US Patent 7361756 Method of making 7-(4-bromobutoxy)-3,4-dihydrocarbostyril

The invention encompasses synthesizing 7-(4-bromobutoxy)-3,4-dihydrocarbostyril by mixing 7-hydroxy-tetrahydroquinolinone, dibromobutane, and at least one base to form a reaction mixture; heating the reaction mixture; cooling the reaction mixture; and isolating the 7-(4-bromobutoxy)-3,4-dihydrocarbostyril from the reaction mixture. The invention also encompasses using phase transfer catalysts during the reaction.