Related Experiment Video
Updated: Oct 13, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Nonenzymatic transformations of enzymatically generated N-acetyldopamine quinone and isomeric dihydrocaffeiyl methyl
M Sugumaran1, V Semensi, H Dali
1Department of Biology, University of Massachusetts, Boston 02125.
Abstract:
We have recently demonstrated that the side chain hydroxylation of N-acetyldopamine and related compounds observed in several insects is caused by a two-enzyme system catalyzing the initial oxidation of catecholamine derivatives and subsequent isomerization of the resultant quinones to isomeric quinone methides, which undergo rapid nonenzymatic hydration to yield the observed products [Saul, S.J. and Sugumaran, M. (1989) FEBS Lett. 249, 155-158]. During our studies on o-quinone/p-quinone methide tautomerase, we observed that quinone methides are also produced nonenzymatically slowly, under physiological conditions. The quinone methide derived from N-acetyldopamine was hydrated to yield N-acetylnorepinephrine as the stable product as originally shown by Senoh and Witkop [(1959) J. Am. Chem. Soc. 81, 6222-6231], while the isomeric quinone methide from dihydrocaffeiyl methylamide exhibited a new reaction to form caffeiyl amide as the stable product. The identity of this product was established by UV and IR spectral studies and by chemical synthesis. We could not find any evidence of intramolecular cyclization of N-acetyldopamine quinone to iminochrome-type compound(s). The importance of quinone methides in these reactions is discussed.
Related Concept Videos
Aldehydes and Ketones with Amines: Imine and Enamine Formation Overview
Oxidation of Phenols to Quinones
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Preparation of Amines: Reductive Amination of Aldehydes and Ketones
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
Amines to Amides: Acylation of Amines
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary amide...
Aldehydes and Ketones with Amines: Enamine Formation Mechanism

