4-Hydroxy-1,2,3,4-Tetrahydroisoquinolines: Potential Reaction Products of Norepinephrine
Isoquinolines derived from DA and excreted in the urine of Parkinsonian patients under L-dopa therapy are called “Mammalian TIQ”.3,4 Pictet-Spengler synthesis5 provides an easy route for the preparation of optically inactive TIQ. Many TIQ have been prepared from DA and carbonyl compounds (phenylpyruvic acids, aldehydes, ketones) in this way and under so-called “physiological” conditions, suggesting that this reaction might have biological significance.6 If so, then similar reactions could take place with the two catecholamines (±)-NE or (±)-E or their optical isomers, resulting in the formation of diastereomeric 4,6,7-trihydroxy TIQ or their optical isomers. The preparation of TIQ alcohols 17 and 28 (Figure 1) belonging to this class of compounds, and prepared from (±)-NE and formaldehyde and (-)-E and acetaldehyde respectively, has been reported.
KeywordsCarbonyl Compound Secondary Amine Methyl Ether Parkinsonian Patient Chemical Conversion
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