One-pot multistep synthesis of 3,4-fused isoquinolin-1(2H)-one analogs

We have developed a robust approach for the synthesis of 3,4-fused isoquinolin-1(2H)-one analogs. A benzonitrile or a nicotinonitrile bearing an ortho-substituent, such as –OH, –SH, or –NHR (R = alkyl or aryl) can be deprotonated by KOtBu and then reacted with methyl 2-(bromomethyl)benzoate (8) to form its corresponding O-, S-, or N-alkylation product. The product thus formed is then treated with KOtBu again to initiate a cascade process that will lead to the formation of its corresponding 3,4-fused isoquinolin-1(2H)-one. This multistep synthesis as well as the final product purification is achieved in a one-pot manner.