Wilzbach tritiation studies. I. Isotope distribution in tritium-labelled anthranilic acid, isopropanol and phenyl allyl ether

1965 ◽  
Vol 18 (3) ◽  
pp. 297 ◽  
Author(s):  
JL Garnett ◽  
SW Law ◽  
AR Till
Keyword(s):  
Anthranilic Acid ◽  
Claisen Rearrangement ◽  
Total Activity ◽  
Hydroxyl Group ◽  
Allyl Ether ◽  
Radical Mechanism ◽  
Isotope Distribution ◽  
Hydrogen Position ◽  
Radiation Induced ◽  
Distribution Studies

Isotope distribution studies with anthranilic acid labelled by the Wilzbach method indicate that positions 3 and 5 have respectively 49.8% and 27.4% of the total activity, tritium incorporation thus tending to be highest at the most electronegative positions. In isopropanol the hydroxyl group contains approximately three times as much isotope as at any other hydrogen position, while tritiation of the secondary C-H is slightly more efficient than the primary C-H. In the tritiation of phenyl ally1 ether, the predominant process is polymerization after reasonable exposure time, little radiation-induced Claisen rearrangement or saturation of the double bond being observed. A free radical mechanism has been proposed to account for the above distributions which have also been compared with results obtained by catalytic exchange. From these model compounds the relative preparative applicability of the Wilzbach and catalytic techniques has been discussed.

scholarly journals Ring-closing-metathesis-based synthesis of annellated coumarins from 8-allylcoumarins

2018 ◽  
Vol 14 ◽  
pp. 2991-2998 ◽  
Author(s):  
Christiane Schultze ◽  
Bernd Schmidt
Keyword(s):  
Double Bond ◽  
Olefin Metathesis ◽  
Claisen Rearrangement ◽  
Allylic Oxidation ◽  
Allyl Ether ◽  
Ring Closing Metathesis ◽  
Wittig Olefination

8-Allylcoumarins are conveniently accessible through a microwave-promoted tandem Claisen rearrangement/Wittig olefination/cyclization sequence. They serve as a versatile platform for the annellation of five- to seven-membered rings using ring-closing olefin metathesis (RCM). Furano-, pyrano-, oxepino- and azepinocoumarins were synthesized from the same set of precursors using Ru-catalyzed double bond isomerizations and RCM in a defined order. One class of products, pyrano[2,3-f]chromene-2,8-diones, were inaccessible through direct RCM of an acrylate, but became available from the analogous allyl ether via an assisted tandem catalytic RCM/allylic oxidation sequence.

scholarly journals Tyrosinase-Immobilized Biosensor Based on the Functionalized Hydroxyl Group-MWNT and Detection of Phenolic Compounds in Red Wines

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Ji-Hoon Yang ◽  
Jae-Chan Lee ◽  
Seong-Ho Choi
Keyword(s):  
Phenolic Compounds ◽  
Graft Polymerization ◽  
Phosphate Buffer Solution ◽  
Hydroxyl Group ◽  
Multiwall Carbon Nanotube ◽  
Hydroxyethyl Methacrylate ◽  
Red Wines ◽  
Buffer Solution ◽  
Radiation Induced ◽  
Multiwall Carbon

The tyrosinase-immobilized biosensor was developed with the hydroxyl group-functionalized multiwall carbon nanotube (MWNT) for phenol detection. The hydroxyl group-modified MWNT was modified to include poly(GVPB)-g-MWNT, or poly(HEMA), by a radiation-induced graft polymerization of glucosyl 4-vinylphenylboronate (GVPB) or 2-hydroxyethyl methacrylate (HEMA) on the surface of MWNT. The response of biosensor was in the range of 0.6–7.0 mM for concentration and in the range of 0.05–0.35 mM for phenol in a phosphate buffer solution, respectively. Various parameters influencing biosensor performance have been optimized: for pH, temperature, and the response to various phenolic compounds. The biosensor was then tested on phenolic compounds contained in three different commercial red wines.

Cotton/Polyester Blends with Improved Dyeability and Physical Performance via Gamma Rays

1976 ◽  
Vol 46 (10) ◽  
pp. 747-751 ◽  
Author(s):  
H. I. Nasr ◽  
M. H. Etman ◽  
E. A. El-Karadly
Keyword(s):  
Tensile Strength ◽  
Gamma Rays ◽  
Radical Mechanism ◽  
Acid Dyes ◽  
Elongation At Break ◽  
Wrinkle Resistance ◽  
Free Radical Mechanism ◽  
Radiation Induced ◽  
Additional Improvement ◽  
Resistance Performance

A cotton/polyester blend is radiation-grafted with a copolymer (allylamine + acrylic acid) to varied add-ons at different doses of Co-60 gamma rays. The amphoteric character imparted to this radiation-chemically-treated blend is due to the fixation of carboxyl and amino groups on the polyester and cotton cellulose chains by a radiation-induced free-radical mechanism. The treated blend acquires new remarkable dyeing affinity towards basic and acid dyes, to which originally both the untreated blend components have no affinity. Hence, dyeing the blend with a single dye, to a desirable solid color, by a one-bath process is feasible. Moreover, an additional improvement in the wrinkle-resistance performance of the treated blended fabrics is recorded, due to the formation of crosslinks between the components chains, accompanied by a significant increase in tensile strength and elongation-at-break. Parameters investigated during this work are radiation dose (0.2–1.6 Mrad for 1/2 to 4 h), composition of treating monomer solutions, effect of pH, and role of neutralizing acids. Textile evaluations reported are visual dyeing affinity, crease-recovery, tensile strength, and elongation-at-break.

Microwave-assisted Claisen Rearrangement of 1-Allyloxy-4-hydroxybenzene in the Presence of Metal Salt

2021 ◽  
Vol 07 ◽  
Author(s):  
Fumiyoshi Ozaki ◽  
Yutaka Okada
Keyword(s):  
Alkali Metal ◽  
Lewis Acid ◽  
Claisen Rearrangement ◽  
Metal Salt ◽  
Alkali Metal Salt ◽  
Metal Salts ◽  
Hydroxyl Group ◽  
Microwave Assisted ◽  
Ethereal Oxygen

: Microwave-assisted Claisen rearrangement of allyloxybenzene with a hydroxyl group was conducted in the presence of metal salts. The rearrangement was promoted in the presence of an alkali metal salt, because the reaction substrate was converted to a phenoxide-type ion, which can efficiently absorb microwaves. In contrast, a Lewis acid was strongly coordinated to the ethereal oxygen, and this structure could also absorb microwaves efficiently.

The carbon analogue of the claisen rearrangement of phenyl allyl ether

Tetrahedron ◽  
1966 ◽  
Vol 22 (2) ◽  
pp. 385-391 ◽  
Author(s):  
W. von E Doering ◽  
R.A. Bragole
Keyword(s):  
Claisen Rearrangement ◽  
Allyl Ether

Biosynthesis of isochorismate in Klebsiella pneumoniae: origin of O-2

1991 ◽  
Vol 37 (4) ◽  
pp. 276-280 ◽  
Author(s):  
Lolita O. Zamir ◽  
Kenneth A. Devor ◽  
Roy A. Jensen ◽  
Robert Tiberio ◽  
Françoise Sauriol ◽  
...  
Keyword(s):  
Amino Acids ◽  
Natural Products ◽  
Mass Spectra ◽  
Biosynthetic Pathway ◽  
Fast Atom Bombardment ◽  
Claisen Rearrangement ◽  
Aromatic Amino Acids ◽  
Hydroxyl Group ◽  
Chorismic Acid ◽  
Important Branch

The shikimate metabolites are key precursors to a large number of natural products, including aromatic amino acids. Chorismic acid is an important branch point in the biosynthetic pathway to aromatic amino acids. Chorismic acid is also unique among natural products since it is the only compound known to undergo an enzymatic Claisen rearrangement. A metabolite of chorismic acid, isochorismic acid, first observed in Aerobacter aerogenes differs in its chemical structure by the location of the hydroxyl group and the double bonds. Isochorismic acid is a precursor to a growing number of shikimate-derived metabolites. Isochorismic acid has also been postulated to be an intermediate of m-carboxyaromatic amino acids, implying another enzymatic Claisen rearrangement. In this publication, we have isolated isochorismate synthase and found that on lyophilization the enzyme is stable for at least 6 months at −20 °C. Incubation of chorismate with this preparation in water enriched with 18O led to incorporation of one atom of 18O as proven from the fast atom bombardment mass spectra of the HPLC purified derived isochorismate. Key words: chorismate, isochorismate, rearrangement, H218O, isochorismate synthetase.

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