Facile and efficient synthesis of quinazoline-2,4(1H,3H)-diones through sequential hydrogenation condensation

A Benzannulation Strategy for Rapid Access to Quinazoline-2,4-diones via Oxidative N-Heterocyclic Carbene Catalysis

N-Heterocyclic carbene-catalyzed formal [4+2] benzannulation of enals with suitably substituted pyrimidine-2,4-diones allowing the mild and facile synthesis of functionalized quinazoline-2,4-diones is presented. This oxidative transformation proceeds via the simultaneous generation of dienolates and α,β-unsaturated acylazoliums and follows a vinylogous Michael/aldol/β-lactonization/decarboxylation/oxidation sequence to afford quinazoline-2,4-diones, including axially chiral ones with suitable substitutions, in an operationally simple procedure. In addition, substituted coumarins as dienolate precursors afforded benzochromen-6-one derivatives.

DMAP-Catalyzed One-Pot Synthesis of Quinazoline-2,4-diones from 2-Aminobenzamides and Di-tert-butyl Dicarbonate

The one-pot synthesis of quinazoline-2,4-diones was developed in the presence of 4-dimethylaminopyridine (DMAP) by metal-free catalysis. The commercially available (Boc)₂O acted as a key precursor in the construction of the 2-position carbonyl of quinazolinediones. The p-methoxybenzyl (PMB)-activated heterocyclization could smoothly proceed at room temperature instead of the microwave condition. This strategy is compatible with a variety of substrates with different functional groups. Furthermore, this protocol was utilized to smoothly prepare Zenarestat with a total yield of 70%.