Competitive 3+2 and 2+2 cycloadditions of ester stabilized azaallyl anions to benzynes. Ring expansion of initial 3+2 products to isoquinolin-3-ones

Reaction of the azaallyllithiums derived from imines of α-amino esters with benzynes results in the formation of 1,3-dihydroisoindoles and 4-hydroxyisoquinolines via 3+2 and 2+2 cycloadditions, respectively. The initially formed 1-carboethoxy-1,3-dihydroisoindoles rearrange under basic reaction conditions to form 3-(2H)-isoquinolinones.