Our group is interested in developing new synthetic methodologies to enable synthesis of biologically active natural compounds and their derivatives in environmental friendly manner. As such manners, we have developed metal-free regioselective cycloaddition of highly reactive o-quinone to form 1,4-benzodioxane and a procedure for construction of benzene ring from o-quinone and terminal alkynes through cycloaddition and photo-decarboxylation. We have also reported concise synthetic route to KDO, a kind of carbohydrate, including elimination of cyclic sulfite as a key step. By collaborative research with a company, functional monomers for dental adhesive resin cements have been developed.