DABCO catalyzed [4+2] annulations of Morita–Baylis–Hillman carbonates with isocyanates

A highly concise method for 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyzed [4+2] annulations of o-amino-acylation of aryl MBH carbonates with isocyanates has been developed. For the first time, MBH carbonates served as 1,4-dipoles, providing functionalized 3,4-dihydroquinazolinones in mild conditions with good to excellent yields. The density functional theory calculations of the mechanism supports our hypothesis.