Brønsted acid-catalyzed two-component tandem condensation and cycloisomerization to 6(2)-isoquinolinones.

An attractive Brønsted acid-catalyzed two-component reaction of 2-alkynyl-4-hydroxybenzaldehydes 1 and primary amines 2 to various 6(2)-isoquinolinones 3 has been developed. This catalytic system realized an efficient tandem condensation and cycloisomerization reaction to 6(2)-isoquinolinones 3 in good to excellent yields a one-pot synthesis, in which two different kinds of C-N bonds were constructed in a straightforward manner. Remarkably, the reaction tolerated various aliphatic, aryl-substituted amines, including chiral amino alcohols and amino acids. The practicality of this approach rendered it a viable alternative for the construction of various 6(2)-isoquinolinones.