A stereoselective three-component reaction:: KAl(SO4)2•12H2O, an efficient and reusable catalyst for the one-pot synthesis of cis-isoquinolonic acids

KAl(SO4)(2).12H(2)O is found to catalyze efficiently the stereo-selective one-pot three-component cyclocondensation of homophthalic anhydride, aldehydes, and amines under mild conditions to afford the corresponding cis-isoquinolonic acids in good yields.