Discovery and optimization of 3-(4-aryl/heteroarylsulfonyl)piperazin-1-yl)-6-(piperidin-1-yl)pyridazines as novel, CNS penetrant pan-muscarinic antagonists

Discovery of VU6028418: A Highly Selective and Orally Bioavailable M4 Muscarinic Acetylcholine Receptor Antagonist

Herein, we report the SAR leading to the discovery of VU6028418, a potent M4 mAChR antagonist with high subtype-selectivity and attractive DMPK properties in vitro and in vivo across multiple species. VU6028418 was subsequently evaluated as a preclinical candidate for the treatment of dystonia and other movement disorders. During the characterization of VU6028418, a novel use of deuterium incorporation as a means to modulate CYP inhibition was also discovered.

Synthesis of Substituted 6,7-Dihydro-5H-pyrrolo[2,3-c]pyridazines/pyrazines via Catalyst-Free Tandem Hydroamination-Aromatic Substitution

Herein, we report an efficient and operationally simple synthesis of 6,7-dihydro-5H-pyrrolo[2,3-c]pyridazines and 6,7-dihydro-5H-pyrrolo[2,3-b]pyrazines via a tandem hydroamination-S_NAr sequence that makes use of mild reagents under catalyst-free conditions in moderate to high yields. This chemistry expands the known scope of pyridazine/pyrazine chemistry and can be applied toward the synthesis of novel drug-like molecules with favorable bioactivity and pharmacokinetic properties.

Pyridazino[1,6-b]quinazolinones as new anticancer scaffold: Synthesis, DNA intercalation, topoisomerase I inhibition and antitumor evaluation in vitro and in vivo

A new anticancer N-containing heterocyclic scaffold was designed and 30 pyridazino[1,6-b]quinazolinone derivatives were synthesized and characterized. Antiproliferation evaluation in vitro against four human cancer cell lines including SK-OV-3(ovarian cell), CNE-2(nasopharyngeal cell), MGC-803(gastric cell) and NCI-H460(lung cell) indicated that most of them exhibited potent anticancer activity and the IC₅₀ value of the most potent compound lowered to sub-μM. DNA interaction assay indicated that compounds 4e, 4g, 6o, 6p, 8o can intercalate into DNA. Compounds 6 and 8 also demonstrated potent topoisomerase I (topo I) activity. Annexin V- FITC/propidium iodide dual staining assay and cell cycle analysis indicated that 2-(4-bromophenyl)-4-((3-(diethylamino)propyl)amino) -10H-pyridazino [1,6-b]quinazolin- 10-one (8p) could induce arrest cell cycle at G2 phase and apoptosis in MGC-803 cells in a dose-dependent manner. The in vivo antitumor efficiency of compound 8p was also evaluated on MGC-803 xenograft nude mice, and the relative tumor growth inhibition was up to 55.9% at a dose of 20 mg/kg per two days. The results suggested that pyridazino[1,6-b]-quinazolinones might serve as a promising novel scaffold for the development of new antitumor agents.

The Muscarinic Acetylcholine Receptor M5: Therapeutic Implications and Allosteric Modulation

The muscarinic acetylcholine receptor (mAChR) subtype 5 (M₅) was the most recent mAChR to be cloned and has since emerged as a potential therapeutic target for a number of indications. Early studies with knockout animals have provided clues to the receptor's role in physiological processes related to Alzheimer's disease, schizophrenia, and addiction, and until recently, useful subtype-selective tools to further probe the pharmacology of M₅ have remained elusive. Small-molecule allosteric modulators have since gained traction as a means by which to selectively examine muscarinic pharmacology. This review highlights the discovery and optimization of M₅ positive allosteric modulators (PAMs) and negative allosteric modulators (NAMs).

Preparation of Unsymmetrical 1,2,4,5-Tetrazines via a Mild Suzuki Cross-Coupling Reaction

N-Alkyl substituted chlorotetrazines were coupled with various boronic acids under Suzuki conditions in high yield at room temperature, giving a mild and straightforward synthetic route toward diverse unsymmetrical 1,2,4,5-tetrazines, a rare heteroarene. This chemistry not only expands the known substrate scope of tetrazine cross-coupling reactions but also allows for the synthesis of novel, tetrazine-containing biologically active molecules with improved DMPK properties.