8- Hydroxy quinoline hydrochloride

The (lS)-5-amino-8,9-dihydroxy-2,3-dihydro-l//-pyrimido[l,2-a]quinoline-3-carboxylic acid (8) form of pyoverdin PaA was halogenated at position 7 with a 30-fold excess of ferric chloride and bromide in acidic water at room termperature for 18 h (97TL97). Acidic hydrolysis of (15)-5-amino-8,9-dihy droxy-2,3-hy dro-1 //-pyrimido [1,2-a] quinoline- 1-carboxylic acid (8) in boiling 6 N hydrochloric acid for 48 h gave the 5,8,9-trihydroxy derivative (90MI2). Treatment of 2,3-dihydro-l//-pyrimido[l,2-a]quinoline hydrochlorides with aqueous 10% sodium hydroxide gave 4a-hydroxy-2,3,4,4a-tetrahydro-l//-pyrimido[l,2-a]quinolines (60) (69YZ759). 

Formaldehyde Glyceryl PABA sunscreens Halogenated hydroxy quinolines Hydralizine hydrochloride Iodine... 

Nucleophilic substitution most readily occurs at the 2- and 4-position of the more electron-deficient heterocyclic ring of quinolines. However, SNAr reactions at the carbocyclic ring can occur, mainly at positions 5 and 7. 5,7-Dibromo-8-hydroxyquinoline, 5-bromo-8-hydroxyquinoline, and 7-bromo-8-hydroxy-5-methylquinoline undergo conversion to the corresponding chloroquinolines on treatment with neat pyridine hydrochloride at 220 °C in a process that is postulated to proceed via the formation of stabilized Meisenheimer complexes <1996TL6695> (Equations 20 and 21). 

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