A novel Pd-catalyzed cyclization reaction of ureas for the synthesis of dihydroquinazolinone p38 kinase inhibitors

2,3-Dihydroquinazolin-4(1H)-one as a privileged scaffold in drug design

2,3-Dihydroquinazolin-4-one (DHQ) belongs to the class of nitrogen-containing heterocyclic compounds representing a core structural component in various biologically active compounds. In the past decades, several methodologies have been developed for the synthesis of the DHQ framework, especially the 2-substituted derivatives. Unfortunately, multistep syntheses, harsh reaction conditions, and the use of toxic reagents and solvents have limited their full potential as a versatile fragment. Recently, use of green chemistry and alternative strategies are being explored to prepare diverse DHQ derivatives. This fragment is used as a synthon for the preparation of biologically active quinazolinones and as a functional substrate for the synthesis of modified DHQ derivatives exhibiting different biological properties. In this review, we provide a comprehensive assessment of the synthesis and biological evaluations of DHQ derivatives.

Diversity oriented synthesis and IKK inhibition of aminobenzimidazole tethered quinazoline-2,4-diones, thioxoquinazolin-4-ones, benzodiazepine-2,3,5-triones, isoxazoles and isoxazolines

The derivatization of resin-bound aminobenzimidazole toward the parallel solid-phase synthesis of aminobenzimidazole tethered pharmacologically important heterocycles such as quinazoline-2,4-diones, thioxoquinazolin-4-ones, benzodiazepine-2,3,5-triones, isoxazoles and isoxazolines is reported. All the compounds were tested for IKK inhibition. Only one compound elicited significant inhibition of IKKε, TBK-1 and IKK2.

Synthesis of new 5-alkyl substituted 4-thiazolidinones utilising condensation with ethyl 2-bromo alkanoates

2-[(3-Ethyl-4-oxo-3,4-dihydroquinazolin-2-yl)mercaptoacetylhydrazono]-3-alkyl/aralkyl-5-ethyl/propylthiazolidin-4-ones were synthesised by the cyclisation of 1-[(3-ethyl-4-oxo-3,4-dihydroquinazolin-2-yl)mercaptoacetyl]-4-alkyl/aralkyl thiosemicarbazides with ethyl 2-bromobutanoate or ethyl 2-bromopentanoate in the presence of anhydrous sodium acetate in anhydrous ethanolic medium. The regioisomer 2-alkyl/aralkyl 3-[(3-ethyl-4-oxo-3,4-dihydroquinazolin-2-yl)mercaptoacetylamino]-5-ethyl/propylthiazolidin-4-ones were not formed.

Synthesis of 3-Aryl-3,4-Dihydroquinazolin-2(1H)-Ones with the Aid of Low-Valent Titanium Reagent (TiCl4-Sm)

A short and facile synthesis of a series of 3-aryl-3,4-dihydroquinazolin-2(1H)-ones was accomplished in good yields via the novel reductive cyclisation of 2-nitrobenzylamines with bis(trichloromethyl)carbonate (triphosgene) promoted by TiCl4/Sm system. The structures of the products were characterised by IR, 1H NMR and elemental analysis and the structure of 3a was confirmed by X-ray diffraction analysis.

Small molecular anti-cytokine agents

The recent successful introduction of the anti-cytokine biologicals Etanercept, Infliximab, Adalimumab, and Anakinra has stimulated the search for anti-cytokine small-molecules. A number of molecular targets have been identified for the development of such small molecular anti-cytokine agents. The focus of this review will be on those inhibitors of cytokine production, which target either p38 mitogen activated protein (MAP) kinase, TNF-alpha converting enzyme (TACE), or IL-1beta converting enzyme (ICE). P38 MAP kinase occupies a central role in the signaling network responsible for the upregulation of proinflammatory cytokines like interleukin 1beta (IL-1beta) and TNF-alpha, and regulates their biosynthesis at both the transcriptional and translational level. TACE and ICE are two proteases required for the processing of proTNF-alpha and proIL-1beta, respectively into their mature, proinflammatory form. Since the mid-1990s, a plethora of inhibitors of p38 MAP kinase, TACE, and ICE has been characterized in vitro, and individual representatives from all three inhibitor classes have in the meantime been advanced into clinical trials. This review will highlight the correlation between effective inhibition at the molecular target and cellular activity in functional assays of cytokine, particularly TNF-alpha and IL-1beta, production. Structure-activity relationships (SAR) will be discussed regarding activity at the respective enzyme target, but also with regard to properties required for efficient in vitro and in vivo cellular activity (e.g., oral availability, solubility, cell penetration, etc.).