Practical catalytic enantioselective synthesis of 2,3-dihydroquin-azolinones by chiral brønsted acid catalysis.

ABSTRACT

Herein, we report on the highly efficient and practical synthesis of 2,3-dihydroquinazolinones directly from diverse aldehydes with excellent yields and enantioselectivity. Particularly, this protocol affords better enantiocontrol for aliphatic aldehydes (up to 99% yield, 97% ee), which always gave unsatisfactory results in the previous studies. Moreover, this catalytic system shows wide tolerance to different functional groups such as alkenyl, nitro and halogens. Most importantly, its practicability is well elucidated via the gram-scale synthesis of different types of products at 0.1 mol% catalyst loading and the simplified work-up procedure. To better understand the reaction pathway and origin of the enantioselectivity, DFT calculations were also performed.