The chemistry of pyrrolic compounds. LVII. The oxidative cyclization of derivatives of 1,19-dideoxybilenes-b

1984 ◽  
Vol 37 (10) ◽  
pp. 2085 ◽  
Author(s):  
PS Clezy ◽  
Lv Thuc
Keyword(s):  
Carbon Atom ◽  
Basic Mechanism ◽  
Ring System ◽  
Oxidative Cyclization ◽  
The Other ◽  
Terminal Position ◽  
Methyl Group ◽  
Derivatives Of

A study of the oxidative cyclization of 13C-labelled bilenes-b substituted with a methyl group at one terminal position and a formyl equivalent at the other, e.g. (1), has clearly established that the methyl group provides the carbon atom to complete the ring system. The basic mechanism of this reaction is discussed.

BEZIEHUNGEN ZWISCHEN SUBSTITUTION IM RING A UND ABBAU IM STOFFWECHSEL BEI VERWANDTEN DES TESTOSTERONS

1962 ◽  
Vol 41 (4) ◽  
pp. 494-506 ◽  
Author(s):  
H. Langecker
Keyword(s):  
Double Bond ◽  
Ring System ◽  
Keto Group ◽  
Hydroxyl Group ◽  
Methyl Group ◽  
Structural Peculiarities ◽  
Metabolic Degradation ◽  
The Difference ◽  
Testosterone Metabolites ◽  
Derivatives Of

ABSTRACT Judging from the metabolites found in the urine, 1-methyl-androst-1-en-17β-ol-3-one (methenolone) and testosterone are metabolized in a different manner. For further clarification, other derivatives of testosterone with modifications in Ring A were investigated with regard to the oxidation of the 17-hydroxyl group. The production of urinary 17-ketosteroids decreased in the following sequence: testosterone; 1α-methyltestosterone and androstan-17β-ol-3-one; 1β-methyl-androstan-17β-ol-3-one; 2α-methyl-androstan-17β-ol-3-one and androst-1-en-17β-ol-3-one; 1α-methyl-androstan-17β-ol-3-one; 1-methyl-androsta-1,4-dien-17β-ol-3-one; 1,17α-dimethyl-androst-1-en-17β-ol-3-one and 1 -methyl-androst-1 -en-17β-ol-3-one (methenolone). The difference in metabolic degradation is also demonstrated in the fractionation of the urinary ketones. While after the administration of testosterone practically only hydrogenated 17-ketones are observed in the urine, the unchanged compound is still traceable in remarkable quantities after the administration of methenolone, along with minor quantities of the corresponding diketone. Testosterone-metabolites here are absent, whereas they represent the major substances present after the administration of androst-1-en-17β-ol-3-on. Following the administration of 1α-methyltestosterone only hydrogenated 17-ketones are detected which are still partly methylated. The 1-methyl-group and the Δ 1-double-bond seem to be responsible for the inhibition of the oxidation of methenolone in the 17-position. In addition, the hydrogenation of the double-bond and the reduction of the 3-keto-group are inhibited, obviously on account of the same structural peculiarities. The demethylation of methenolone is also inhibited. Any change in the steroid ring system forms a new substrate, thus producing new conditions for the enzymatic attack in the metabolic degradation.

Two New Reagents for the Fluorescence Derivatization of NH and OH Containing Compounds

1983 ◽  
Vol 38 (2) ◽  
pp. 248-250 ◽  
Author(s):  
Reinhold Wintersteiger ◽  
Otto S. Wolfbeis
Keyword(s):  
Ring Closure ◽  
The Other ◽  
Fluorescence Derivatization ◽  
Methyl Group ◽  
Derivatives Of

Abstract The synthesis of three new reagents, namely the bromomethyl derivatives of a pyrano-[3,2-c]benzopyran (2b) and of 11H-pyrido[1,2-b]quinazolin-11-one (3b, d) is described. Introduction of the reactive bromomethyl group was accomplished in one case (2 b) by a ring closure reaction using ethyl y-chloroacetoacetate, and in the other cases (3 b, d) by bromination of a methyl group using N-bromosuccinimide. 2 b is suitable for the derivatization of barbiturates, whilst 3d reacts with oxygen nucleophiles like alcohols, phenols or carboxylates.

Natural and Synthetic Rubber. XIV. A Structural Formula for Ebonite

1934 ◽  
Vol 7 (3) ◽  
pp. 520-524
Author(s):  
Thomas Midgley ◽  
Albert L. Henne ◽  
A. F. Shepard
Keyword(s):  
Carbon Atom ◽  
Structural Formula ◽  
The Other ◽  
Pyrolysis Products ◽  
Methyl Group ◽  
Synthetic Rubber ◽  
The One ◽  
Natural And Synthetic

Abstract A formula for ebonite has been proposed, where sulfur is linked to a carbon atom bearing a methyl group on the one side and to the next third carbon atom of the rubber chain on the other side This formula is based on a consideration of the pyrolysis products of ebonite.

Thio derivatives of β-diketones and their metal chelates. II. α-Substituted Monothio-β-diketones as ligands

1965 ◽  
Vol 18 (12) ◽  
pp. 1927 ◽  
Author(s):  
RKY Ho ◽  
SE Livingstone ◽  
TN Lockyer
Keyword(s):  
Carbon Atom ◽  
Metal Complexes ◽  
Infrared Spectra ◽  
Steric Hindrance ◽  
Metal Chelates ◽  
Methyl Group ◽  
Central Carbon Atom ◽  
Complexing Ability ◽  
Central Carbon ◽  
Derivatives Of

The α-methyl substituted monothio-β-diketones, 4-mercapto-3-methylpent-3-en-2-one, MeC(SH)=C(Me)COMe, and 3-mercapto-2-methyl-1,3-diphenylprop-2-en-1-one, PhC(SH)=C(;Me)COPh, were prepared; the former was not obtained pure. The complexing ability of these ligands appears to be weaker than that of other monothio-β-diketones; this can be partly explained on the basis of steric hindrance caused by the methyl group attached to the central carbon atom. The diamagnetic complexes, Ni(MeCS=CMeCOMe)2, Co(MeCS=CMeCOMe)3, and Ni(PhCS=CMeCOPh)2 were obtained but attempts to prepare other metal complexes of these ligands were unsuccessful. The infrared spectra of the three metal chelates display four characteristic bands for which assignments are given: 1570-1540 cm-1, v(C--C); 1525-1500 cm-1, v(C-0); 1230-1223 cm-1, v(C--8); 497-458 cm-1, v(M-0).

Synthesis of tridentate amine Pt(II) complexes and study of their reactions with purine and pyrimidine bases

1994 ◽  
Vol 72 (5) ◽  
pp. 1225-1229
Author(s):  
Fernande D. Rochon ◽  
Guylaine Laperrière
Keyword(s):  
The Other ◽  
New Method ◽  
Direct Reaction ◽  
Chloro Complexes ◽  
Methyl Group ◽  
Alkyl Groups ◽  
Nmr Techniques ◽  
Pyrimidine Bases ◽  
The One ◽  
Derivatives Of

Complexes of the type [Pt(L)X] where L is a tridentate N ligand and X = Cl or I, were synthesized and characterized. Three of the ligands are N-derivatives of diethylenetriamine, (2-aminoethyl)(N-dimethyl-2-aminoethyl)amine, (2-aminoethyl)(N-diethyl-2-aminoethyl)amine, and (2-aminoethyl)(N-methyl-2-aminoethyl)N-methylamine. The other two ligands are di(3-amino-propyl)amine and (2-aminoethyl)(3-aminopropyl)amine. A new method for the synthesis of the chloro complexes from the direct reaction of the amine with K2[PtCl4] was developed. The reactions of these five compounds with several purine and pyrimidine bases were studied by NMR techniques. The Pt(II) complexes containing two five-membered chelates were shown to be more reactive than the one containing two six-membered rings, while the complex containing one five- and one six-membered chelates showed intermediate reactivity. For the diethylenetriamine derivatives, the complexes containing ligands with two alkyl groups on the same terminal N atom were more reactive than the one containing one methyl group on a terminal N atom and one methyl group on a non-terminal N atom.

Energy Approximation

2017 ◽  
Author(s):  
Philip Isett
Keyword(s):  
Main Lemma ◽  
The Other ◽  
Coarse Scale ◽  
Continuous Solutions ◽  
Material Derivative ◽  
Energy Variation ◽  
Energy Approximation ◽  
The Difference ◽  
Derivatives Of

This chapter presents the equations and calculations for energy approximation. It establishes the estimates (261) and (262) of the Main Lemma (10.1) for continuous solutions; these estimates state that we are able to accurately prescribe the energy that the correction adds to the solution, as well as bound the difference between the time derivatives of these two quantities. The chapter also introduces the proposition for prescribing energy, followed by the relevant computations. Each integral contributing to the other term can be estimated. Another proposition for estimating control over the rate of energy variation is given. Finally, the coarse scale material derivative is considered.

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.

scholarly journals Stereoselective total syntheses of (±)-sinularene and (±)-5-epi-sinularene: a general intramolecular Diels–Alder approach to tricyclic sesquiterpenes

1985 ◽  
Vol 63 (4) ◽  
pp. 993-995 ◽  
Author(s):  
Kazimierz Antczak ◽  
John F. Kingston ◽  
Alex G. Fallis
Keyword(s):  
Double Bond ◽  
Methyl Ester ◽  
Total Synthesis ◽  
Ring System ◽  
Diels Alder ◽  
Exocyclic Double Bond ◽  
Total Syntheses ◽  
Methyl Group ◽  
Secondary Hydroxyl ◽  
Selective Hydrogenolysis

Stereoselective total synthesis of (±)-sinularene and (±)-5-epi-sinularene are described. The sequence employs a "blocked" cyclopentadiene in which the cyclopropane unit also serves as a latent methyl group. Thus intramolecular [4 + 2] cycloaddition of the substituted methyl spiro[2.4]hepta-4,6-dien-1-yl)-2-pentenoate 11 affords 5-benzyloxy-6-isopropyl-8-carbomethoxytetracyclo[5.4.01,7.02,4.02,9]undec-10-ene (12) which after selective hydrogenolysis generates the tricyclo[4.4.01,6.02,8]decane (sinularene) ring system. Removal of the secondary hydroxyl function (Ph3P/CCl4/CH3CN; H2/Pd/C), reduction of the methyl ester (LiAlH4), and introduction of the exocyclic double bond (acetate pyrolysis, 550 °C) completes the synthesis of (±)-sinularene in 14 steps from cyclopentadiene. A parallel series of reactions employing the isopropyl epimer of 12 affords (±)-5-epi-sinularene.

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