Palladium‐Catalyzed [3+2+1]/[4+2] Heteroannulation of Allylamines with <scp>CO</scp> and 1,4‐Enynes Leading to 1,7,8,8a‐Tetrahydroisoquinolin‐3(<scp>2<i>H</i></scp>)‐ones

Comprehensive Summary Aminocarbonylative heteroannulation of unsaturated hydrocarbons with amines and CO has become a key transformation in organic synthesis to build N ‐heterocycles. In this report, a new palladium‐catalyzed aminocarbonylative [3+2+1]/[4+2] heteroannulation of allylamines with CO and 4‐en‐1‐yn‐3‐yl acetates for the synthesis of 1,7,8,8a‐tetrahydroisoquinolin‐3(2 H )‐ones has been developed. The method enables the construction of two new six‐membered rings in a single reaction step leading to the formation of the isoquinolinone scaffolds, featuring excellent selectivity, good functional group compatibility and broad substrate scope. A possible mechanism involving Pd‐catalyzed isomerization to form the allenyl‐Pd intermediate, aminocarbonylation and cycloaddition was proposed.