Synthesis and properties of 2-mono- and 2,3-disubstituted thiochromones

Data on the methods of synthesis, chemical reactivity and biological activity of 2-mono- and 2,3-disubstituted thiochromones are integrated and described systematically. Particular sections of the review address 2-arylthiochromones (thioflavones), 2-alkyl- and 2,3-dialkyl-substituted thiochromones and functionalized thiochromones with electron-donating (amino, hydroxy or mercapto group) or electron-withdrawing (cyano, nitro, formyl or carboxyl group or halogen atom) groups in positions 2 and/or 3. Analysis of published data indicates that chemical transformations of thiochromones, including functional derivatives, are rarely accompanied by thiopyrone ring opening, which distinguishes these compounds from representatives of the chromone system. Reaction conditions and product yields and data on the biological activities of some compounds of this class are given.
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