ABSTRACT. Synthesis of [3,4-b] [1,3,4]thiadiazines from the condensation of 4-amino-6-methyl-3-thioxo-1,2,4-triazine-5(2H)-one (AMTTO) or 4-amino-1,4-dihydro-5-methyle-1,2,4-triazole-5-thione (AMTT) with phenacyl bromide in the presence of a catalytic amount of various heteropolyacids (HPAs) under refluxing conditions is reported.

Polyethylene glycol‐(N‐methylimidazolium) hydroxide‐grafted hydroxyapatite encapsulated γ‐Fe2O3 nanoparticles, γ‐Fe2O3@HAp@PEG(mim)OH, were prepared and characterized by FTIR, SEM, TEM, TGA, and EDAX. This nanocomposite was applied as a novel, green, nanomagnetic, and recyclable basic phase‐transfer catalyst for the synthesis of tetrahydrobenzopyrans in high yields via the three‐component reaction of aromatic aldehydes, malononitrile, and dimedone or 1,3‐cyclohexanedione in aqueous media at ambient temperature.

The title compound, C15H13ClN6, contains two pyrimidine rings and one benzene ring, where the dihedral angle between the planes through the pyrimidine rings is 81.57 (10)°, and those between the pyrimidine rings and the benzene ring are 84.02 (8) and 89.46 (7)°, indicating that the three rings are almost perpendicular. In the crystal, inter­molecular N—H⋯N hydrogen bonds link the mol­ecules into infinite chains along (100).

In the present study, a new magnetically recyclable nanocatalyst, Fe3O4@SiO2@(CH2)3-en-SO3H/H2SO4, was prepared through the immobilization of sulfonated ethylenediamine on the silica-coated magnetite nanoparticles. The catalyst was fully characterized by several physicochemical techniques, including FT-IR, FESEM, TEM, EDS, VSM, XRD and TGA. The resultant nanocatalyst was then utilized in the green synthesis of 2,3-dihydroquinazolin-4(1H)-ones via the cyclocondensation reaction of various aldehydes and ketones with anthranilamide in refluxed EtOH. Short reaction times, high product yields, environmentally friendly reaction conditions, simple operation and reusability of the catalyst are important features of the present procedure. The catalyst can magnetically be recycled and reused several times without notable loss in activity.

In the title compound, C14H13N7, inter­molecular N—H⋯N and C—H⋯N hydrogen bonds link the mol­ecules into infinite one-dimensional chains along (100). A C—H⋯π inter­action also occurs in the crystal.