Synthesis and biological activity of novel 3-heteroaryl-2H-pyrido[4,3-e][1,2,4]thiadiazine and 3-heteroaryl-2H-benzo[e][1,2,4]thiadiazine 1,1-dioxides

One-pot Tandem Synthesis and Spontaneous Product Separation of N-heterocycles based on Bifunctional Small-molecule Photocatalyst

Homogeneous and heterogeneous reactions wherein the resulting products remain dissolved in solvents generally require complicated separation and purification process, despite the advantage of heterogeneous systems allowing retrieval of catalysts. Herein, we have developed an efficient approach for the one-pot tandem synthesis of quinazolines, quinazolinones and benzothiadiazine 1,1-dioxides from alcohols and amines utilizing a bifunctional bipyridinium photocatalyst with redox and Lewis acid sites using air as an oxidant. Through solvent-modulation strategy, the photocatalytic system exhibits high performance and enables most products to separate spontaneously. Consequently, the homogeneous catalyst can be reused by direct centrifugation isolation of the products. Notably, the method is also applicable to the less active substrates, such as heterocyclic alcohols and aliphatic alcohols, and thus provides an efficient and environmentally friendly photocatalytic route with spontaneous separation of N-heterocycles to reduce production costs and meet the needs of atomic economy and green chemistry.

Synthesis of Novel Pyrido[4,3-e][1,2,4]triazino[3,2-c][1,2,4]thiadiazine 6,6-dioxide Derivatives with Potential Anticancer Activity

A series of novel 3-/2,3-substituted pyrido[4,3-e][1,2,4]triazino[3,2-c][1,2,4]thiadiazine 6,6-dioxides 4-28 have been synthesized by the reaction of 3-amino-2-(4-thioxo-1,4-dihydropyridin-3-yl-sulfonyl)guanidine with either 2-oxoalkanoic acids and its esters, or phenylglyoxylic hydrates in glacial acetic acid. Some of them exhibited reasonable or moderate anticancer activity toward human cancer cell lines, HCT-116, MCF-7 and HeLa. The structure of this novel heterocyclic ring system was confirmed by ¹D-NMR and ²D-NMR spectroscopic data including COSY, ROESY and HMBC, elemental analyses and MS spectrometry.

6-Chloro-N-(pyridin-4-ylmeth-yl)pyridine-3-sulfonamide

In the title sulfonamide derivative, C11H10ClN3O2S, the dihedral angle between the pyridine rings is 46.85 (12)°. The N atom of the chloro-pyridine ring is anti to the N-H bond. In the crystal, mol-ecules are linked through N-H⋯N hydrogen bonds into zigzag chains parallel to [001] with a C(7) graph-set motif.