1,2-Dichloroethane as a Gaseous Acetylene Source for the Rapid Assembly of Isoquinolino[1,2-<i>b</i>]quinazolinone Scaffolds

Reported herein is a novel ruthenium(II)-catalyzed [4 + 2] annulation of quinazolinones with 1,2-dichloroethane (DCE), resulting in a myriad of isoquinolino[1,2-<i>b</i>]quinazolinone scaffolds. In this protocol, DCE serves not only as a solvent but also as an acetylene source. The fused quinazolinones undergo versatile transformations and provide a rapid and convenient way to access several important bioactive molecule analogues such as Rutecarpine, Euxylophoricine B and Euxylophoricine E. The potential reaction pathway was elucidated through detailed mechanistic studies and Density Functional Theory (DFT) calculations.