoside (1) and quercetin 3-O-α-L-rhamnosyl (1′“→6″)-O-β-D-galactopyranoside 7-O-β-D-apiofuranoside (2). LC-MS and LC-MSn (with post-column manganese complexation) were applied to elucidate the structures of some of the studied compounds.

Electrooxidation of 2-arylfurans

1981 ◽  
Vol 46 (4) ◽  
pp. 906-916 ◽  
Author(s):  
Miroslav Janda ◽  
Jan Šrogl ◽  
Hana Dvořáková ◽  
Dalimil Dvořák ◽  
Ivan Stibor
Keyword(s):  
Electronic Spectra ◽  
Nmr Spectra ◽  
Model Compounds ◽  
Methyl Group ◽  
C Nmr

Electrochemical methoxylation of 2-phenylfuran (I) and 2-(4-nitrophenyl)furan (VI) proceeded anomalously, affording 5-methoxy-2-phenylfuran (XI) and 5-methoxy-2-(4-nitrophenyl)furan (XIII), respectively. 2-Phenyl-5-methylfuran (II) and methyl-2-(2-methylphenyl)-3-furoate (VIII) behaved normally giving the respective 2,5-dimethoxy-2,5-dihydrofuran derivatives XII and XIV. The suggested ECNECB mechanism of the anomalous methoxylation was confirmed by methoxylation of compound II, in which the methyl group hinders the last CB step, and also of compound VIII in which the automaticity is suppressed by forced deviation from planarity. Forced deviation from planarity was moreover studied also on 2-(4-methylphenyl)furan (III), 5-methyl-2-(2-methylphenyl)furan (IV) and 3,5-dimethyl-2-(2-methylphenyl)furan (V) as model compounds. For all the derivatives the INDO charges were calculated and correlated with the 1H- and 13C-NMR spectra. The experimental electronic spectra were correlated with the theoretical ones (INDO-S-CI). All the results obtained confirm the suggested mechanism.

Acid-catalyzed rearrangements of an A(1)-nor-triterpenoid 2α,3α-epoxide

1989 ◽  
Vol 54 (2) ◽  
pp. 413-429 ◽  
Author(s):  
Jiří Klinot ◽  
Jiří Liška ◽  
Alena Forgáčová ◽  
Miloš Buděšínský ◽  
Jiří Protiva ◽  
...  
Keyword(s):  
Acidic Medium ◽  
Boron Trifluoride ◽  
Mass Spectra ◽  
Boron Trifluoride Etherate ◽  
Methyl Group ◽  
Unsaturated Alcohols ◽  
Acid Catalyzed ◽  
C Nmr

Reactions of 2α,3α-epoxide X, derived from 19β,28-epoxy-A(1)-nor-18α-oleanane, with acids proceed with migration of the 10β-methyl group into the position 2β, giving rise to unsaturated alcohols XII and XIV and diene IX. Reaction with boron trifluoride etherate afforded ketone XI in addition to XII and XIV. Olefin VIII rearranged in acidic medium to give olefins XXVI and XXVII. The rearranged products were converted into other derivatives and their structure was established by 1H and 13C NMR, IR, UV and mass spectra.

Condensation of Schiff bases with 2-oxazolin-5-ones: simultaneous introduction of arylidene and amino moieties

1982 ◽  
Vol 60 (3) ◽  
pp. 317-322 ◽  
Author(s):  
Arya K. Mukerjee ◽  
Pradeep Kumar
Keyword(s):  
Acetic Acid ◽  
Schiff Bases ◽  
Sodium Acetate ◽  
Glacial Acetic Acid ◽  
Methyl Group

Schiff bases condense with 2-oxazolin-5-ones having a C-4 methylene and/or C-2 methyl group, and the reaction in glacial acetic acid, containing freshly fused sodium acetate, produces 4-arylidene- and/or 2-styryl-2-imidazoline-5-ones as a result of simultaneous introduction of arylidene and amino moieties.

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