Due to stability issue of isoquinolone’s, their N-methylation is a challenging task, achieved the synthesis of Nmethylated 2-methylisoquinoline-1,5,8(2H)-trione using readily available precursor 2-(2,5-dimethoxyphenyl) ethanamine via multistep strategy, finally oxidation of 5,8-dimethoxy-2-methyl-3,4-dihydroisoquinolin-1(2H)-one with ceric ammonium nitrate (CAN) lead to target isoquinolone in good yield, further oxidation conditions in final step were optimized using different catalyst ratio, reaction time, and temperature conditions.
