Preparation of 4(3H)-quinazolinones from aryldiazonium salt, nitriles and 2-aminobenzoate via a cascade annulation

One-Step Construction of 2-Methylquinazolin-4(3H)-ones Using Solid Calcium Carbide as an Alternative to Gaseous Acetylene

2-Methylquinazolin-4(3H)-ones were efficiently constructed using solid calcium carbide as an alkyne source, 2-aminobenzamides or 2-aminobenzohydrazides as substrates, and p-tolylsulfonyl azide as a mediator through simultaneous formation of two C-N bonds in one step. The salient features of this protocol are the use of an inexpensive, abundant and easy-to-use alkyne source as a substitute for flammable and explosive gaseous acetylene, low-cost catalyst, wide substrate scope, satisfactory yield, and simple manipulation. This method can also be extended to gram scale.

One-Pot Three-Component Reaction for the Synthesis of 3,4-Dihydroquinazolines and Quinazolin-4(3H)-ones

A highly efficient and straightforward one-pot synthesis of diversely substituted 3,4-dihydroquinazolines and quinazolin-4(3H)-ones has been achieved through a domino three-component assembly reaction of arenediazonium salts, nitriles, and bifunctional aniline derivatives. This new protocol involves three C-N bond formations through the initial formation of N-arylnitrilium intermediates from arenediazonium salts and nitriles, followed by the sequential nucleophilic addition and cyclization reactions with bifunctional anilines, leading to such N-heterocyclic compounds of biological and pharmacological importance. This method offers a simple, expedient, and robust approach with the use of amenable and easily accessible reactants/reagents under metal-free mild conditions, good functional group tolerance, and high efficiency. The synthetic applications were also demonstrated by derivatization of the products obtained from these processes and syntheses of a diverse range of valuable polycyclic N-heterocycles.

N2,N6-Bis(6-iodo-2-methyl-4-oxoquinazolin-3(4H)-yl)pyridine-2,6-dicarboxamide

A green chemistry method was applied in the synthesis of N2,N6-bis(6-iodo-2-methyl-4-oxoquinazolin-3(4H)-yl)pyridine-2,6-dicarboxamide. The desired compound was synthesized mechanochemically, using a choline chloride-based deep eutectic solvent as a catalyst. The synthesis took 20 min and the new compound was characterized using different spectral methods.

One-Pot Synthesis of α-Amino Bisphosphonates from Nitriles via Tf2O/HC(OR)3-Mediated Interrupted Ritter-Type Reaction

A versatile synthesis of α-amino bisphosphonates has been achieved through one-pot interrupted Ritter-type reaction under mild conditions. The reactive Ritter intermediate nitrilium is in situ generated by treatment of nitrile with readily accessible Tf₂O/HC(OR¹)₃, which is trapped by phosphite ester to deliver the desired product. This protocol is efficient, scalable, and well compatible with a broad scope of substrates. In addition, plentiful characteristic J_P-C couplings including unusual five-bond long-range ⁵J_P-C and ³J_P-C across quaternary carbon and hetero (N) atoms were observed in ¹³C NMR spectra.

α-Hydroxy acid as an aldehyde surrogate: metal-free synthesis of pyrrolo[1,2-a]quinoxalines, quinazolinones, and other N-heterocycles via decarboxylative oxidative annulation reaction

A metal-free and efficient procedure for the synthesis of pyrrolo[1,2-a]quinoxalines, quinazolinones, and indolo[1,2-a]quinoxaline has been developed. The key features of our method include the in situ generation of aldehyde from α-hydroxy acid in the presence of TBHP (tert-butyl hydrogen peroxide), and further condensation with various amines, followed by intramolecular cyclization and subsequent oxidation to afford the corresponding quinoxalines, quinazolinones derivatives in moderate to high yields.

Synthesis, Antiproliferative, and Antioxidant Evaluation of 2-Pentylquinazolin-4(3H)-one(thione) Derivatives with DFT Study

The current study was chiefly designed to examine the antiproliferative and antioxidant activities of some novel quinazolinone(thione) derivatives 6–14. The present work focused on two main points; firstly, comparing between quinazolinone and quinazolinthione derivatives. Whereas, antiproliferative (against two cell lines namely, HepG2 and MCF-7) and antioxidant (by two methods; ABTS and DPPH) activities of the investigated compounds, the best quinazolinthione derivatives were 6 and 14, which exhibited excellent potencies comparable to quinazolinone derivatives 5 and 9, respectively. Secondly, we compared the activity of four series of Schiff bases which included the quinazolinone moiety (11a–d). In addition, the antiproliferative and antioxidant activities of the compounds with various aryl aldehyde hydrazone derivatives (11a–d) analogs were studied. The compounds exhibited potency that increased with increasing electron donating group in p-position (OH > OMe > Cl) due to extended conjugated systems. Noteworthy, most of antiproliferative and antioxidant activities results for the tested compounds are consistent with the DFT calculations.