Bis(2-methoxyethyl)ether promoted intramolecular acceptorless dehydrogenative coupling to construct structurally diverse quinazolinones by molecular oxygen

A simple, efficient, and clean approach for the synthesis of diverse dihydroisoquinolino[2,1-a]quinazolinones, 2-aryl quinazolinones, and analogues through intramolecular acceptorless dehydrogenative coupling has been achieved. The combination of bis(2-methoxyethyl)ether and molecular oxygen was identified as a highly efficient system for this oxidative dehydrogenative coupling sequential transformation without an external initiator, catalyst, and additive. The applicability and practicability were demonstrated by a scope of twenty-nine examples and a gram-scale reaction. Some control experiments were also conducted to support a possible reaction pathway.