A new reaction of amino acids: conversion to benzoxazoles

Zwan, Michael C. Vander; Hartner, Frederick W.; Reamer, Robert A.; Tull, Roger

doi:10.1021/jo00397a028

Cited by 14 publications

(2 citation statements)

References 7 publications

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“…Studies by VanderZwan et al (30) have shown that the formation of benzoxazoles, which requires a 1,2-addition, appears to be specific for 3,5-disubstituted o-quinones while unsubstituted quiñones that undergo 1,4-addition remove the possibility for benzoxazole formation. Our studies have shown for the first time that 3,4-disubstituted o-quinones (such as 3,4-EQ) are also capable of benzoxazole formation.…”

Section: Resultsmentioning

confidence: 99%

Estrogen quinones: Reaction with propylamine

Khasnis¹,

Abul-Hajj

1994

Chem. Res. Toxicol.

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Reaction of propylamine with 2,3-estrone o-quinone (2,3-EQ) and 3,4-estrone o-quinone (3,4-EQ) gave a complex mixture of mostly unidentifiable products. Several reaction products were isolated and identified using spectroscopic techniques. With 3,4-EQ, both 1,2- and 1,6-Michael addition reactions were observed in which 4-hydroxyestradiol, an estrogen oxazole, and a violet compound identified as the iminoquinone adduct that was obtained by condensation of one molecule of an estrogen o-aminophenol with the 1,6-Michael addition product of propylamine to 3,4-EQ were identified. Unlike reactions of 3,4-EQ, only 1,2-Michael addition reactions were observed with 2,3-EQ leading to the formation of 2-hydroxyestradiol, two monoiminoquinone compounds, and a bisiminoquinone product.

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Section: Resultsmentioning

confidence: 99%

Estrogen quinones: Reaction with propylamine

Khasnis¹,

Abul-Hajj

1994

Chem. Res. Toxicol.

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“… The copper ion appears to be bound to the TOPA cofactor and it may serve as the site of O 2 binding in the reoxidation process. , Model studies have provided evidence that Cu(bpy) 2+ and TOPA, together, may be used to catalyze the aerobic deamination of benzylamine . Quinones, and specifically 3,5-di- tert -butyl-1,2-benzoquinone, have been used in amine and amino acid deamination reactions, although, the formation of benzoxazole side-products is often a complication . Catechols undergo condensation with ammonia to give 2-aminophenols and bis(1-hydroxyphenyl)amines .…”

Section: Introductionmentioning

confidence: 99%

Studies on Aerobic Reactions of Ammonia/3,5-Di-tert-butylcatechol Schiff-Base Condensation Products with Copper, Copper(I), and Copper(II). Strong Copper(II)−Radical Ferromagnetic Exchange and Observations on a Unique N−N Coupling Reaction

et al. 1996

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Stoichiometric quantities of 3,5-di-tert-butylcatechol and aqueous ammonia react in pyridine solution to form 2-amino-4,6-di-tert-butylphenol. Under an atmosphere of dioxygen the aminophenol is oxidized to either the corresponding iminosemiquinone or iminobenzoquinone. In the presence of Cu(II) iminosemiquinone condensation with the aminophenol gives the Cat-N-SQ radical ligand obtained as the Cu(py)2(Cat-N-SQ) complex. Metal and ligand magnetic orbitals are orthogonal and couple ferromagnetically to give a S = 1 molecular spin state at temperatures up to 300 K. In nonpolar solvents the complex undergoes ligand oxidation and disproportionation to give Cu(Cat-N-BQ)2. Crystallographic characterization on crystals obtained as the i-propanol solvate [orthorhombic, C2221, a = 19.548(3) Å, b = 24.536(5) Å, c = 23.655(5) Å, V = 11346(4) Å3, Z = 8, R = 0.068] show that the expected Jahn−Teller distortion appears in the trans Cu−O lengths of the equatorial plane rather than for the axial Cu−N lengths. Reactions carried out with both Cu(I) and Cu metal require metal oxidation to give the Cu(II) products obtained. With metallic Cu this occurs by a reaction with iminoquinone to give bis(iminosemiquinone)copper(II). Further reaction of this product with aminophenol gives Cu(py)2(Cat-N-SQ) by condensation, and, with O2, oxidation gives a coordinated azophenolate ligand in Cu(py)(azophenolate) by a unique N−N bond-forming reaction. Cu(py)(azophenolate) has been characterized crystallographically [monoclinic, P21/n, a = 10.990(2) Å, b = 10.736(3) Å, c = 26.848(4) Å, β = 98.09(1)°, V = 3136(1) Å3, Z = 4, R = 0.048].

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3,5-Di-t-butyl-1,2-benzoquinone

Horák¹,

Mermersky²

2001

Encyclopedia of Reagents for Organic Synthesis

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A new reaction of amino acids: conversion to benzoxazoles

Cited by 14 publications

References 7 publications

Estrogen quinones: Reaction with propylamine

Estrogen quinones: Reaction with propylamine

Studies on Aerobic Reactions of Ammonia/3,5-Di-tert-butylcatechol Schiff-Base Condensation Products with Copper, Copper(I), and Copper(II). Strong Copper(II)−Radical Ferromagnetic Exchange and Observations on a Unique N−N Coupling Reaction

3,5-Di-t-butyl-1,2-benzoquinone

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