Studies on pyran,its analogs,and related compounds

The action of guanidine on esters of chromone-2-carboxylic acids leads to the opening of the pyrone ring and to the formation of hydantoin derivatives — 2-imino-5-(2-hydroxybenzoylmethylene)tetrahydroimidazol-4-ones — in addition to other reaction products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 7, pp. 874–875, July, 1970.