The work presented here consists of general introduction, nomenclature, structural type, biosynthesis, extensive examples on biological activities, some of the most important methods of synthesis and reactions of isocoumarins and 3,4-dihydroisocoumarins from the literature. It includes a partial synthesis of naturally occurring thunberginol C, isolated from Hydrangea macrophylla var. thunbergii., which was conveniently synthesized in a quantitative yield with key intermediate 3,5-dimethoxyhomophthalic acid (which itself is synthesized through several steps) by direct condensation with...