Variously substituted isoxazolo[5,4-c]quinolines can be easily prepared in high yields by Pd-catalyzed heteroannulation of 5-carbonyl-4-haloisoxazoles with 2-aminophenylboronic acid derivatives. 4-Unsubstituted isoxazolo[5,4-c]quinolines can be readily modified at C4 via a chlorination/substitution sequence.