Synthesis of 3-aminoalkyl-2-arylaminoquiazolin-4(3H)-ones and 3,3′-disubstituted bis-2-arylaminoquinazolin-4(3H)-onesviareactions of 1-aryl-3-(2-ethoxycarbonylphenyl)carbodiimides with diamines

Synthesis, antitumor activity, 3D-QSAR and molecular docking studies of new iodinated 4-(3H)-quinazolinones 3N-substituted

A novel series of 6-iodo-2-methylquinazolin-4-(3H)-one derivatives, 3a–n, were synthesized and evaluated for their in vitro cytotoxic activity. Compounds 3a, 3b, 3d, 3e, and 3h showed remarkable cytotoxic activity on specific human cancer cell lines when compared to the anti-cancer drug, paclitaxel. Compound 3a was found to be particularly effective on promyelocytic leukaemia HL60 and non-Hodgkin lymphoma U937, with IC₅₀ values of 21 and 30 μM, respectively. Compound 3d showed significant activity against cervical cancer HeLa (IC₅₀ = 10 μM). The compounds 3e and 3h were strongly active against glioblastoma multiform tumour T98G, with IC₅₀ values of 12 and 22 μM, respectively. These five compounds showed an interesting cytotoxic activity on four human cancer cell types of high incidence. The molecular docking results reveal a good correlation between experimental activity and calculated binding affinity on dihydrofolate reductase (DHFR). Docking studies proved 3d as the most potent compound. In addition, the three-dimensional quantitative structure–activity relationship (3D-QSAR) analysis exhibited activities that may indicate the existence of electron-withdrawing and lipophilic groups at the para-position of the phenyl ring and hydrophobic interactions of the quinazolinic ring in the DHFR active site.

New iodinated 4-(3H)-quinazolinones 3N-substituted with antitumor activity and 3D-QSAR and molecular docking studies as dihydrofolate reductase (DHFR) inhibitors.

Carbodiimide-based synthesis of N-heterocycles: moving from two classical reactive sites to chemical bond breaking/forming reaction

Carbodiimides are a unique class of heterocumulene compounds that display distinctive chemical properties. The rich chemistry of carbodiimides has drawn increasing attention from chemists in recent years and has made them exceedingly useful compounds in modern organic chemistry, especially in the synthesis of N-heterocycles. This review has outlined the extensive application of carbodiimides in the synthesis of N-heterocycles from the 1980s to today. A wide range of reactions for the synthesis of various types of N-heterocyclic systems (three-, four-, five-, six-, seven-, larger-membered and fused heterocycles) have been developed on the basis of carbodiimides and their derivatives.

Synthesis and biological activity of arylsulfonamide derivatives containing 2-arylamino-4(3H)-quinazolinone

Twenty arylsulfonamide derivatives containing 2-arylamino-4(3H)-quinazolinone were synthesized and evaluated for their bioactivities. 4-Fluoro-N-(2-(4-oxo-2-(4-(trifluoromethoxy)phenyl)amino)quinazolin-3(4H)-yl)ethyl benzenesulfonamide, showed excellent activity both against Ralstonia solanacearum and Gibberella zeae with the inhibition rates of 100% (200 mg/L) and 95% (100 mg/L), and 69% (50 mg/L), respectively, exceeding that of the assigned commercial bactericide (thiodiazole-copper) and fungicide (hymexazol). The preliminary structure activity relationships (SAR) showed that both benzene rings of arylamino and arylsulfonamido moieties containing electron-withdrawing substitutes may be preferable for improving the bioactivity of target compounds.

Synthesis of tricyclic quinazolinones via intramolecular cyclization of 3-(2-aminoalkyl)-2-(phenylamino)quinazolin-4(3H)-ones

Bioactive tricyclic quinazolines class of 3,4-dihydro-1H-pyrimido[2,1-b]quinazolin-6(2H)-ones I and 2,3-dihydroimidazo[2,1-b]quinazolin-5(1H)-ones II were synthesized by the formic acid-catalyzed intramolecular cyclization of 3-(2-aminoalkyl)-2-(phenylamino)quinazolin-4(3H)-ones 1 in high yields. A plausible mechanism of the cyclization step is proposed.

Design, synthesis, and antibacterial activity of novel Schiff base derivatives of quinazolin-4(3H)-one

Novel imine derivatives of quinazolin-4(3H)-one were designed and synthesized by using aminoethyl moieties to increase the amine bridge of quinazolin-4(3H)-one amine and then introducing various aromatic aldehydes. The target compounds were characterized by proton nuclear magnetic resonance spectroscopy ((1)H NMR), carbon nuclear magnetic resonance spectroscopy ((13)C NMR), mass spectrometry (MS), infrared spectroscopy (IR), elemental analysis, and X-ray diffraction crystallography. Bioassay results indicated that some of the compounds showed good to excellent antibacterial activities against tobacco bacterial wilt and tomato bacterial wilt. The 50% effective concentrations (EC50) of the compounds against tobacco and tomato bacterial wilts ranged from 63.73 μg/mL to 201.52 μg/mL and 38.64 μg/mL to 81.39 μg/mL, respectively, which are lower than that the positive control thiodiazole copper (216.70 and 99.80 μg/mL). These results indicated that novel Schiff base derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco and tomato bacterial wilts.

Recent advances in 4(3H)-quinazolinone syntheses

The new routes and strategies for the synthesis of valuable 4(3H)-quinazolinones have been summarized.

Synthesis and bioactivity evaluation of novel arylimines containing a 3-aminoethyl-2-[(p-trifluoromethoxy)anilino]-4(3H)-quinazolinone moiety

Twenty-seven novel (E)-3-[2-arylideneaminoethyl]-2-[4-(trifluoromethoxy)anilino]-4(3H)-quinazolinone derivatives were synthesized by reacting various aromatic aldehydes with intermediate 6. The target compounds were characterized by (1)H NMR, (3)C NMR, IR, and elemental analysis. Bioassay results revealed that some of the compounds have strong antifungal activities against six fungi ( Gibberella zeae , Fusarium oxysporum , Clematis mandshurica , Paralepetopsis sasakii , Phytophthora infestans , and Sclerotinia sclerotiorum ) and three bacteria ( Xanthomonas oryzae , tomato bacterial wilt, and tobacco bacterial wilt). Notably, these compounds exhibited the highest activity against tomato bacterial wilt and X. oryzae, with 50% effective concentration (EC50) values ranging from 45.96 to 93.31 μg/mL and from 20.09 to 21.33 μg/mL, respectively, which are superior to those of the commercial antibacterial agents thiodiazole-copper (99.80 μg/mL) and bismerthiazol (92.61 μg/mL). These results indicate that novel arylimine derivatives containing the 4(3H)-quinazolinone moiety can effectively control tobacco bacterial wilt, tomato bacterial wilt, and X. oryzae. Evaluation of their bactericidal properties in field studies as well as the mechanisms underlying their enhanced antibacterial activity should be interesting topics for future investigations.

One-Pot Three-Component Synthesis of 1,4-bis[thiazolo[4,5-d]pyrimidin-7(6H)-one]piperazine derivatives

A simple one-pot efficient method is described for the synthesis of 1,4-bis[thiazolo[4,5-d]pyrimidin-7(6 H)-one] piperazine derivatives by a domino three-component process involving an aza-Wittig reaction/heterocyclisation in the presence of sodium ethoxide as catalyst. Ethyl 4-[(triphenylphosphanylidene)amino]-2,3-dihydro-3-phenyl-2-thioxothiazole-5-carboxylate reacted with aromatic isocyanates to give carbodiimide intermediates. This was followed by the addition of piperazines to give the corresponding guanidine intermediates. The guanidine intermediates were then cyclised in the presence of catalytic amount of sodium ethoxide to give 1,4-bis[thiazolo[4,5-d]pyrimidin-7(6 H)-one]piperazine derivatives in good yields.

2-Anilino-3-(2-hy-droxy-phen-yl)quinazolin-4(3H)-one-triphenyl-phosphine oxide (1/1)

In the title compound, C₂₀H₁₅N₃O₂·C₁₈H₁₅OP, the pyrimidinone heterocycle and the fused phenyl ring are inclined at 1.92 (7)°. Only the hy­droxy group is involved in hydrogen bonding, whereas the amino group is shielded from potential acceptors.

2-Anilino-3-(2-hy-droxy-phen-yl)quinazolin-4(3H)-one methanol monosolvate

In the title compound, C₂₀H₁₅N₃O₂·CH₃OH, the quinazolin­one ring system is approximately planar, the dihedral angle between the pyrimidinone ring and the adjacent benzene ring being 1.73 (6)°. The pyrimidinone ring makes dihedral angles of 77.58 (6) and 29.62 (6)°, respectively, with the hy­droxy­phenyl and phenyl rings. In the crystal, the components are connected by O—H⋯O and C—H⋯O hydrogen bonds, forming a zigzag chain along the b axis.

2-[2-(2-Anilino-4-oxo-3,4-dihydro-quinazolin-3-yl)phen-oxy]-3-phenyl-quinazolin-4(3H)-one methanol hemisolvate

In the title compound, C₃₄H₂₃N₅O₃·0.5CH₃OH, each pyrimid­in­one heterocycle and its adjacent benzene ring are almost coplanar, making dihedral angles of 0.69 (13) and 1.87 (13)°. The lower pyrimidinone ring makes a dihedral angle of 40.41 (15)° with the —NH— bonded phenyl ring. O—H⋯O hydrogen bonds and weak C—H⋯π inter­actions are observed in the crystal structure. The methanol solvent molecule is disordered over two positions of equal occupancy.

3-(2-Amino-eth-yl)-2-[4-(trifluoro-meth-oxy)anilino]quinazolin-4(3H)-one

In the title compound, C₁₇H₁₅F₃N₄O₂, the dihedral angle between the trifluoro­meth­oxy-substituted benzene ring and the pyrimidinone ring is 45.1 (5)°, while that between the fused benzene ring and the pyrimidinone ring is 0.67 (1)°. Part of one of the benzene rings and its trifluoro­meth­oxy substituent are disordered over two positions of approximately equal occupancy (0.51:0.49). Inter­molecular N—H⋯O and N—H⋯N hydrogen bonds contribute to the stability of the crystal structure. A weak intra­molecular C—H⋯F contact is also found. In addition, π–π stacking inter­actions, with centroid–centroid distances in the range 3.673 (6)–3.780 (8) Å, and weak C—H⋯π inter­actions are also observed.

2-(4-Fluoro-anilino)-3-(2-hydroxy-ethyl)quinazolin-4(3H)-one

The mol-ecular and crystal structures of the title compound, C(16)H(14)FN(3)O(2), are stabilized by intra-molecular N-H⋯O and inter-molecular O-H⋯O hydrogen bonds. The existence of non-classical intra-molecular C-H⋯N hydrogen bonds provides a dihedral angle between the fluoro-substituted benzene and pyrimidinone rings of 7.9 (1)°.

3,3'-Bis(4-chloro-phen-yl)-2,2'-(m-phenyl-enedi-oxy)diquinazolin-4(3H)-one

In the title compound, C(34)H(20)Cl(2)N(4)O(4), the two quinazoline heterocyclic systems and the adjacent chloro-benzene rings are not coplanar, but oriented at dihedral angles of 66.66 (13) and 52.48 (12)°, respectively. The quinazoline ring systems are nearly planar, with dihedral angles between the planes of the two rings of 5.43 (16) and 3.40 (14)°, and are oriented at dihedral angles of 79.73 (13) and 83.52 (13)° with respect to the adjacent benzene ring between them. Inter-molecular C-H⋯O hydrogen bonds contribute to the stability of the structure. In addition, weak π-π stacking inter-actions [centroid-to-centroid distances = 3.872 (1) and 3.876 (1) Å] are observed in the crystal structure.

3-(2-Amino-ethyl)-2-(4-chloro-anilino)-quinazolin-4(3H)-one methanol 0.75-solvate

In the asymmetric unit of the title compound, C(16)H(15)ClN(4)O·0.75CH(3)OH, there are two independent quinazolin-4(3H)-one mol-ecules and one and a half methanol mol-ecules. One of the methanol mol-ecules is disordered over two positions with equal occupancies. The dihedral angles between the quinazoline ring system and the chloro-benzene ring in the two quinazolin-4(3H)-one mol-ecules are essentially the same, at 39.83 (1) and 39.84 (1)°. Intra-molecular N-H⋯N and O-H⋯O, and inter-molecular N-H⋯O and N-H⋯N hydrogen bonds are observed. In addition, π-π stacking inter-actions, with centroid-to-centroid distances of 3.654 (1), 3.766 (1) and 3.767 (1) Å, and weak C-H⋯π inter-actions, are observed.

3-(2-Hydroxy-ethyl)-2-(p-tolyl-amino)-quinazolin-4(3H)-one

In the title compound, C₁₇H₁₇N₃O₂, the quinazolinone ring system is essentially planar. The benzene ring is twisted with respect to it by a dihedral angle of 32.7 (5)°. The mol­ecular conformation is stabilized by an N—H⋯O hydrogen bond, and the crystal structure is stabilized by inter­molecular O—H⋯N inter­actions.

2-(4-Chloro-anilino)-3-(2-hydroxy-ethyl)quinazolin-4(3H)-one

In the title mol-ecule, C(16)H(14)ClN(3)O(2), the dihedral angle between the chloro-phenyl and pyrimidinone rings is 14.8 (1)°, while the dihedral angle between the fused benzene ring and the pyrimidinone ring is 3.8 (1)°. In the crystal structure, intra-molecular N-H⋯O hydrogen bonds, together with inter-molecular O-H⋯O hydrogen-bonding inter-actions, are present.

3-(2-Amino-ethyl)-2-(4-fluoroanilino)-quinazolin-4(3H)-one

In the title mol­ecule, C₁₆H₁₅FN₄O, the dihedral angle between the fluoro-substituted benzene ring and the pyrimidinone ring is 52.34 (7)°, while the dihedral angle between the fused benzene ring and the pyrimidinone ring is 3.30 (6)°. An intra­molecular N—H⋯N hydrogen bond may, in part, influence the conformation of the mol­ecule. In the crystal structure, inter­molecular N—H⋯N hydrogen bonds and weak C—H⋯π(arene) inter­actions link pairs of mol­ecules into centrosymmetric dimers.