Microwave-Assisted Efficient and Convenient Synthesis of 2,4(1H,3H)-Quinazolinediones and 2-Thioxoquinazolines

Metal-Free N-H/C-H Carbonylation by Phenyl Isocyanate: Divergent Synthesis of Six-Membered N-Heterocycles

We disclose a method using phenyl isocyanate to synthesize carbonyl-containing N-heterocycles. The metal-free novel approach for both N-H and C-H carbonylation processes was successfully refined, delivering a range of synthetically valuable derivatives of quinazoline-2,4(1H,3H)-dione, 2H-benzo[e] [1,2,4] thiadiazin-3(4H)-one 1,1-dioxide, and pyrrolo[1,2-a] quinoxalin-4(5H)-one. The protocol features broad substrates with diverse reactions suitable for excellent yields, mild conditions, and good functional group compatibility. Moreover, the applicability of the reaction was characterized by gram-scale synthesis and synthetic transformations for drug molecules.

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.

Quinazolin-4(3H)-one based potential multiple tyrosine kinase inhibitors with excellent cytotoxicity

A series of quinazolin-4(3H)-one derivatives were synthesised and evaluated for their cytotoxicity against human Caucasian breast adenocarcinoma (MCF-7) and human ovarian carcinoma (A2780) cell lines. Cytotoxicity of the most tested compounds was 2- to 30-fold more than the positive control lapatinib (IC₅₀ of 2j = 3.79 ± 0.96; 3j = 0.20 ± 0.02; and lapatinib = 5.9 ± 0.74) against MCF7 cell lines except two compounds (IC₅₀ of 2 b = 15.72 ± 0.07 and 2e = 14.88 ± 0.99). On the other hand, cytotoxicity was 4 − 87 folds (IC₅₀ of 3a = 3.00 ± 1.20; 3 g = 0.14 ± 0.03) more the positive control lapatinib (IC₅₀ = 12.11 ± 1.03) against A2780 cell lines except compound 2e (IC₅₀ = 16.43 ± 1.80). Among the synthesised quinazolin-4(3H)-one derivatives, potent cytotoxic 2f-j and 3f-j were investigated for molecular mechanism of action. Inhibitory activities of the compounds were tested against multiple tyrosine protein kinases (CDK2, HER2, EGFR and VEGFR2) enzymes. As expected, all the quinazolin-4(3H)-one derivatives were showed comparable inhibitory activity against those kinases tested, especially, compound 2i and 3i showed potent inhibitory activity against CDK2, HER2, EGFR tyrosine kinases. Therefore, molecular docking analysis for quinazolin-4(3H)-one derivatives 2i and 3i were performed, and it was revealed that compounds 2i and 3i act as ATP non-competitive type-II inhibitor against CDK2 kinase enzymes and ATP competitive type-I inhibitor against EGFR kinase enzymes. However, in case of HER2, compounds 2i act as ATP non-competitive type-II inhibitor and 3i act as ATP competitive type-I inhibitor. Docking results of known inhibitors were compared with synthesised compounds and found synthesised 2i and 3i are superior than the known inhibitors in case of interactions. In addition, in silico drug likeness properties of quinazolin-4(3H)-one derivatives showed better predicted ADME values than lapatinib.

Eco-friendly reactions in PEG-400: a highly efficient and green approach for stereoselective access to multisubstituted 3,4-dihydro-2(1H)-quinazolines using 2-aminobenzylamines

An efficient and stereoselective synthesis of novel 3,4-dihydro-2(1H)-quinazolines has been developed through cyclization reactions of 2-aminobenzylamines with α-oxoketene dithioacetals using PEG-400 as an inexpensive, easy to handle, non-toxic and recyclable reaction medium. The developed protocol is operationally simple and tolerates various substrates having different functionalities. This protocol features several attributes such as excellent yields, no work up, green reaction conditions, and being environmentally benign. The attractive feature of this new strategy is that all the reported final compounds have been isolated as single (E)-stereoisomeric forms, which was confirmed by 1HNMR and X-ray crystallographic studies.

Palladium-Catalyzed Incorporation of Two C1 Building Blocks: The Reaction of Atmospheric CO2 and Isocyanides with 2-Iodoanilines Leading to the Synthesis of Quinazoline-2,4(1H,3H)-diones

A Pd-catalyzed insertion and cycloaddition of CO₂ and isocyanide into 2-iodoanilines under atmospheric pressure has been developed and affords quinazoline-2,4(1H,3H)-diones through the formation of new C-C, C-O, and C-N bonds under mild conditions. This reaction provides a new and practical method not only for the construction of quinazoline-2,4(1H,3H)-diones but also for the efficient utilization of carbon dioxide.

A mechanistic study on guanidine-catalyzed chemical fixation of CO2 with 2-aminobenzonitrile to quinazoline-2,4(1H,3H)-dione

Both basicity of TMG and acidity of the [TMGH]⁺ guanidinium are crucial for a reaction.

Efficient synthesis of quinazoline-2,4(1H,3H)-diones from CO2 catalyzed by N-heterocyclic carbene at atmospheric pressure

Under atmospheric pressure, quinazoline-2,4(1H,3H)-diones were obtained from the reaction of 2-aminobenzonitriles with carbon dioxide (0.1 MPa) with a catalytic amount of N-heterocyclic carbene in DMSO.

Amine functionalized MCM-41: an efficient heterogeneous recyclable catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones from carbon dioxide and 2-aminobenzonitriles in water

Covalently linked amine functionalized MCM-41 was investigated as an efficient catalyst for the synthesis of various quinazoline-2,4(1H,3H)-dione derivatives from 2-aminobenzonitriles and carbon dioxide in water.

A new and facile synthetic approach to substituted 2-thioxoquinazolin-4-ones by the annulation of a pyrimidine derivative

A new and facile synthesis of 2-thioxoquinazolin-4-ones by introducing a benzenoid system in the pyrimidine moiety by reacting ethoxymethylene derivatives of 1,3-diarylthiobarbituric acids (DTBA) with active methylene compounds, such as malononitrile and ethyl cyanoacetate, in presence of ZnCl₂ has been developed.

Traceless solid-phase synthesis of 2,4,6-trisubstituted thiazolo[4,5-d]pyrimidine-5,7-dione derivatives

An expedient, traceless, solid-phase synthesis of 2,4,6-trisubstituted thiazolo[4,5-d]pyrimidine-5,7-dione derivatives has been developed. The solid-phase synthetic route utilizes urea formation by a microwave irradiation promoted reaction of a thiazole amino ester resin with an isocyanate. The resulting urea resin is converted to a thiazolopyrimidinedione resin, containing two diversity elements at N-4 and N-6, by using a one-pot cyclization/N-alkylation process. After oxidation to form a sulfone, nucleophilic C-2 substitution with amines, the third diversity element, gives the target 2,4,6-trisubstituted thiazolo[4,5-d]pyrimide-5,7-dione derivatives. This highly efficient solid-phase synthetic sequence enables the incorporation of three points of diversity into the preparation of the thiazolo[4,5-d]pyrimidine-5,7-dione ring system.

One-pot synthesis of quinazolinone derivatives from nitro-compounds with the aid of low-valent titanium

The synthesis of a series of quinazolinone derivatives such as 2-thioxoquinazolinones, imidazo[1,2-c]quinazolin-5-amines, and benzimidazo[1,2-c]quinazolin-5-amines, starting from nitro-compounds has been described. This general approach features a easy way for access to the target quinazolinone derivatives. The key cyclization step embraces the formation of a thiourea intermediate, mediated by low-valent titanium, and the other important intermediate was also obtained. A variety of substrates can participate in the process with good yields, making this methodology suitable for library synthesis in drug discovery efforts.

Room-temperature palladium-catalyzed C-H activation: ortho-carbonylation of aniline derivatives

Pd and CO--ureally got me! The title reaction proceeds efficiently at 18 degrees C under CO (1 atm) with 5 % [Pd(OTs)(2)(MeCN)(2)] as precatalyst. Depending on the solvents used, either anthranilates or cyclic imides can be obtained in high yields (see picture, BQ = benzoquinone, Ts = 4-toluenesulfonyl).