Search results for "Hydantoin"
showing 4 items of 14 documents
In vitro skin penetration of bronidox, bronopol and formaldehyde from cosmetics
2020
The objective was to evaluate the influence of the formulation in the in vitro transdermal absorption through pig ear skin of three preservatives, bronopol, bronidox and formaldehyde as well as the absorption of formaldehyde from bronopol and dimethyloldimethyl hydantoin (DMDM hydantoin). An aqueous solution, an O/W emulsion and a hydrogel were assayed. Bronidox and bronopol absorption depends on the formulation. The O/W emulsion was the system that least promoted absorption of bronidox while the absorption of bronopol was lower from the hydrogel. The aqueous solution provided maximal transdermal absorption of both preservatives. Moreover, the transdermal absorption of formaldehyde released…
Synthesis of 1,3,5-Trisubstituted Hydantoins by Regiospecific Domino Condensation/Aza-Michael/O→N Acyl Migration of Carbodiimides with Activated α,β-…
2005
[reaction: see text] Carbodiimides and suitably activated alpha,beta-unsaturated carboxylic acids react effectively to afford a vast array of 1,3,5-trisubstituted hydantoins by means of a regiospecific domino condensation/aza-Michael/N--O acyl migration. The reaction works well in very mild conditions (20 degrees C, dichloromethane) with fumaric acid derivatives bearing an electron-withdrawing group in the beta position. Good results have been obtained also with less activated substrates bearing only one electron-withdrawing group in the beta position, using more polar solvents (acetonitrile, DMF), and in the presence of a base (2,4,6-trimethylpyridine). Reactions with asymmetric carbodiimi…
ChemInform Abstract: Convenient High Yielding Gram Scale Solution Synthesis of Methionine-Enkephalin.
2010
A simple, large-scale synthesis of a cytokine, methionine-enkephalin, Tyr-Gly-Gly-Phe-Met, has been elaborated. Classical solution peptide chemistry methods without protection of amino acid side-chain functions and 1+(2+2) segment condensation were used. A nine-step synthesis from commercial amino acid derivatives was developed with yields ranging from 86% to 99%, averaging 92%. The purity of all intermediates was found to be 99.0-100% by HPLC. The process has been used to prepare greater than 150 g quantities of the pentapeptide as a monohydrate of 100% purity. Hydantoin formation was observed during saponification of Boc-Tyr-Gly-Gly-Phe-Met-OMe and minimised.
Convenient High Yielding Gram Scale Solution Synthesis of Methionine-Enkephalin.
1998
A simple, large-scale synthesis of a cytokine, methionine-enkephalin, Tyr-Gly-Gly-Phe-Met, has been elaborated. Classical solution peptide chemistry methods without protection of amino acid side-chain functions and 1+(2+2) segment condensation were used. A nine-step synthesis from commercial amino acid derivatives was developed with yields ranging from 86% to 99%, averaging 92%. The purity of all intermediates was found to be 99.0-100% by HPLC. The process has been used to prepare greater than 150 g quantities of the pentapeptide as a monohydrate of 100% purity. Hydantoin formation was observed during saponification of Boc-Tyr-Gly-Gly-Phe-Met-OMe and minimised.