Phthalazine

Abstract: The synthesis of nitrogen-containing heterocycles from alkyl dihalides (ditosylates) and primary amines and hydrazines via a simple and efficient cyclocondensation in an alkaline aqueous medium that occurs under microwave irradiation is described. This improved greener synthetic methodology provides a simple and straightforward one-pot approach to the synthesis of a variety of heterocycles, such as substituted azetidines, pyrrolidines, piperidines, azepanes, N-substituted 2,3-dihydro-1H-isoindoles, 4,5-dihydropyrazoles, pyrazolidines, and 1,2-dihydrophthalazines.

Abstract: The direct visible light-mediated C–H alkylation of heteroarenes using aliphatic carboxylic acids is reported. This mild method proceeds at low catalyst loadings (0.5 mol %) and has a high functional group tolerance and a broad substrate scope. Notably, functionalization of (iso)quinoline, pyridine, phthalazine, benzothiazole, and other heterocyclic derivatives with both cyclic and acyclic primary, secondary, and tertiary carboxylic acids as well as amino and fatty acids proceeded under the standard conditions at room temperature. This protocol enables the rapid conversion of abundant feedstock materials into medically relevant “drug-like” moieties.

Abstract: Silica sulfuric acid as an efficient and reusable heterogeneous catalyst have been used for the preparation of 2H-indazolo[2,1-b]phthalazine-1,6,11(13H)-trione derivatives from the three-component condensation reaction of phthalhydrazide, dimedone, and aromatic aldehydes under solvent-free conditions in good to excellent yields and short reaction times.